TNT2012 Abstract Book by Phantoms Foundation

Your Journey to the Nanoscale Begins Here For over 60 years, FEI has been a global leader in focused electron and ion beam microscopy technologies. From the most powerful, commercially-available microscope, the Titan™ G2 60-300 S/TEM, to the Magellan™, the ﬁrst extreme high resolution (XHR) SEM, FEI produces innovative imaging solutions for the material science, life science, electronics and natural resource markets, revolutionizing your exploration and discovery at the nanoscale.

TNT2012 index

Foreword

Committees

Poster awards

Sponsors

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TNT 2012 madrid (spain)

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Exhibitors

TNT2012

Nanotec Electronica is one of the leading companies in the Nanotechnology Industry. In only ten years Nanotec Electronica has established itself as one of the strongest companies that design, manufacture and supply Scanning Probe Microscopes (SPM). Our highly qualified team uses cutting-edge technology in order to provide a cost-effective tool to gain access to the nanometer scale for both scientific and industrial communities. With its headquarters based in Spain and distributors located around the world, Nanotec ensures global presence and guarantees total customer satisfaction. Nanotec´s Cervantes FullMode Atomic Force Microscope (AFM) in its several configurations allows not only imaging samples with atomic precision but also the study of magnetic, electronic and mechanical properties at the nanoscale, making it a powerful tool for physicists, chemists, biologists and engineers willing to characterize their samples at the nanometer scale. Its robust design provides strong mechanical stability to ensure high imaging resolution, and its semi-automated and open design allows scientists to exploit the capability of SPM to its maximum for both research and academic purposes. Nanotec Electronica also provides Dulcinea Control Systems, with an open and modular design that facilitates interfacing with any other standard AFM/SNOM/STM system available in the market. Highly versatile, it allows different modes of operation from Contact Mode to Frequency Modulation Mode and lithography ensuring a reliable and accurate performance of all SPM systems. Nanotec has also developed and freely distributes SPM software WSxM. Its user-friendly interface ensures easy operation of SPM microscopes and data processing. WSxM is available for its free download at www.nanotec.es. If you have any questions, or want any information about Nanotec Electronica, please contact us at: Nanotec Electronica Centro Empresarial Euronova 3 Ronda de Poniente 12, 2º C 28760 Tres Cantos (Madrid) SPAIN Tel: +34-918043347 www.nanotec.es

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Nanotec Red with offices in Spain, Argentina, Brazil, and the USA is dedicated to the transfer of Nanotechnology solutions to the retail sector, industrial companies, big and SME companies, and government entities in Spanish speaking countries. Our team of experts is in constant contact with companies and government entities interested in embracing advanced technology to achieve their objectives and they rely on Nanotec Red to find the best solutions. Talk to Nanotec Red if you want representation in these countries representing over 500MM people and thousands of companies that will adopt Nanotechnology over the coming 10 years. Rely on us, this is a great opportunity, don't let it pass. Nanotec Red Via Augusta 252 , planta 4, puerta A 08017 Barcelona España Tel: (+34) 902 009 469 Email: info@nanotecred.com Web: www.nanotecred.com

Raith manufactures high performance electron and ion beam lithography tools for nanotechnology applications in research and development. Raith tools are designed to meet the needs of researchers, designers, and engineers in both university and industry settings. Raith nanolithography products range from stand alone electron or ion beam lithography and nanoengineering tools (RAITH150TWO, e_LiNEplus, PIONEER, ionLiNE) to retroﬁt lithography attachments for SEM or SEM/FIB systems (ELPHY MultiBeam, ELPHY Plus, ELPHY Quantum). Raith electron beam lithography tools are in use throughout the world. Customers such as ST Microelectronics, The Massachusetts Institute of Technology in Boston or the IBM Research Centre are among the Raith clientele. The Raith ELPHY pattern generator family has become a standard for SEM and FIB based nanolithography during past 30 years. Raith GmbH Exhibit Contact: Andreas REMSCHEID Konrad-Adenauer-Allee 8 - PHOENIX West 44263 Dortmund- Germany Phone: +49 (0)231 / 95004 - 0 Fax: +49 (0)231 / 95004 - 460 E-mail: sales@raith.com / remscheid@raith.de Web: www.raith.com

TNT 2012 madrid (spain)

Exhibitors Our main area of activity is focused on biomedical, pharmaceutical and biotechnology companies, cosmetic, veterinary and agro-food market and research groups interested in the use of nanostructures with potential biotechnological applications. nanoimmunotech main objective is to become a world leader in Functionalization and Characterization of nanometric systems, offering products and services within the Biotechnology and Health sectors. The company has highly qualified and internationally recognized human resources, state-of-the-art laboratory capabilities, standardized protocols and finally, the know how to perform proper supervision, advice and validation of different nanosystems, as a first step to the previous use of nanoparticles in biotechnological applications.

nanoimmunotech AnaĂŻs Normand Marketing Department Edificio Cero Emisiones Avenida de la AutonomĂa 7 50003 Zaragoza, Spain Mobile: (+34) 610 182 755 Phone: (+34) 876 440 071 Fax: (+34) 876 440 200 Email: a.marketing@nanoimmunotech.es Website: www.nanoimmunotech.es

IOP Publishing provides publications through which leading-edge scientific research is distributed worldwide. Since launch we have expanded rapidly to become one of the leading international STM publishers. We have a global reach, with offices in Philadelphia, Washington DC, Mexico City, Munich, Moscow, St. Petersburg, Wroclaw, Beijing and Tokyo as well as Bristol and London in the UK Web: http://publishing.iop.org/

TNT 2012 madrid (spain)

Schaefer Techniques has a long history as a supplier of high performance and reliable scientific instruments. We provide a wide range of products in the fields of vacuum technology, scanning probe microscopy, surface and materials analysis. During the TNT conference, we will present mainly four different products: 1. TT-AFM from AFM Workshop: the TT-AFM is a complete and affordable AFM for nanotechnology researchers, instruments innovators and teachers. Right out of the box, the TT-AFM includes all standard modes such as contact, dynamic, phase and lateral forces. All I/O electronic signals are accessible from rear panel connectors. With an open design, the LabView-based software is ready for custom applications. 2. GBS smartWLI product family, white light interferometers: Two economical microscopes called smartWLI-Basic and smartWLI-Extended as well as an upgrade to existing microscopes called smartWLImicroscope are available. The strength of these instruments is the economical price as well as an extremely fast calculation algorithm which makes them the fastest WLI on the market! smartWLI allows noncontact measurement with nanometer accuracy. 3. RHK Technology: RHK manufactures and supports customized, integrated UHV AFM/STM Systems and Controls used by University and Government Labs worldwide for advanced surface science research. RHK products include the new all-digital, ultra-fast, ultra lownoise R9 Universal SPM Controller; multi-purpose Beetle VT (25-1500 K) AFM/STM; rugged PanScan LT AFM/STM for mK and high-Tesla applications; sophisticated QuadraProbe LT AFM/STM 4-Probe (<6 K) for electrical measurements and transport studies; and specialized Prep/Analysis chambers and instruments. 4. Alemnis: In-situ SEM Indenter. Alemnis is specialized in developing, manufacturing and integrating customized instruments and tools for mechanical characterization and manipulation in all kinds of micro- and nanotechnology applications. The in-situ indenter is a compact test platform for in-situ materials characterization. It has been developed to work inside scanning electron microscopes as well as other types of microscopes. It includes long-range stick-slip piezoelectric actuators to position and test the samples with nanometer resolution. Schaefer Techniques 1, rue du Ruisseau Blanc F-91620 NOZAY Tel : +33(0)1 64 49 63 50 e-mail : info@schaefer-tech.com Web : www.schaefer-tec.com

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TNT2012

nanoimmunotech is the first European company specialized in the functionalization, biological and physico-chemical characterization of nanoparticles.

Exhibitors

TNT2012

Nanotechnology has been our everyday business since long before the term ever existed. Founded in 1984 by Norbert Nold, Omicron started business by introducing the SPECTALEED and the legendary Ultra High Vacuum STM 1 as their first and highly successful products. The STM 1, which still delivers state-of-the-art performance even by today's standards in nearly 200 laboratories worldwide, firmly established Omicron's present position as the world market leader in UHV scanning probe microscopy. Today, our products like, for example, the new NanoESCA or the UHV Gemini Column are right at the forefront of research. We are used to redefining the limits of the technically feasible again and again. More than 500 articles demonstrate this to the full. Many of them were published in leading journals such as Nature, Science, Physical Review Letters or Chemical Review Letters. Omicron NanoTechnology GmbH Limburger Str. 75 65232 Taunusstein Germany Tel: 06128/987-0 / Fax: 06128/987-185 email: info@omicron.de web: www.omicron.de

NanoInnova Technologies SL (www.nanoinnova.com) is a spin-off company of the Universidad Autónoma de Madrid. NanoInnova Technologies designs, develops and commercializes Chemical Vapor Deposition (CVD) instruments for bottom up graphene synthesis and chemically modified graphene. A range of raw materials such as graphene oxide, reduced graphene oxide, Palladium (0) nanoparticles supported in reduced graphene oxide, etc, are part of the Nanoinnova Technologies SL portfolio. Nanoinnova Technologies SL is involved in the development and commercialization of new catalyst for fine chemical transformations such as cross coupling reactions, nanostructured modification of electrodes, new stationary phases in purification and new supports and functionalities of biomolecules.

This ambitious project is presented jointly by the Complutense and the Technical Universities of Madrid, together with other partner institutions located in the Campus such as the CIEMAT, the CSIC and the INIA. Its main purpose is to transform the Campus of Moncloa into an international reference regarding research, education and innovation. The project is structured as a collaborative agreement between the integrating institutions to achieve scientific excellence and internationalization; to guarantee connectivity and integration; to make the Campus a sustainable system that will boost student employment and contribute to innovation and development. Our aim is to create a plural and participatory campus, fuelled by the transforming power of diversity, exchanges and dialogue; an efficient and transparentlygoverned university campus, open to all its members and to all its partner institutions, as well as to the interaction with the social, economic and cultural fabric. The Campus commits itself to a specialization into six thematic clusters to achieve scientific and teaching excellence: • Global Change and New Energies • Materials for the Future • Agriculture, Food Industry and Health • Innovative Medicine • Heritage • Sustainable mobility The distinctive strengths in each of them converge to create unique configurations marked by their innovative and interdisciplinary character, being not only highly competitive at the European level, but also capable of producing a significant progress in the transfer of knowledge. Campus de Excelencia Internacional: Campus Moncloa CEI Campus Moncloa Office Royal Botanic Gardens Building, Alfonso XIII Ciudad Universitaria 28040 Madrid, Spain www.campusmoncloa.es

Nanoinnova Technologies SL Science Park of Madrid C/Faraday 7 28049-Madrid Tel: +34 918317366 Web: www.nanoinnova.com Email: info@nanoinnova.com

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Exhibitors Irida Iberica S.L. Diligencia 9 28108 Madrid, Spain Tel. +34911130824 Email: info@irida.es Web: www.irida.es

Renishaw is a global company with core skills in measurement, motion control, spectroscopy and precision machining. We develop innovative products that significantly advance our customers' operational performance - from improving manufacturing efficiencies and raising product quality, to maximising research capabilities and improving the efficacy of research procedures. Renishaw manufactures a wide range of optical spectroscopy products, including: Raman microscopes, Raman analyzers for scanning electron microscopes, combined systems for Raman/SPM measurements etc...Recent developments in ultra-fast imaging enables you to produce Raman chemical images far faster than has been possible before. Raman images that used to take hours to produce can now be created in minutes. This technology is perfectly suited to carbon measurements for Nanotechnology (Graphene, Carbon Nanotubes etc...)

The TechnoFusión project, currently in a preparatory study phase, involves the construction of a Singular Scientific-Technical Facility (National Centre for Fusion Technologies - TechnoFusión) in the Region of Madrid, Spain, creating the required infrastructure for the development of the technologies required for future commercial fusion reactors, and assuring participation by Spanish research groups and companies. The performance of materials and components under the extreme conditions of a fusion reactor is largely unknown. For this purpose, facilities are required for the manufacture, testing and analysis of critical materials. Additional resources will be needed to develop and exploit numerical codes for the simulation of materials in special environments, to develop remote handling technologies and other areas related to the management of liquid metals used in several components of the reactor. TechnoFusión Scientific-Technical Facility will consist of a complex of seven large research areas related to fusion technologies: material production and processing, material irradiation, plasma-wall interaction studies, liquid metal technologies, material characterization techniques, remote handling technologies and computer simulation. Many of these technological areas will be unique in the world. The goal of TechnoFusión is to bring together sufficient human and material resources to contribute significantly to the development of a safe, clean, and inexhaustible source of energy for future generations. Web: www.technofusion.es

Renishaw Ibérica, S.A.U. Gavà Park C. Imaginació, 3 08850 GAVÀ Barcelona Email: Sebastien.Maussang@Renishaw.com Web: www.renishaw.es

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TNT2012

Irida Iberica is one of the youngest but most dynamic nanotechnology instruments providers in Spain. We introduce novel techniques and the best technological solutions for most of the nanotechnology applications challenges. Irida offers a unique value to price combination for a wide variety of surface analysis products like Optical Profilers or Atomic Force Microscopes, as well as the most versatile configurations for material science and biological samples analysis. Our products, manufactured by world leading companies, are some of the most sophisticated instruments in the market because of their cutting edge technology. But it is our service department that makes the difference because is what gives our clients the security of a nonstop research or production work.

Exhibitors

TNT2012

UAM (Universidad Autónoma de Madrid, with 2500 teaching staff and 34000 students) and CSIC (Spanish National Research Council, that has in UAM's campus four institutes and five mixed UAM+CSIC institutes, with a research staff of more than 2000) joined forces to host a large number of top scientists from both institutions that carry out highly competitive research in several areas. The aggregation of the UAM and CSIC in the International Campus of Excellence (CEI), along with other research and transfer centres, companies, business organisations, local authorities and Madrid regional authorities, will give significant impetus to improve the Campus teaching, research and knowledge transfer capacities.

The Spanish Institute for Foreign Trade (ICEX) ("Instituto Español de Comercio Exterior") is the Spanish Government agency serving Spanish companies to promote their exports and facilitate their international expansion, assisted by the network of Spanish Embassy’s Economic and Commercial Offices and, within Spain, by the Regional and Territorial Offices. It is part of the Spanish Ministry of Economy and Competitiveness (“Ministerio de Economía y Competitividad”). España, Technology for life: www.spainbusiness.com Web: www.icex.es

The project’s main goals are two: to increase the international relevance of this particular Campus of Excellence, seeking that the CEI UAM+CSIC be the leading Spanish campus by 2015 and among the 100 top universities in the world and top 50 in Europe and to integrate it very closely with its surroundings, in order to lead the social, cultural and economic development of Madrid North. Web: http://campusexcelencia.uam-csic.es

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TNT 2012 madrid (spain)

Index alphabetical order

TNT2012 Speakers

page Pablo Alonso González (CIC nanoGUNE Consolider, Spain)

Oral Senior

"Optical nano-imaging of gate-tuneable graphene plasmons"

Plenary Session

Masakazu Aono (MANA / NIMS, Japan)

Keynote

"Synaptic characteristics of the atomic switch"

Plenary Session

Takao Aoyagi (MANA / NIMS, Japan)

Keynote

"Molecular design of Smart Biomaterials for Nano Life"

Plenary Session

Carlos Arroyo Rodríguez (Delft University of Technology , Netherlands)

Oral Senior

"Quantum interference effects on charge transport through a single benzene ring"

Plenary Session

Joël Azevedo (CEA Saclay / SPEC, France) "Graphene and carbon nanotubes film organization with a new solution-based method: a substrate independent transfer for transparent electrode applications”

Myriam Barrejón (Universidad de Castilla-La Mancha, Spain)

Parallel Session

Tiziana Bond (Lawrence Livermore National Lab, USA)

Keynote

"Plasmonic to enhance sense and sensitivity at the nanoscale"

Plenary Session

Paolo Bondavalli (Thales Research and Technology, France) "Electrodes based on mixture of Graphene/Graphite/Carbon nanotubes obtained by a new dynamic spray-gun technique for supercapacitor related applications"

Eduardo M. Bringa (Universidad Nacional de Cuyo, Argentina)

Plenary Session

Keynote Plenary Session

Andreu Cabot (IREC, Spain)

Oral Senior

"I2–II–IV–VI4 Nanocrystals: Synthesis and Thermoelectric Properties"

Plenary Session

Keynote

"Nanotechnology for high frequency communications: nitrides and graphene"

Plenary Session

Mercedes Carrascosa (Universidad Autónoma de Madrid, Spain)

Oral Senior

"Applications of photovoltaic fields of iron doped LiNbO3 in nanotechnology"

Parallel Session

Jean-Christophe Charlier (Université Catholique de Louvain, Belgium) "Electronic properties and quantum transport in doped and defective graphene"

Eugene Choulkov (DIPC - UPV/EHU, Spain)

Keynote Plenary Session

Keynote

"Electronic Stucture of Topological Insulators"

Plenary Session

Fabiano Corsetti (Asociacion CIC nanoGUNE, Spain)

Oral Senior

"New implementations of the orbital minimization method in the SIESTA code"

Parallel Session

Aron W. Cummings (Sandia National Laboratories, United States) "Enhanced Performance of Carbon Nanotube Field-Effect Transistors Due to Gate-Modulated Electrical Contact Resistance"

Silvano de Franceschi (CEA, France)

34 35 37 38 40 41 42 44 46 48 49

Oral Senior Plenary Session

Keynote

"Silicon-based quantum electronics"

Plenary Session

Carmen Del Hoyo Martínez (University of Salamanca, Spain)

Oral Senior

"Nanoclays as adsorbents of organic contaminants for a sustainable application"

Parallel Session

Francisco Del Pozo (CTB-UPM, Spain)

Oral Senior Parallel Session

Alexandr Dobrovolsky (Linkoping University, Sweden)

Oral Senior

"Optical studies and defect properties of GaP/GaNP core/shell nanowires"

Parallel Session

TNT 2012 madrid (spain)

Oral Senior

"Multiscale simulations of irradiated nanofoams"

Fernando Calle Gómez (ISOM and ETSI Telecomunicación / UPM, Spain)

Oral PhD Parallel Session

Oral PhD

"Synthesis of a new GO-C60 hybrid by “click” chemistry"

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51 53 54 56

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Speakers

page

TNT2012

Maysoun Douas (Inst. Ciencia Materiales de Madrid (ICMM),Spain) "Identification of nanocavities water content"

Oral PhD Parallel Session

Alberto Eljarrat Ascunce (Universitat de Barcelona, Spain)

Oral PhD

"EELS-HAADF spectrum imaging for characterization of (AlGa)N multilayer heterostructures."

Toshiaki Enoki (Tokyo Institute of Technology, Japan)

Parallel Session

Keynote

"Electronic properties of graphene edges"

Plenary Session

Roch Espiau de Lamaestre (CEA-Leti, France)

Keynote

"Integration of plasmonics within a CMOS environment"

Plenary Session

Virginia Estévez (Universidad del Pais Vasco, Spain)

Oral Senior

"Angular dependence of the tunneling magnetoresistance in nanoparticle arrays"

Plenary Session

Maël Dehlinger (CNRS-CINaM, France)

Oral Senior

"Towards sub-100nm resolution chemical mapping by XRF combined to simultaneous topography"

Plenary Session

Michael Fluss (Lawrence Livermore National Laboratory, USA)

Plenary Session

Katerina Foteinopoulou (Institute of Optoelectronics and Microsystems (ISOM) and ETSII, UPM, Spain)

Oral Senior Parallel Session

"Entropy-driven phase transition in dense packings of athermal chain molecules"

Oral PhD

"Molecular Dynamics simulation of liquid metals for nuclear fusion technology"

Parallel Session

Luis S. Froufe-Pérez (Inst. de Estructura de la Materia, CSIC, Spain) "Light emission statistics as a local probe for structural phase switching" Javier García de Abajo (IQFR-CSIC, Spain)

Oral Senior

"Graphene plasmonics"

Plenary Session

Sandra García-Gil (CEMES-CNRS, France)

Oral Senior

"Progress towards a single swap molecule with Ruthenium complexes: DFT study on a gold surface"

Parallel Session

Mari Cruz García Gutiérrez (Instituto de Estructura de la Materia, IEM-CSIC, Spain)

Oral Senior

"Tuning physical properties of polymers by nanoconfinement"

Plenary Session

Keynote

Francisco José García Vidal (UAM, Spain)

Keynote

"Light-matter coupling mediated by surface plasmons"

Plenary Session

David Garoz (Institute of Nuclear Fusion, Spain)

Oral Senior

"Crack mechanical failure in ceramic materials under ion irradiation: case of lithium niobate crystal"

Parallel Session

Philippe Ghosez (Université de Liège, Belgium)

Keynote

“Coupling of lattice modes in oxides superlattices: Wedding of three"

Plenary Session

María José Gómez-Escalonilla (U. Castilla-La Mancha, Spain)

Oral Senior

"Photochemical Evidence of Electronic Interwall Communication in Double-Wall Carbon Nanotubes"

Parallel Session

Raquel Gómez-Medina (Universidad Autónoma de Madrid, Spain) "Negative scattering asymmetry parameter for dipolar particles: Unusual reduction of the transport mean free path and radiation pressure"

Parallel Session

Oral Senior

"Nanostructured tungsten as a first wall material for the future nuclear fusion reactors"

Plenary Session

Keynote

"DNA programmed assembly of molecules"

Plenary Session

Stephan Götzinger (Max Planck Institute for the Science of Light, Germany) "Optical antennas: nanoscience meets quantum optics" Peter Gruetter (McGill University, Canada)

Plenary Session

"What can AFM tell us about organic photovoltaic systems?"

Plenary Session

Francisco Guinea (ICMM-CSIC, Spain) "Interaction effects in graphene heterostructures"

Kelli Hanschmidt (Institute of Physics, University of Tartu, Estonia) "Properties optimisation of titania microfibers by direct drawing"

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61 63 64 65 66 68 70 72 74 75 76 78 79 80 81

Oral Senior

Nuria Gordillo García (Instituto de Fusión Nuclear/ ETSI de Industriales-UPM, Spain) Kurt Gothelf (Aarhus University, Denmark)

Keynote

"Nano-dispersed particles in Fe(Crx) and their performance under dual (He+Fe) and triple (H+He+Fe) ion beam irradiation"

Alberto Fraile García (Institute of Nuclear Fusion, Spain)

Keynote Keynote Keynote Plenary Session

Oral PhD Parallel Session

83 85 86 199 87 88 89

TNT 2012 madrid (spain)

Kikuo Harigaya (Nanosystem Research Institute, AIST, Japan)

Oral Senior

"Theoretical Study of Edge States in BC2N Nanoribbons with Zigzag Edges"

Parallel Session

Anwar Hasmy (Universidad Simón Bolívar, Venezuela)

Keynote

"Nanotechnology in Latin America and the Caribbean: Current Situation and perspective"

Antonio Hernando (Universidad Complutense, Spain)

Plenary Session

Keynote

"Metallic microwires as non-reflective microwave systems"

Plenary Session

Tibor Hianik (Comenius University, Slovakia)

Keynote

"Application of nanostructures in aptamer based biosensors"

Plenary Session

Kevin Inderbitzin (U. Zurich - Physics-Institute, Switzerland)

Oral PhD

"Ultrafast X-Ray Nanowire Single-Photon Detectors and Their Energy-Dependent Response"

Masashi Ishii (National Instit. for Materials Science (NIMS), Japan)

Parallel Session

Plenary Session

José Ignacio Izpura (GMME-CEMDATIC. UPM, Spain)

Oral Senior

"On the origin of RTS noise in nanoFETs "

Parallel Session

Christian Joachim (CEMES/CNRS - GNS, France)

Keynote

"Design of Atom and Single Molecule Boolean Logic gates"

Plenary Session

"Calibrated Nanoscale Capacitance and Dopant Profile Measurements using a novel Nearfield Scanning Microwave Microscope"

W. Joshua Kennedy (NASA Johnson Space Center, United States) "Optical limiting by absorption bleaching in carbon nanotube devices: comparison of field-induced and electrochemically-induced charge injection “

Vladimir Labunov (Belarusian State University of Informatics and Radioelectronics, Belarus) "Novel “Carbon Nanotube/Graphene Layer” Nanostructures Obtained by Injection CVD Method for Electronic Applications "

Uzi Landman (Georgia Tech, USA)

Parallel Session

Cheng-An Lin (Chung Yuan Christian University, Taiwan) "Rapid Conversion from Protein-Caged Nanomaterials to Microbubbles: A Sonochemical Route toward Bimodal Imaging Agents"

Plenary Session

Oral Senior

"Nanopillars as Plasmonic Platform to Enhance Nonlinear Vibrational Sum-Frequency Generation Spectroscopy"

Plenary Session

Keynote

"Nanoscale Metallic and Metal-Ceramic Multilayers for Radiation-Resistant Applications"

Plenary Session

Maria Jesús López Bosque (Parc Cientific de Barcelona/Plataforma de Nanotecnologia, Spain)

Oral Senior Parallel Session

"Hierarchical micro-nano-structures for cell adhesion studies"

Fernando López-Tejeira (Instituto de Estructura de la Materia (IEM-CSIC), Spain)

Oral Senior

"Refractive Index Sensing based on Plasmonic Fano-like Interference"

Parallel Session

Raquel Lucena García (I. de Catálisis y Petroleoquímica-CSIC,Spain) "New Intermediate band sulphide nanoparticles acting in the full visible light range spectra as an active photocatalyst"

Antonio Luque (Universidad Politécnica de Madrid, Spain)

101 103 104 106 107 109 110 111 112 114 115 117

Oral PhD Parallel Session

Keynote

"Quantum Dot Intermediate Band Solar Cells: Issues for an Attractive Concept"

Plenary Session

Maria Ada Malvindi (Italian Institute of Technology, Center for Bio-Molecular Nanotechnologies@Unile, Italy)

Oral Senior Parallel Session

"Silica nanostructures toxicity assessment and their potential for biomedical applications"

José María Riola (Ministry of Defense, Spain)

Oral Senior

"Nanotechnologies for security and defense - Sectors of interest"

Plenary Session

TNT 2012 madrid (spain)

Oral Senior

Dan Lis (University of Namur - FUNDP, Belgium) Fco. Javier Llorca (IMDEA Materiales, Spain)

Oral Senior

Oral PhD

"Fabrication and characterization of nanopores in Si based materials"

Oral Senior

Plenary Session

Yael Liebes (Ben Gurion University of the Negev, Israel)

Oral Senior

Keynote

"Emergent non-scalable behavior in the nanoscale"

Keynote

"Nano-probing of the surface excited by keV photon: What should we detect for high spatial resolution?"

Gerald Kada (Agilent Technologies, Austria)

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Speakers

TNT2012

page

Speakers

TNT2012

page Manuel Marqués (Universidad Autónoma de Madrid, Spain)

Oral Senior

"Plasmonic nanoparticle chain in a light field: a resonant optical sail"

Plenary Session

Richard Martel (Université de Montreal, Canada)

Keynote

"Environmental Effects in Carbon Nanotube and graphene-based Transistors"

Plenary Session

Gema Martínez-Criado (European Synchrotron Radiation Facility, France)

Oral Senior

"Imaging the carrier confinement within a single nanowire"

Parallel Session

Remo Masut (École Polytechnique de Montréal, Canada) "Reciprocal space and transmission electron microscopy study of heterogeneous GaP:MnP magnetic epilayers containing MnP nanoclusters"

Diogo Mata (University of Aveiro, Portugal)

Parallel Session

Sébastien Maussang (Renishaw Ibérica, Spain)

Oral Senior

"Recent advances in fast imaging Raman technology for nano materials characterisation"

Parallel Session

Keynote Plenary Session

Rodolfo Miranda (UAM/IMDEA Nanociencia, Spain)

Keynote

"Evidence for magnetic order in a purely organic 2D layer adsorbed on epitaxial graphene"

Laurens W. Molenkamp (Wurzburg University, Germany)

Plenary Session

Keynote

"Dirac fermions in HgTe quantum wells"

Plenary Session

Juan Ramon Morante (IREC, Spain)

Oral Senior

"Three dimensional electrodes base on core/shell nanowires for photoelectrochemical cells"

Parallel Session

Edgar Muñoz (Instituto de Carboquímica (ICB-CSIC), Spain)

Oral Senior

"Metal-Carbon Nanohybrid Foams: from Laser Chemistry to Nanochemistry"

Parallel Session

Jeffrey B. Neaton (Lawrence Berkeley National Laboratory, USA)

Keynote

"Understanding Electronic Structure and Charge Transport in Single-Molecule Junctions"

Bernat Olivera (University of Alicante, Spain)

Plenary Session

Oral PhD

"Measurement of the capacitance across a tunnel barrier"

Parallel Session

Cornelia G. Palivan (University of Basel, Switzerland)

Oral Senior

"Protein-polymer nanoreactors and processors act as artificial organelles"

Parallel Session

Ovidio Y. Peña Rodríguez (IFN - ETSII Madrid /UPM, Spain) "Plasmonic nanoparticles for the protection of the final optics in inertial confinement fusion facilities: Capabilities and limitations"

Daniel Pérez-Estévez (University of Vigo, Spain) "Functionalizated magnetic nanoparticles for biodetection, imaging and separation of Mytilus galloprovincialis larvae using NIT-zipper® technology”

Parallel Session

Oral Senior Plenary Session

Marcos Pita (Inst. of Catalysis and Petroleumquemistry-CSIC,Spain)

Oral Senior

"Improving the Direct Electron Transfer Efficiency in Laccase Electrodes for Biofuel Cell Cathodic Reactions"

Parallel Session

Julio Plaza (Technological Institute "La Marañosa" (Ministry of Defense), Spain)

Oral Senior

"Strategies and activities in nano"

Plenary Session

Dieter Pohlenz (Omicron NanoTechnology GmbH, Germany)

Oral Senior

"High Precision local electrical Probing: A New Low Temperature 4-Tip STM with Gemini UHV-SEM Navigation"

Parallel Session

Keynote Plenary Session

Juris Purans (University of Latvia, Latvia)

Keynote

"Near field X-ray spectromicroscopies: new tools for nanoscience"

Plenary Session

Akhilesh Rai (University of Coimbra, Portugal)

Oral Senior

"One pot synthesis of potent antimicrobial gold nanoparticles"

Parallel Session

Rebeca Ribeiro (Laboratoire National des ChamO Magnetiques Inteses, France) "Unveiling the Landau Levels Structure of Graphene Nanoribbons"

16 |

september 10-14, 2012

128 130 131 132 133 134 135 137 138 139 141

Oral Senior

"Urchin-inspired zinc oxide as building blocks for nanostructured solar cells"

"S-layer proteins as patterning elements in the life and non-life sciences"

126

Keynote Plenary Session

Laetitia Philippe (EMPA Materials Science & Technology, Switzerland)

Dietmar Pum (BOKU - University of Natural Resources and Life Sciences, Austria)

125

Oral PhD Parallel Session

"Unusual nucleic acid structures for DNA-based nanotechnologies"

200

Oral Senior

"Spatial and temporal control of osteoblastic cells proliferation on electroconductive carbon nanotubebased bone grafts"

Jean-Louis Mergny (INSERM U869 – U.Bordeaux Segalen, France)

124

Oral PhD Parallel Session

142 143 145 147 148 149 150 152

TNT 2012 madrid (spain)

Carlos Rivera (Technological Institute "La Marañosa" (Ministry of Defense), Spain)

Oral Senior

"Graphene potentialities for space and defense applications: focus on mechanical properties"

Plenary Session

Juan Rodríguez (Universidad Nacional de Ingenieria, Peru) "Supported Nanomaterials for Photocatalytic Water disinfection at rural areas: From Lab. Scale to on site experiments"

Miguel Romera (Universidad Politécnica de Madrid, Spain) "Substantial increase of the critical current on a Spin Transfer Nanopillar by adding an Fe/Gd/Fe trilayer"

Volker Rose (Argonne National Laboratory, USA)

Keynote Plenary Session

Parallel Session

Keynote Plenary Session

Gabino Rubio-Bollinger (Universidad Autónoma de Madrid, Spain)

Oral Senior

"Mechanical properties of freely suspended atomically thin dielectric layers of mica"

Plenary Session

Oral PhD

"An Efficient MRI Contrast Agent Based on PEGylated Iron Oxide Nanoparticles"

Carlos Sabater (Universidad de Alicante, Spain)

Parallel Session

Oral PhD

"Creating nanowires with atomic precision"

Parallel Session

Akira Saito (Osaka University, Japan)

Keynote

"Nanoscale elemental analysis and applications using STM combined with brilliant hard X-rays"

Beatriz Salinas (Centro Nacional de Investigaciones Cardiovasculares, Spain)

Plenary Session

Oral PhD

"Biorthogonal chemistry for the functionalization of superparamagnetic nanoparticles: cross olefin metathesis"

Parallel Session

Pablo San José (Instituto de Estructura de la Materia (CSIC), Spain)

Oral Senior

"AC Josephson effect in finite-length nanowire junctions with Majorana modes"

Plenary Session

Cristina Sánchez (CTB-UPM, Spain)

Parallel Session

Rafael Sánchez (ICMM-CSIC, Spain)

Oral Senior

"Maximal entanglement out of transport through double quantum dots"

Parallel Session

Keynote

“TDDFT simulations of the energy loss of moving projectiles in solids and nanostructures"

Marcus Semones (WaveGuide Corp., USA)

Plenary Session

Keynote

“WaveGuide's u-NMR and Magnetic Nanoswitches for Security and Defense Applications"

Paz Sevilla (Universidad Complutense de Madrid, Spain) "Fluorescence and Raman characterization of a transport system formed by the anti tumoral drug emodin, silver nanoparticles and porous silicon”

We-Hyo Soe (IMRE / A*STAR, Singapore)

Plenary Session

David Soriano (Institut Català de Nanotecnologia (ICN), Spain) "Disorder-induced Randomization of Spin Polarization and Interfacially Protected Surface States in Threedimensional Models of Topological Insulators"

Marek Szymonski (Jagiellonian University/NANOSAM, Poland)

Parallel Session

Plenary Session

Philippe Tamarat (LP2N, Université de Bordeaux, Institut d'Optique Graduate School & CNRS, France)

Oral Senior Plenary Session

"Efficient biexciton emission in single CdSe nanocrystals"

Concha Tojo (University of Vigo, Spain)

Oral Senior

"Microemulsions as reaction media for the synthesis of bimetallic nanoparticles"

Parallel Session

Jessica Topple (McGill University, Canada)

Oral Senior

"Small Molecule Organic Photovoltaics at the Nanoscale"

Parallel Session

TNT 2012 madrid (spain)

161 163 165 167 169 170 172 173 175 176 178 179

Keynote Plenary Session

Keynote

"Atomistic Models of Charge Separation and Recombination in Organic Photovoltaics Interfaces"

160

Oral Senior

"Atomically precise construction and electronic properties of dangling-bond nanostructures on hydrogen passivated Ge(001) surface"

Alessandro Troisi (University of Warwick, UK)

159

Oral Senior Keynote

"Manipulation of molecular quantum states in an STM tunneling junction using classical metal atom inputs"

157

Oral PhD

"Thermal and mechanical effects of different excitation modes based on low frequency laser modulation in optical hyperthermia"

Daniel Sánchez Portal (CFM/EHU-CSIC, Spain)

156

Oral Senior

"New Capabilities at the Interface of X-rays and Scanning Tunneling Microscopy"

Amalia Ruíz (ICMM-CSIC, Spain)

154

Plenary Session

september 10-14, 2012

181 182 184 186 188

| 17

Speakers

TNT2012

page

Speakers

page

TNT2012

Joaquin Tutor (ETSI-ICAI Universidad Pontificia Comillas, Spain) "Present and Perspectives on Dissemination and Training in Nanotechnology in IberoAmerica: Red NANODYF â&#x20AC;&#x201C; CYTED"

Takashi Uchihashi (NIMS, Japan)

Oral Senior Plenary Session

Keynote

"Superconductivity at adatom/molecule-induced silicon surfaces and interfaces"

Plenary Session

Yoshio Ukyo (Toyota R&D Labs, Japan)

Keynote

â&#x20AC;&#x153;Microstructural change of li(NiCo)O2 based materials of li ion battery during charge and discharg"

Plenary Session

Helena Varela (Universidad de Alicante, Spain)

Oral Senior

"Monitoring the oxygen content in graphene oxide"

Plenary Session

Hiroshi Yao (University of Hyogo, Japan) "Postsynthetic Asymmetric Transformation of Boronic-Acid-Protected Gold Nanoclusters Studied by Magnetic Circular Dichroism (MCD) and Electronic Circular Dichroism (ECD)"

Plenary Session

Oral Senior

"Laser heating control with polarized light in isolated multi-walled carbon nanotubes"

Plenary Session

september 10-14, 2012

190 192 194

Oral Senior

Mariusz Zdrojek (Warsaw University of Technology, Poland)

18 |

189

195 197

TNT 2012 madrid (spain)

Keynotes

TNT2012 Speakers

page Masakazu Aono (MANA / NIMS, Japan)

"Synaptic characteristics of the atomic switch"

Takao Aoyagi (MANA / NIMS, Japan)

"Molecular design of Smart Biomaterials for Nano Life"

Tiziana Bond (Lawrence Livermore National Lab, USA)

"Plasmonic to enhance sense and sensitivity at the nanoscale"

Eduardo M. Bringa (Universidad Nacional de Cuyo, Argentina)

"Multiscale simulations of irradiated nanofoams"

Fernando Calle Gómez (ISOM and ETSI Telecomunicación / UPM, Spain) "Nanotechnology for high frequency communications: nitrides and graphene"

Jean-Christophe Charlier (Université Catholique de Louvain, Belgium) "Electronic properties and quantum transport in doped and defective graphene"

42 46

Eugene Choulkov (DIPC - UPV/EHU, Spain)

"Electronic Stucture of Topological Insulators"

Silvano de Franceschi (CEA, France)

"Silicon-based quantum electronics"

Toshiaki Enoki (Tokyo Institute of Technology, Japan)

"Electronic properties of graphene edges"

Roch Espiau de Lamaestre (CEA-Leti, France)

"Integration of plasmonics within a CMOS environment"

Michael Fluss (Lawrence Livermore National Laboratory, USA) "Nano-dispersed particles in Fe(Crx) and their performance under dual (He+Fe) and triple (H+He+Fe) ion beam irradiation"

Javier García de Abajo (IQFR-CSIC, Spain)

"Graphene plasmonics"

Francisco José García Vidal (UAM, Spain)

"Light-matter coupling mediated by surface plasmons"

Philippe Ghosez (Université de Liège, Belgium)

“Coupling of lattice modes in oxides superlattices: Wedding of three"

Kurt Gothelf (Aarhus University, Denmark)

"DNA programmed assembly of molecules"

Stephan Götzinger (Max Planck Institute for the Science of Light, Germany) "Optical antennas: nanoscience meets quantum optics" Peter Gruetter (McGill University, Canada) "What can AFM tell us about organic photovoltaic systems?"

Francisco Guinea (ICMM-CSIC, Spain)

199 87 88

"Interaction effects in graphene heterostructures"

Anwar Hasmy (Universidad Simón Bolívar, Venezuela) "Nanotechnology in Latin America and the Caribbean: Current Situation and perspective"

Antonio Hernando (Universidad Complutense, Spain)

93 94

"Metallic microwires as non-reflective microwave systems"

TNT 2012 madrid (spain)

september 10-14, 2012

| 19

Speakers

page

TNT2012

Tibor Hianik (Comenius University, Slovakia)

"Application of nanostructures in aptamer based biosensors"

Masashi Ishii (National Instit. for Materials Science (NIMS), Japan) "Nano-probing of the surface excited by keV photon: What should we detect for high spatial resolution?"

Christian Joachim (CEMES/CNRS - GNS, France)

99 103

"Design of Atom and Single Molecule Boolean Logic gates"

Uzi Landman (Georgia Tech, USA)

109

"Emergent non-scalable behavior in the nanoscale"

Fco. Javier Llorca (IMDEA Materiales, Spain) "Nanoscale Metallic and Metal-Ceramic Multilayers for Radiation-Resistant Applications"

Antonio Luque (Universidad Politécnica de Madrid, Spain)

114 120

"Quantum Dot Intermediate Band Solar Cells: Issues for an Attractive Concept"

Richard Martel (Université de Montreal, Canada)

200

"Environmental Effects in Carbon Nanotube and graphene-based Transistors"

Jean-Louis Mergny (INSERM U869 – U.Bordeaux Segalen, France)

131

"Unusual nucleic acid structures for DNA-based nanotechnologies"

Rodolfo Miranda (UAM/IMDEA Nanociencia, Spain) "Evidence for magnetic order in a purely organic 2D layer adsorbed on epitaxial graphene"

Laurens W. Molenkamp (Wurzburg University, Germany)

132 133

"Dirac fermions in HgTe quantum wells"

Jeffrey B. Neaton (Lawrence Berkeley National Laboratory, USA) "Understanding Electronic Structure and Charge Transport in Single-Molecule Junctions"

137

Ovidio Y. Peña Rodríguez (IFN - ETSII Madrid /UPM, Spain) "Plasmonic nanoparticles for the protection of the final optics in inertial confinement fusion facilities: Capabilities and limitations"

Dietmar Pum (BOKU - University of Natural Resources and Life Sciences, Austria) "S-layer proteins as patterning elements in the life and non-life sciences"

Juris Purans (University of Latvia, Latvia)

141 149 150

"Near field X-ray spectromicroscopies: new tools for nanoscience"

Juan Rodríguez (Universidad Nacional de Ingenieria, Peru) "Supported Nanomaterials for Photocatalytic Water disinfection at rural areas: From Lab. Scale to on site experiments"

Volker Rose (Argonne National Laboratory, USA)

156 159

"New Capabilities at the Interface of X-rays and Scanning Tunneling Microscopy"

Akira Saito (Osaka University, Japan) "Nanoscale elemental analysis and applications using STM combined with brilliant hard X-rays"

Daniel Sánchez Portal (CFM/EHU-CSIC, Spain) “TDDFT simulations of the energy loss of moving projectiles in solids and nanostructures"

Marcus Semones (WaveGuide Corp., USA) “WaveGuide's u-NMR and Magnetic Nanoswitches for Security and Defense Applications"

We-Hyo Soe (IMRE / A*STAR, Singapore) "Manipulation of molecular quantum states in an STM tunneling junction using classical metal atom inputs"

165 173 175 178

Marek Szymonski (Jagiellonian University/NANOSAM, Poland) "Atomically precise construction and electronic properties of dangling-bond nanostructures on hydrogen passivated Ge(001) surface"

Alessandro Troisi (University of Warwick, UK) "Atomistic Models of Charge Separation and Recombination in Organic Photovoltaics Interfaces"

Takashi Uchihashi (NIMS, Japan) Yoshio Ukyo (Toyota R&D Labs, Japan) “Microstructural change of li(NiCo)O2 based materials of li ion battery during charge and discharg"

september 10-14, 2012

188 190

"Superconductivity at adatom/molecule-induced silicon surfaces and interfaces"

20 |

181

192

TNT 2012 madrid (spain)

Orals - senior (plenary session)

TNT2012 Speakers

page Pablo Alonso González (CIC nanoGUNE Consolider, Spain)

"Optical nano-imaging of gate-tuneable graphene plasmons"

Carlos Arroyo Rodríguez (Delft University of Technology , Netherlands) "Quantum interference effects on charge transport through a single benzene ring"

Andreu Cabot (IREC, Spain)

38 41

"I2–II–IV–VI4 Nanocrystals: Synthesis and Thermoelectric Properties"

Aron W. Cummings (Sandia National Laboratories, United States) "Enhanced Performance of Carbon Nanotube Field-Effect Transistors Due to Gate-Modulated Electrical Contact Resistance"

Virginia Estévez (Universidad del Pais Vasco, Spain) "Angular dependence of the tunneling magnetoresistance in nanoparticle arrays"

Maël Dehlinger (CNRS-CINaM, France)

51 64

"Towards sub-100nm resolution chemical mapping by XRF combined to simultaneous topography"

Luis S. Froufe-Pérez (Inst. de Estructura de la Materia, CSIC, Spain) "Light emission statistics as a local probe for structural phase switching" Mari Cruz García Gutiérrez (Instituto de Estructura de la Materia, IEM-CSIC, Spain)

"Tuning physical properties of polymers by nanoconfinement"

Nuria Gordillo García (Instituto de Fusión Nuclear/ ETSI de Industriales-UPM, Spain) "Nanostructured tungsten as a first wall material for the future nuclear fusion reactors"

76 85

Cheng-An Lin (Chung Yuan Christian University, Taiwan) "Rapid Conversion from Protein-Caged Nanomaterials to Microbubbles: A Sonochemical Route toward Bimodal Imaging Agents"

Dan Lis (University of Namur - FUNDP, Belgium) "Nanopillars as Plasmonic Platform to Enhance Nonlinear Vibrational Sum-Frequency Generation Spectroscopy"

José María Riola (Ministry of Defense, Spain)

112 -

"Nanotechnologies for security and defense - Sectors of interest"

Manuel Marqués (Universidad Autónoma de Madrid, Spain)

124

"Plasmonic nanoparticle chain in a light field: a resonant optical sail"

Laetitia Philippe (EMPA Materials Science & Technology, Switzerland) "Urchin-inspired zinc oxide as building blocks for nanostructured solar cells"

Julio Plaza (Technological Institute "La Marañosa" (Ministry of Defense), Spain) "Strategies and activities in nano"

Carlos Rivera (Technological Institute "La Marañosa" (Ministry of Defense), Spain) "Graphene potentialities for space and defense applications: focus on mechanical properties"

Gabino Rubio-Bollinger (Universidad Autónoma de Madrid, Spain) "Mechanical properties of freely suspended atomically thin dielectric layers of mica"

Pablo San José (Instituto de Estructura de la Materia (CSIC), Spain) "AC Josephson effect in finite-length nanowire junctions with Majorana modes"

TNT 2012 madrid (spain)

111

september 10-14, 2012

143 147 154 160 169

| 21

Speakers

page

TNT2012

Philippe Tamarat (LP2N, Université de Bordeaux, Institut d'Optique Graduate School & CNRS, France) "Efficient biexciton emission in single CdSe nanocrystals"

179 182

Joaquin Tutor (ETSI-ICAI Universidad Pontificia Comillas, Spain) "Present and Perspectives on Dissemination and Training in Nanotechnology in IberoAmerica: Red NANODYF – CYTED"

Helena Varela (Universidad de Alicante, Spain)

189 194

"Monitoring the oxygen content in graphene oxide"

Mariusz Zdrojek (Warsaw University of Technology, Poland) "Laser heating control with polarized light in isolated multi-walled carbon nanotubes"

22 |

september 10-14, 2012

195 197

TNT 2012 madrid (spain)

Orals - senior (parallel session)

TNT2012 Speakers

page Mercedes Carrascosa (Universidad Autónoma de Madrid, Spain) "Applications of photovoltaic fields of iron doped LiNbO3 in nanotechnology"

Fabiano Corsetti (Asociacion CIC nanoGUNE, Spain) "New implementations of the orbital minimization method in the SIESTA code"

Carmen Del Hoyo Martínez (University of Salamanca, Spain) "Nanoclays as adsorbents of organic contaminants for a sustainable application"

Francisco Del Pozo (CTB-UPM, Spain)

44 49 54 -

Alexandr Dobrovolsky (Linkoping University, Sweden)

"Optical studies and defect properties of GaP/GaNP core/shell nanowires"

Katerina Foteinopoulou (Institute of Optoelectronics and Microsystems (ISOM) and ETSII, UPM, Spain) "Entropy-driven phase transition in dense packings of athermal chain molecules"

Sandra García-Gil (CEMES-CNRS, France) "Progress towards a single swap molecule with Ruthenium complexes: DFT study on a gold surface"

David Garoz (Institute of Nuclear Fusion, Spain) "Crack mechanical failure in ceramic materials under ion irradiation: case of lithium niobate crystal"

María José Gómez-Escalonilla (U. Castilla-La Mancha, Spain) "Photochemical Evidence of Electronic Interwall Communication in Double-Wall Carbon Nanotubes"

68 75 79 81

Raquel Gómez-Medina (Universidad Autónoma de Madrid, Spain) "Negative scattering asymmetry parameter for dipolar particles: Unusual reduction of the transport mean free path and radiation pressure"

Kikuo Harigaya (Nanosystem Research Institute, AIST, Japan)

83 91

"Theoretical Study of Edge States in BC2N Nanoribbons with Zigzag Edges"

José Ignacio Izpura (GMME-CEMDATIC. UPM, Spain)

101

"On the origin of RTS noise in nanoFETs "

Gerald Kada (Agilent Technologies, Austria) "Calibrated Nanoscale Capacitance and Dopant Profile Measurements using a novel Nearfield Scanning Microwave Microscope"

104

106

Maria Jesús López Bosque (Parc Cientific de Barcelona/Plataforma de Nanotecnologia, Spain) "Hierarchical micro-nano-structures for cell adhesion studies"

Fernando López-Tejeira (Instituto de Estructura de la Materia (IEM-CSIC), Spain) "Refractive Index Sensing based on Plasmonic Fano-like Interference"

Maria Ada Malvindi (Italian Institute of Technology, Center for Bio-Molecular Nanotechnologies@Unile, Italy) "Silica nanostructures toxicity assessment and their potential for biomedical applications"

TNT 2012 madrid (spain)

september 10-14, 2012

107 115 117 122

| 23

Speakers

page

TNT2012

Gema Martínez-Criado (European Synchrotron Radiation Facility, France) "Imaging the carrier confinement within a single nanowire"

125

Remo Masut (École Polytechnique de Montréal, Canada) "Reciprocal space and transmission electron microscopy study of heterogeneous GaP:MnP magnetic epilayers containing MnP nanoclusters"

Sébastien Maussang (Renishaw Ibérica, Spain) "Recent advances in fast imaging Raman technology for nano materials characterisation"

Juan Ramon Morante (IREC, Spain) "Three dimensional electrodes base on core/shell nanowires for photoelectrochemical cells"

Edgar Muñoz (Instituto de Carboquímica (ICB-CSIC), Spain)

126 130 134 135

"Metal-Carbon Nanohybrid Foams: from Laser Chemistry to Nanochemistry"

Cornelia G. Palivan (University of Basel, Switzerland)

139

"Protein-polymer nanoreactors and processors act as artificial organelles"

Marcos Pita (Inst. of Catalysis and Petroleumquemistry-CSIC,Spain) "Improving the Direct Electron Transfer Efficiency in Laccase Electrodes for Biofuel Cell Cathodic Reactions"

Dieter Pohlenz (Omicron NanoTechnology GmbH, Germany) "High Precision local electrical Probing: A New Low Temperature 4-Tip STM with Gemini UHV-SEM Navigation"

Akhilesh Rai (University of Coimbra, Portugal)

142 145 148 -

"One pot synthesis of potent antimicrobial gold nanoparticles"

Miguel Romera (Universidad Politécnica de Madrid, Spain) "Substantial increase of the critical current on a Spin Transfer Nanopillar by adding an Fe/Gd/Fe trilayer"

Rafael Sánchez (ICMM-CSIC, Spain)

157 172

"Maximal entanglement out of transport through double quantum dots"

Concha Tojo (University of Vigo, Spain) "Microemulsions as reaction media for the synthesis of bimetallic nanoparticles"

Jessica Topple (McGill University, Canada) "Small Molecule Organic Photovoltaics at the Nanoscale"

24 |

september 10-14, 2012

176 184 186

TNT 2012 madrid (spain)

Orals - PhD (parallel session)

TNT2012 Speakers

page Joël Azevedo (CEA Saclay / SPEC, France) "Graphene and carbon nanotubes film organization with a new solution-based method: a substrate independent transfer for transparent electrode applications”

Myriam Barrejón (Universidad de Castilla-La Mancha, Spain)

35 37

"Synthesis of a new GO-C60 hybrid by “click” chemistry"

Maysoun Douas (Inst. Ciencia Materiales de Madrid (ICMM),Spain) "Identification of nanocavities water content"

Alberto Eljarrat Ascunce (Universitat de Barcelona, Spain) "EELS-HAADF spectrum imaging for characterization of (AlGa)N multilayer heterostructures."

Alberto Fraile García (Institute of Nuclear Fusion, Spain) "Molecular Dynamics simulation of liquid metals for nuclear fusion technology"

Kelli Hanschmidt (Institute of Physics, University of Tartu, Estonia) "Properties optimisation of titania microfibers by direct drawing"

Kevin Inderbitzin (U. Zurich - Physics-Institute, Switzerland) "Ultrafast X-Ray Nanowire Single-Photon Detectors and Their Energy-Dependent Response"

Yael Liebes (Ben Gurion University of the Negev, Israel)

57 59 70 89 97 110

"Fabrication and characterization of nanopores in Si based materials"

Raquel Lucena García (I. de Catálisis y Petroleoquímica-CSIC,Spain) "New Intermediate band sulphide nanoparticles acting in the full visible light range spectra as an active photocatalyst"

118

Diogo Mata (University of Aveiro, Portugal) "Spatial and temporal control of osteoblastic cells proliferation on electroconductive carbon nanotube-based bone grafts"

Bernat Olivera (University of Alicante, Spain)

128 138

"Measurement of the capacitance across a tunnel barrier"

Rebeca Ribeiro (Laboratoire National des ChamO Magnetiques Inteses, France) "Unveiling the Landau Levels Structure of Graphene Nanoribbons"

Amalia Ruíz (ICMM-CSIC, Spain) "An Efficient MRI Contrast Agent Based on PEGylated Iron Oxide Nanoparticles"

Carlos Sabater (Universidad de Alicante, Spain)

152 161 163

"Creating nanowires with atomic precision"

Beatriz Salinas (Centro Nacional de Investigaciones Cardiovasculares, Spain) "Biorthogonal chemistry for the functionalization of superparamagnetic nanoparticles: cross olefin metathesis"

167

Cristina Sánchez (CTB-UPM, Spain) "Thermal and mechanical effects of different excitation modes based on low frequency laser modulation in optical hyperthermia"

TNT 2012 madrid (spain)

september 10-14, 2012

170

| 25

TNT2012 Abstracts

Optical nano-imaging of gate-tuneable graphene plasmons 1

CICnanoGUNE, 20018, Donostia–SanSebastián, Spain ICFO-Institut de Ciéncies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain 3 IQFR-CSIC, Serrano119, 28006, Madrid, Spain 4 IKERBASQUE, BasqueFoundationforScience, 48011, Bilbao, Spain 2

Centro de Fisica de Materiales (CSIC-UPV/EHU) and Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastián, Spain 6 NeaspecGmbH, 82152, Martinsried, Munich, Germany 7 Graphenea S.A., 20018, Donostia-SanSebastián, Spain 8 CNM-IMB-CSIC–Campus UAB, 08193, Bellaterra, Barcelona, Spain 9 GREMAN, UMR7347, UniversitédeTours/CNRS, France

Graphene holds great promise for ultra-compact and electronically controlled plasmonics [1,2]. Recently, resonant coupling of propagating THz waves to plasmons in micro-ribbons has been demonstrated [3], while IR near-field microscopy has been applied to observe the coupling of graphene plasmons to phonons [4]. In our work [5] we use (similar to ref. [6]) scattering-type scanning near-field optical microscopy (s-SNOM) to visualize propagating and localized infrared plasmon modes in graphene nanostructures in real space (Fig. 1). By spectroscopic imaging we measure the graphene plasmon wavelength λp as a function of excitation wavelength, which confirms the theoretically predicted plasmon dispersion. We observe that the plasmon wavelength λp=λ0/40 is remarkably reduced compared to the illumination wavelength λ0, which can directly be attributed to the twodimensionality and unique conductance properties

P. Alonso-González1, J. Chen5,1, M. Badioli2, S. Thongrattanasiri3, F. Huth1,6, J. Osmond2, M. Spasenović2, A. Centeno7, A. Pesquera7, P. Godignon8, A. Zurutuza7, N. Camara9, J. Garcia de Abajo3, R. Hillenbrand1,4 and F. Koppens2 p.alonso@nanogune.eu

of graphene. Furthermore, we demonstrate tunability of the plasmon wavelength by gating graphene nanoribbons on a SiO2 substrate. The possibility to tune plasmons of extreme subwavelength electronically opens up a new paradigm in optical and opto-electronic telecommunications and information processing.

References [1] A. Vakil, N. Engheta, Science 332, 1291–1294 (2011) [2] F.H.L. Koppens, D.E. Chang, J. Garcia de Abajo, Nano lett. 11, 3370 (2011) [3] L. JU, et al., Nat. Nanotech. 6, 630 (2011) [4] Z. Fei, et al., Nano Lett. 11, 4701 (2011) [5] J. Chen, et al., arXiv:1202.4996 [6] Z. Fei, et al., arXiv:1202.4993

Figure 1. Imaging propagating and localized graphene plasmons by s-SNOM. a) Schematic of the experimental configuration used to launch and detect propagating surface waves in graphene. The near fields generated at the apex of an illuminated metal tip launch plasmons on graphene. Back reflection of the plasmons at the graphene edge yields plasmon interference. b) Near-field amplitude image acquired for a tapered graphene ribbon on top of 6H-SiC, revealing interference of graphene plasmons. The imaging wavelength is λ0=9.7 μm. The tapered ribbon is 12 μm long and up to 1 μm wide.

TNT 2012 madrid (spain)

september 10-14, 2012

| 29

Synaptic characteristics of the atomic switch 1

WPI Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Tsukuba, Japan 2 Low-power Electronics Association and Project (LEAP), Tsukuba, Japan

More than ten years ago, some of the present authors (Aono, Hasegawa and Terabe) and coworkers developed the atomic switch [1, 2]. The atomic switch is generally known as such nanoscale switching devices that make ON/OFF switching by the growth and shrinkage of a conduction path composed of metal atoms (in contrast with other nanoscale switching devices collectively called the resistive switch in which a conduction path is formed by anion [e.g. oxygen ion] vacancies, etc.). Actually, the atomic switch has more interesting functionalities depending on its structure and constituent materials (see Fig. 1). In this paper, after reviewing the general characteristics of the atomic switch briefly, we would like to concentrate on the discussion of the synaptic characteristics of the atomic switch.

Figure 1. Various types of the atomic switch, which have different structures and constituent materials.

The atomic switch was first developed as a nanoscale, two-terminal, nonvolatile switch with a nanoscale vacuum gap between a solid-electrolyte (Ag2S) electrode and a simple-metal counter

30 |

september 10-14, 2012

Masakazu Aono1, Tsuyoshi Hasegawa1, Kazuya Terabe1, Tohru Tsuruoka1, Takeo Ohno1, Alpana Nayak1 and Toshitsugu Sakamoto2

electrode, i.e. a gap-type atomic switch [1, 2]; if necessary, a volatile atomic switch can be made [3]. It has been found later that the vacuum gap can be filled with soft organic molecules [4] and if the molecules are photoconductive, a photosensitive atomic switch can be made, where ON/OFF switching is controlled by photons [4]. The switching mechanism of the gap-type atomic switch has been studied in detail [5-7]. Soon after the development of the gap-type atomic switch, we developed a gapless- type atomic switch without a gap between a solid-electrolyte electrode (Cu2S was used) and a simple-metal counter electrode [8-11]; this gapless-type atomic switch is advantageous for practical application. We have also found that the solid electrolyte in the gaplesstype atomic switch can be a polymer-based electrolyte (e.g. poly-ethylene + AgClO4) [12], suggesting that a flexible two-dimensional atomic switch array can be fabricated. Moreover, it has been found that the electrolyte in the gapless-type atomic switch can be replaced by a metal oxide (e.g. Ta2O5) [13-17]; the metal oxide is not a solid electrolyte but works as an ion transport layer. The switching mechanism of this ion-transport-layer atomic switch has been studied in detail [18-21]. We have succeeded to develop three-terminal atomic switches (transistors) using a solid electrolyte (Cu2S) [22, 23] or an ion-transport layer (Ta2O5) [24, 25]. Interest-ingly, an atomic transistor using Ta2O5 can be operated in either volatile or non-volatile modes by simply controlling applied voltage [24]. Interestingly, we have revealed that the twoterminal gap-type atomic switch exhibits learning ability [26, 27]; namely, the conductivity of the

TNT 2012 madrid (spain)

Remarkable results related to the neuromorhpic circuits constructed by atomic switches are discussed in detail in this paper.

References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19]

K. Terabe et al., Riken Review No. 37 (July, 2001) 7. K. Terabe et al., Nature 433 (2005) 47. T. Hasegawa et al., to be published. T. Hino et al., Small 6 (2010) 1745. A. Nayak et al., J. Phys. Chem. Lett. 1 (2010) 604. A. Nayak et al., Appl. Phys. Lett. 98 (2011) 233501. I. Valov et al., Nature Mater., in press. T. Sakamoto et al., Appl. Phys. Lett. 82 (2003) 3032. S. Kaeriyama et al., IEEE J. Solid-State Circuits 40 (2005) 168. N. Banno et al., IEICE Trans. Electron. E89-C (2006) 1492. N. Banno et al., IEEE Trans. Electron Devices 55 (2008) 3283. S. Wu et al., Adv. Funct. Mater. 21 (2011) 93. T. Sakamoto et al., Appl. Phys. Lett. 91 (2007) 092110. N. Banno et al., Appl. Phys. Lett. 97 (2010) 113507. M. Tada et al., IEEE Trans. Electron Devices 57 (2010) 1987. Y. Tsuji et al., Appl. Phys. Lett. 96 (2010) 023504. N. Banno et al., Jpn. J. Appl. Phys. 50 (2011) 074201. T. Tsuruoka et al., Nanotechnology 21 (2010) 425205. T. Tsuruoka et al., Nanotechnology 22 (2011) 379502.

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[20] T. Tsuruoka et al., Adv. Funct. Mater. 22 (2012) 70. [21] A. Nayak et al., Nanotechnology 22 (2011) 235201. [22] T. Sakamoto et al., IEDM Technical Digest (2005) 475. [23] T. Sakamoto et al., Appl. Phys. Lett. 96 (2010) 252104. [24] T. Hasegawa et al., Appl. Phys. Express 4 (2011) 015204. [25] H. Kawaura et al., Electronics and Communications in Japan 94 (2011) 55. [26] T. Hasegawa et al., Adv. Mater. 22 (2010) 1831. [27] T. Hasegawa et al., Appl. Phys. A 102 (2011) 811. [28] T. Ohno et al., Nature Mater. 10 (2011) 591. [29] T. Ohno et al., Appl. Phys. Lett. 99 (2011) 203108. [30] A. Nayak et al., submitted. [31] R. Yang et al., submitted. [32] A. Stieg et al., Adv. Mater. 24 (2012) 286. [33] R. Waser, M. Aono, Nature Mater. 6 (2007) 833. [34] T. Hasegawa et al., MRS Bulletin 34 (2009) 929. [35] M. Aono, T. Hasegawa, Proc. IEEE 12 (2010) 2228. [36] T. Hino et al., Sci. Technol. Adv. Mater. 12 (2011) 013003. [37] T. Hasegawa et al., Adv. Mater. 24 (2012) 252.

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switch can have inter-mediate values between the OFF and ON conductivities, depending on the history of input signals. More interestingly, the atomic switch show interesting characteristics similar to a synapse in neural network [28-30]; such characteristics are also observed in a certain gapless-type atomic switch [31]. On the basis of these results, we have been developing neuromorphic circuits made of atomic switches [28, 31, 32]. These studies have been partially reviewed in Refs. 33-37.

Molecular design of smart biomaterials for nano life

Takao Aoyagi, Yong-Jin Kim, Yohei Kotsuchibashi and Mitsuhiro Ebara

International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science, 1-1, Namiki, Tsukuba, Ibaraki, 305-0044, Japan

AOYAGI.Takao@nims.go.jp

Recent progress in biological field enables development of new biological drugs for human health. Nanostructured materials also contribute to fabricate new diagnosis or medical devices and so on. That is, interdisciplinary research including biology, materials science and nanotechnology give us new system or materials to open new area more and more. We are interested in developing ‘smart’ biotechnologies using nanostructured stimuli-responsive polymers that respond to small changes in external stimuli with large discontinuous changes in their physical properties. These ‘smart’ biomaterials are designed to act as an “on-off” switch for drug delivery technologies, gene therapy, affinity separations, chromatography, diagnostics etc.

Design of nanostructure of smart polymers and application for smart nanofiber Poly(N-isopropylacrylamide) (abbreviated as PIPAAm) is one of the typical thermo-responsive materials and much attention is attracting in nanobio-field. So far, we newly designed series of functional IPAAm-based functional monomers as shown in Figure 1. Such monomers have the same polymerizable group (acrylamide) and corresponding copolymer shows completely random sequences and as a result, can show very sensitive responses. For example, the copolymers with carboxyl group are useful stimuli-responsive thin hydrogel coating with nano-level thickness (Figure 2). The modified magnetite nano particles were attracted to magnet and speed was accelerated by heating over it transition temperature. Moreover, the particles can response to the external alternating magnetic field based on inductive heating. Hydorphilicity and hydrophobicity of nanoparticles surface can be modulated by on–off of only current switch [1]. Such materials would be applied to diagnosis after conjugation with biomolecules such as antibody using functional groups effectively. Such functional group enables the design of highly functional stimuli-responsive materials. Photo-, pH- and temperature-responsive polymers were designed as shown in Figure 3 [2]. Photo-reactive benzophenone is very effective to C-C bond formation by radical reaction.

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Figure 1. Molecular structures of developed monomers.

Figure 2. Magnetite nanoparticle coated with stimuliresponsive polymers.

Figure 3. Photo, pH and temperature-responsive polymer.

Namely, photo irradiation leads cross-linking reaction in the materials. Then, we prepared here a new type of “smart” nanofibers (NFs) with dynamically and reversibly tunable properties using thermally crosslinkable IPAAm copolymers via electrospinning. PIPAAm is soluble in aqueous milieu below LCST. Cross-linking reaction prevent the nanofibers from solubilization. Actually, the cross-linked NFs web was used for cell capture and release aiming at cell container [3]. First, temperatureresponsive dynamic behavior of the NF web was investigated. When soaked in PBS and heated to 37C, the web underwent drastic shrinking due to a conformational change of the copolymer. As the crosslinked NFs had an LCST of approximately 18C, the web surface size decreased to almost one-third of the original size after this first heating. The temperature was then alternated below and above the LCST and, correspondingly, the web first swelled, and then shrank.

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Figure 4. SEM image of cross-linked nanofiber composed of PIPAAm.

Interestingly, the web did not return to the original size when the temperature was lowered below the LCST. It is plausible that the porosity of the NF web gradually decreased during heating and cooling cycles, thereby reducing the ability of water to hydrate the entire surface area of the web. Next, the cell wrapping, encapsulation, and releasing capability of NF webs were evaluated by incubating cells on the webs. Normal human dermal fibroblasts (NHDFs) were dropped on cross-linked NF webs at 37C. We found that the web immediately started to fold upperward and wrapped the droplet. The releasing capability of cells from the NF webs was evaluated by collecting released medium from the web during the heating process from 4 to 37C. Approximately 70%, 19%, and 6% of cells were released from the web at 1st, 2nd, and 3rd cycle of temperature alternation, respectively. In other words, almost all cells seeded on the web were released after 3 temperature cycles, whereas only negligible amounts of cells were released during the swelling process from 37 to 4C.

Figure 5. Synthesis of double thermo-responsive block copolymer by ATRP.

Figure 6. Nano-assembly by double thermo-responsive block copolymer. HO O O

As seen in Figure 6, in cold condition that is below first LCST, the block copolymer is completely soluble in aqueous milieu. Increasing the solution temperature, between first and second LCST, they form the micellelike associates and are very useful to reserve drug molecules in the core phase. In hot condition that is above second LCST, the outer polymer chains that form shell structure also shrink and eventually they form the aggregates. The unstable structure would improve the drug release form the core phase.

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n HN

O O

b O

Block copolymer design for nano-assembly We designed the double thermo-responsive block copolymer aiming at effective targeting drug delivery. To achieve this purpose, we synthesized the block copolymers applying an atom transfer radical polymerization (abbreviated as ATRP). The block copolymer, Poly(PIAAm-b-poly(IPAAm-co-BMAAm), comprises two segments (blocks), which have two different lower critical solution temperatures (abbreviated as LCST) as shown in Figure 5 [4].

O b

O O

OH OH OH O

NH O

Figure 7. Highly functional nano-assembly for target drug delivery.

References [1] H. Wakamatsu, K. Yamamoto, A. Nakao, T. Aoyagi, J. Mag. Mag. Mater., 302, (2006) 327. [2] D. Matsukuma, K. Yamamoto, T. Aoyagi , Langmuir, 22, (2006) 5911. [3] Y-J Kim, M. Ebara, T. Aoyagi, Angew. Chem., submitted. [4] Y. Kotsuchibashi, M. Ebara, K. Yamamoto, T. Aoyagi, J. Polym. Sci.: Polym. Chem., 48,(2010) 4393. [5] Y. Kotsuchibashi, M Ebara, N. Idota, R. Narain, Takao Aoyagi, Polym. Chem., in press.

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Recently, we developed highly functional nano-assembly as shown in Figure 7 [5]. This system comprises the mixing of three kinds of well-designed block copolymer. These copolymers contain common segment structure with lower specific LCST. Heating above the specific LCST, all copolymer participate and form micelle-like structure. Sugar moieties are pilot to interact to hepatocyte. Actually, we confirmed the affinity in vitro.

Quantum interference effects on charge transport through a single benzene ring 1

Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands 2 Department of Chemical Engineering, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands

Carlos R. Arroyo1, Simge Tarkuc2, Riccardo Frisenda1, Johannes S. Seldenthuis1, Charlotte H.M. Woerde2, Rienk Eelkema2, Ferdinand C. Grozema2 and Herre S. J. van der Zant1 c.arroyorodriguez@tudelft.nl

We explore charge transport through a single benzene ring, which is a prototypical molecular system where quantum interference effects are expected. Using the mechanically controllable break junction technique, we measured the low-bias conductance of molecular junctions where the benzene ring is wired between gold electrodes through thienyl anchoring groups and ethynyl spacers. We show that the conductance for a meta-coupled benzene ring is more than an order of magnitude smaller than that of a para-coupled benzene. The dramatic reduction of the conductance is consistent with destructive quantum interference effects in the meta-coupled benzene. This is supported by non-equilibrium Greenâ&#x20AC;&#x2122;s function calculations that confirm the occurrence of quantum interference in these systems.

Figure 1. (a) Layout of a mechanically controlled break-junction (MCBJ) setup. Two-dimensional trace histograms constructed from 500 consecutive breaking traces taken at ambient conditions and 0.1 V bias for junctions exposed to molecules coupled in (b) para and (c) meta configuration. Calculated transmission of para (blue line) and meta (red line) in the gas phase.

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Graphene and carbon nanotubes film organization with a new solutionbased method: a substrate independent transfer for transparent electrode applications

Joël Azévédo1, S. Campidelli1, Claire CostaCoquelard2, Jean-Jacques Benattar2, Sébastien Sorgues3, Christophe Colbeau-Justin3 and V. Derycke1

joel.azevedo@cea.fr

CEA Saclay, IRAMIS, SPEC (URA CNRS 2464), LEM, 91191 Gif sur Yvette, France CEA Saclay, IRAMIS, SPEC (URA CNRS 2464), MOB, 91191 Gif sur Yvette, France 3 Université Paris-Sud 11, LCP, 91405 Orsay Cedex, France 2

Graphene and carbon nanotubes (CNT) have exceptional properties that make them fascinating objects for both academic and application-oriented studies. In particular, with the combination of their electronic, mechanical and optical properties, they are considered as potential candidates for new generations of transparent electrodes in o-PV cells, touch screens and flexible displays. However, such technologies rely on the capacity to form highquality thin-films with a controlled morphology. In order to address the related issues a low-cost and original method based on the transfer of surfactant-stabilized water films has been developed in our group. This bubble deposition method (BDM) proved very efficient to organize and transfer, under ambient conditions, dense and homogeneous monolayers of nano-objects such as nanowires and nanoparticles, over large areas. The BDM does not require sophisticated transfer processes and is compatible with a large panel of substrates (silicon, glass, polymers…), both hydrophilic or hydrophobic. Recently we proved the usefulness of this approach to self-assemble carbon materials such as singlewall carbon nanotubes (SWNTs)[1] and graphene oxide sheets (GO)[2] into close-packed monolayers. Of particular interest is the compatibility of this technique with: (i) a pre-structuration of the substrate in micro-channels, such structuration leading to the specific increase of the deposition density within the channels (see figure 1)[3]; (ii) TNT 2012 madrid (spain)

homogeneous transfers at the wafer scale using vertical water films in place of bubbles; (iii) a simple layer-by-layer approach, enabling the formation of thickness-adjusted films through multiple depositions. This layer-by-layer approach was extended notably to realize hybrid materials and, as a proof of concept, a stacked structure was formed by alternating SWNTs and GO layers[2].

Figure 1. SEM images of a carbon nanotube film transferred on a lithographically patterned glass substrate.

Our results provide insight into important problems that impeded the development of SWNT and Graphene based devices. Indeed, in contrast with most methods (such a spin coating), BDM leads to the transfer of the full amount of engaged material. It is thus compatible with high added-value materials, such as SWNTs selected by chirality. We also present how this method can be used to aligned carbon nanotubes at various scales using the drainage of the water confined in the double surfactant wall of the bubble[1].

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Despite the variety of existing methods there is still a lack of a simple, efficient and substrateindependent technique enabling the deposition of graphene sheets free of wrinkles. The Langmuir Blodgett approach is highly efficient to selfassemble a monolayer but the roughness of the films deteriorates rapidly when several layers are tentatively stacked. In contrast, we show that this drawback can be almost completely suppressed using our approach with both small (1-10 µm2) and large (10-500 µm2) GO sheets (see figure 2). As well as the precise control of the nano-objects assembly, the efficient chemical reduction of GO into graphene is still a pressing issue that limits the development of GO-based electrodes. We are currently investigating this point and will report our last results combining the BDM with a postdeposition reduction step.

Figure 2. AFM images of a close-packed arrangement of small (left) and large (right) graphene oxide sheets in a dense and homogeneous monolayer film.

optically transparent and yield adequate and uniform electronic properties. They could be used as replacement for ITO in both light emitting devices and photovoltaic ones. Concerning PV, one particularly interesting system is the carbon/silicon heterostructure that was shown to display very high efficiency of light-to-current conversion despite its simplicity. Using the BDM, ultra-thin and uniform films of both SWNTs and GO were deposited on silicon substrates and the mechanism of charge separation at the carbon/silicon interfaces is studied by the non-invasive Time Resolved Microwave Conductivity (TRMC) method.[3] This technique is based on the analysis of the evolution of the microwave absorption of the studied samples containing mobile charges generated by a nanosecond laser excitation. The measured signal is proportional to the conductance change and consequently to the number of charge carrier and to their mobility. It allows studying the evolution of the lifetime of the photo-generated carriers as a function of the heterostructure properties. As an example, the charge carrier lifetime in the case of a modified silicon-nanotube junction (see figure 3) is 100 times longer than for the bare silicon. Such signature of an efficient charge separation at the carbon/silicon interface measured by TRMC is very helpful to understand and optimize nanotube-silicon solar cells.

References [1] Guolei Tang, Xinfeng Zhang, Shihe Yang, Vincent Derycke, Jean-Jacques Benattar, Small, 6 (2010), 1488 [2] J. Azevedo, C. Costa-Coquelard, P. Jegou, T. Yu and J.-J. Benattar, Journal of Physical Chemistry C, 115 (2011), 14678 [3] Claire Costa-Coquelard, Joël Azevedo, Florence Ardiaca and Jean-Jacques Benattar, submitted to Applied Surface Science [4] C. Swiatkowski, A. Sanders, K.-D. Buhre and M. Kunst, Journal of Applied Physics, 78(3) (1995), 1763 Figure 3. Amplitude of the TRMC signal of Si, {SDBSCNT}-Si and CNT-Si surfaces.

The BDM is both versatile and scalable, and is adapted to a wide variety of applications. Of particular interest are conductive films that are

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Synthesis of a new GO-C60 hybrid by “click” chemistry 1

Instituto de Nanociencia, Nanotecnología y Materiales Moleculares (INAMOL), Universidad de Castilla-La Mancha, 45071 Toledo, Spain 2 Instituto de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049, Madrid, Spain 3 Université de Strasbourg,France

Myriam Barrejón1, María Vizuete1, María José Gómez-Escalonilla1, Jose Luis G. Fierro2, Jean François Nierengarten3 and Fernando Langa1 Myriam.Barrejon@uclm.es

Graphene (GS) and graphene oxide (GO) have attracted great interest for its superior physical, chemical, mechanical, and electrical properties that enable a wide range of applications from electronics to nanoelectromechanical systems [1]. Functionalization of these materials can allow to modulate their electronic, optical and electrical properties, and due to the insolubility and the relatively inert surface of the GS and GO, new methods for functionalization are being explored [2]. As precedent, hybrid materials of Carbon Nanotubes (CNTs) and fullerenes have generated intense attention, driven by the possibility of combining some of the outstanding properties of the CNTs with those of fullerenes rising new properties of the hybrid. The presence of fullerenes in the SWCNTs environment could improve the mechanical properties of the SWCNTs and tune the electronic and optical properties of both, the CNT and the fullerene cage, a subject of great interest for optoelectronic applications [3]. "Click” chemistry is a well-known, versatile and clean reaction and it is extremely efficient to connect discrete molecules, polymers or nanoparticles onto the nanotube sidewalls, through the formation of a triazole ring linker.

modified by the Tour procedure, affording the alkyne group followed by click chemistry between the modified GO and an azide fullerene derivative yielding the fullerene-triazole-GO (GO-C60) hybrid. This hybrid material has been fully characterized by using a number of complementary techniques, including Raman, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), high resolution transmission electron microscopy (HRTEM); finally the photophysical properties of the resulting multicomponent system have been investigated in detail.

References [1] M.J. Allen, V. C. Tung and R. B. Kaner, Chem. Rev,110, (2010),132. [2] L. Yan, Y. B. Zheng, F. Zhao, S. Li, X. Gao, B. Xu, P. S. Weiss and Y. Zhao, Chem. Soc. Rev., 41, (2012), 97. [3] (a) M. Vizuete, M. J. Gómez-Escalonilla, J. L. G. Fierro, M. Yudasaka, S. Iijima, M. Vartanian, J. Iehl, J.-F Nierengarten and F. Langa, Chem. Commun., 47, (2011), 12771 (b) M. Vizuete, M. Barrejón, María J. Gómez-Escalonilla and F. Langa, Nanoscale, (2012), DOI: 10.1039/c2nr30376.

In this sense, the preparation of hybrids involving graphene and fullerenes will permit to explore the potentials applications of these materials. Based on this consideration, we present the synthesis and the characterization of a soluble hybrid material, GO-C60 that combines fullerene and graphene oxide (GO) into a single structure. The GO was firstly

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Electrodes based on mixture of Graphene/Graphite/Carbon nanotubes obtained by a new dynamic spray-gun technique for supercapacitor related applications

Paolo Bondavalli and Colin Delfaure paolo.bondavalli@thalesgroup.com

Thales Research and technology, 128 Rt Dpt, Palaiseau, France

The emergency of a new generation of supercapacitors based on new kind of nanomaterials has been pointed out by several important papers recently issued [1-3]. In this context the graphene/graphite and carbon nanotubes present extremely interesting properties. This contribution deals with the fabrication of supercapacitors using an original dynamic air-brush deposition technique [4]. The advantages of this technique are the compatibility with different kind of surfaces, the completely automatic process (Figure 1a and 1b), the uniformity of the material deposited and the versatility. Using this technique we have fabricated graphite/carbon nanotubes based electrodes (Fig.2 and 3) using different percentages of the two materials sprayed on the surface in order to study the influence of the different concentrations [5]. We are able to achieve flexible electrodes using graphite as collectors with capacitances from 20 to 50F/g with energy density of around 5 Wh/kg and power density around 10 kW/kg. Thickness can be modulated from some nms to tenths of Âľms. Our aim is to exploit the mixing of the two nanomaterials in order to enhance the potential electrode surface allowing to the ions to access all the potential surface achieving a sort of hierarchical assembly of the nanomaterials [3]. All the materials are put into solution using a very simple process (Figure 2). This technique can constitute a real breakthrough for the fabrication of new kind of electrodes using fine mixing of nanomaterials to improve supercapacitor performances using an industrially suitable process, moreover compatible with flexible surfaces. Our process is able to impact very quickly product for everyday life and can be

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considered relatively low-cost considering that it can be easily employed in a extremely reproducible way. a)

Figure 1. a) and b) Spray-gun deposition machine

Figure 2. Carbon Nanotubes/Graphite solution

Figure 3. Electrode achieved using spray-gun deposition method

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Abstracts [1] Simon, P. Gogotsi Y, Materials for electrochemical capacitors, Nature Materials, 7, 845-854, 2008. [2] A. Izadi-Najafabadi, T.Yamada,D.N.Futaba, M. Yudasaka, H. Takagi, H. Hatori, Sumio Iijima, and K. Hata, High-Power Supercapacitor Electrodes from Single-Walled Carbon Nanohorn/ Nanotube Composite, , 5, 2, pp 811–819, ACNANO, 2011. [3] Q.Cheng, J.Tang, J.Ma, H.Zhang, N. Shinyaa and L-C.Qin, Graphene and carbon nanotube composite electrodes for supercapacitors with ultra-high energy density, Phys. Chem. Chem. Phys., 13, 17615– 17624, 2011. [4] Nouvelle méthode pour la réalisation de dépôts modulables et reproductibles de nanomatériaux sur des grandes surfaces et potentielles applications, P.Bondavalli, L. Gorintin, P. Legagneux, 2010 Patent FR1004031. [5] Procédée de fabrication d’ un assemblage collecteur-électrode pour cellule de stockage d 'énergie électrique, assemblage collecteur-électrode cellule de stockage d'énergie, P.Bondavalli, P.Legagneux 2011 FR 11 01690.

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References

Multiscale simulations of irradiated nanofoams

E. M. Bringa ebringa@yahoo.com

CONICET & Instituto de Ciencias Bรกsicas, Universidad Nacional de Cuyo, 5500 Mendoza, Argentina

Materials with nanoscale porosity appear in several different scenarios, from radiation damage in nuclear reactors to evolution of astrophysical dust. Nanoscale porosity can affect mechanical properties and evolution of radiation damage, leading to possible tailoring of desirable properties like enhanced ductility and radiation endurance. We use molecular dynamics (MD) and Monte Carlo simulations to analyze the radiation damage and surface modification of nanofoams, i.e. solids with large porosity at the nanoscale. Atomistic simulations can provide valuable insights when experimental techniques can be difficult to use and interpret. We consider two different irradiation regimes: (a) irradiation with ions with keV energies, where nuclear stopping dominates radiation damage, of interest for fusion and fission energy applications; (b) swift heavy ion irradiation, with energies up to few GeV, relevant for track formation and interstellar grain evolution.

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We find that irradiation effects have larger spatial extent than for full-density solids and include the production of point-defects and twins which change the mechanical properties of the samples. For swift ions, porosity does not always decrease surface ejection [J. Rodriguez-Nieva et al., Astrophys. J. Letters 743, L5 (2011)]. We use our MD results as input for a Monte Carlo (MC) code to calculate sputtering yields from nanofoams of different geometries under different irradiation conditions. For keV ions, we find that nanofoams can act as efficient sinks for radiation-induced defects and, therefore, that they can be radiation resistant [E.M. Bringa et al., Nano Letters 12, 3351 (2012)]. We then use our MD results to build models which predict possible radiation endurance under intense irradiation. This work was carried out in collaboration with J. Rodriguez-Nieva, J. Monk, J.A. Caro, M.J. Loeffler, T. Cassidy, R. E. Johnson, R. Baragiola, and D. Farkas.

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I2–II–IV–VI4 Nanocrystals: synthesis and thermoelectric properties Departament Electronica, Universitat de Barcelona, Barcelona, 08028, Spain & Catalonia Institute for Energy Research, IREC, Sant Adria del Besos, Barcelona, 08930, Spain

Today’s main strategy to produce materials with high thermoelectric figures of merit is to trigger phonon scattering at multiple length scales without disturbing the charge carrier transport. The goal is to minimize the lattice thermal conductivity in highly electrically conductive materials; the socalled electron-crystal phonon-glass paradigm. This strategy is implemented by two main approaches: i) the scattering of phonons at the atomic length scale by the synthesis of complex crystal phases that include 1D phonon scattering centers, such as vacancies or rattling atoms, and/or 2D layered crystallographic structures; ii) the scattering of phonons at the 1-100 nm scale by reducing the crystal domain dimensions to the nanoscale. In this scenario, colloidal synthesis routes are particularly well suited for the production of thermoelectric materials. Solution-processing methods have a high potential for the production of low-cost, high-yield, large-scale, high-output and shape-adaptable devices. Moreover, bottom-up approaches allow to directly obtain nanocomposites with reduced crystal domain size and controlled geometry.

Maria Ibáñez, Doris Cadavid, Joan Ramon Morante and Andreu Cabot acabot@irec.cat

We will present a novel colloidal synthetic route to prepare I2–II–IV–VI4 quaternary nanocrystals with controlled size, shape and composition. We put special effort in designing a cost-effective and scalable process susceptible of being implemented in real applications. The synthetic route is applied to the preparation of grams of the quaternary chalcogenide Cu2+xCd1-xSnSe4 (0 ≤ x ≤ 0.5) with accurately controlled composition and narrow size distributions. The electrical and thermoelectric properties of these materials were characterized over a wide temperature range. We will show how these materials have high Seebeck coefficients (150-300 μV/K), electrical conductivities up to 14000 S/m, and thermal conductivities down to 0.3 W/mK, leading to ZT values up to 0.4 at 700 K. Besides, the advantages and disadvantages of this bottom-up approach to produce thermoelectric nanomaterials will be discussed.

At the same time, some quaternary chalcogenides have the required attributes to be potentially excellent thermoelectric materials. Not only the complex structures of these quaternary compounds are associated with intrinsically low thermal conductivities, but also their different cationic valences provide a means of controlling their Fermi level by adjusting their cation ratios. Besides, some I2-II-IV-VI4 materials crystallizing in the stannite phase are characterized by a convenient structure layering, which allows decoupling the electrical conductivity from both the thermal conductivity and the Seebeck coefficient.

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Fernando Calle1 and Tomás A. Palacios2

Nanotechnology for high frequency communications: nitrides and graphene

fernando.calle@upm.es

ISOM and Dept. Ingeniería Electrónica, ETSI Telecomunicación, UPM, Campus de Excelencia Internacional Moncloa. Avda. Complutense 30, 28040 Madrid, Spain 2 Dept. Electrical Engineering and Computer Science, Massachusetts Institute of Technology, 77 Massachusetts Ave., Bldg. 39-567B, Cambridge, MA 02139

The achievement of higher frequencies (HF) and the reduction of energy consumption, to improve sensing, communication and computation, involve the continued scaling down to the nanometer level. This scaling is enabled by of innovative device designs, improved processing technologies and assessment tools, and new material structures. In this work, we have used all these factors to demonstrate state-of-the-art HF devices in two materials with quite different electronic properties: wide semiconductor bandgap III-nitrides for resonators and power amplifiers; and graphene, a zero bandgap material expected to revolutionize low noise and HF flexible electronics. Some issues faced during their development will be discussed during the talk. Surface acoustic wave (SAW) devices are required for radar systems and wireless communications, as well as for high performance sensors. These SAW devices consist of an interdigitated transducer (IDT) on a piezoelectric substrate with a large sound velocity. To enhance their frequency, we exploit the combination of a compact IDT fabricated with ebeam lithography, the highest sound velocity provided by a diamond substrate, and the confined Sezawa modes in a thin AlN piezoelectric layer deposited on top. Both the IDT period and the film thickness are key parameters in the design and fabrication of the devices. The sputtering deposition of the piezoelectric layer on micro and nanocrystalline diamond and the lithography of the transducers are optimized. HF SAW resonators operating in the 10-20 GHz range (Fig. 1), showing up to 40 dB out-of-band rejection and Q factors larger than 10,000 are demonstrated [1]. Pressure sensors have also been developed on free standing AlN/diamond membranes.

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Figure 1. Measured and simulated reflection coefficient (S11) (top) and susceptance (bottom) for λ=800 nm oneport SAW resonators on a 600 nm thick AlN film on diamond. Several resonances corresponding to Sezawa modes are observed.

The huge power density of AlGaN/GaN high electron mobility transistors (HEMTs) has brought during the last decade new possibilities and advantages for the design of wide and multiband amplifiers. High power-gain cutoff frequency (fmax) has been achieved by combining low-damage gaterecess technology, scaled device geometry, and recessed source/drain ohmic contacts to enable minimum short-channel effects (i.e., high output resistance Rds) and very low parasitic resistances [2]. SiC substrates are required to minimize selfheating, as shown in Fig. 2(a). Some challenges for long-term reliability and device scaling, due to the strain induced by the large lattice mismatch between the AlGaN barrier and the GaN buffer, TNT 2012 madrid (spain)

700

Sim: 300 K 400 K 500 K

300 K 400 K 500 K

RTH=56 Kmm/W

600

500

RTH=45 Kmm/W

400

RTH=36 Kmm/W

300 250

(b) SiC substrate

300 K 400 K 500 K

Abstracts

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5 100 100

200 200

(b)

LLg (nm) (nm)

150 100 50 0 0 50 100 150 200 250 Gate Length Lg (nm) Lg = 30-nm

50 lh21l2

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(a) Sapphire substrate

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may be solved using the lattice-matched InAlN/GaN heterostructure. LG=30 nm InAlN/GaN HEMTs on a SiC substrate with a record fT in excess of 300 GHz were obtained by applying an oxygen plasma treatment [3]. The thin oxide layer on the InAlN surface suppressed the gate leakage current, passivated the surface, and significantly improved the RF performance. Further efforts are dedicated to identify the limiting factors and dominant failure mechanisms to improve GaN-based HEMT reliability, in particular heat spreading, by means of diamond layers and other C-based materials such as graphene and nanotubes.

RTH=21 Kmm/W

500

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400

fT = 300 GHz

RTH=11 Kmm/W

300 0

P (W/mm) 250

0 1

Vds = 4 V Vgs = -2.9 V

10 100 300 Frequency (GHz)

Figure 2. Left: Tchannel vs output power for different Tamb in devices grown on sapphire (a) and SiC (b). Right: RF performance of the 30-nm-gate-length InAlN/GaN HEMT with fT = 300 GHz. (From [3]).

Graphene is a carbon, one-atom-thick layer, the thinnest but strongest material in the world. It is a zero bandgap semiconductor with a roomtemperature electron and hole mobility above 100,000 cm2/V.s. A multidisciplinary effort among physicists, chemists, material scientists and device engineers has led to new electronic devices and circuits taking advantage of its unique properties. Some examples include RF multipliers, mixers, modulators and demodulators [4] (see fig. 3). Several technological issues during graphene devices processing (including growth technique, substrates, electrical isolation, contamination and passivation, etc. [5]) will be discussed. TNT 2012 madrid (spain)

Figure 3. Top: First BN/Graphene/BN field effect transistor with LG=400 nm. Bottom: Output power of a HF doubler for an input signal of 8 GHz (a), and gain frequency response (b).

The authors thank their students and colleagues at ISOM-UPM and MIT for their contribution to this work. That at ISOM-UPM has been funded by the Spanish Government projects ReADi (TEC2010-19511), AEGAN (TEC2009-14307) and RUE (CSD-2009-00046).

References [1] J.G. Rodríguez, G.F. Iriarte, J. Pedrós, O.A. Williams, F. Calle, IEEE Electron Dev. Lett. 33 (2012) 495. [2] J. Chung, W. Hoke, E. Chumbes, T. Palacios, IEEE Electron Dev. Lett. 31 (2010) 195. [3] D.S. Lee, X. Gao, S. Guo, D. Kopp, P. Fay, T. Palacios, IEEE Electron Dev. Lett. 32 (2011) 1525. [4] T. Palacios, A. Hsu, H. Wang, IEEE Commun. Mag. 48 (2010) 122. [5] F. Calle, A. Boscá, D. López-Romero, T. Palacios, Graphene Sectorial Meeting, Castelldefels (2011).

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Applications of photovoltaic fields of iron doped LiNbO3 in nanotechnology 1

Dpto. de Física de Materiales, Universidad Autónoma de Madrid, 28049 Madrid, Spain CMAM, Universidad Autónoma de Madrid, 28049 Madrid, Spain 3 Instituto de Ciencias Biomédicas, CSIC, C/ Arturo Duperier 4 28029 Madrid, Spain 4 Dpto. de Biología, Universidad Autónoma de Madrid, 28049 Madrid, Spain

H. Burgos1, M. Jubera, A. García-Cabañes1, Blázquez-Castro1, J. Espada3, J. C. Stockert4, F. Agulló-López1,2 and M. Carrascosa1

As it is well known, the bulk photovoltaic effect (PVE) [1] appears in certain crystalline materials (usually ferroelectrics), that show an asymmetric crystal cell unit arrangement. It produces a directional electronic drift when electrons are excited to the conduction band through visible light illumination. The drift induces a charge separation and generates an electric field between the illuminated edges of crystal. Reported measurements of this electric field reach values as high as 105 V/cm in the material employed in our experiments, i.e. iron doped LiNbO3 [2]. In this communication we will summarize our results in two applications of the PV fields in nanotechnology i) micro/nanoparticle trapping and structuring on the surface of LiNbO3 crystals, and ii) Effects of PV fields of LiNbO3 micro- and nanoparticles in tumour cells.

m.carrascosa@uam.es

have developed a set of experiments with different kind of particles, either dielectric (CO3Ca, polystyrene) or conducting (graphite, aluminium and silver). Holographic patterns as well as single beam illumination have been used. The data are analyzed within a theoretical scheme we have recently proposed [6]. The results allow for a more meaningful assessment of the possible applications of the PV effect for trapping and patterning of nanoparticles. As an illustration, Fig. 1 shows the particle arrangements obtained using dielectric (CO3Ca, diameter ~1 μm) particles (a), and metallic (silver, diameter ~100 nm) particles, (b), under periodic light pattern with spatial periodicity Λ = 20 and 10 μm respectively. In all cases the periodicity of the obtained pattern was the same to that of the exciting light.

As photovoltaic material we have used congruent LiNbO3 with a 0.1% wt Fe doping 19 3 ([Fe] = 4.25×10 cm ). In these crystals, photovoltaic fields in the range 50-70 kV/cm have been measured using optical techniques.

Particle trapping and structuring Recently, a method based on the evanescent fields generated by the bulk photovoltaic effect in iron doped LiNbO3 has been proposed and first experiments reported [3-5]. The main advantage of this procedure for particle trapping is that the involved electrophoretic and/or dielectrophoretic forces do not require any electrodes and massive manipulation of nanoparticles can be achieved using the patterning capabilities of light. Then, we

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Figure 1. Particle pattern obtained on the surface of LiNbO3 plates after sinusoidal illumination with period Λ: (a) CaCO3 particles (Λ=20 μm) (b) silver particles (Λ=10 μm).

Biomedical applications We have recently demonstrated the effect of PV fields on biological media by culturing tumour cells on Fe:LiNbO3 plates. A massive necrotic cell death was induced in human tumour cell cultures after TNT 2012 madrid (spain)

This work was supported by MICIN under grant MAT2008-06794-C03 and MAT2011-28379-C03-01.

References

Figure 2. Time evolution of the number of viable (circles) and necrotic (squares) cells evaluated through morphological criteria for HeLa cell cultures with LNB micro-particles. Representative viable and necrotic cells are shown in the microphotographs at the top of both figures. The gray bars indicate the period of green light exposure.

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[1] B. Sturman and V. M. Fridkin, The Photovoltaic and Photorefractive Effects in Noncentrosymetric Materials, Gordon & Breach Science Publishers, Amsterdam 1992. [2] E. M. de Miguel.,J. Limeres, M. Carrascosa and L.Arizmendi, J. Opt. Soc. Am. B 17, (2000) 1140. [3] X. Zhang, J. Wang, B. Tang, X. Tan, R.A. Rupp, L. Pan, Y. Kong, Q. Sun, J. Xu, Opt. Express 17, (2009) 9981. [4] H.A. Eggert, F.Y. Kuhnert, K. Buse, J.R. Adleman, D. Psaltis, Appl. Phys. Lett. 90, (2007) 241909. [5] M. Esseling, F. Holtmann, M. Woerdemann, C. Denz, Opt. Express 18, (2010) 17404. [6] J. Villarroel, H. Burgos, A. García-Cabañes, M. Carrascosa, A. Blázquez-Castro, F. AgullóLópez; Opt. Express 19, (2011) 24320. [7] A. Blázquez-Castro, J.C. Stockert, B. LópezArias, A. Juarranz, F. Agulló-López, A. GarcíaCabañes, M. Carrascosa, Photochem. Photobiol. Sci. 10, (2011) 956.

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The next step is to reduce particle size to a diameter of tenths of nm to induce their incorporation by cells. Experiments to evaluate the effect of nanoparticles in cells for different light doses are now in progress.

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irradiation with low intensity visible light [7]. In order to explore the potential of PVE for future biomedical applications we are now investigating the effect of LiNbO3:Fe micro-nanoparticles on tumour (HeLa) cell cultures. In a first experiment cells were incubated with microparticles (1-3 μm diameter). Cells did not show any morphology change in dark whereas after 60 min irradiation (546 nm, 133.2 J/cm2 light dose), about half of the cells had a round and refringent aspect, i.e. they show a certain damage. Two hours after ending illumination most cells were necrotic as represented in Figure 2. Control cultures (without microparticles) exposed to 546 nm light for 60 min showed no damage.

Electronic properties and quantum transport in doped and defective graphene

Jean-Christophe Charlier1, Aurelien Lherbier1, Andrés R. Botello-Méndez1 and Stephan Roche2

jeanchristophe.charlier@uclouvain.be

Université catholique de Louvain (UCL), Institute of Condensed Matter and Nanoscience (IMCN), Nanoscopic Physics (NAPS), Chemin des étoiles 8, 1348 Louvain-la-Neuve, Belgium 2 CIN2 (ICN-CSIC) and Universitat Autonoma de Barcelona (UAB), Catalan Institute of Nanotechnology, Campus UAB, 08193 Bellatera (Barcelona), Spain

Graphene, a one atom-thick membrane, has sparked out intense research activities from both experimental and theoretical sides since almost a decade now. The striking properties of graphene in various fields, such as mechanical, thermal, or electronic transport properties, are intrinsically related to its two-dimensional aspect and to its honeycomb lattice structure yielding both to the peculiar electronics of Dirac Fermions. From the electronic transport point of view, clean graphene samples exhibit particularly long coherence length and high electronic mobility both interesting for devices applications in nanoelecronics. Graphene provide simultaneously is genuine playground for fundamental researches such as exploration of Anderson (anti-)localization phenomena in real two-dimensional systems. In this presentation, simulations of electronic transport in defective graphene membranes are exposed. Employing tight-binding models validated by ab initio calculations, and using a real-space order-N Kubo-Greenwood transport method [1-2], the effect of structural defects disrupting the ideal honeycomb lattice is investigated theoretically. The effect of various concentrations of “point defects” such as vacancies and Stone-Wales defects on both the electronic and transport properties of graphene is examined. Using molecular dynamics simulations, highly defective graphene membranes presenting domains of amorphous graphene structure [3] are created, and their transport properties are carefully inspected. Structural defects are found to induce strong resonant scattering states at different energies depending on the nature and the concentration of defects. These induced resonant scattering states can yield to extremely short mean

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free paths and low mobilities. At low temperatures, they also lead to an enhanced contribution of quantum interferences driving to localization phenomena in the quantum transport regime. In case of highly defective graphene membrane, the amorphization of the structure changes the system into a strong two-dimensional Anderson insulator material [3], which could be experimentally confirmed by the observation of a variable range hopping transport behavior at low temperatures. The modification of the electronic properties of sp2 carbon nanostructures by the controlled addition of foreign atoms into the carbon lattice has been widely proposed and investigated, in close analogy to the doping of silicon in the semiconductors industry. However, in contrast with conventional materials, the effect of foreign atoms in nanostructures is expected to depend significantly on the position and surrounding of each atom due to the quantum confinement of the electrons. In principle, the fact that nitrogen atoms contain one additional electron than carbon, suggests that nitrogen doped carbon nanostructures will exhibit the characteristics of an n-type material [4]. Furthermore, recent experiments on graphene reveal through scanning tunneling microscopy (STM) images, that N doping can occur in different kinds of geometries [4]. This presentation explores different configurations for nitrogen atoms incorporated onto graphene, and investigates their effects and properties using ab initio electronic structure calculations. The computed total and local density of states reveal specific signatures for each type of defect, which could be correlated with experimental scanning tunneling spectroscopy (STS) measurements. In addition, STM images are TNT 2012 madrid (spain)

References [1] A. Lherbier, S.M.-M. Dubois, X. Declerck, S. Roche, Y.M. Niquet, and J.-C. Charlier, Phys. Rev. Lett. 106, 046803 (2011). â&#x20AC;¨ [2] A. Lherbier, S.M.-M. Dubois, X. Declerck, Y.M. Niquet, S. Roche, and J.-C. Charlier, Phys. Rev. B 86, 075402 (2012). [3] A. Lherbier, S. Roche, O.A. Restrepo, Y.M. Niquet, A. Delcorte, J.-C. Charlier, submitted for publication (2012). [4] R. Lv, Q. Li, A.R. Botello-MĂŠndez, et al., NATURE Scientific Reports, in press (2012).

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presented in order to aid the eventual large scale identification of these defects. Our calculations, and recent experimental observations suggest that the classically assumed nitrogen incorporations into graphitic structures (i.e., single substitution and pyridinic), are not necessarily the most common [4]. It is generally true, however, that substitution defects (single, double substitution) dopes graphene with electrons, and vacancy-nitrogen complexes (e.g. pyridinic, or single nitrogen + vacancy) add holes to the system.

Electronic stucture of topological insulators a

Departamento de Física de Materiales, Facultad de Ciencias Químicas, UPV/EHU, Apdo. 1072, 20080 San Sebastián, Basque Country, Spain b Donostia International Physics Center (DIPC), Paseo de Manuel Lardizabal, 4, 20018 San Sebastián/Donostia, Basque Country, Spain c Centro de Física de Materiales, CFM-MPC, Centro Mixto CSIC-UPV/EHU, Apdo.1072, 20080 San Sebastián/Donostia, Basque Country, Spain d Tomsk State University, pr. Lenina 36, 634050, Tomsk, Russian Federation e Institute of Strength Physics and Materials Science, pr. Academicheskiy 2/4, 634021, Tomsk, Russian Federation f Max-Planck-Institut für Mikrostrukturphysik Weinberg 2, D-06120, Halle, Germany g Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi Hiroshima 739-8526, Japan h Physik-Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland

The recently discovered three-dimensional topological insulators (TIs) belong to a class of insulators in which the bulk gap is inverted due to the strong spin-orbit interaction [1]. A direct consequence of such bulk band structure arises at the surface: the spin-polarized topologically protected massless metallic states, forming a Dirac cone [2-5]. These surface states (SS) exhibit many interesting properties resulting from the fact that the spin of electron is locked perpendicular to its momentum, thus forming a SS spin structure that protects electrons from backscattering. This makes topological insulators potentially promising materials for creation of new quantum devices.

Evgueni V. Chulkova,b,c, Sergey V. Eremeevb,d,e, Tatiana V. Menshchikovad, Maia Vergnioryb, Yury M.Koroteevb,d,e, Arthur Ernstf, Jürgen Henkf, A. Kimurag and J. Hugo Dilh

References [1] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys. 82, 3045 (2010). [2] K. Kuroda et al., Phys. Rev. Lett., 105, 076802 (2010). [3] S. V. Eremeev, Yu. M. Koroteev, and E. V. Chulkov, JETP Lett. 92, 161 (2010). [4] K. Kuroda et al., Phys. Rev. Lett., 108, 206803 (2012). [5] S.V. Eremeev et al., Nature Communications, 3, 635 (2012).

Here recent theoretical and experimental results on electronic structure obtained for new families of TIs are presented. Comparison of topological surface states with classical and Rashba split surface states as well as Dirac cone state in graphene is given. The origin of buried topological surface states is discussed. Materials science problems and perspectives in the field of TIs are discussed.

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New implementations of the orbital minimization method in the SIESTA code

Fabiano Corsettia and Emilio Artachoa,b f.corsetti@nanogune.eu

CIC nanoGUNE Consolider, E-20018 Donostia-San Sebastiรกn, Spain Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, United Kingdom b

The orbital minimization method (OMM) is the general name given to a class of iterative minimization algorithms devised for solving the generalized eigenvalue problem in the context of linear-scaling DFT [1]. The central idea of the method is to find the Wannier functions of the electronic system that describe the occupied subspace by direct unconstrained minimization of an appropriately constructed functional [2,3]. The method is made to scale linearly with system size by imposing a localization radius on the Wannier functions, which in turn determines the truncation range of the density matrix.

algorithm is therefore both accurate and efficient, due to the fact that no explicit orthogonalization operation is required between orbitals, and that the solution from each minimization can be reused iteratively for multiple self-consistent field steps and ab initio MD steps. We also show that the sparsity pattern of the Hamiltonian matrix in SIESTA can be used in this context to significantly reduce the computational cost; in conclusion, the method has proven to be competitive with explicit diagonalization even in small systems despite the large ratio of occupied states to total basis size that is used in SIESTA and other atomic orbital codes.

Unfortunately, the OMM suffers from a serious problem of multiple local minima, requiring in practice that the initial guess reflect the correct bonding properties of the system. Alternatively, Kim et al. [4] have proposed to work with more orbitals than those needed to span the occupied subspace, leading to a linearly dependent basis. This eliminates the local minima problem, but introduces the electronic chemical potential as an unknown parameter.

Secondly, we discuss a number of approaches for imposing the correct electron number in the augmented OMM of Kim et al. that can be used with Wannier localization for linear-scaling DFT calculations; we report on an automated adjustment of the chemical potential to preserve electron number, a projected gradient method and a normalization transformation of the Wannier function coefficients. We discuss the connection between our approaches and those used in density matrix methods; in particular, the OMM presents further challenges in this respect due to the fact that we do not have direct access to the density matrix in the Wannier basis. Finally, we present initial results for a modified OMM functional that allows for smeared Fermi level calculations (pseudo finite temperature), opening up the possibility of performing linear-scaling DFT for metallic systems in SIESTA.

We report on several OMM in the SIESTA exploit the efficiency while circumventing above.

new implementations of the [5] DFT code, that aim to and stability of the method the limitations described

Firstly, we show the potential of the original OMM method as a conventional DFT solver (without the linearscaling approximation), as the local minima are no longer present when the Wannier functions are allowed to extend over the whole system. The

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References [1] [2] [3] [4] [5]

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D. R. Bowler and T. Miyazaki, Rep. Prog. Phys., 75 (2012) 036503. P. Ordej贸n, D. A. Drabold, R. M. Martin, and M. P. Grumbach, Phys. Rev. B, 51 (1995) 1456. F. Mauri, G. Galli, and R. Car, Phys. Rev. B, 47 (1993) 9973. J. Kim, F. Mauri, and G. Galli, Phys. Rev. B, 52 (1995) 1640. J. M. Soler et al., J. Phys.: Condens. Matter, 14 (2002) 2745.

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Enhanced performance of carbon nanotube field-effect transistors due to gate-modulated electrical contact resistance

Aron W. Cummings and FranĂ§ois LĂŠonard awcummi@sandia.gov

Sandia National Laboratories, MS9161, Livermore, CA, USA

Due to their unique electrical properties, carbon nanotubes (CNTs) have attracted a great deal of interest for their potential in next-generation nanoelectronics [1,2]. While individual CNTs can exhibit favorable electronic properties, it is often the CNT/metal contacts that govern the behavior and performance of CNT devices [3,4]. Thus, it is important to develop a fundamental understanding of contacts to CNTs in order to fully realize the potential of CNT devices. Recent experimental work [5,6] has provided new insight by demonstrating that the nanotube/palladium (Pd) contact resistance depends on the contact length, and that appropriate control of the contacts allows for the realization of high-performance short-channel CNT field-effect transistors (FETs) with subthreshold swings that surpass those expected from conventional scaling theory. This last result is particularly important not only for technology, but also because it suggests that new paradigms govern the properties of these nanoscale transistors. For example, it has been suggested that modulation of the contacts by the gate, a phenomenon not usually observed in conventional transistors, could lead to such behavior [6]. In this work [7], we use numerical simulations to study these recent experimental measurements and explicitly demonstrate that the superior scaling behavior is due to a strong modulation of the contacts by the gate. This results not only in modulation of the band alignment at the contact, but also leads to a novel phenomenon where the subthreshold swing is dominated by gate control of the near-contact region in the channel. This gives rise to subthreshold swings for short-channel devices that are below what is predicted by

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standard theory, performance.

allowing

for

improved

The simulated CNT FET is shown in Figure 1. For this work, we consider a (16,0) nanotube with a diameter (dCNT) of 1.2 nm, which matches the average size of the CNTs in Ref. 5. We also consider two different contact geometries. In Figure 1a, there is metal both above and below the nanotube, as a model for a CNT completely embedded in metal. In Figure 1b, we consider a contact where the metal only sits on top of the CNT. To determine the transport properties of the FET, we use a selfconsistent non-equilibrium Greenâ&#x20AC;&#x2122;s function (NEGF) approach [8] that allows us to calculate the lowbias current through the device.

Figure 1. Schematic of a carbon nanotube field-effect transistor. In part (a) the source and drain metals are above and below the nanotube (embedded contact), while in part (b) the metal only sits on top of the nanotube (top contact).

Using the NEGF approach, we calculated the transfer characteristics of the CNT FETs for channel and contact lengths that match the experimental devices. The results are shown in Figure 2, where the experimental data is given by the symbols and the theoretical data is given by the solid lines. The top row of Figure 2 shows the results for Lch = 40 nm, the middle row is for Lch = 20 nm, and the september 10-14, 2012

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bottom row is for Lch = 15 nm. The left column shows the simulation results for embedded contacts (see Figure 1a), while the right column is for top contacts (see Figure 1b). The experimental data is the same for both columns. An important feature of the experimental data is the extremely good scaling of the transistor characteristics as the channel length is reduced. Indeed, comparing the experimental data for the channel lengths of 40, 20, and 15 nm in Figure 2, one can see that the subthreshold swing is essentially unchanged as the channel length is scaled down. While the thin HfO2 dielectric provides good control over the FET channel, our simulations indicate that this by itself is not sufficient to explain the good subthreshold behavior. This can be seen by comparing the left and right columns of Figure 2. The left column shows the simulation results for the embedded contacts. In this case, the theoretical subthreshold swing is much larger than the experimental value for small channel lengths, and we see a poor fit to the experimental results. However, when we remove the metal below the CNT, the subthreshold swing is significantly reduced for the short-channel devices and we obtain excellent agreement with the experimental data, as shown in the right column of Figure 2. Thus, the geometry of the contact plays a crucial role in determining device performance and scaling, and the improved behavior upon removing the bottom metal indicates a strong influence of the gate on the contact properties. In summary, we presented simulations of shortchannel ballistic CNT FETs that explain recent experimental results using Pd contacts. We have reached the important conclusion that the contacts are strongly modulated by the gate when no bottom metal contact is present, allowing for lower subthreshold swings for short channels and improved scaling behavior. This result introduces important design considerations for CNT electronic devices, and should also apply to devices made of other nanomaterials such as nanowires and graphene.

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Figure 2. Current vs. gate voltage for short-channel CNT FETs. The top, middle, and bottom rows are for Lch = 40, 20, and 15 nm, respectively. The left (right) column is the case for embedded (top) contacts. The symbols represent experimental results from Ref. 5, and the solid lines represent the results from numerical simulations.

References [1] J.-C. Charlier, X. Blase, and S. Roche, Rev. Mod. Phys. 79 (2007), 677-732. [2] P. Avouris, Z. Chen, and V. Perebeinos, Nat. Nanotechnol. 2 (2007), 605-615. [3] Z. Chen, J. Appenzeller, J. Knoch, Y. Lin, and P. Avouris, Nano. Lett. 5 (2005), 1497-1502. [4] F. LĂŠonard and A. A. Talin, Nat. Nanotechnol. 6 (2011), 773-783. [5] A. D. Franklin and Z. Chen, Nat. Nanotechnol. 5 (2010), 858-862. [6] A. D. Franklin, M. Luisier, S.-J Han, G. Tulevski, C. M. Breslin, L. Gignac, M. S. Lundstrom, and W. Haensch, Nano Lett. 12 (2012), 758-762. [7] A. W. Cummings and F. LĂŠonard, ACS Nano, in press, DOI: 10.1021/nn301302n. [8] S. Datta, Electronic Transport in Mesoscopic Systems (Cambridge University Press, Cambridge, 1995).

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Silicon-based quantum electronics

Silvano De Franceschi

CEA, Grenoble, France

Low-dimensional silicon-based nanostructures constitute a versatile and convenient platform for novel electronic devices with quantum functionalities. After a brief overview of the most promising development routes, I shall report on a recent experiment in which we have been able to observe a gate-tunable tunneling current through a series of two donor atoms embedded in the channel of a multi-gate silicon transistor. The lowest energy states, corresponding to a single electron on either of the two donors, form a twolevel system well separated from all other electronic levels. Gigahertz driving results in a quantum interference pattern associated with the absorption or the stimulated emission of up to ten microwave photons, from which we estimate a charge dephasing time of 0.3 nanoseconds. This experimental achievement is an essential step towards either charge- or spin- based quantum computing devices in silicon.

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Related publications: [1] Katsaros et al., “Hybrid superconductorsemiconductor devices made from selfassembled SiGe nanocrystals on silicon”, Nature Nanotechnology 5, 458 (2010). [2] Katsaros et al., “Observation of spin-selective tunneling in SiGe nanocrystals”, Phys. Rev. Lett. 107, 246601 (2011). [3] Dupont-Ferrier et al., “Coupling and coherent electrical control of two dopants in a silicon nanowire”, arXiv:1207.1884v1.

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Nanoclays as adsorbents of organic contaminants for a sustainable application

Carmen del Hoyo Martínez, Jorge Cuéllar Antequera, Vicente Sánchez Escribano, Marina Solange Lozano García and Raul Cutillas Díez

Facultad de Ciencias Químicas Plaza de la Merced s/n- 37008 Salamanca University of Salamanca - Spain

hoyo@usal.es

Thanks to the development of the science and the technology of the nourishment in the last 50 years, there have revealed itself several new substances that can fulfill beneficial functions in the food, and these substances, named food additives, are today within reach of all. The food additives recover a very important role in the complex nourishing supply. The additives fulfill several useful functions in the food, which often we give for sat. Nevertheless the widespread use of food additives in the food production also influences the public health. The food industries, which are very important for the economy, spill residues proved from its activity that they have to be controlled to evaluate the environmental impact and to offer the necessary information about the quantitative evaluation of the chemical risk of the use of food additives for the public health.

immobilize these compounds and to avoid the pollution of the water with the consequent reduction of environmental and economic costs. Regarding innocuous and low cost materials, it is necessary to mention clays and clay minerals, which colloidal properties, facility of generating structural modifications, abundance in the nature and low cost make them very adapted for the adsorption of chemical pollutants. The clayey materials have given place to numerous applications to preserve the water contamination and its efficiency having being demonstrated as natural or modified adsorbents of all kinds of pollutants (Yariv, 2002). We have studied the adsorption of several food additives by natural or thermally modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the public health.

The clay materials have led to numerous applications in the field of public health (del Hoyo, 2007; Volzone, 2007) having been demonstrated its effectiveness as adsorbents of all contaminants. Some biodegradable materials are used for for adsorption of chemical contaminants: lignins (Valderrabano et al., 2008) and also clays and clay minerals, whose colloidal properties, ease of generating structural changes, abundance in nature, and low cost make them very suitable for this kind of applications.

There are different materials used in the adsorption and immobilization of chemical contaminants, most of whom remain under patent, so they do not know the procedures and products used, but in all cases the safety and / or biodegradability of materials used is an important issue in their choice for environmental applications. The most used are based on the use of organo-montmorillonites and hydrotalcite (del Hoyo et al., 2008; Undabeytia et al. 2008).

Among the strategies used at present to preserve the quality of the water and this way to diminish the environmental risk that supposes the chemical pollution, stands out the use of adsorbents of under cost, already they are natural or modified, to

Likewise, by means of mechanical and chemical treatments clays can be transformed in materials with a high surface (> 300m2) and high reactivity. The acid treatment causes the partial dissolution of the octahedric layer giving place to an increase of

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We have studied the adsorption of several contaminants by natural or modified clays, searching their interaction mechanisms and the possible recycling of these materials for environmental purposes and prevention of the health.

References [1] del Hoyo, C., Rives, V., Vicente, M.A. (1999). PhD Thesis. Drug-clay systems. University of Salamanca. [2] del Hoyo, C.; Dorado, C.; Rodríguez-Cruz, S.; Sánchez-Martín, M.J. (2008). Journal of Thermal Analysis and Calorimetry. 1, 1-8. Physico-chemical study of selected surfactant-clay mineral systems. [3] del Hoyo, C. (2007b). Applied Clay Science. 36, 103-121.Layered Double Hydroxides and human health: An overview. [4] Torres-Sánchez L, Lopez-Carrillo L, Ríos C. (1999). Salud Pública de México. 41, 106-108. Lead elimination by traditional acidic curing. [5] Undabeytia T., Nir S, Sanchez-Verdejo T, Morillo, E. Water Research. 42. 1211-1219. (2008). A clayvesicle system for water purification from organic pollutants. [6] Valderrábano, M., Rodríguez-Cruz, S., del Hoyo, C., Sánchez-Martín, M.J. (2006). 4th International Workshop "Bioavalailability of pollutants and soil remediation". 1, 5-6. Physicochemical study of the adsorption of pesticides by lignins. [7] Volzone, C. (2007). Applied Clay Science. 36, 191-196. Retention of pollutant gases: Comparison between clay minerals and their modified products. [8] Yariv S., Cross H. (2002). Marcel Dekker, New York, U.S.A. 225 pp. Organo-clays complexes and interactions

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the acid sites type Brönsted (Torrers Sánchez et al., 1999). Other treatments of the clays that might optimize the adsorption of organic compounds, are the utilization of the grinding by attrition and the thermal treatment of clays (del Hoyo et al., 1999). The grinding by attrition provokes a modification in the crystalline structure of the clays, which produces a change in the properties of superficial load, modification of the coordination of the octahedric Al and irreversible collapse of the interlayer.

Optical studies and defect properties of GaP/GaNP core/shell nanowires 1

Department of Physics, Chemistry and Biology, Linkรถping Univ, 581 83 Linkรถping, Sweden Department of Physics, University of California, San Diego, La Jolla, California 92093, USA 3 Graduate Program of Material Science and Engineering, University of California, San Diego, La Jolla, California 92093, USA 4 Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92093, USA 2

III-V core/shell nanowires (NWs) have recently attracted much attention due to their potential applications in optoelectronic and photonic devices, in particular solar cells and LEDs. Among all III-V compounds, GaP-based materials have the smallest lattice mismatch to Si and are, therefore, the best candidate for epitaxial growth of III-V materials on Si substrates. Adding a small amount of N to GaP allows one to tune the band gap energy and also to change the band gap character from an indirect one in GaP to a direct-like one in the GaNP alloys, leading to improvements in light emission efficiency. Unfortunately, the above described properties desired for optoelectronic applications have not been fully utilized, largely due to degradation of optical and electrical properties caused by defects present in GaNP. The growth of these materials in the form of NWs offers the possibility to overcome the limitations. In this work, we investigate optical properties and influence of defects on optical quality of the GaP/GaNxP1-x core/shell NWs grown on Si (111) substrates employing temperature-dependent photoluminescence (PL), time-resolved PL and optically detected magnetic resonance (ODMR) measurements.

A. Dobrovolsky1, S. Chen1, J. Stehr1, Y. J. Kuang2, S. Sukrittanon3, H. Li4, C. W. Tu3,4, W. M. Chen1, and I. A. Buyanova1 aledo@ifm.liu.se

source molecular beam epitaxy (MBE). For a comparison, a 250 nm-thick GaN0.009P0.991 epilayer grown by gas-source MBE on a (001)-oriented GaP substrate was also investigated. Scanning electron microscopy (SEM) showed that the GaP/GaNP NWs are uniform in sizes and have an axial length of about 2.5 ฮผm, a total diameter of about 220 nm, and a typical diameter of the GaP core of ~110 nm. By using a variety of optical characterization techniques we demonstrate the NWs grown on Si substrates have an excellent optical quality that is comparable to that of the GaNP epilayer grown on GaP substrates. In all structures, the PL spectra have the same line shape and originate from radiative transitions within N-related localized states. However, the core/shell NW samples have weaker PL intensity and faster PL decay at room temperature, indicative for a higher defect density leading to efficient nonradiative recombination. From the performed ODMR measurements, the responsible defects most likely involve a P atom at their core and are located either at the GaP/GaNP interface or at the GaNP surface. The high defect density in the NWs is tentatively attributed to a high surface-to-volume and interface-to-volume ratios in these structures.

The GaP/GaNxP1-x core/shell NW samples with x = 0.9% studied in this work were grown by gas-

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TNT 2012 madrid (spain)

Maysoun Douas1,2, Manuel. I. Marqués1 and Pedro. A. Serena2

Identification of nanocavities water content 1

Departamento de Física de Materiales, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco 28049 Madrid, Spain. 2 Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas, Cantoblanco, 28049 Madrid, Spain.

Water condensation at the nanoscale is known to play an important role in the collapse of virial capsids during desiccation [1]. The meniscus formation along with the geometry of the nanocavity allows capillary force to modify the mechanical stability towards collapse [2]. The changes on the near field optics, during the desiccation process, may be a good tool showing how this process takes place. Indeed, scan near field optical microscope (SNOM) can characterize sample composition by the changes in the optical near field. Since the virial capsides are almost transparent at optical wavelengths [3], different water contents in these nanocavities will produce different output signals distinct enough to characterize the desiccation sequence by SNOM experiments. Here we present a theoretical study in which we combine the lattice gas model to simulate water meniscus formation and a finite difference time domain (FDTD) algorithm for light propagation through the media involved. We simulate a tapered dielectric waveguide that scans, at constant height, a sample containing a virial capsides (Fig. 1). Our results show different contrasts related to different water contents (Fig. 2) and different meniscus orientations. We propose this method as a way to study water content and evaporation process in nanocavities being either biological, like virial capsides, or nonbiological like photonic crystals.

TNT 2012 madrid (spain)

maysoun.douas@uam.es

References [1] C. Carrasco, M. Douas, R. Miranda, M. Castellanos, P.A. Serena, J.L. Carrascosa, M.G. Mateu, M.I. Marqués, and P.J.d. Pablo, Proceedings of the National Academi of Science, 106 (2009) 5475-5480. [2] P.A. Serena, M. Douas, M.I. Marqués, C. Carrasco, P.J.d. Pablo, R. Miranda, J.L. Carrascosa, M. Castellanos, and M.G. Mateu, Physica Status Solidi C, 6 (2009) 2128-2132. [3] W. M. Balch, J. Vaughn, J. Novotny, D. T. Drapeau, R. Vaillancourt, J. Lapierre, and A. Ashe, Limnol. Oceanogr., 45 (2000) 492-498

Figure 1. Schematic representation of the region of interest for the simulated tapered coated optical fiber tip. The tip is used for illuminating the region under the aperture, while transmitted signal is detected at a distance of 100 nm form the sample (Integration plane).

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EELS-HAADF spectrum imaging for characterization of (AlGa)N multilayer heterostructures

A. Eljarrat1, L. LópezConesa1, Ž. Gačević2, S. Fernández-Garrido2,3, E. Calleja2, C. Magén4,5, S. Estradé1,6 and F. Peiró1

Lab. of Electron NanoScopies, LENS-MIND-IN2UB, Dept. Electrònica, Universitat de Barcelona, Spain 2 Inst. de Sistemas Optoelectrónicos y Microtecnología, ISOM, Univ. UPM, Spain 3 Also at Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, D-10117 Berlin, Germany 4 Laboratorio de Microscopías Avanzadas (LMA) - INA and Departamento de Física de la Materia Condensada, Universidad de Zaragoza, 50018 Zaragoza, Spain 5 Fundación ARAID, 50004 Zaragoza, Spain. 6 TEM-MAT, (CCiT), Universitat de Barcelona, Solís i Sabarís 1, Barcelona, Spain

Group III nitride materials promise production of optoelectronic devices that cover the entire visible range thanks to their widely–tunable room– temperature band gap energy. Nevertheless, in– plane lattice mismatch between the binary components is an issue affecting their design and growth. This causes proneness of the structures to present defects at the interfaces between compounds, finally decreasing the overall performance of the devices. In the present case we deal with a heterostructure of the binaries AlN/GaN for the configuration of distributed Bragg reflectors (DBR) [1-3]. Reflectivity and X-ray diffraction reciprocal space mapping (XRD–RSM) measurements have been performed in high reflectivity, crack–free, 6, 10 and 20 period AlN/GaN multilayer structures grown by Molecular Beam Epitaxy. These methods are useful for testing optical and structural properties of the samples, viewed as a whole. Furthermore, the sample is thoroughly probed at a local scale through combined high angle annular dark field (HAADF) and low-loss electron energy loss spectroscopy (EELS) in a scanning transmission electron microscope (STEM) equipped with an aberration corrected and a monochromator. Our own-made computer routines are presented as they are useful in the automatization of the analysis of this kind of spectra [4-5]. The combination of these techniques and the great quality of the measured data allows us to recover information of the sample at the nanoscale, with sub-eV energy resolution (for the

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aeljarrat@el.ub.edu

EEL spectra [6]). Besides the complete structural characterization of the AlN and GaN layers, the formation of AlGaN transient layers is demonstrated (thick and thin, see Fig.1). The origin of these layers is investigated and its impact in the DBRs optical properties is discussed. Z contrast HAADF imaging shows that structural quality is preserved through the formation of transient AlGaN layers with exceptionally high reproducibility of the segregation phenomenon (See Fig.1). Peak reflectivity and stopband width results are presented for all the samples and compared to theoretically expected values. The analysis points out that to further improve the optical performance of the DBRs, the thicker transient AlGaN interlayer has to be significantly reduced. This would increase interface abruptness and decrease the “thickness disorder” bringing thus direct benefits to the peak reflectivity and stopband width. The mechanisms to control interlayer thickness remain unclear at the moment, constraining thus further advance. Reflectivity in our samples is high (> 90%), and XRD-RSM has shown a good structural quality, assessed by HAADF-STEM micrographs showing a crack–free, highly periodic structure, up to 20 periods. The widths of four layers that compose the periodic heterostructure are measured through the combined HAADF-EELS techniques: ~ 10, 15, 50 and 15 nm for AlGaN1 (AlN–on–GaN), GaN, AlGaN2 (GaN–on–AlN) and AlN layers.

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Finally, hyper-spectral images at the nanoscale are analyzed with some new designed specialized computer routines. These retrieve important information for the chemical and structural characterization of some anomalous segregations in the multilayer heterostructure (See Fig.1). 2D maps are produced measuring and filtering properties present in the spatially localized spectra. Among these properties are the plasmon excitation, relative thickness or zero-loss-peak (elastic scattering). The combination of EELS and HAADF in STEM has proved to be a valuable tool in the characterization of structural properties from local measurements with great spatial resolution and chemical sensibility.

References [1] T. Ive, O. Brandt, H. Kostial, T. Hesjedal, M. Ramsteiner, and K. H. Ploog, Appl. Phys. Lett. 85 (2004). [2] G. Koblmueller, F. Wu, T. Mates, J. Speck, S. Fernandez-Garrido, and E. Calleja, Appl. Phys. Lett. 91 (2007). [3] G. Koblmueller, R. Averbeck, L. Geelhaar, H. Riechert, W. Hosler, and P. Pongratz, J. Appl. Phys. 93 (2003). [4] A. Eljarrat, Z. Gacevic, S. Fernández-Garrido, E. Calleja, C. Magén, S. Estradé, and F. Peiró, Journal of Physics: Conference Series 326 (2011). [5] Z. Gacevic, S. Fernández-Garrido, D. Hosseini, S. Estradé, F. Peiró, and E. Calleja, J. Appl. Phys. 108, 113117 (2010). [6] R. F. Egerton, Rep. Mod. Phys. 72, 016502 (2009).

Figure 1. (a) STEM-HAADF image of a 20-period AlN/GaN DBR showing the full structure, from the GaN buried layer at right hand side to the top of the DBR. The high periodicity of the structure is appreciated in this image, while lower panel (c) shows a detail of two successive periods. Top graph, (b), shows the aluminum ratio profiles (circles) calculated through Vegard Law analysis of the plasmon excitation energy position along with the HAADF intensity profile (blue). Below, (d) shows the result of determining the plasmon excitation energy (chemically sensitive) in a whole hyperspectral image datacube, corresponding to a nanoscale anomalous segregation.

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Electronic properties of graphene edges Department of Chemistry, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan

The presence of edges significantly modifies the electronic properties of graphene where low energy electrons behave like massless Dirac fermions. When graphene is cut into pieces and edges are introduced into the infinite π-electron system, the electronic properties near the edges are changed from the intrinsic one. The resultant modulation of the electronic states depends on the distinct type of graphene edge termination called zigzag- and armchair- directions (Fig. 1), which correspond to the two fundamental crystal directions of bipartite lattice. Graphene bipartite lattice consists of inequivalent A and B hexagonal sublattices, in which zigzag direction is defined as a line across A-A (B-B) atoms, while armchair direction is a line along A-B atoms. In this presentation, we report the results of scanning probe characterization of the two finite effects on the electronic properties near the graphene edges. The standing wave state is identified as superperiodic patterns in observed π states of armchair-terminated graphene edges [1] and nanographene [2]. The standing wave state is highly correlated with geometry-dependent electronic properties of polycyclic aromatic hydrocarbon molecules in terms of Clar theory. The observed π state with √3a×√3a periodicity (a = 0.25 nm) in armchair-terminated nanographene fragments that is prepared by chemical oxidation of graphene [2] (Fig. 2) is in good agreement with expected π-electron distributions based on the Clar theory. In Clar theory armchair-terminated nanographene is characterized by localization of aromatic sextets, which is analogous to the localized standing wave due to the interference. The edge state is characterized as enhanced amplitude of local density of state (LDOS) at the zigzag edges, in which energy dispersion of the π

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Toshiaki Enoki and Shintaro Fujii enoki.t.aa@m.titech.ac.jp

Figure 1. Schematic illustration of zigzag- and armchairedges.

Figure 2. Observed π state with √3a×√3a periodicity in armchair-terminated nanographene fragments.

state reveals a sharp distribution at the Fermi level [3]. The observed high-resolution LDOS image of the zigzag edge that is prepared by expansion of atomic vacancies of graphite by exposure of atomic hydrogen [4] shows good matching with simulated september 10-14, 2012

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image based on density functional theory (Fig. 3). The key point in achieving well-defined zigzag edges is to perform all preparation and measurement procedures strictly under the ultrahigh vacuum conditions, avoiding contact with ambient environment. As predicted from Ď&#x20AC;electron distributions based on the Clar theory, zigzag-terminated nanographene has Ď&#x20AC; radical character at the edge sites, indicating that the zigzag edge site is chemically reactive and can be oxidized in ambient conditions. In general, electronic properties of graphene edges can be altered by edge terminations and therefore it is essential to gain better understanding of the influence of edge chemistry on the edge state. We will thus focus on the experimental characterization of modified edge states musty due to variation in edge terminations such as di-hydrogenated- and/or klein- sites. Depending on the edge terminations the edge state i.e. the enhanced LDOS at the edge sites is vanished. Detail will be discussed in combination with DFT simulations.

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Figure 3. Experimental LDOS image of hydrogenated zigzag edge (left) and simulated DFT image (right).

References [1] Sakai, K., Takai, K., Fukui, K., Nakanishi, T. and Enoki, Phys. Rev. B 81 (2010) 235417-1-7. [2] Fujii, S.; Enoki, T. Angew. Chem. Int. Ed. (2012), 10.1002/anie.201202560 and 10.1002 /ange.201202560. [3] Kobayashi, Y., Fukui, K., Enoki, T. and Kusakabe, K., Phys. Rev. B 73 (2006), 125415-1-8. [4] M. Ziatdinov, S. Fujii, K. Kusakabe, M. Kiguchi, T. Mori, and T. Enoki, to be submitted.

TNT 2012 madrid (spain)

Integration of plasmonics within a CMOS environment

Roch Espiau de Lamaestre

CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex, France

We are interested in assessing the potential of plasmonics for improved optical performances in various fields of applications such as imaging, sensing and integrated Si-photonics. Indeed the use of nanostructured metals can help achieve, for example, compact color filters or low loss, low energy consumption optical components. We have taken up the corresponding challenges of the development of large scale fabrication of plasmonic components, in a microelectronic environment such as the one provided by the CMOS platforms at CEA-LETI.

optical loss plasmonic functionalities, thanks to very high quality materials. Impact of grain boundaries on the plasmon propagation at a Cu surface will be illustrated [2], as well as use of Cu in some Si-photonics integrated devices such as couplers [3] or electro-optical modulators [4]. Throughout those examples, I will discuss the CMOS compatibility of plasmonics in terms of technological process and devicesâ&#x20AC;&#x2122; reliability.

References I will highlight some noticeable realizations of past years, and emphasize the peculiarities of CMOS plasmonics. For example, elementary CMOS processes can be used to fabricate metallic optical filters in the IR range whose rejection properties are interesting for imaging and sensing applications [1]. We also demonstrated that Cu interconnect technology can be very valuable to achieve low

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[1] J. Le Perchec, et al., Optics Express 19 (2011) 15720. [2] H.S. Lee, et al, Optics Express 20 (2012) 8974. [3] C. Delacour, et al, NanoLetters 10 (2010) 2922. [4] A. Emboras, et al., Optics Express 20 (2012) 13612.

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Angular dependence of the tunneling magnetoresistance in nanoparticle arrays

V. Estévez and K.Y. Guslienko

virginia.estevez@ehu.es Dpto. Física de Materiales, Universidad del Pais Vasco, 20018 San Sebatian, Spain

Due to the small size of the nanoparticles, the transport through metallic nanoparticle arrays is governed by the Coulomb blockade physics. To add one charge to a nanoparticle costs a finite energy, the charging energy Ec. The transport is suppressed for energies smaller than the charging energy. Once there is current through the system, it is a strongly non-linear function of the voltage because of the charging effects [1]. When the nanoparticle arrays are placed between two ferromagnetic electrodes, the interplay between the ferromagnetism and the charging effects controls the transport through the system. In the case of a single nanoparticle if the spin relaxation time is long, spin accumulation appears when the magnetic moments of the electrodes have anti-parallel orientation, but not for parallel one. In a recent paper [2], it has been showed that the interplay between ferromagnetism and charging effect has a dramatic influence on the nanoparticle arrays, leading to unexpected results. For arrays with N≥ 3 nanoparticles, there is a regime with large negative differential conductance and a huge enhancement of the tunneling magnetoresistance with respect to the cases of one or two nanoparticles, see Fig. 1. How these effects are affected by different factors as asymmetry, dimensionality, disorder or range of interaction have been also analyzed [3]. The works [2,3] have been done for parallel and antiparallel magnetic orientations of the electrodes. Now we want to study the case in which the magnetization directions of the electrodes are noncollinear. This means that the magnetization directions of the electrodes form an angle θ, that is different to 0 or π. For noncollinear magnetization, the spin accumulation at the nanoparticles, the flow of current and the tunneling magnetoresistance will depend on θ [4], as occurs in the case of a single nanoparticle, see Fig 2.

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Figure 1. Tunneling magnetoresistance as a function of -4 the bias voltage for different arrays sizes at KBT=10 Ec , and spin polarization p=0.7. Main figure: arrays of N=3,10 and 20 nanoparticles. Inset: values for one and two nanoparticles.

Figure 2. Tunneling magnetoresistance as a function of θ -4 for a single nanoparticle at KBT=10 Ec, and p=0.7.

References [1] E. Bascones, V. Estévez, J.A. Trinidad, and A.H. MacDonald, Phys. Rev. B, 77 (2008) 245422. [2] V. Estévez and E. Bascones, Phys. Rev. B, 83 (2011) 020408 (R). [3] V. Estévez and E. Bascones, Phys. Rev. B, 84 (2011) 075441. [4] V. Estévez and K.Y. Guslienko, in preparation. TNT 2012 madrid (spain)

Towards sub-100nm resolution chemical mapping by XRF combined to simultaneous topography

C. Fauquet, M. Dehlinger, S. Lavandier and D. Tonneau

Aix Marseille Université, CNRS, CINaM UMR 7325, 13288, Marseille, France

fauquet@cinam.univ-mrs.fr

The aim of our work is to develop new instrumentation providing physical and chemical characterization of individual nanoobjects. For that purpose, we have designed and fabricated a new characterization tool combining X-Ray Spectroscopy and Shear Force Microscopy, working at ambient conditions, allowing surface topography measurement simultaneously to chemical mapping [1,2]. This apparatus is based on the visible luminescence collection of a sample through the microscope probe. However, this apparatus only allows the study of luminescent materials, limited mainly to semiconductors. To extend the use of the technique to a wider range of materials, we want now to collect the X-ray Fluorescence instead of the visible luminescence during SFM scan, in a similar concept, as shown in Fig. 1.

with the surface and vibrating thanks to a quartz tuning fork, its apex can be used as a probe of a shear-force microscope head. This equipment is thus able to combine simultaneous chemical mapping and topography of a sample. For that purpose, we have designed a test-bed to show the feasibility of this project. Experiments achieved with a 10 µm diameter X-ray capillary used for detection carried out with an in-lab microfocused source show high signal to noise ratio. Extrapolation of signal intensity that can be expected if the capillary used is shrunk to 1 µm and indicate that the concept is realistic in lab, and that sub 100 nm lateral resolution is achievable in synchrotron environment.

EDX detector pinhole

References

X-ray fluorescence Quartz tuning fork

Xray monocapillary

Excitation X-ray beam

Sample

[1] C. Fauquet, M. Dehlinger, F. Jandard, S. Ferrero, D. Pailharey, S. Larcheri, R. Graziola, J. Purans, A. Bjeoumikhov, A. Erko, I. Zizak, B. Dahmani and D. Tonneau, Nanoscale Research Letters, 6 (2011) 308. [2] M. Dehlinger, C. Dorczynski, C. Fauquet, , F. Jandard, A. Bjeoumikhov, S. Bjeoumikhova, R. Gubzhokov, A. Erko, I. Zizak, D. Pailharey, S. Ferrero, B. Dahmani, D. Tonneau, Int. J. Nanotechnol., 9 No 3-7 (2012) 460.

Figure 1. Scheme of the instrument principle designed to simultaneous collect XRF and topography, based on a Shear-Force Microscope

An incident X-ray beam laterally irradiates a sample which emits XRF collected through an X-ray monocapillary and analyzed by an EDX detector. Approached in near-field mechanical interaction TNT 2012 madrid (spain)

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Nano-dispersed particles in Fe(Crx) and their performance under dual (He+Fe) and triple (H+He+Fe) ion beam irradiation 1 2

M. J. Fluss1, L. Hsiung1, S. Tumey1, B. William Choi1 and P. Hosemann2

Lawrence Livermore National Laboratory, Livermore, CA Department of Nuclear Engineering, University of California, Berkeley, CA

Considerable research has been performed on irradiated nano-dispersed ferritic-martensitic steels to deduce their radiation hardening and embrittlement behavior. At low doses (1-5 dpa) the radiation hardening and DBTT shift saturates [1]. Higher dose studies are necessary to confirm this behavior and to also investigate the effects of helium and hydrogen production at relevant doses for fusion conditions. These studies can be accomplished with triple beam irradiation where displacement damage is produced by heavy-ions and hydrogen and helium are injected “simultaneously”. A particularly interesting candidate material class is the nano scale oxide dispersed strengthened (ODS) steels.

Figure 1. The triple ion beam chamber at CEA Saclay where heavy ions, H, and He can simultaneously irradiate one or more specimens (p’vt communication).

Several radiation mechanisms are likely to determine the upper temperature limit for these steels: thermal creep and loss of strength, high temperature helium (and hydrogen) embrittlement,

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void swelling (accelerated by helium and hydrogen), and corrosion [1]. The objective for accelerated ion-beam testing of materials is to define more accurately the operational temperature limits for specific materials and to identify any unknown mechanisms for materials degradation that would put these material(s) out of specification for nuclear energy design purposes. Dual and triple multiple simultaneous ion-beam (MSIB) irradiations were conducted at JANNUSSaclay (see Figure 1) followed by TEM and micromechanical post irradiation examination. Fe14Cr alloy and K3-ODS steel coupons that were irradiated with 24 MeV Fe+8 ions to produce displacement damage and energy-modulated He and H ions were implanted simultaneously to emulate the production of transmutation products from nuclear reactions. The displacement damage, in dpa (displacements per atom), from Fe8+, as a function of depth into the specimen, and the He and H implantation profiles were deduced using the SRIM code. A typical calculated profile of the dual (Fe+He) and triple (Fe+He+H) beam implant is shown in Figure 2. As shown, the overlap region for the dpa, He, and H was chosen to be at a shallower depth than the implanted Fe to avoid the “added ion effect”. The scientific challenge is to understand the relationship between materials processing of the nano-dispersed steel and its radiation performance. Our experiments are thus focusing on helium management, cavity growth, and mechanical property changes as they relate to structure of the nano-particles.

TNT 2012 madrid (spain)

Figure 2. SRIM Calculation of the implantation profile in Fe of 24 MeV Fe and energy degraded He and H. The dpa produced by the Fe is shown and the He and H implants are given in terms of appm/dpa.

We will report some preliminary measurements of the mechanical properties as a function of the depth from the surface into the irradiated volume of the irradiated materials utilizing FIB extracted and FIB shaped specimens followed by micromechanical testing; indentation and pillar compression. These measurements reveal the robustness of the ODS steel to radiation induced changes in mechanical properties.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC5207NA27344. This work was funded by the Laboratory Directed Research and Development Program at LLNL under project tracking code 12-SI002.

References

Figure 3. A HRTEM image of helium bubbles in association with “cluster domains” of various shape. Here each helium bubble appears as white contrast surrounded by a dark Fresnel fringe in each underfocused image. The image shows the trapping of several individual bubbles at a disordered cluster domain, which suggests that the appearance of cluster core/bubble shell is a result of the coalescence of small bubbles as conceptualized in the illustration on the right.

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[1] S.J. Zinkle, and N.M. Ghoniem, Fusion Engineering and Design 51–52 (2000) 55–71, and N. Baluc et al, Nucl. Fusion 47 (2007) S696–S717, and E.E. Bloom, S.J. Zinkle , F.W. Wiffen, Journal of Nuclear Materials 329–333 (2004), pp. 12–19. [2] L. L. Hsiung, M. J. Fluss, S. J. Tumey, B. W. Choi, Y. Serruys, F. Willaime, and A. Kimura, Phys. Rev. B 82, 184103 2010.

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In earlier work [2] we have characterized the nature of helium sequestration at the nanoparticle/matrix interface. In these TEM examinations of the irradiated ODS steel we have discovered that the nano-particle size distribution can be heavily biased to sub nano-meter scale particles. This discovery (see Figure 3) has led us to explore, in more depth, the processing origin of the structure of the nano-particles. From this work we have deduced that a complex chemistry during the consolidation of the precursor powders influences crystallization, stoichiometry, and leads to the wellknown core-shell structure observed for the nanodispersoids in ODS steels. Controlling these complex chemical and kinetic processes may well be a key to optimizing the material microstructure so as to achieve the best radiation tolerance and long-term performance.

Entropy-driven phase transition in dense packings of athermal chain molecules

Katerina Foteinopoulou, Nikos Ch. Karayiannis, Manuel Laso kfoteinopoulou@etsii.upm.es

Institute of Optoelectronics and Microsystems (ISOM) and ETSII, Universidad Politecnica de Madrid (UPM), Jose Gutierrez Abascal 2, 28006, Madrid, Spain

The random or ordered packing of objects has been in the spotlight of research since early times. How spheres, cubes, disks, whether oranges, candies or molecules, stack up when poured into a vessel is an intriguing problem with a wide range of practical applications in colloids, engineering, biology, materials and polymer science. Hard spheres constitute the simplest, nontrivial model which captures interactions based exclusively on the concept of excluded volume; as such it is amenable to analytic approaches. Simulations on crystallization in monomeric hard-sphere packings were first presented back in 1950s in the works of Wood and Jacobson [1] and Alder and Wainwright [2]. Given that athermal systems do not incur into energetic gains or penalties upon configurational transitions, entropy is the driving force for phase transition (crystallization) [3,4]. It is now well established that given sufficient time, crystal nucleation and growth can be naturally observed in monomeric hard-sphere assemblies at all packing densities above the melting point [5]. While the disorder-order transition and the corresponding crystal nucleation and growth are readily observable in simulations of monoatomic hard spheres the modeling of the corresponding process in dense packings of hard-sphere chains (macromolecules) remained, until recently, elusive. Whether the chain connectivity and the related holonomic constraints completely halt, partially frustrate or even do not affect at all, athermal crystallization remained a controversial topic. In the present contribution we employ extensive Monte Carlo (MC) simulations, based on chainconnectivity-altering algorithms, to generate and successively equilibrate random (disordered)

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packings of freely-jointed chains of tangent hard spheres of uniform size [6]. Through this modeling approach thousands of statistically uncorrelated configurations of the simulated chain systems are generated at concentrations ranging from very dilute up to the close vicinity of the maximally random jammed (MRJ) state [7] within modest computational time [8]. The degree of ordering (crystallization) is monitored by means of the characteristic crystallographic element (CCE) norm [9], a strictly monotonic and structure-discriminating measure of order based on the point symmetry group of the local environment of a site. The CCE norm has been shown to sensitively and quantitatively detect changes in local ordering, while identifying the emerging ordered structure with high specificity [9]. Once applied to the athermal polymer packings the CCE norm revealed that in the absence of any external influence the hard-sphere chains were observed to systematically and spontaneously crystallize at all packing densities above 0.56 [10]. Furthermore, the observed phase transition appears to be insensitive to variations in chain length and polydispersity, and the crystallinity of the established stable phase increases with increasing concentration [11]. By far the most salient feature of the crystal polymer structures is the presence of a randomly stack-faulted, layered morphology with a single stacking direction (Fig. 1). Thus, incipient nucleus consists of parallel, two-dimensional layers of either hexagonal close packed (hcp) or face center cubic (fcc) character in random alternation.

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Finally, we discuss some recent simulation findings on the effect of the intensity of the holonomic constraints (here in the form of bond lengths) on the ability of chains to crystallize at packing densities near the melting transition. Current insights from athermal polymer crystallization can shed light on the role of entropy in chemically more complicated phenomena like protein folding and crystallization in the bulk and under confinement.

Abstracts

References [1] W. W. Wood and J. D. Jacobson, J. Chem. Phys. 27 (1957) 1208. [2] B. Alder and T. Wainwright, J. Chem. Phys. 27 (1957) 1208. [3] L. Onsager, Ann. N. Y. Acad Sci. 51 (1949) 627. [4] D. Frenkel, H. N. W. Lekkerkerker and A. Stroobants, Nature 332 (1988) 822. [5] M. D. Rintoul and S. Torquato, Phys. Rev. Lett. 77 (1996) 4198. [6] N. C. Karayiannis and M. Laso, Macromolecules 41 (2008) 1537. [7] S. Torquato, T. M. Truskett and P. G. Debenedetti, Phys. Rev. Lett. 84 (2000) 2064. [8] N. C. Karayiannis and M. Laso, Phys. Rev. Lett. 100 (2008) 050602. [9] N. C. Karayiannis, K. Foteinopoulou and M. Laso, J. Chem. Phys. 130 (2009) 074704. [10] N. C. Karayiannis, K. Foteinopoulou and M. Laso, Phys. Rev. Lett. 103 (2009) 045703. [11] N. C. Karayiannis, K Foteinopoulou, C. F. Abrams and M. Laso, Soft Matter 6 (2010) 2160.

Figure 1. System configurations at (a) early stage of simulation (amorphous packing), and (b) late stage where the majority of sites possess a highly ordered local environment. Blue and red colored spheres correspond to sites with fcclike and hcp-like local order, respectively (c) and (d) same as in (a) and (b) but all sites are colored according to the parent chain [10].

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To understand better the driving mechanism and the entropic origins of the phase transition we study the rearrangement of local free volume around each site. Here, local density is determined as the reciprocal of the volume of the corresponding Voronoi polyhedron. It is shown that local free volume becomes more spherical and more symmetric through the phase transition. In turn, ordered sites are able to explore their local vicinity more efficiently increasing their mobility. Thus, there is a significant increase in translational entropy which drives the nucleation and growth of crystals.

Molecular Dynamics simulation of liquid metals for nuclear fusion technology

Alberto Fraile, Santiago Cuesta-López, J. Manuel Perlado, Roberto Iglesias and Alfredo Caro

Instituto de Fusión Nuclear, ETSII, Madrid Spain afraile@denim.upm.es

Liquid metals and alloys could be present in future nuclear reactors as breeder blankets (coolant and tritium production system) and/or plasma facing materials in wet walls, divertors in magnetic confinement reactors etc [1, 2]. In breeding blankets tritium and helium will be produced by Li splitting but tritium extraction and tritium interaction with helium bubbles is still far from being well understood. Lithium-Lead eutectic alloy is one of the most promising candidates because of its low chemical activity compared to pure lithium and good breeding ratio [3]. Here we present some atomistic simulations in hydrogen liquid metal systems. We have studied H (and its isotopes) diffusion in two different liquid metals making use of two different interatomic potentials, namely an Embedded Atom Method (EAM) potential for Pd-H system [4] and one more advanced EAM/angular dependent potential for Al-H system [5]. A full theory of H behavior in liquid metals is, to date, lacking and experimental results are scarce. Also we have developed a Li-Pb EAM interatomic potential capable to predict LiPb eutectic properties [6] after careful validation of Li and Pb EAM potentials [7-9]. Capabilities to reproduce database are shown. We address several features dealing to H diffusion in liquid metals as well as self diffusion of Li in LiPb systems.

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Figure 1. Diffusivity values for H in Al and Pd (see inset) compared with host metal self-diffusivity (black squares). H diffusivity (blue line) is close to the calculated (red = Theory) just as DH= DM√mM where mM stands for the mass of the host metal.

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Abstracts [1] V A Evtikhin1 et al. Lithium divertor concept and results of supporting experiments. 2002 Plasma Phys. Control. Fusion 44 955 [2] Norajitra P. The EU advanced dual coolant blanket concept, Fusion Eng. Des. 61–62 (2002) 449–453. [3] Wong C. P. C. An overview of dual coolant Pb–17Li breeder first wall and blanket concept development for the US ITER-TBM design. Fusion Engineering and Design 81 (2006) 461–467. [4] X. W. Zhou and J. A. Zimmerman, B. M. Wong and J. J. Hoyt. An embedded-atom method interatomic potential for Pd–H alloys. J. Mater. Res., Vol. 23, No. 3, Mar 2008 [5] F. Apostol and Y. Mishin. Angular-dependent interatomic potential for the aluminum-hydrogen system. Phys. Rev. B 82, 144115 (2010). [6] A. Fraile, S. Cuesta-López, A. Caro, J. M. Perlado. To be published. [7] Zhou X. W. Atomic scale structure of sputtered metal multylayers. Acta Mater. 49, 4005 (2001). [8] Belashchenko D. Application of the Embedded Atom Model to Liquid Metals: Liquid Lithium. High Temperature vol 47 No 2 211-218.(2009). [9] A. Fraile, S. Cuesta-López, R. Iglesias, A. Caro and J. M. Perlado. Submitted to Journal of Nuclear Materials. [10] E. M. Sacris and N. A. D. Parlee. The diffusion of hydrogen in liquid Ni, Cu, Ag, and Sn. Metallurgical and Materials Transactions B. Vol. 1, No 12 (1970), 3377-3382. [11] E. Ahmed, J. I. Akhter, M. Ahmad. Molecular dynamics study of thermal properties of noble metals. Computational Materials Science 31 (2004) 309–316 [12] A. Meyer. Self-diffusion in liquid copper as seen by quasielastic neutron scattering. Phys. Rev. B 81, 012102 (2010) [13] A. Meyer. Determination of self-diffusion coefficients by quasielastic neutron scattering measurements of levitated Ni droplets. Phys. Rev. B 77, 092201 (2008).

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References

Light emission statistics as a local probe for structural phase switching

Luis S. Froufe-Pérez1, N. de Sousa2, J.J. Sáenz2 and A. García Martín3

Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, 28049 Madrid, Spain 3 Instituto de Microelectrónica de Madrid, CSIC, Isaac Newton 8, Tres Cantos, 28760 Madrid, Spain 2

The statistical properties of light transport and emission in disordered media has been a matter of intense research during the last century. Being the basis of coherent multiple scattering of waves well known, the phenomenon itself is not yet fully explored and understood. These multiple wave scattering effects are at the heart of emerging behaviors like Anderson localization of light and electrons, band structure in crystalline solids or photonic crystals (PhC), among many others. Although the limits of perfectly ordered systems on the one hand, and uncorrelated and relatively weakly scattering systems on the other hand, are quite well understood. There is a gap between both limits which is largely unexplored. In particular, it has been shown in many different situations that disordered systems exhibiting certain structural correlations can share properties of both crystalline and fully disordered systems. For instance, the conductivity of liquid metals [1] or the cornea transparency [2] can be understood in the same footing: a disordered but correlated system can present spectral regions of high transparency for electron or light transport. The effects of disorder in an initially ordered structure, such as a PhC, might lead to strong Anderson localization, as the scattering mean free path can be severely reduced in the band edges [3]. Also, strongly correlated charged colloids can scatter light in such a way that the transport mean free path presents a strong chromatic dispersion [4]. Even in the absence of practically any long range correlations, the structure of the scatterers itself can be used to modify the light emission and transport properties of a disordered system in such a way that transport parameters [5], or even the

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luis.froufe@iem.cfmac.csic.es

threshold of a random laser [6], can present resonances which can be tuned in advance. The effect of correlations in a disordered structure regarding light emission properties of single fluorescent emitter has been a matter of much less intense research efforts. It is clear that the structure surrounding a single emitter can largely alter its emission dynamics [7]. In the last years, several groups considered such effects in a statistical way suitable for the description of disordered systems [7,8,9]. In particular, in ref.[9] it was shown that several structural properties near a phase transition can be accessed via fluorescence intensity fluctuations. It has been theoretically proven that near field scattering in random systems alters fluorescence dynamics in such a way that microscopic information about the surroundings of a single emitter can be obtained from lifetime fluctuations or from the shape of the statistical distribution tails [10,11]. In this presentation, we theoretically show how, in the previous context, fluorescence emission rate statistics are largely altered due to the appearance of structural correlations in a disordered system. We have developed a model of point resonant interacting scatterers which are placed at random. Emission dynamics of a single emitter is calculated for each sample of an ensemble of structural realizations of the system. While keeping constant the scattering properties of single scatterers, the global geometry, and scatterers density, the structural correlations are TNT 2012 madrid (spain)

It is shown that fluorescence decay rate statistics of a the single emitter correlates with the structural phase transitions of the system. In the low temperature limit, the structure freezes in an face center cubic lattice. This structure presents a gap (frequency range of low photonic density of states) corresponding to a small fluorescence decay rate. As usual, it also presents narrow frequency windows of high density of states, corresponding to band edges of the perfect infinite crystalline structure, leading to high decay rates. At frequencies corresponding to both a band gap and a band edge, we perform decay rate statistics varying the temperature of the system. It is shown that, at low temperature, decay rates hardly fluctuates and its average value corresponds to the crystalline one. On temperature raising, fluctuations of decay rate grow, and the averaged values undergoes a relatively sharp transition to a different value. This transition can be identified with a structural phase transition in the system. Interestingly, there is a narrow range of temperatures in which a strongly confined system can switch between two metastable structures which can be identified with liquid and gas. In this phase switching region, the statistical properties of the emission dynamics of a single emitter immersed in the system is strongly coupled to the structural phase switching. Hence, performing lifetime statistics can serve as a tool for monitoring phase switching and nucleation dynamics in volumes comparable with the emission wavelength or smaller.

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Abstracts

References [1] N. W. Aschcroft and J. Lekner, Phys. Rev. 145 (1966) 84. [2] [2] R. W. Hart and R. A. Farrell, J. Opt. Soc. Am. 59 (1969) 766. [3] Sajeev John, Phys. Rev. Lett. 58 (1987) 2486. [4] L. F. Rojas-Ochoa, J. M. Mendez-Alcaraz, J. J. Sáenz, P. Schurtenberger, and F. Scheffold, Phys. Rev. Lett. 93 (2004) 073903. [5] P. D. García, R. Sapienza, A. Blanco, and C. López, Adv. Mater. 19, 2597 (2007); R. Sapienza, P.D. García, J. Bertolotti, M.D. Martín, A. Blanco, L. Viña and C. López, D.S. Wiersma, Phys. Rev. Lett. 99, (2007) 233902. [6] S. Gottardo, R. Sapienza, P.D. Garcia, A. Blanco, D. S. Wiersma and C. Lopez, Nat. Phot. 2 (2008) 429. [7] Jordi Hernando, Erik M. H. P. van Dijk, Jacob P. Hoogenboom, Juan-José García-López, David N. Reinhoudt, Mercedes Crego-Calama, María F. García-Parajó, and Niek F. van Hulst, Phys. Rev. Lett. 97 (2006) 216403. [8] H. Gersen, M. F. García-Parajó, L. Novotny, J. A. Veerman, L. Kuipers, and N. F. van Hulst, Phys. Rev. Lett. 85 (2000) 5312. [9] R. A. L. Vallee, M. Van der Auweraer W. Paul and K. Binder, Phys. Rev. Lett. 97 (2006) 217801. [10] L. S. Froufe-Pérez, R. Carminati and J. J. Sáenz, Phys. Rev. A 76 (2007) 013835. [11] L. S. Froufe-Pérez and R. Carminati, Phys. Stat. Sol. (a) 205 (2008) 1258.

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controlled changing the temperature of the interacting set of scatterers.

Graphene plasmonics 1 2

IQFR – CSIC, Serrano 119, 28006 Madrid, Spain ICFO, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain

Sukosin Thongrattanasiri1, Alejandro Manjavacas1, Frank Koppens2 and Javier García de Abajo1 J.G.deAbajo@csic.es

We will discuss the extraordinary optical properties of highly doped graphene, along with new classical and quantum phenomena involving plasmons in this material. Doped graphene can host low-energy collective plasmon oscillations with unprecedented levels of spatial confinement, large near-field enhancement, and long lifetimes, which facilitate their application to enhanced light-matter interaction, optical detection, sensing, and nonlinear optics. Graphene plasmons only exist when the carbon sheet is electrically charged, as they involve collective motion of the doping charge carriers, and their frequencies, which scale up with the doping density, can be readily controlled through electrostatic gates, thus opening a realistic avenue towards electrical modulation of plasmonrelated phenemona. We will start with a tutorial description of graphene plasmons and a critical comparison with conventional noble-metal plasmons. A summary of recent experimental observations will be presented, including spatial mapping of confined graphene plasmons and spectroscopic evidence of plasmon-mediated resonant absorption [1]. Theoretical descriptions of graphene plasmons will be examined, ranging from classical electromagnetic theory to first-principles quantum-mechanical approaches. We will elucidate the conditions under which quantum nonlocality shows up in the optical response of this material. The interaction with quantum emitters (e.g., quantum dots) placed in the vicinity of the carbon sheet will be shown to reach the strong-coupling regime and potentially serve as a robust platform for quantum-optics devices that can achieve temporal control of plasmon blockade, Rabi splitting, super-radiance, and other quantum phenomena via electrostatic doping [2]. Classical devices for infrared spectroscopy, sensing, and light modulation will be also discussed [3]. Prospects to extend these phenomena to the visible and nearinfrared regimes will be examined. These advances

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in graphene constitute a viable realization of strong light-matter interaction, temporal control of quantum phenomena, and ultrafast electro-optical tunability in solid-state environments, thus bringing the expectations raised within the field of plasmonics closer to reality.

Figure 1. Complete optical absorption (top) and quantum plasmon blockade (bottom) in graphene.

References [1] Chen et al., Nature 487, 77 (2012); Fei et al., Nature 487, 82 (2012). [2] Manjavacas, Nordlander, and García de Abajo, ACS Nano 6, 1724 (2012). [3] Thongrattanasiri, Koppens, and García de Abajo, Phys. Phys. Lett. 108, 047401 (2012).

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Progress towards a single SWAP molecule with Ruthenium complexes: DFT study on a gold surface

S. García-Gil, J. Bonvoisin and X. Bouju sandra.garcia-gi l @ cemes.fr

CEMES-CNRS 29 rue Jeanne-Marvig F-31055 Toulouse, France

The idea of embedding molecules in between electrodes to make an electronic device that could perform the basic functions of digital electronics begin in the 70's . Due to the intrinsic difficulties of connecting one molecule to another to make complete circuits, it was proposed [1] to use just a single molecule: “mono-molecular electronics” which could integrate the hole circuit. One possibility to arrive to these “mono molecular circuits” is to divide the molecule in “qubits” in order to exploit the quantum engineering developed for several years around quantum computers [2]. The project to be developped consists in synthetising a molecule which could be able to realize a logical function such an inversor (SWAP).

electronic and geometrical properties of this complexes. Especially how the ligands can affect the magnetism and transport properties of these metal complexes when adsorbed on surfaces. Some recent experimental STM images on these complexes will also be presented. This work is part of a collaboration between Univ. Zaragoza-INA and CEMES-CNRS within the TRAIN2 project (Trans-Pyrenees Action on Advanced Infrastructures for Nanosciences and Nanotechnology).

References [1] [2]

[3]

[4]

[5]

This molecular logic gate would be made of Ruthenium (III) and (II) metal centers [3,4,5], which magnetic interaction could be turned on/off by changing the oxidation state of the central molecule using an appropiate light radiation. It is very important to have a good understanding of the behaviour of the building blocks of the target molecule. In particular we present a DFT study of the building blocks (Ru (II) and Ru (III) complexes) on Au(111) in order to understand the magnetic,

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[6]

C. Joachim, J.K. Gimzewski, A. Aviram, Nature, 2000, 408, J41. M.A. Nielsen, I.L. Chiang, Quantum computation & quantum information, Cambridge University Press 2000. Synthesis and characterization of bis(bipyridine)ruthenium(II) complexes with bromo and protected ethynyl ß-diketonato ligands. S. Munery, J. Jaud & J. Bonvoisin. Inorg. Chem. Commun.(2008)11,975-977. Synthesis and characterization of ß-diketonato ruthenium(II) complexes with two 4-bromo or protected 4-ethynyl-2,2’-bipyridine ligands. C. Viala & J. Bonvoisin. Inorg. chim. Acta (2010) 363, 1409-1414. Synthesis and characterization of a series of ruthenium tris(ß-diketonato) complexes with UHVSTM investigation and numerical calculations. S. Munery, N. Ratel-Ramond, Y. Benjalal, L. Vernisse, O. Guillermet, X. Bouju, R. Coratger & J. Bonvoisin. Eur. J. Inorg. Chem. (2011), 2698–2705. UHV-STM Investigations and Numerical Calculations of a Ruthenium β-Diketonato Complex with Protected Ethynyl Ligand: [Ru(dbm)2(acac-TIPSA)]Loranne Vernisse, Sabrina Munery, Nicolas Ratel-Ramond, Youness Benjalal, Olivier Guillermet, Xavier Bouju, Roland Coratger, and Jacques Jean BonvoisinJ. Phys. Chem. C, Just Accepted ManuscriptDOI: 10.1021/jp304523f.

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Tuning physical properties of polymers by nanoconfinement

Mari Cruz García-Gutiérrez, Amelia Linares, Jaime J. Hernández, Ignacio Martín-Fabiani, Daniel R. Rueda and Tiberio A. Ezquerra

Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid, Spain maricruz@iem.cfmac.csic.es

Arrays of polymer nanostructures exhibit an interesting behavior that makes them promising candidates for use in photonics, electronics, mechanical, and sensor devices [1-3]. High aspect ratio (length/diameter) one-dimensional (1D) nanostructures are also appropriate for studying size-dependent processes with length scales comparable to the nanostructures’ size.

200 nm

5 µm Figure 1. SEM image of PVDF nanostructures prepared by solution template wetting. Side view and top view (inset) showing the nanorod morphology when the alumina template has been removed.

Material properties strongly depend upon molecular order and orientation. Crystallization is one of the simplest molecular-scale self-

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organization processes capable to control spatially the ordering of molecules and hence to tune the properties of partially crystalline polymer nanostructures, as they will largely depend upon the properties of their crystalline domains. Recent studies of polymer crystallization in restricted geometries shed some light on the possibility of controlling crystallization at the nanoscale. Some of the methods used allow well-defined nanostructures to be generated, such as via nanoimprint lithography (NIL) [2], and template wetting [1, 3]. Wetting of porous anodic aluminum oxide (AAO) templates has been used in this work for the preparation of 1D polymer nanostructures. This technique is based on the fact that both polymer melts and solutions tend to wet the walls of nanoporous templates avidly if the walls exhibit a high surface energy [4] (see Figure 1). This contribution will cover recent research on these phenomena, demonstrating the use of wetting nanoporous alumina (AAO) template with polymer solution to produce arrays of poly(vinylidene fluoride) (PVDF) ferroelectric γ-type nanorods supported onto a nonpolar α-structure film (Figure 2). The method is based upon a crystal phase transition due to PVDF confinement within alumina nanoporous [5]. Based on the previous experience, we extended our research to poly(vinylidene-co-trifluoroethylene) (PVDF-TrFE) random copolymer nanoarrays. X-ray microdiffraction using synchrotron radiation has been performed at ID13 beamline (European Synchrotron Radiation Facility). Scanning the sample with 1 µm diameter X-ray beam, from the residual polymer film (bulk) to the nanorod array, we have investigated the effects of confinement on

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Acknowledgements: The authors thank the financial support from the MICINN (grant MAT2011-23455).

α form

Abstracts

References [1] C. R. Martin, Science, 266 (1994) 1961. [2] Z. Hu, M. Tian, B. Nysten, A.M. Jonas, Nat. Mater., 8 (2009) 62. [3] M. Steinhart, R.B. Wehrspohn, U. Gösele, J.H. Wendorff, Angew. Chem. Int. Ed. 43 (2004) 1334. [4] M. Zhang, P. Dobriyal, J.T. Chen, T.P. Russell, J. Olmo, A. Merry, Nano Lett., 6 (2006) 1075. [5] M.C. García-Gutiérrez, A. Linares, J.J. Hernández, D.R. Rueda, T.A. Ezquerra, P. Poza, R. Davies, Nano Lett., 10 (2010) 1472. [6] S.J. Kang, I. Bae, Y.J. Shin, Y.J. Park, J. Huh, S-M. Park, H-C. Kim, C. Park, Nano Lett., 11 (2011) 138.

Figure 2. Two-dimensional X-ray diffraction patterns recorded in transmission geometry. (top) Diffraction pattern of the residual PVDF film and (bottom) diffraction pattern of PVDF nanorods inside porous alumina. The SAXS region of the patterns has been enlarged and presented as insets.

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crystal phase transition, degree of crystallinity and crystal orientation with the aim of optimizing the ferroelectric properties of polymer nanostructures for their application in organic electronics [6].

Light-matter coupling mediated by surface plasmons

Francisco J. Garc铆a-Vidal fj.garcia@uam.es

Departamento de F铆sica Te贸rica de la Materia Condensada and IFIMAC, Universidad Aut贸noma de Madrid, Madrid 28049, Spain

In this talk I will analyze two phenomena associated with light-matter coupling and in which surface plasmon polaritons (SPPs) play a key role. First I will present a fundamental study on how SPPs in a quasi onedimensional plasmonic waveguide can be used to engineer the entanglement between two distant qubits. This two-qubit entanglement is due to the dissipative part of the effective qubit-qubit coupling provided by the SPPs. The second part of my talk will be devoted to present the theoretical foundation of the phenomenon of strong coupling between quantum emitters and propagating SPPs observed in twodimensional metal surfaces. The case of a single emitter will be analyzed first, exploring the range of parameters in which the strong coupling regime could emerge. Then we study an ensemble of N quantum emitters and incorporate the presence of dephasing mechanisms and external pumping into the theoretical framework. In the final part of the talk the capabilities of graphene surface plasmons to act as mediators in different light-matter coupling scenarios will be discussed .

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Crack mechanical failure in ceramic materials under ion irradiation: case of lithium niobate crystal.

David Garoz, Antonio Rivera, J. Olivares, F. Agullo-Lopez and J. M. Perlado

Institute of Nuclear Fusion (UPM) JosĂŠ GutiĂŠrrez Abascal 2 Madrid, Spain

david.garoz@upm.es

Swift heavy ion irradiation (ions with mass heavier than 15 and energy exceeding MeV/amu) transfer their energy mainly to the electronic system with small momentum transfer per collision. Therefore, they produce linear regions (columnar nano-tracks) around the straight ion trajectory, with marked modifications with respect to the virgin material, e.g., phase transition, amorphization, compaction, changes in physical or chemical properties. In the case of crystalline materials the most distinctive feature of swift heavy ion irradiation is the production of amorphous tracks embedded in the crystal. Lithium niobate is a relevant optical material that presents birefringence due to its anysotropic trigonal structure. The amorphous phase is certainly isotropic. In addition, its refractive index exhibits high contrast with those of the crystalline phase. This allows one to fabricate waveguides by swift ion irradiation with important technological relevance. From the mechanical point of view, the inclusion of an amorphous nano-track (with a density 15% lower than that of the crystal) leads to the generation of important stress/strain fields around the track. Eventually these fields are the origin of crack formation with fatal consequences for the integrity of the samples and the viability of the method for nano-track formation. For certain crystal cuts (X and Y), these fields are clearly anisotropic due to the crystal anisotropy. We have used finite element methods to calculate the stress/strain fields that appear around the iongenerated amorphous nano-tracks for a variety of ion energies and doses. A very remarkable feature for X cut-samples is that the maximum shear stress appears on preferential planes that form +/-45Âş with respect to the crystallographic planes. This leads to the generation of oriented surface cracks when the dose increases. The growth of the cracks along the anisotropic crystal has been studied by means of novel extended finite element methods, which include cracks as discontinuities. In this way we can study how the length and depth of a crack evolves as function of the ion dose. In this work we will show how the simulations compare with experiments and their application in materials modification by ion irradiation.

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Coupling of lattice modes in oxides superlattices: wedding of three

Philippe Ghosez Philippe.Ghosez@ulg.ac.be

Theoretical Physics of Materials, University of Liège, Allée du 6 août 17 (B5a), 4000 Liège, Belgium

Complex transition metal oxides form an important class of compounds, exhibiting a wide variety of functional properties exploited in various devices. Thanks to advances in deposition techniques, these oxides can nowadays be combined in heterostructures, with a structural quality comparable to what is achieved for conventional semiconductors. Creating such heterostructures gives not only the possibility to combine the intrinsic properties of different compounds but also to induce totally new phenomena at their interfaces. Recent examples include the metallic and superconducting interface found at the boundary between the two band insulators LaAlO3 and SrTiO3 or the emergence of so-called improper ferroelectricity in ultrashort period PbTiO3/SrTiO3 superlattices. In the latter system, the ferroelectric polarization is no more the primary driver of the phase transition but arises from an unexpected trilinear coupling of one polar and two non-polar lattice modes, producing a complex structural ground state and unusual dielectric properties. Recently, a similar type of coupling was shown by Benedek and Fennie to be a way to achieve an unprecedented control of the magnetization by an electric field in single-phase Ca3Mn2O7, a naturally occurring layered perovskite of the RuddlesdenPopper series. The wedding of lattice modes in layered perovskites looks like a promizing approach to achieve enhanced magneto-electric coupling but the identification of compounds realizing that at room temperature remains a challenge.

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After a brief introduction regarding the emergence of exotic phenomena at oxide interfaces, I will explain the concepts of improper and hybrid improper ferroelectricity. I will discuss the conditions for the appearance of a trilinear coupling of polar and non-polar lattice modes in different types of artificial and naturally-occuring layered perovskites and emphasize the interest of such a coupling to generate new and/or enhanced functional properties. Relying on first-principes simulations, I will then discuss the specific example of a 1/1 BiFeO3/LaFeO3 superlattice, showing that this system appears as a promizing candidate to realize electric switching of the magnetization at room temperature.

Works done in collaboration with Z. Zanolli, E. Bousquet, J. Zhao, H. Djani, A.Safari, A. Prikockyté and D. Fontaine at ULG, J. Iñiguez and J. C. Wojdel at ICMAB, P. Hermet at University of Montpellier and the experimental groups of J.-M. Triscone and P. Paruch at the University of Geneva. Supported by the European project OxIDes (EC-FP7), the ARC project TheMoTher and the Francqui Foundation (Belgium).

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Photochemical evidence of electronic interwall communication in doublewall carbon nanotubes a

Instituto de Nanociencia, Nanotecnología y Materiales Moleculares (INAMOL), Universidad de Castilla-La Mancha, 45071-Toledo, Spain. b Instituto de Catálisis y Petroleoquímica, CSIC, Cantoblanco, 28049, Madrid, Spain. c Instituto Universitario de Tecnología Química CSIC-UPV, Universidad Politécnica de Valencia, 46022-Valencia, Spain

Double-wall carbon nanotubes (DWCNTs) [1] have attracted considerable attention when compared to single-wall CNT (SWCNTs), because show some advantages like higher thermal and chemical stability and are mechanically more robust [2]. In addition, DWCNTs, being the simplest example of multi-wall carbon nanotubes (MWCNTs), are ideal structures for studying how the interwall interactions influence the properties of the CNTs with two or more walls for chemical [3] and physical [4,5] applications. The electronic communication between outer and inner tubes is observed by in situ Raman spectroelectrochemistry of unmodified DWCNTs; charge transfer from the outer tube to the inner tube occurs only if the electronic states of the outer tube are filled with electrons or holes and if these filled states are higher in energy than those of the inner tube [6].

Donor-acceptor nanohybrids prepared by covalent functionalization of SWCNTs with electron donors are very actively studied as donor–acceptor

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María J. GómezEscalonillaa, María Vizuetea, Sergio GarcíaRodriguezb, José Luis G. Fierrob, Pedro Atienzarc, Hermenegildo Garcíac * and Fernando Langa a MariaJose.Gomez@uclm.es

nanohybrid models and as building blocks for optoelectronic devices [7]. Nevertheless, there are not examples in the literature where a valid comparison of the photochemical properties of DWCNT and SWCNT with identical degree of functionalization has been provided. Despite the interest in understand the role of the inner, intact graphenic wall in the properties of CNTs, there are scarce examples of functionalization of this kind of CNTs, but, from the avalible data, it is well established that the functional moiety is selectively attached to the sidewall of the outer shell of DWCNTs without disrupting the properties of inner tubes. In the current work, we compare the behaviour of functionalized SWCNT and DWCNT in photoinduced electron transfer. Single and double wall carbon nanotubes (CNTs) having dimethylanilino (DMA) units covalently attached to the external graphene wall have been prepared by the reaction of dimethylaminophenylnitronium ion with the corresponding CNT. The samples have been characterized by Raman and XPS spectroscopies, thermogravimetry and high-resolution transmission electron microscopy where the integrity of the single or double wall of the CNT and the percentage of substitution (one dimethylanilino group every 45 carbons of the wall for the single and double walled samples) has been determined. Nanosecond laser flash photolysis has shown the generation of transients that has been derived from the charge transfer between the dimethylanilino as electron donor to the CNT graphene wall as electron acceptor. Time resolved spectroscopy data indicate september 10-14, 2012

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that the charge mobility in DWCNT is much higher than in the case of SWCNT, suggesting that DWCNT should be more appropriate to develop fast response devices for nanoelectronics.

References [1] R. Pfeeiffer, T. Pichler, Y. A. Kim and H. Kuzmany, Double-Wall Carbon Nanotubes, Carbon Nanotubes: Advanced Topics in the Synthesis, Structure, Properties and Applications, Ed. A. Jorio, M. S. Dresselhaus and G. Dresselhaus, Springer, New York, (2008), pp 495-530. [2] Y. A. Kim, H. Muramatsu, T. Hayashi, M. Endo, M. Terrones and M. S. Dresselhaus, Chem. Phys. Lett.,398, (2004), 87. [3] A. H. Brozena, J. Moskowitz, B. Y. Shao, S. L. Deng, H. W. Liao, K. J. Gaskell and Y. H. Wang, J. Am. Chem. Soc.,132, (2010), 3932. [4] A. A. Green and M. C. Hersam, Nat. Nanotechnol.,4,(2009),64. [5] A. A. Green and M. C. Hersam, ACS Nano,5,(2011),1459. [6] M. Kalbac, A. A. Green, M. C. Hersam and L. Kavan, Chem. Eur. J., 17,(2011),9806. [7] V. Sgobba and D. M. Guldi, Chem. Soc. Rev.,38,(2009),165.

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Negative scattering asymmetry parameter for dipolar particles: unusual reduction of the transport mean free path and radiation pressure

R. Gómez-Medina1, L. S. Froufe-Pérez1, M. Yépez1, F. Scheffold2, M. Nieto-Vesperinas3 and J. J. Sáenz1 r.gomezmedina@uam.es

Dpto. Física de la Materia Condensada and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid 28049, Spain 2 Department of Physics, University of Fribourg, Chemin du Muse 3, 1700 Fribourg, Switzerland 3 Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco, Madrid 28049, Spain

Propagation of light and image formation in turbid media has long been a subject of great interest [1] and constitutes the core of powerful techniques with countless applications including biomedical imaging [2, 3] and dynamic spectroscopy techniques [4-6], characterization of composite materials and complex fluids [7], remote sensing or telecommunications [8] to mention a few. Lossless dielectric nanospheres (made of nonmagnetic materials) with relatively low refraction index may present strong electric and magnetic dipolar resonances [9-11]. We establish a relationship between the optical force [12,13] from a plane wave on small electric and magnetic dipolar particles, the transport cross section, and the scattering asymmetry parameter g [14]. In this way we predict negative g (that minimize the transport mean free path below values of the scattering mean free path) for a dilute suspension of both perfectly reflecting spheres as well as of lossless dielectric nanospheres made of moderate permittivity materials, e.g., silicon or germanium nanospheres in the infrared region. Lossless dielectric Mie spheres of relatively low refraction index (as low as 2.2) are shown to present negative g in specific spectral ranges [14].

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Figure 1. (a) Color map of the g factor for spherical absorptionless particles as a function of their refractive index m and size parameter y = mka. As seen in the attached scale, green areas correspond to negative values of g. (b) Color map of the sphere scattering cross section. Red corresponds to dominant electric dipole contributions to the scattering cross section. Green corresponds to dominant magnetic dipole contributions, while blue sums up all higher-order multipole terms. Vertical dashed lines coincide with y parameter for maximum electric dipole contribution (right vertical line) and maximum magnetic dipole contribution (left vertical line). The white horizontal line at m ≈ 3.5 which corresponds to a silicon sphere. (After Ref.[14]).

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References [1] Waves and Imaging through Complex Media, edited by P. Sebbah (Kluwer Academic, Dordrecht, 2001); in Wave Scattering in Complex Media: From Theory to Applications, edited by B. A. van Tiggelen and S. E. Skipetrov, NATO Science Series II: Mathematics, Physics and Chemistry,Vol. 107 (Kluwer Academic, Dordrecht, 2003). [2] A. Yodh and B. Chance, Phys. Today 48(3), 34 (1995); S. K. Gayen and R. R. Alfano, Opt. Photon. News 7 (1996) 17. [3] J. Ripoll, V. Ntziachristos, J. P. Culver, D. N. Pattanayak, A. G. Yodh, and M. Nieto-Vesperinas, J. Opt. Soc. Am. A 18 (2001) 821. [4] D. A. Weitz and D. J. Pine, in Dynamic Light Scattering, edited by W. Brown (Oxford University Press, New York, 1993). [5] G. Maret and P. E. Wolf, Z. Phys. B 65 (1987) 409; D. J. Pine, D. A. Weitz, P. M. Chaikin, and E. Herbolzheimer, Phys. Rev. Lett. 60 (1988) 1134. [6] R. Lenke and G. Maret, in Multiple Scattering of Light: Coherent Backscattering and Transmission, edited by W. Brown (Gordon & Breach, Reading, UK, 2000). [7] F. Scheffold and P. Schurtenberger, Soft Mater. 1 (2003) 139. [8] A. Derode, A. Tourin, J. de Rosny, M. Tanter, S. Yon, and M. Fink, Phys. Rev. Lett. 90 (2003) 14301; G. Lerosey, J. de Rosny, A. Tourin, and M. Fink, Science 315 (2007) 1120. [9] A. García-Etxarri, R. Gómez-Medina, L. S. Froufe-Pérez, C. López, L. Chantada, F. Scheffold, J. Aizpurua, M. Nieto-Vesperinas and J. J. Sáenz, Opt. Express, 19 (2011) 4815-4826. [10] R. Gómez-Medina, B. García-Cámara, I. Suárez-Lacalle, F. González, F. Moreno, M. Nieto-Vesperinas and J. J. Sáenz, J. Nanophoton. 5 (2011) 053512. [11] M. Nieto-Vesperinas, R. Gómez-Medina, and J. J. Sáenz, J. Opt. Soc. Am. A, 28 (2011) 54-60. [12] M. Nieto-Vesperinas, J. J. Sáenz, R. Gómez-Medina, and L. Chantada, Opt. Express, 18 (2010) 11428-11443. [13] R. Gómez-Medina, M. Nieto-Vesperinas and J. J. Sáenz, Phys. Rev. A, 83 (2011) 033825. [14] R. Gómez-Medina, L. S. Froufe- Pérez, M. Yépez, F. Scheffold, M. Nieto-Vesperinas and J. J. Sáenz, Phys. Rev. A, 85 (2012) 035802.

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Nanostructured tungsten as a first wall material for the future nuclear fusion reactors 1

Instituto de Fusión Nuclear, ETSI de Industriales, UPM, C/ José Gutierrez Abascal, 2, E-28006 Madrid, Spain. 2 CEI Campus Moncloa, UCM-UPM 3 Instituto de Energía Solar (IES), UPM, Avenida Complutense s/n, E-28040 Madrid, Spain 4 Instituto de Microelectrónica de Madrid, IMM-CNM-CSIC, Isaac Newton 8 PTM, E-28760 Tres Cantos, Madrid, Spain. 5 Dpto. de Física de Materiales, Facultad de CC. Físicas, UCM, Ciudad Universitaria s/n, E28040 Madrid, Spain. 6 Dpto. de Física de Materiales, Facultad de CC. Químicas, UCM, Ciudad Universitaria s/n, E-28040 Madrid, Spain. 7 Dpto. de Ciencia de Materiales CISDEM, ETSI de Caminos, UPM, E-28040 Madrid, Spain.

The lack of materials able to withstand the severe radiation conditions (high thermal loads and atomistic damage) expected in fusion reactors is the actual bottle neck for fusion to become a reality. The main requisite for plasma facing materials (PFM) is to have excellent structural stability since severe cracking or mass loss would hamper their protection role which turns out to be unacceptable. Additional practical requirements for plasma facing materials are among others: (i) high thermal shock resistance, (ii) high thermal conductivity (iii) high melting point (iv) low physical and chemical sputtering, and (v) low tritium retention. W has been proposed to be one of the best candidates for PFM for both laser (IC) and magnetic (MC) confinement fusion approaches. However, works carried out up to know have identified some limitations for W which have to be defeated in order to fulfill specifications [1, 2, 3]. Nowadays engineered 3D surfaces are being fabricated to reduce the thermal loads arriving to the PFM by increasing the surface area and thus, minimize the energy density deposited into the material [4]. On the other hand, ultrafine grain and nanostructured materials are being developed to facilitate the light species release and to improve the W mechanical properties [5]. We report on the growth of nanostructured W by using DC magnetron sputtering and high impulse power magnetron sputtering (HIPIMS) on different

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N. Gordillo1,2, R. GonzalezArrabal1, A. Rivera1, I. Fernandez-Martinez3,4, F. Briones4, J. Del Río5, C. Gomez6, J. Y Pastor7, E. Tejado7, M. Panizo-Laiz1 and J. M. Perlado1

kind of substrates under different deposition conditions. X-ray diffraction (XRD) patterns illustrate that films are polycrystalline and preferentially oriented along the (110) axes. Transmission electron microscopy (TEM) and field emission gun-scanning electron microscopy (FEGSEM) evidence that films consists of nanocolumns perpendicular to the substrate with a diameter in between 50 and 250 nm depending on the deposition conditions. Some of the samples were annealed in an Ar atmosphere at temperatures in the range from RT to 1000ºC in order to study their thermal stability. Cross-sectional FEG-SEM images show no significant change in the nanocolumn shape but they point up the poor adhesion between film and substrate for those samples deposited on steels and heated at temperatures higher than 800ºC.

References [1] Takeshi Hirai, Koichiro Ezato and Patrick Majerus, Materials Transactions, 46, (2005) 412-424. [2] Kajita S., Sakaguchi W., Ohno N., Yoshida N., Saeki T. 2009. Nucl. Fus. 49, 095005. [3] Sharafat S., Takahashi A., Hu Q., Ghoniem N.M. 2009. J. Nucl. Mat. 386-388, 900. [4] T. J. Renk, P. P. Provencio, T. J. Tanaka, J. P. Blanchard, C. Martin , and T. R. Knowles, Fusion Science and technology 61 (2012) 1-24. [5] M. Rieth et al. private communication.

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DNA programmed assembly of molecules

Kurt V. Gothelf

Centre for DNA Nanotechnology (CDNA), iNANO and Department of Chemistry, Aarhus University, 8000 Århus C, Denmark

The idea behind our research is to use DNA as a programmable tool for directing the self-assembly of molecules and materials. The unique specificity of DNA interactions, our ability to code specific DNA sequences and to chemically functionalize DNA, makes it the ideal material for controlling selfassembly of components attached to DNA sequences. We have developed some new approaches in this area such as the use of DNA for self-assembly of organic molecules[1] and position dendrimers. We have used DNA origami to assemble organic molecules, study chemical reactions with single molecule resolution [4]. We have also formed 3D DNA origami structures [5] and dynamic DNA structures [6]. Our recent progress on surface modification of DNA origami structures will also be presented.

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References [1] Ravnsbæk; J. B et al. Angew. Chem. Int. Ed. 2011, 50, 10851–10854. [3] Liu, H. et al. J. Am. Chem. Soc. 2010, 132, 18054-18056. [4] Voigt, N. V. et al. Nature Nanotech. 2010, 5, 200-205. [5] Andersen, E. S. et al. Nature 2009, 459, 73-76. [6] Zhang, Z. et al. Angew. Chem. Int. Ed. 2011, 50, 3983–3987.

TNT 2012 madrid (spain)

What can AFM tell us about organic photovoltaic systems?

J. Topple, Z. Schumacher, A. Tekiel, and P. Grutter

Physics Dept., McGill University, Montreal (Quebec), Canada

The major challenge in Photovoltaic (PV) is the cost per kWh. It is also clear that continuous growth of PV will not be achievable by concentrating on just one material system (such as Si), due to materials limitations (Ag, In etc. necessary for electrodes). Hybrid organic-inorganic systems are low cost, but also have a low efficiency and lifetimes, so the cost per kWh of energy is currently not very attractive. The reason for this is fundamentally not well understood, as the conversion of photons to electrical power is a complicated many-step process. Organic Photovoltaic (OPV) diodes based on distributed heterojunctions of organic semiconductors currently produce solar power conversion efficiencies approaching 10%. Photocurrent generation in these devices requires interfacial charge separation of singlet excitons at donor-acceptor heterojunctions to produce charge carriers, and it is now clear that this is a multi-step process involving dissociation of intermediate electron and hole pairs that are bound by Coulomb interactions. This last process competes with relaxation into charge-transfer-exciton states localized at the heterojunction. Such interfacial excitons are central to electronic processes at organic heterojunctions in two important ways. Firstly, charge-transfer excitons act as intrinsic traps that limit photocarrier generation, due to their large binding energy (~300 meV). Secondly, there is now phenomenological information establishing the importance of charge-transfer excitons in defining the open-circuit voltage and short-circuit photocurrent in organic solar cells, but fundamental understanding on molecular length scales lacks.

experimental observation of excitons in a model OPV system. Thin films of PTDCI (an electron donor) and copper (II) phthalocyanine (an electron acceptor) molecular islands were grown under ultra high vacuum conditions on insulators. Structure and surface contact potential were simultaneously mapped using nc-AFM and Kelvin probe force microscopy on a nm scale. We could clearly detect changes of surface potentials at molecular heterojunctions under illumination. This open the possibility of directly correlating exciton diffusion length, diffusion anisotropy and trapping sites with atomic scale structure, allowing us to gain deep fundamental insights.

Figure 1. 3D rendered NC-AFM topography and corresponding simultaneous KPFM images, overlayed to illustrate the correlation between film morphology and surface work function distribution under on/off illumination conditions. The change in KPFM signal on the island indicated by the green arrow suggests that enhanced charge-carrier separation takes place across the organic heterojunction under illumination.

Building upon previous morphological studies of tailoring molecular island size and nucleation site distribution, I will present preliminary results of our

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Interaction effects in graphene heterostructures

Francisco Guinea

paco.guinea@icmm.csic.es

Instituto de Ciencia de Materiales de Madrid. Consejo Superior de Investigaciones CientĂficas Sor Juana InĂŠs de la Cruz 3. 28049 Madrid. Spain

New graphene heterostructures built up of graphene and boron nitride layers have a high tunability, and they can be the basis of new devices[1-3]. They show intriguing new phenomena, such as electron localization induced by screening, and large Coulomb drag between carriers in different graphene layers. The tunability of these devices allow for sizable modifications of the interactions between electrons. We discuss here possible new phases induced by the electron-electron interaction, including superconductivity at sufficiently high carrier density.

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References [1] L. A. Ponomarenko, A. K. Geim, A. A. Zhukov, R. Jalil, S. V. Morozov, K. S. Novoselov, V. V. Cheianov, V. I. Fal'ko, K. Watanabe, T. Taniguchi, et al., Nature Phys.7, 958 (2011). [2] L. Britnell, R. V. Gorbachev, R. Jalil, B. D. Belle, F. Schedin, M. I. Katsnelson, L. Eaves, S. V. Morozov, N. Peres, J. Leist, et al., Science 335, 947 (2012). [3] R. V. Gorbachev, A. K. Geim, M. I. Katsnelson, K. S. Novoselov, T. Tudorovskiy, I. V. Grigorieva, A. H. MacDonald, K. Watanabe, T. Taniguchi, L. A. Ponomarenko, arXiv:1206.6626 (2012).

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Properties optimisation of titania microfibers by direct drawing 1

Institute of Physics, University of Tartu, Riia 142, 51014 Tartu, Estonia Department of Materials Engineering, Tallinn University of Technology, Ehitajate 5, 19086 Tallinn, Estonia 3 Department of Aerospace Engineering, University of Illinois at Urbana-Champaign, 306 Talbot Lab, 104 South Wright Street, Urbana, Illinois 61801, USA 2

Ceramic microfibers are interests both in scientific and technological means. One of the main factors that is supporting the use of fibres is their edgeless cylindrical geometry, which for externally applied mechanical stresses can not localize into specific spots to easily cause cracks. Nanostructured polycrystalline titania (TiO2) microfibres, studied in this work were produced by direct drawing from visco-elastic alkoxide precursors [1,2]. The fibre crystallinity and grain size were shown to depend on applied post-treatment (calcination temperature) conditions. Single fibre tensile tests showed a strong sensitivity of the elastic modulus and the tensile strength to the microstructural features of the fibres. The elastic modulus of asfabricated fibres increased about 10 times after calcination at 700 째C, while the strain at failure remained almost of the same percentage of ~1.4% [3]. The highest tensile strength of more than 800 MPa was exhibited by nanoscale grained fibres with a bi-modal grain size distribution consisting of rutile grains embedded into anatase matrix [4]. This structure is believed to have reduced the critical defect size and thus increased the tensile strength. The resultant materials showed properties that were appropriate for reinforcement of different matrixes.

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Kelli Hanschmidt1,3, Tanel T채tte1, Irina Hussainova2, Marko Part1, Hugo M채ndar1, Kaspar Roosalu1 and Ioannis Chasiotis3 kelli84@fi.tartu.ee

(a)

(b) Figure 1. Changes in modulus of elasticity (a) and tensile strength (b) with temperature of heat treatment.

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References [1] T. Tätte, M. Hussainov, J. Gurauskis, H. Mändar, G. Kelp, K. Hanschmidt, I. Hussainova, Nanotechnology (2010) 245-248. [2] T. Tätte, M. Hussainov, M. Paalo, M. Part, R. Talviste, V. Kiisk , H. Mändar, K. Põhako, T. Pehk, K. Reivelt, M. Natali, J. Gurauskis, A. Lõhmus, U. Mäeorg, Sci Tech Adv Mater. 12 (2011) 1-12. [3] S. Sakka, K. Kamiya, Mater Sci Res. 17 (1984) 83–94. [4] H. Gleiter, Prog Mater Sci. 33 (1989) 223-315.

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Theoretical study of edge states in BC2N nanoribbons with zigzag edges 1

Nano-scale Theory Group, NRI, AIST Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan 2 First-Principles Simulation Group, CMSU, NIMS, Sengen 1-2-1, Tsukuba, Ibaraki 305-0047, Japan

Graphene is an atomically thin carbon sheet in which carbon atoms are arranged in a honeycomb lattice. Due to their outstanding electronic structure and electron transport properties, graphene attracts much interest for future electronic devices. Graphene nanoribbons are finite width graphene sheets. The electronic properties of graphene nanoribbons strongly depend on the edge structures [1]. Graphene nanoribbons with zigzag edges have the so-called flat bands at the Fermi level [1]. The states corresponding to the flat bands are localized at the zigzag edges [1]. For the so-called edge states, the A- (B-) sublattice structure plays decisive role, i.e., the distribution of electronic charge of the edge states becomes finite only one sublattice sites including the outermost sublattice. Recently, graphene nanoribbons were fabricated by e-beam lithography [2] and unzipping of carbon nanotubes [3], and were synthesized using bottom-up processes [4]. Furthermore, quite recently, the edge states in graphene nanoribbons were confirmed by STM/STS measurement [5]. On the other hand, boron and nitrogen atoms behave as acceptors and donors, respectively. Therefore, boron-carbon-nitride, i.e., graphene sheet doped with B and N, should show interesting electronic properties with controllability by doping. BC2N sheet is organic analogous of graphene, which can be regarded as one of example of boroncarbon-nitride. Graphite-like BC2N was synthesized using chemical vapor depositions of boron trichloride, BCl3, and acetronitrile, CH3CN [6]. The electronic properties of BC2N sheets depend on the atomic arrangement [7]. The electronic properties of nanoribbons made with BC2N were investigated by several authors [8]. However, there are no

TNT 2012 madrid (spain)

Kikuo Harigaya1 and Tomoaki Kaneko2 k.harigaya@aist.go.jp

reports on the presence of the flat bands and edge states in BC2N nanoribbons. In this paper, we investigate the electronic properties of BC2N nanoribbons with zigzag edges using a tight binding model. In the tight-binding model, B and N atoms are described by higher and lower site energy, EB and EN, compared with that of C atom, EC, respectively [9]. Let N be a number of the zigzag lines. We shall consider three different structures of BC2N nanoribbons with zigzag edges as shown in the left part of Fig. 1 (a). In this figure, B and N atoms are indicated by the black and white circles, and C atoms are located the empty vertices. It should be noted that atoms are arranged as B-CN-C along the zigzag line in these BC2N nanoribbons. Figure 1 (b) shows calculated results of the band structures of BC2N nanoribbons for N = 10. We observed the flat bands at E = 0. However, we confirm that the flat bands are absent if atoms are not arranged as B-C-N-C along the zigzag lines. Therefore, we can conclude that B-C-N-C arrangement along the zigzag line is necessary to obtain the flat bands. In the right part of Fig. 1 (a), the local density of states (LDOS) at E = 0 for several structures are shown by the circles. In this figure, the radii of the circles are proportional to the magnitude of the LDOS at each site. The electronic charge is localized at the BC2N nanoribbons edges, showing the presence of the edge states. As discussed below, the edge states in BC2N nanoribbons is different from those in conventional graphene nanoribbons. In the model-1, the charge distributions at the both edges are different each other, i.e., the charge

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distribution at the edge, where the outermost sites are occupied with C atoms, is similar to that at the conventional zigzag edge, while the charge of the edge states at the edge, where the outermost sites are occupied with B and N atoms, distributes the both sublattice sites. Recently, Kaneko et al. showed that the edge states in zigzag graphene nanoribbons are robust on the substitution of outermost C atoms with B and N atoms alternately [10]. However, such substitution causes change in charge distribution, i.e., the sublattice structure is broken [10]. The edge states at the edge, where the outermost sites are occupied with B and N atoms alternately, are similar to those discovered by Kaneko et al. [10]. In the model-2 nanoribbon, the charge distribution of the edge states is similar to that of graphene nanoribbons, but the sublattice structure is broken inside the nanoribbons. In the model-3 nanoribbon, the charge distributes over both sublattice sites, showing the similarity of those discovered by Kaneko et al. [10]. In this paper, we also performed the first-principles calculations based on the density functional theories within projector-augmented wave method and the local density approximation implemented in VASP code. We shall discuss the comparison of

the results within the tight-binding model with those within the density functional theories.

References [1] M. Fujita, et al., J. Phys. Soc. Jpn., 65 (1996) 1920, K. Nakada et al., Phys. Rev. B, 54 (1996) 17954. [2] M. Y. Han et al., Phys. Rev. Lett., 98 (2007) 206805. [3] D. V. Kosynkin et al., Nature, 458 (2009) 872; L. Y. Jiao et al., Nature Nanotech., 5 (2010) 321. [4] J. M. Cai et al., Nature, 466 (2010) 470. [5] C. Tao, et al., Nature Nanotech., 7 (2011) 616. [6] M. Kawaguchi, Adv. Matter., 9 (1997) 615. [7] A. Y. Liu, R. M. Wentzcovitch, and M. L. Cohen, Phys. Rev. B, 39 (1989) 1760; H. Nozaki and S. Itoh, J. Phys. Chem. Solids, 57 (1996) 41. [8] P. Lu, et al., J. Phys. Chem. C, 115 (2011) 3572; Appl. Phys. Lett., 96 (2010) 133103; B. Xu, et al., Phys. Rev. B, 81 (2010) 205419; L. Lai and J. Lu, Nanoscale, 3 (2011) 2583. [9] T. Yoshioka, H. Suzuura, and T. Ando, J. Phys. Soc. Jpn., 72 (2003) 2656. [10] T. Kaneko, K. Harigaya, and H. Imamura, (in preparation).

Figure 1. (a) Schematic illustration of BC2N nanoribbons (left side) and corresponding LDOS at E=0 for N=10 (right side). In this schematic illustration, the black and white circles represent B and N atoms, respectively. (b) The band structures of BC2N nanoribbons with N=10.

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Nanotechnology in Latin America and the Caribbean: current situation and perspective

Anwar Hasmy anwarhasmy@hotmail.com

Universidad Simón Bolívar / Red Venezolana de Nanotecnología Caracas, Venezuela

Through the manipulation of nanosized materials to create new products and processes, nanotechnology is being a leading driver for socioeconomic development in emerging countries, in particular in those technology based business. In Latin America many countries begin to consider and implement national strategies in order to lever up the industrialization and competitiveness of the manufacturing sectors (1-4). The talk will summarizes and highlights the behavior of bibliometric indexes as well the activities organized in the last decades on Nanoscience and Nanotechnology in Latin America and the Caribbean region. The current state and perspectives of nanotechnology, as well the intra and inter-regional cooperation, will be discussed.

(a)

(b)

References [1] Kay L & Shapira P (2009) “Developing nanotechnology in Latin America” J. Nanopart. Res. 11: 259-278. [2] López MS, Hasmy A & Vessuri H (2011) “Nanoscience and Nanotechnology in Venezuela” J. Nanopart. Res. 13: 3101-3106. [3] Delgado GC & Takeuchi N (Eds.) (2011) “Divulgación y Formación de la nanotecnología en Iberoamérica: Informe de la Red ‘José Roberto Leite’-NanoDyF/Cyted”, Mundo Nano. 4, No. 2. [4] Foladori G, Invernizzi N & Záyago E (Coords.) Perspectivas sobre el desarrollo de las nanotecnologías en América Latina ISBN: 978607-401-538-6, ReLANS-UAZ-Porrúa Eds., México, 2012.

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Figure 1. (a) The total Nanotechnology publications in the three more populated Latin American countries (Argentina, Brazil and Mexico) are compared with the total number of publications of the region (CELAC) and Spain in the last two decades. (b) Distribution of the international cooperation of nanotechnology publications in Latin America and the Caribbean region.

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Metallic microwires as non-reflective microwave systems

Antonio Hernando

Universidad Complutense, Spain

It has been shown that either magnetic or non magnetic metallic microwires, forming composites, attenuate microwave reflection of metallic surfaces. The frequency of maximum antireflective effect (30dB) can be tuned through the control of volume fraction and aspect ratio of the microwires. It has been found that the high conductivity of the microwires enable an outstanding enhancement of the electrical permittivity of the composite. This increase gives rise to the possibility of achieving the destructive interference condition for composite thickness much shorter than the vacuum wavelength. Experiments carried out on radar reflections for a Spanish Navy ship previously painted with a composite of microwires and paint are shown and discussed.

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Application of nanostructures in aptamer based biosensors 1

Faculty of Mathematics, Physics and Informatics, Comenius University, Mlynská dolina F1, 842 48 Bratislava, Slovakia 2 Institute of Animal Biochemistry and Genetics, Slovak Academy of Sciences, 900 28 Ivanka pri Dunaji, Slovakia 3 Analytical Chemistry Department, Kazan Federal University, 18 Kremlevskaya Street, Kazan, 42008, Russian Federation 4 Institut de Chimie Moléculaire et de Matériaux d’Orsay, Université Paris-Sud, Bâtiment 420, 91405 Orsay, France 5 Biophysics Institute, Johannes Kepler Univ. Linz, Altenbergertrasse 69, 4040 Linz, Austria

DNA and RNA aptamers are single stranded oligonucleotides with high affinity to proteins or other ligands that are similar to those of antibodies. The aptamers are selected in vitro by the SELEX method [1]. In solution, aptamers maintain an unique 3D configuration that contains specific binding site to the ligand. Aptamers can be easily modified by biotin, SH or amino- groups, leading to a variety of immobilization strategies on solid supports. Using simple molecular engineering based on DNA hybridization it is possible to develop aptamer dimers containing two binding sites like antibodies [2,3]. These aptamer dimers (aptabodies) are characterized by enhancing sensitivity to the analyte, for example to thrombin or cellular prions. We have shown that typical guanine quadruplexes that form binding site for thrombin are stable in aptamer dimers [4]. Currently there is increased interest in development of aptamer based biosensors (aptasensors) for detection of proteins and other molecules using various sensing methods, such us optical, acoustical and electrochemical [5,6]. Aptasensors could be used for fast and low cost medical diagnostics. The sensitivity of detection depends not only on the selectivity of binding site, but also on the supporting part added to the aptamer that serves for better immobilisation onto a solid support. Nanostructures such as carbon and ZnO nanotubes, graphenes, molecularly imprinted polymers, and that modified by calixarenes and dendrimers are of great advantage in aptamer immobilisation and also improve detection of ligands especially in combination with electrochemical methods. TNT 2012 madrid (spain)

Tibor Hianik1, Gabriela Castillo1, Maja Šnejdarková2, Alexandra Poturnayová2, Anna Porfireva3, Gennady Evtugyn3, Anna Miodek4, Helene Dorizon4, Hafsa Korri-Youssoufi4 and Andreas Ebner5 tibor.hianik@fmph.uniba.sk

In this contribution we report various immobilisation and detection strategies of proteins using nanostructured aptasensors. By means of multiwalled carbon nanotubes (MWCNTs) as an immobilization matrix we developed high sensitive biosensor for detection of human thrombin [2] and cellular prions (PrPC) [7] in biological liquids. We have shown that immobilisation of aptamers and aptamer dimers at MWCNTs improved the sensitivity of the sensor for thrombin and allowed detection in a complex matrix such as blood plasma. By means of electrochemical quartz crystal microbalance method (EQCM) we performed comparative analysis of the sensitivity of DNA aptamers and antibodies specific to PrPC immobilised on a surface of MWCNTs. We found that the limit of detection (LOD) for both aptamers (50 pM) and antibodies (20 pM) was comparable. Most recently we substantially improved the LOD using immobilisation of aptamers onto multilayer surface composed of MWCNTs with covalently attached polyamidoamine dendrimers (PAMAM) of fourth generation (G4) conjugated with ferrocene-1'-(N(3-butylpyrrole)butanamide) (FeNHP). Streptavidin-biotin conjugation served as linker with biotin-modified aptamer designed for specific prion recognition (Fig. 1a). Using cyclic voltammetry (CV) it has been possible to record reversible redox currents of the ferrocene with oxidation and reduction peaks corresponding to the potentials 0.24 mV and 0.17 mV (vs. Ag/AgCl reference electrode), respectively. The current decreased with increasing PrPC concentrations form 1 pM to 10 µM and reaches saturation after 1 µM (Fig. 1b). The current decay was due to limitation of the electron exchange in the sensing layer. LOD was september 10-14, 2012

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found to be 1.3 pM which is acceptable for practical applications. The sensor was tested also in a human blood serum with satisfactory recovery in average of 74%. The interferences with BSA up to concentrations 10 µM were negligible.

current recorded after 10 min incubation decayed with increased thrombin concentration due to limitation of the electron exchange in the surface layer. The aptasensor makes it possible to determine thrombin in concentration range 0.1–50 nM (LOD 0.05 nM) in blood serum without any alteration of the response in the presence of 100 fold excess of serum proteins. Acknowledgements: Financial support of Agency for Promotion Research and Development under the project No. APVV-0410-10 and SK-FR-0025-09, Slovak Academy of Sciences under the project mnt-era.net (proposal No. 2009-50), VEGA 1/0785/12 by Centre of Excellence SAS for Functionalized Multiphase Materials (FUN-MAT) and by the Grant of Education and research ministry of French government are gratefully acknowledged. We are grateful to Dr. Human Rezaei and Dr. Jasmina Vidic from VIM group of INRA France for generous gift of PrPC proteins.

References

Figure 1. a) The scheme of the biosensor based on MWCNTs-dendrimer- ferrocene-streptavidin layer with C immobilised aptamers sensitive to PrP (1-MWCNT, 2Dendrimer, 3-Fe-NHP, 4-Biotinylated aptamer connected C to streptavidin, 5-PrP ). b) Relative changes of the current peak corresponding to the ferrocene oxidation C vs. concentration of PrP or bovine serum albumin (BSA), respectively (ΔI=I-I0, where I0 and I are amplitudes of the current prior and after addition of the analyte, respectively).

Recently we developed new approach for aptamer immobilisation using electropolymerized layer of Neutral Red (NR) at glassy carbon electrode (GCE) onto which polycarboxylated thiacalix[4]arene has been adsorbed by electrostatic accumulation. NR and aminoterminated thrombin-specific aptamer were then covalently linked to the thiacalixarenes by EDC-NHS chemistry (Fig. 2) [8]. The NR reduction

[1] A.D. Ellington, J.W. Szostak, Nature, 346 (1990) 818. [2] T. Hianik, A. Porfireva, I. Grman, G. Evtugyn, Protein and Peptide Letters, 15 (2008) 799. [3] T. Hianik, I. Grman, I. Karpišová, Chem. Commun., 41 (2009) 6303. [4] S. Ponikova, K. Tlučková, M. Antalík, V. Víglaský, T. Hianik, Biophys. Chem., 155 (2011) 29. [5] T. Hianik, J. Wang, Electroanalysis, 21 (2009) 1223. [6] M. Mascini (Ed.) Aptamers in Bioanalysis, Wiley, New Jersey, 2009. [7] T. Hianik, A. Porfireva, I. Grman, G. Evtugyn, Protein and Peptide Letters, 16 (2009) 363. [8] G. Evtugyn, V. Kostyleva, c R. Sitdikov, A. Porfireva, M. Savelieva, I. Stoikov, I. Antipin, T. Hianik Electroanalysis, 24 (2012) 91.

Figure 2. General scheme of the aptasensor assembling for detection thrombin at glassy carbon electrode. Neutral Red (NR) is the electroactive probe [8].

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Ultrafast X-ray nanowire single-photon detectors and their energy-dependent response

Kevin Inderbitzin1, A. Engel1, A. Schilling1, K. Ilâ&#x20AC;&#x2122;in2 and M. Siegel2 kevin.inderbitzin@physik.uzh.ch

Physics Institute, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland Institute for Micro- and Nanoelectronic Systems, Karlsruhe Institute of Technology, Hertzstr. 16, 76187 Karlsruhe, Germany

More than a decade before the successful development of superconducting nanowire singlephoton detectors (SNSPD) for the optical and nearIR wavelength range [1], serious efforts were undertaken to use this detection principle for the detection of X-ray photons with keV-energies [2]. However, these preliminary X-ray detectors struggled with problems regarding the relaxation back into the superconducting state after photon detection, called latching, making it difficult to operate the devices in a continuous detection mode. Recently, SNSPDs were used in time-of-flight spectrometry of molecules [3, 4]. For this purpose, a SNSPD from 5 nm thin NbN was successfully tested for X-ray detection in a feasibility study [5]. However, the absorptivity of thin NbN films for Xray photons and therefore the quantum efficiency of the detectors were low. In order to enhance the absorptivity of the superconducting detector, we fabricated an X-ray superconducting nanowire single-photon detector (X-SNSPD) from 100 nm thick niobium (Fig. 1(a)). The detector geometry was designed for a kinetic inductance large enough to significantly reduce the above mentioned problem with continuous photon detection, and small enough for ultrafast pulse recovery times. We report on the detection of X-ray photons [6] with keV-energies in continuous mode with an ultrafast pulse recovery time TP of less than 4 ns (Figs. 1(b) and (c)) and an average pulse rise time of about 190 ps (Fig.1(d)), the latter being limited by our electronics setup. In contrast to optical photondetection in thin-film SNSPDs, X-ray photon detection was possible even at bias currents

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smaller than 0.4 percent of the critical current (Fig. 2 inset (a)).

Figure 1. (a) Optical image of examined X-SNSPD from 100 nm thick niobium. (b) Typical voltage pulses after X ray photon absorption, with definition of the pulse length TP shown schematically. (c) Pulse length TP histogram. (d) Pulse rise time histogram (time spans between 15 and 85 percent of pulse amplitude). For (b) (d) the X SNSPD was irradiated by the X-ray tube with an acceleration voltage of 49.9 kV.

Most remarkably, we observed that the X-SNSPD signal amplitude distribution depends significantly on the acceleration voltage of the photon emitting X-ray tube. Figure 2 shows the corresponding normalized pulse amplitude histograms at different acceleration voltages between 7 kV and 50 kV. Since the detector operates in a single-photon detection mode (Fig. 2 inset (b)) the variation of the signal amplitude distribution can be attributed to the variation of the photon energy spectrum at different X ray tube settings. This phenomenon, which is new for SNSPDs, is explained by the orders-of-magnitude smaller resistance of the normal conducting domains as compared to the

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situation in thin-film SNSPDs. For acceleration voltages of the X-ray tube larger than 12.5 kV, we observe distinct preferred signal amplitudes (see arrows in Fig. 2) which we may tentatively ascribe to the main characteristic emission lines of the tungsten target at 8.4 kV and 9.7 kV, for which a minimum excitation energy equal to 10.2 keV or 11.5 keV resp. is necessary. These observations may hint to a certain energy-resolving capability of our niobium X-SNSPD.

Figure 2. Histograms of signal amplitudes from photons emitted by the X-ray tube at different tube acceleration voltages (indicated in the legend) and from photons emitted by a radioactive Fe-55 source, which mainly emits at 5.9 keV. The tube acceleration voltage determines the maximum energy of the emitted photons. The histograms use a bin size of 4 mV (5.2 mV for the Fe-55 data respectively) and are normalized at 79 mV, which lies below the noise level. The two arrows indicate preferred signal amplitudes which may tentatively be ascribed to the main characteristic emission lines of the tungsten target at 8.4 kV and 9.7 kV. Inset (a) shows a plot of the count rate as a function of the reduced bias current at an acceleration voltage of 49.9 kV. Inset (b) shows that the X-SNSPD photon count rate is proportional to the photon flux, which is varied by the X-ray tube anode current.

sources, free-electron lasers and hot plasmas (as in nuclear fusion experiments). In addition, X-SNSPDs from 100 nm thick TaN have been fabricated and characterized, which show an increased X ray absorptivity and reduced sensitivity for latching compared to the X-SNSPD from Nb.

References [1] G. N. Gol’tsman, O. Okunev, G. Chulkova, A. Lipatov, A. Semenov, K. Smirnov, B. Voronov, A. Dzardanov, C. Williams, and R. Sobolewski, Appl. Phys. Lett., 79 (2001) 705 [2] A. Gabutti, R. G. Wagner, K. E. Gray, R. T. Kampwirth, and R. H. Ono, Nucl. Instrum. Methods A, 278 (1989) 425. [3] K. Suzuki, K. Suzuki, S. Miki, Z. Wang, Y. Kobayashi, S. Shiki, and M. Ohkubo, J. Low Temp. Phys., 151 (2008) 766. [4] N. Zen, A. Casaburi, S. Shiki, K. Suzuki, M. Ejrnaes, R. Cristiano, and M. Ohkubo, Appl. Phys. Letters, 95 (2009) 172508. [5] D. Perez de Lara, M. Ejrnaes, A. Casaburi, M. Lisitskiy, R. Cristiano, S. Pagano, A. Gaggero, R. Leoni, G. Golt’sman, and B. Voronov, J. Low Temp. Phys., 151 (2008) 771. [6] K. Inderbitzin, A. Engel, A. Schilling, K. Il’in, and M. Siegel, to be published

Moreover, no dark count events were triggered in over five hours of measurement, even with bias currents very close to the critical current. Our results show that ultrafast dark-count-free XSNSPDs can be fabricated which can operate in a large spectral range. They could find applications where very high count rates, precise timing, a good signal-to-noise ratio and response in a wide spectral range for photon counting are required, such as experiments with synchrotron X ray

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Nano-probing of the surface excited by keV photon: what should we detect for high spatial resolution?

Masashi Ishii ISHII.Masashi@nims.go.jp

National Institute for Materials Science (NIMS) 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, Japan

X rays, keV photons with high transmittance and low refraction indices, are not easy to focus on nano-scale area. Meanwhile, scanning probe microscopy (SPM) detecting physical properties is not favorable for chemical state mapping. SPM of x ray excited surface (X-SPM) is expected to compensate these disadvantages and be profitable for both of x-ray analyses and surface science: XSPM limits its detection area on nano-meter-scale under the tip and probes x-ray absorption sensitive to chemical states. Various SPMâ&#x20AC;&#x2122;s detecting photoelectrons, tunneling current, chemical bonding force, optical emission, etc., have been examined to detect the x-ray absorption for this technique. Now we confront a problem: What should we detect in X-SPM? In spite of considerable efforts by a lot of researchers on this field, we still have difficulties with this technique. These are mainly caused by a little x-ray absorption effect on surface and high background level owing to x-ray excitation of deeper and wider region than the probing area with SPM. In order to solve these difficulties, we developed X-SPMâ&#x20AC;&#x2122;s based on two original ideas, (1) lifetime conversion and (2) AC detection [1-3].

the valence states. The valence states excitation normally has long lifetime of ~ms detectable with SPM. The conversion from ~fs to ~ms realizes high efficient detection equivalently. Generally speaking, the localized electrons can be found in defects, surface, interface, etc. These localized electrons have a great potential to induce functionality and significant change in material properties. This fact indicates that we can discuss the scientific interests with X-SPM using the lifetime conversion technique.

Figure 1. Lifetime conversion from fs to ms.

(1) Lifetime conversion

(2) AC detection

It is well known that the lifetime of inner-shell excitation by x rays is about femtoseconds, fs. It is obviously undetectable time for SPM. Therefore, we focused on specific objects which have metastable excitation states with a long lifetime of milliseconds, ms. As show in Fig. 1, if a sample has localized electrons in valence states, a sequential relaxation after the x-ray excitation finally ionizes

Basically, DC current (including photocurrent and tunneling current) detections with SPM receive significant background of photoelectrons from the outside of the probing area. Therefore, we detected AC current or force instead of the DC current. Since the AC current can be represented with impedance, capacitance probe, i.e., scanning capacitance microscope (SCM) is available for the

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X-SPM. Figure 2 shows the first report of x-ray absorption spectra obtained with SCM [1]. The successful application of SCM suggests that other related techniques such as EFM (Electrostatic Force Microscopy) and KFM (Kelvin Force Microscopy) can be used for X-SPM. The force detection is more effective to avoid the photoelectrons. By using EFM, we achieved chemical mapping with a spatial resolution of a few nm [2].

Surface defects

In spite of these particular successes, application to general samples is not established. In these methods, the lifetime of the localized electrons in the valence states determines the detection efficiency. Unfortunately, the lifetime strongly depends on samples and is unknown factor normally. We recently developed another technique, (3) charge confinement for the lifetime control. As shown in the inset of Fig. 3, when AC electric field is applied to samples, the charges are confined in trapping levels above some frequency corresponding to an escape time of the charges. Figure 3 shows an experimental evidence of the charge confinement in TiO2. The charges are confined above 1 kHz with an impedance peak, resulting in enhancement of luminescence from Sm dopants as a marker [4]. We conclude that AC frequency is a key parameter for the lifetime control for technique (2). EFM with a wider bandwidth AC oscillator is expected to realize XSPM for more general samples.

References Figure 2. X-SCM for the AC detection technique.

[1] M. Ishii, Jpn. J. Appl. Phys. 41, 4415 (2002). [2] M. Ishii, B. Hamilton, N. R. J. Poolton, N. Rigopoulos, Stefan De Gendt, and K. Sakurai, Appl. Phys. Lett. 90, 063101 (2007). [3] M. Ishii, B. Hamilton, and N. R. J. Poolton, J. Appl. Phys. 104, 103535 (2008). [4] M. Ishii, S. Harako, X. Zhao, S. Komuro, and B. Hamilton, Appl. Phys. Lett., 99, 101909 (2011).

Figure 3. Charge confinement using AC frequency tuning.

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On the origin of RTS noise in nanoFETs Group of Microsystems and Electronic Materials. GMME-CEMDATIC ETSIT. Universidad Politécnica de Madrid. 28040-Madrid. Spain.

Electronic nano-devices are giving rise to new phenomenological effects, since the high surface to volume ratio associated to their nano-scale volume makes superficial effects to predominate over bulk effects. With the reduction of the size of the devices to the nano-scale, the modeling of some phenomena traditionally treated as statistical effects should be carefully revised. A clear example of these phenomena is the noise in nano-devices whose dimensions have been reduced looking for “zero trap” (or “zero dopant”), and thus “zero noise” devices. In this communication we analyze the Random Telegraph Signal (RTS) noise in a nano-scaled cylindrical transistor specifically designed to eliminate the presence of traps that commonly account for RTS noise in micro-sized devices [1], such as metal oxide semiconductor field effect transistors [2] or AsGa heterostructures [3]. We apply a new Admittance-based noise model [4], in which the electrical noise arises from Fluctuations of electrical energy in the susceptance of the device under test followed by their subsequent Dissipations by the accompanying conductance. This model, which complies with the thermodynamic laws and the principles of the quantum physics, has interesting repercussions in many systems, allowing to explain some of the effects [5,6] that are not well managed by the common theory in use today. In the field of electrical noise in field effect transistors, which is considered in this communication, it explains in a simple way the RTS instability observed in nano-

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Jose Ignacio Izpura, Enrique Iborra and Marta Clement joseignacio.izpura@upm.es

scaled cylindrical transistors which are designed looking for a “zero-trap-device”. Contrary to common theory where the low–frequency noise in FETs has been attributed to modulation in mobility and/or carrier density owing to the trapping and de-trapping processes taking place at bulk and interface states, the Admittancebased model shows that any phenomenon that modulates the space charge region in the vicinity of the semiconductor surface causes a modulation of the channel trough the familiar Field-Effect used in transistors and not by an unlike (though possible) modulation of the channel conductivity. In particular, this explains why trapping effects appear in the “zero-trap” transistor presented in [1]. In this case, the ungated (thus uncontrolled) channel portion outside the controlling gate is the responsible of the excess of noise. Not only the Admittance-based model accounts for this excess of noise but also explains the tunability of this RTS noise with a surface voltage, which is disregarded in the traditional model. In conclusion, the fluctuation-dissipation phenomena (noise) that take place by individual particles (electrons, phonons, polarons, etc) in nano-scaled electronic devices can be totally explained with the new Admittance-based model of noise. A correct evaluation of this noise based in thermodynamics and quantum mechanics principles is of major interest for designing new devices.

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References [1] T. A. Kramer, R. F. W. Pease, “Low frequency noise in sub-100 nm MOSFETs”, Physica E, 19, (2003), pp. 13-17. [2] K.K. Hung, P.K. Ko, Chenming Hu, Yiu Chung Cheng. “Random Telegraph Noise in DeepSubmicrometer MOSFETSs”, IEEE Electron. Dev. Let., 11 (1990), pp. 90-92. [3] C. Surya, Sze-Him Ng, E.R. Brown, and P.A. Maki. “Spectral and random telegraph noise characterizations of low-frequency fluctuations in GaAs/Al0.4Ga0.6As resonant tunneling diodes” Electron Devices, IEEE Trans. 41 (1994), pp. 2016-2022. [4] J. I. Izpura, J. Malo, “A Fluctuation-Dissipation model for electrical noise,” Circuits and Systems, Vol. 2, No. 3, 2011, pp. 112-120. [5] J. I. Izpura, “On the electrical origin of flicker noise in vacuum devices,” IEEE Trans. Instrum. Meas., Vol. 58, 2009, pp. 3592-3601. [6] J. I. Izpura, J. Malo, and E. Iborra, “On the effects of Electronic Feedback in the noise of MEMS and two-Terminal Devices”. Sensors and Actuators A, To be published.

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Design of atom and single molecule boolean logic gates

C. Joachim

Nanoscience Group & MANA Satellite CEMES-CNRS Toulouse AtMol (www.atmol.eu) A*STAR VIP Atom Tech, IMRE Singapore

An atomic scale Boolean logic gate is a single quantum system (a molecule or a surface dangling bond circuit) electronically interacting with atomic scale metallic electrodes supposed to perform alone an â&#x20AC;&#x153;M inputs - P outputsâ&#x20AC;? digital logic function. All the known designs of atomic scale logic gates: semi-classical circuits, quantum Hamiltonian circuits and qubit circuits are different versions of a quantum control. Semi-classical and quantum circuit design rules will be recalled. They differ in the way the classical input data are encoded on the quantum system and how the quantum to classical conversion proceeds at the outputs. A quantum design also can benefit from decoherence coming from the interconnections in a way to be planar implanted at the surface of a passivated semiconductor as explored in the AtMol Integrated European Project.

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Calibrated nanoscale capacitance and dopant profile measurements using a novel nearfield scanning microwave microscope 1

Agilent Technologies Austria, Mooslackengasse 17, 1190 Vienna, Austria JKU University of Linz, Institute for Biophysics, Altenbergerstr. 69, 4040 Linz, Austria 3 Agilent Technologies Inc., NanoDivision, 4330 W. Chandler Blvd., Chandler, AZ 85226, USA 4 National Institute for Standards and Technology (NIST), Electromagnetic Division, Boulder, CO, USA 5 Technical University of Vienna, Institute for Solid State Electronics, Floragasse 7, 1040 Vienna, Austria 2

A scanning microwave microscope (SMM) for spatially resolved capacitance measurements in the attoFarad-to-femtoFarad regime is presented. The system is based on the combination of an atomic force microscope (AFM) and a performance network analyzer (PNA).

Figure 1. SiO2 staircase in 3D-topography view (left) and corresponding PNA amplitude signal (right) used for calibrated capacitance measurements.

For the determination of absolute capacitance values from PNA reflection amplitudes, a calibration sample of conductive gold pads of various sizes on a SiO2 staircase structure was used (figure 1). The thickness of the dielectric SiO2 staircase ranged from 10 nm to 200 nm. The quantitative capacitance values determined from the PNA reflection amplitude were compared to control measurements using an external capacitance bridge [1]. Depending on the area of the gold top electrode and the SiO2 step height, the corresponding capacitance values, as measured with the SMM, ranged from 0.1 fF to

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Gerald Kada1, Matthias A. Fenner1, Hans-Peter Huber2, Hassan Tanbakuchi3, Manuel Moertelmaier1, Pavel Kabos4,5Juergen Smoliner5, Peter Hinterdorfer2 and Ferry Kienberger1 Gerald_Kada@Agilent.com

22 fF at a noise level of ~2 aF and a relative accuracy of 20% [2]. For dopant profiling, n- and p-doped reference samples with densities between 1014 and 1019 atoms/cm3 in 1.5 micron-wide regions were imaged in dC/dV modulation mode (figure 2). A calibration curve relating signal levels and dopant densities was established [3]. Possible applications of an SMM range from quality control of integrated circuits (ICs), solar cells, and other semiconductor devices to materials science, (e.g. measurements of quantum dot dielectric constants), and to bioscience (e.g. the detection of viruses, and thickness measurements of protein layers). Examples shown will include capacitance and dielectric measurements on organic thin films (SAMs), graphene, nanotubes and nanowires as well as magnetic bacteria.

Figure 2. Si Dopant density calibration test sample with 14 19 densities ranging from 10 (left side, yellow) to 10 3 Atoms/cm (right side, blue.)

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Abstracts

[1] H.P. Huber, M. Moertelmaier, T.M. Wallis, C.J. Chiang, M. Hochleitner, A. Imtiaz, Y.J. Oh, K. Schilcher, M. Dieudonne, J. Smoliner, P. Hinterdorfer, S.J. Rosner, H. Tanbakuchi, P.Kabos, F. Kienberger, Rev Sci Instrum, 81 (2010) 113701. [2] J. Smoliner, H.-P. Huber, M. Hochleitner, M. Moertelmaier, F. Kienberger, J Appl Phys, 108 (2010) 064315. [3] H. P. Huber, I. Humer, M. Hochleitner, M. Fenner, M. Moertelmaier, C. Rankl,A. Imtiaz, T. M. Wallis, H. Tanbakuchi, P. Hinterdorfer, P. Kabos, J. Smoliner, J. J. Kopanski, and F. Kienberger. J Applied Phys 111(2012), 014301.

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References

Optical limiting by absorption bleaching in carbon nanotube devices: comparison of field-induced and electrochemically-induced charge injection

W. Joshua Kennedy william.j.kennedy@nasa.gov

NASA Johnson Space Center 2101 NASA Parkway B13 ES4, Houston, USA

We studied direct charge injection in a heterogeneous film of single-wall carbon nanotubes using the technique of charge-induced absorption. We found that the injected charges screen the excitons in the semiconducting tubes, reducing their binding energy and transferring oscillator strength from the exciton transitions to free carriers. These effects parallel those of the electrochemical doping in the same samples. Furthermore, we interpret the bleaching bias in the electroabsorption (a chi-3 process) in isolated SWNT as being due to injected charges, which has implications for a variety of SWNT-based optoelectronic devices. I will discuss the experiments and some potential methods for using this effect in optoelectronic switches.

References [1] W. Joshua Kennedy and Z. Valy Vardeny, Applied Physics Letters, 98 (2011) 263110. [2] Christoph Gadermaier, Enzo Menna, Moreno Meneghetti, W. Joshua Kennedy, Z. Valy Vardeny, and Guglielmo Lanzani, Nano Letters, 6 (2006) 301-305

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V. Labunov1, A. Prudnikava1, I. Komissarov1, B. Shulitski1, Y. Shaman2, V. Galperin2 and A. Basaev2

Novel “Carbon Nanotube/Graphene Layer” nanostructures obtained by injection CVD method for electronic applications 1

Belarusian State University of Informatics and Radioelectronics, Brovka Str. 6, Minsk 220027, Belarus 2 Technological Center, Moscow State Institute of Electronic Technology, K-498, Moscow 103498, Russia

As it was predicted theoretically, a 3D network nanostructure, composed of parallel graphene layers stabilized by vertically aligned CNTs, when doped with lithium cations can be efficient structure for hydrogen storage [1], and, moreover, this nanostructure is considered as a novel material with tailored multidimensional thermal transport characteristics [2]. First practical realization of CNT/graphene nanostructures with vertically aligned CNTs grown in between the graphene layers by CVD method was reported in ref. [3]. The exfoliated graphene oxide was selected as the substrate to grow CNTs. These nanostructures have been successfully used as the electrodes in supercapacitors. The existence of CNTs in these nanostructures significantly enhanced the graphene property by, as believed, bridging the defects for electron transfer and increasing the basal spacing between graphene sheets.

Composite carbon structures were synthesized by the injection CVD method using xylene/ferrocene solution, as described in refs [4, 5]. Rate of injection was varied in the range 0,01-0,2 cm3/min. The constant flow of Ar (100 cm3/min) through a reactor was provided during the processes of reactor heating and cooling and CNTs synthesis. The content of ferrocene in the feeding solution was 1,0 (wt %). The process was carried out at the atmospheric pressure at the working temperatures of 850˚C. Wafers of n-type Si with 600 nm thermal oxide layer were used as substrates. The elemental composition were investigated by Auger and EDX spectroscopy, structural characterization was performed using scanning and transmission electron microscopy, Raman Spectroscopy. а

However, the proposed method of CNT/graphene nanostructures realization is extremely complicated. The experimental fabrication of such nanostructures with the low cost processes is challenging. Present investigation is devoted to the creation of composite nanostructures of the arrays of vertically aligned CNTs and the planar graphene (graphite) layers (PGL) located at the top of the CNT arrays (CNT-PGL nanostructures) by using the only one-step process - the most simple and low cost CVD process with the injected catalyst realized at ambient conditions. One-layer [4], as well as multi-layer nanostructures [5] were created. The last nanostructures we designated as CNT-PGL nanostacks.

TNT 2012 madrid (spain)

labunov@bsuir.by

SiO2 Si

Figure 1. SEM images of the fragments of the one-layer CNT-PGL nanostructure: (a) nanostructure formed on Si/SiO2 substrate, (b) graphene strips detached from the surface of CNT array at different magnifications, (c) back side of a strip with the attached CNTs.

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The growth mechanism of one- and multi-layer CNTPGL nanostructures was proposed.

In Fig. 1 the SEM images of the fragments of onelayer CNT-PGL nanostructure are presented. It was proved that the structure consists of carbon, i.e. represents CNT-PGL structure indeed. What is particular, PGL can be easily detached from the CNT array (Fig. 1a-d). The strips of graphene may be used for the production of different devices or for the physical experiments.

0.5 μm

In Fig. 2 it is shown that by the developed technology one can produce any number of layers of CNT-PGL nanostructures. For example, three-layer (Fig. 2a) and four-layer (Fig. 2b) nanostructures are presented. a

0.4 μm

Figure 3. (a, b). “Disordered” CNT/graphene nanostructures shown at different magnifications (SEM).

In our approach the high-quality CNT/graphene nanostructures are produced by a very low cost process. We expect to observe extraordinary electrical properties of these structures and compatible commercialization conditions with any other approach. Moreover, the used CVD technique is versatile and scalable. The obtained nanostructures can enable many applications including high-performance elastic and flexible conductors, electrode materials for lithium ion batteries and supercapacitors, thermal management, catalyst and biomedical supports, electrical energy storage devices based on this new class of carbon material, and so on.

References 3 μm

Figure 2. SEM images of multi-layer CNT-PGL nanostructures: (a) three-layer (indicated with arrows) and (b) four-layer nanostructures.

The CNT-PGL nanostructures presented in Figs. 1,2 are “ordered” nanostructures, because they demonstrate strongly organized configuration of CNT-PGL layers. Another type of CNT/graphene nanostructures, “disordered”, obtained by the same method, but in different regimes are presented in Fig. 3.

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[1] Dimitrakakis, G.; Tylianakis, E.; Froudakis, G., Nano Letters, 10 (2008) 3166-3170. [2] Varshney, V.; Patnaik, S.; Roy, A.; Froudakis, G.; Farmer, B., ACS nano, 2 (2010) 1153-1161. [3] Fan, Z.; Yan, J.; Zhi, L.; Zhang, Q.; Wei, T.; Feng, J.; Zhang, M.; Qian, W.; Wei, F., Advanced Materials, 33 (2010) 3723-3728. [4] Labunov, V. A.; Shulitski, B. G.; A.L. Prudnikava; Y.P. Shaman; Basaev, A. S., Semiconductor Physics, Quantum Electronics & Optoelectronics, 2 (2010) 137-141. [5] Labunov, V.; Shulitski, B.; Prudnikava, A.; Basaev, A., physica status solidi (a) (2010) 1-6.

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Emergent non-scalable behavior in the nanoscale

Uzi Landman

School of Physics, Georgia Institute of Technology Atlanta, GA 30332-0430 USA

Finite materials systems of reduced sizes exhibit discrete quantized energy level spectra and specific structures and morphologies, which are manifested in unique, non-scalable, size-dependent physical and chemical properties. Indeed, when the scale of materials structures is reduced to the nanoscale, emergent behavior often occurs, that is not commonly expected, or deduced, from knowledge learned at larger sizes. Characterization and understanding of the size-dependent evolution of the properties of materials aggregates, and their propensities for size (“magic numbers”) and shape self-selection and for self-assembly, are among the major challenges of modern materials science. Using computer-based first-principles quantum computations and simulations [1], often in conjunction with laboratory experiments, we highlight and illustrate such behavior in diverse nano-scale systems. In particular, we focus on the following topics: (i) Charging effects in Nanocatalysis [2], (ii) Pathways of post-ionization proton-coupled-electron-transfer (PCET) DNA reactions underlying mutagenesis and malignancy, and involving a segmented water-wire transport mechanism [3]; (iii) Coexistence of correlated electron liquids and weakly-pinned Wigner crystals under high magnetic fields in the fractional quantum Hall effect regime, observed recently in the neighborhood of 1/3 fractional filling in 2D semiconductor quantum dots, and explained by a unified microscopic theory [4].

References [1] U. Landman, “Materials by Numbers: Computations as Tools of Discovery”, Proc. Nat. Acad. Sci. (USA) 102, 6671 (2005). [2] A. Sanchez, et al., J. Phys. Chem. A 103, 9573 (1999); B. Yoon, et al., Science, 307, 403 (2005); U. Landman, et al., Topics in Catalysis 44, 145 (2007); S. M. Lang, et al., JPC C 115, 6788 (2011); B. Yoon, et al., JPC C 116, 9594 (2012); [3] R.N. Barnett, et al., Science 294, 567 (2001); J. Am. Chem. Soc. 128, 10798 (2006); Acct. Chem. Res., 43, 280 (2010); J.J Joseph et. al., Am. Chem. Soc. (2012). [4] C. Yannouleas and U. Landman, Phys. Rev. B 84, 165327 (2011).

* Supported by the US Department of Energy and the Air Force Office of Scientific Research.

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Fabrication and characterization of nanopores in Si based materials

Liebes Yael, Rapaport Hanna and Ashkenasy Nurit nurita@bgu.ac.il

Ben-Gurion University of the Negev, P. O. Box 653, Beer-Sheva, Israel

The use of single nanopores (NPs) as biomolecule sensing elements has gained a lot of interest in recent years. In such biosensors the change in ionic current when the analyte molecule translocates through the NP is monitored, providing both quantitative and qualitative analytical information. The membrane’s material is important factor for determining the resulting shape and surface properties that are extremely important for the sensing process, and also affects fabrication conditions. Thus, there is a constant quest for novel techniques allowing the fabrication of NPs tunable, in both size and materials properties. Herein, we present fabrication, electrical and shape characterization methodologies of NPs drilled in silicon based membranes, including Si3N4, crystalline Si and multilayered SiO2/Si/SiO2 membranes. A novel method for the fabrication of NPs using focused electron beam induced etching (FEBIE) will be presented [1-3]. In this technique, pores are etched by a cyclic process of reducing either nitride or oxide membrane to elementary oxide followed by spontaneous etching of the Si by XeF2. NPs can be drilled with high precision with diameter in the range of 10–200 nm, depending on electron exposure time and acceleration voltage, and XeF2 pressure. The 3D shape of the NP is shown to depend on the type of membrane used. Forming NPs in both Si3N4 and SiO2/Si/SiO2 multilayers membranes results in a funnel-like shape NPs [2, 3]. However, in the latter case cylindrical shape can be obtained, depending on the post exposure time to XeF2. This method facilitates the formation of high aspect-ratio structures in rather thick membranes, for which other the traditional NP drilling by transmission electron microscope (TEM) fails. Additionally, due to the chemical nature of the

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method, the chemical structure of the NP rims is identical to that of the bulk material. This single step process opens the way to fast integration with silicon technology, making the suggested devices especially suited for lab-on-chip applications.

I will further present a model we developed to extract the 3D shape of the NPs from the dependence of the ionic conductance of NPs on the ionic strength of the electrolyte used in the experiments [4], eliminating the need for elaborated and expensive electron microscope analysis. The suggested methodology can be used to monitor changes in the NP shape after manufacture and during electrical characterizations with high precision.

References [1] Yemini M, Hadad B, Liebes Y, Goldner A and Ashkenasy Nanotechnology, 20 (2009) 245302. [2] Liebes Y, Hadad B and Ashkenasy N, Nanotechnology 22 (2011) 285303. [3] Liebes Y., Bandalo V., Sökmen Ü., Tornow Marc and Ashkenasy N., (submitted). [4] Liebes Y, Drozdov M, Avital Y Y, Kauffmann Y, Rapaport H, Kaplan W D and Ashkenasy N, Appl. Phys. Lett. 97 (2010) 223105. TNT 2012 madrid (spain)

Rapid conversion from protein-caged nanomaterials to microbubbles: a sonochemical route toward bimodal imaging agents †

‡

Departments of Biomedical Engineering, Physics, Bioscience Technology, Center for Nano Bioengineering, and Center for Nano-Technology, Chung Yuan Christian University, Chung-Li 32023, Taiwan; + Department of Biomedical Engineering and Environmental Sciences, National Tsing Hua University, Hsinchu 30013, Taiwan; ┴ Departments of Medical Research and Internal Medicine, Mackay Memorial Hospital, and Department of Medicine, Mackay Medical College, Taipei 10449, Taiwan; # Department of Health Developing and Health Marketing, Kainan University, Taoyuan 33857, Taiwan; ║ Graduate Institute of Clinical Medicine, Graduate Institute of Medical Sciences, and Graduate Institute of Biomaterials, Taipei Medical University, Taipei 110, Taiwan

We report a facile method for nanoparticle (NP)coated microbubbles (MBs), which can be used for bimodal ultrasound contrast agent. Based on our previous reported amphiphilic polymer [1], hydrophobic NPs not only can be transferred to aqueous solution, but can offer a universal surface for proteins assembly as core-shell complex of NP/protein corona. The polycarboxylate polymer was used successfully for linking inorganic colloidal NPs of different materials (Au, CdSe/ZnS, Fe3O4) to BSA protein corona. A second type of protein-caged nanomaterials, protein-caged gold nanoclusters (AuNCs) can be synthesized by intra-protein “biomineralization” or self-assembly of AuNCs with proteins, thus resulting in high photoluminescence in red to near-infrared emission. Both types of proteincaged nanomaterials can be rapidly converted into MBs by introducing sonochemical route, which promote disulfide crosslinking of cysteine residues between protein-caged nanomaterials and free albumin during acoustic cavitation. Further, the functionalization of MBs can be easily achieved by adjusting the original NP/protein mixture. We also demonstrated different imaging modalities with biocompatible AuNC-coated MBs, used in conjunction with both in vitro/ in vivo ultrasound and TNT 2012 madrid (spain)

Cheng-An J. Lin†§, Wen-Kai Chuang†, Zih-Yun Huang†, Shih-Tsung Kang+, Ching-Yi Chang†, Ching-Ta Chen†, Jhih-Liang Li†, Jimmy K. Li†, Hsueh-Hsiao Wang┴, FuChen Kung#, Ji-Lin Shen‡§, Wen-Hsiung Chan¶§, ChihKuang Yeh+, Hung-I Yeh┴, Wen-Fu T. Lai║ and Walter H. Chang†§ chengan_lin@cycu.edu.tw

fluorescent imaging, which can held many potential applications in medical diagnostics and therapy [2].

Figure 1. Scheme of synthesis of protein-caged nanomaterials toward dual-functional MBs.

References [1] Lin, C.-A. J.; Sperling, R. A.; Li, J. K.; Yang, T. Y.; Li, P. Y.; Zanella, M.; Chang, W. H.; Parak, W. G. J., Design of an amphiphilic polymer for nanoparticle coating and functionalization. SMALL 2008, 4, (3), 334-341. [2] Lin C. A. J., Chuang W.K., Huang Z.Y., Kang S.T., Chang C.Y., Chen C.T., Li J.L., Li J.K., Wang H.H., Kung F.C., Shen J.L., Chan W.H., Yeh C.K., Yeh H.I., Lai W.F.T., and Chang W.H., Rapid Transformation of Protein-Caged Nanomaterials into Microbubbles As Bimodal Imaging Agents, ACS Nano, ASAP, 2012. DOI: 10.1021/nn300768d. september 10-14, 2012

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Nanopillars as plasmonic platform to enhance nonlinear vibrational sumfrequency generation spectroscopy 1

Lasers and Spectroscopies Laboratory (LLS), Research Centre in Physics of Matter and Radiation (PMR), University of Namur (FUNDP), Belgium 2 Institute of Condensed Matter and Nanosciences - Bio & Soft Matter (IMCN/BSMA), Université catholique de Louvain (UCL), Belgium 3 it4ip, Seneffe, Belgium

Metallic nanostructures such as nanopillars and nanoantennas are able to confine the energy of an incident radiation into volumes much smaller than the wavelength of incoming waves through localized surface plasmon resonance (LSPR) [1]. This electromagnetic-field enhancement, attributed to the collective motion of free electrons, has been extensively used for surface-enhanced Raman scattering (SERS) and other surface-enhanced spectroscopic processes. This has driven metal nanostructures to become a powerful tool for chemical and biological optical sensing experiments[2]. In this work, we coupled such localized electromagnetic-field enhancement effect to a nonlinear second-order optical spectroscopy to obtain high molecular signal intensity and sensitivity. The technique is based on a three waves mixing process in which one infrared (ω1) and one visible (ω2) photon interact together with matter to generate a new coherent photon at the sum frequency (ωsfg = ω1 +ω2). The whole process relying on the second order nonlinear susceptibility χ(2), the sum frequency generation (SFG) signal can be emitted only where the centrosymmetry is broken, that is at surfaces and interfaces separating two bulk media[3,4]. In fine, SFG spectroscopy is a background free vibrational surface-sensitive spectroscopy able to retrieve accurate information on molecular thin films properties, such as conformation, orientation, dynamics, biorecognition processes, phase transitions.

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Dan Lis1, Yves Caudano1, Marie Henry2, Sophie DemoustierChampagne2, Etienne Ferain3 and Francesca Cecchet1 dlis@fundp.ac.be

Here, we report a strong enhancement of the vibrational SFG signal from molecules adsorbed on metallic nanopillars when those latter are excited at their localized plasmon resonance frequencies. In detail, gold nanopillars, sizing around 100 nm in height and 60 nm in diameter, stand vertically on a substrate of gold or platinum. The nanopillars exhibit two plasmon modes that can be selectively excited by the incident visible laser beam or by the generated SFG beam itself. Until now, for a density of 109 nanopillars/cm2, the molecular SFG signal obtained on such nanostructured surfaces is more than 100 times larger that what can be achieved on unstructured flat surfaces. Besides, because of the directional profile of the two plasmon modes, an adequate choice of the beams polarizations and frequencies leads to a spatial selectivity of the SFG emission. It is indeed likely possible to selectively probe the molecules adsorbed onto the nanopillar side wall, the nanopillar top part (as shown on Figure 1), or the flat region of the substrate inbetween the pillars. This gives promising issues to set up label free vibrational bio-recognition platforms with “multi-zone” enhanced sensitivity.

References [1] L. Novotny and N. van Hulst, Nat. Photon. 5 (2011) 83 [2] Willets, K. A.; Van Duyne, R. P., Annu. Rev. Phys. Chem., 58 (2007) 267-297. [3] Shen, Y. R., Nature, 337 (1989) 519-525. [4] Vidal, F.; Tadjeddine, A., Rep. Prog. Phys. 68 (2005) 1095-1127.

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Abstracts

TNT2012 Figure 1. The left figure shows SFG spectra in ppp polarization (in the order SFG, Vis and IR beam) of a dodecanethiol (DDT) molecular film adsorbed over the sample surfaces. The red curve corresponds to the spectra of the DDT layer adsorbed over a flat platinum surface, while the blue curve is the spectra recorded on the gold nanopillar region when those latter have their longitudinal LSPR mode excited at 650 nm by the visible laser beam. A schematic representation of the the experimental conditions is shown in the right figure. An important SFG intensity increase (blue curve) is observed thanks to the excitation of the LSPR mode of the nanopillar.

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| 113

Nanoscale metallic and metal-ceramic multilayers for radiation-resistant applications

Javier LLorca javier.llorca@imdea.org

IMDEA Materials Institute, C/Erik Kandel 2, Tecnogetafe, 28906 Getafe (Madrid), Spain Depart. of Materials Science, Polytechnic University of Madrid, 28040 Madrid, Spain

High energy neutron and proton radiation can induce serious damage in structural metals, including void swelling and embrittlement. Hence the design of advanced metallic materials with significantly enhanced radiation tolerance is critical for the application of advanced nuclear energy systems. Nanoscale metallic and metal-ceramic multilayers are currently under consideration as potential candidates to overcome this problem as a result of their unique mechanical properties and of their ability to withstand radiation without degradation of the mechanical performance. Both behaviors come about as a result of the large area fraction of interfaces which control the multilayer mechanical properties and radiation resistance when the layer thickness is below 100 nm.

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In this presentation, the mechanical behavior of two nanoscale multilayer systems (Cu/Nb and Al/SiC) is analyzed as a function of processing route (magnetron sputtering or accumulated roll bonding), layer thickness (in the range 5 nm to 50 nm) and temperature (from room temperature up to 400ยบC). Results form novel nanoindentation and micropillar compression tests at different temperatures, combined with transmission electron microscopy and numerical modeling, together with current theoretical models are used to understand the dominant deformation and fracture micromechanisms of this novel nanostructured materials.

TNT 2012 madrid (spain)

Hierarchical micro-nano-structures for cell adhesion studies a

Nanotechnology Platform, Parc Científic Barcelona, 08028 Barcelona, Spain Advanced Digital Microscopy Core Facility, Inst. for Research in Biomedicine, 08028 Barcelona, Spain c Institut de Bioenginyeria de Catalunya, 08028 Barcelona, Spain b

María Jesús López-Bosquea, Marina Cazorlaa, Judith Linaceroa, Esther TejedaMontesa, Yolanda Atienzaa, Anna Lladob, Julien Colombellib, Elizabeth Engelc, Alvaro Mataa mjlopez@pcb.ub.cat

Introduction The capacity to fabricate materials exhibiting welldefined features able to selectively interact with biology at cellular and subcellular levels has had tremendous implications in the field of tissue engineering. It is now well established that cell behaviors can be controlled, enhanced, or diminished by interacting with surface topographies of different size scales (1-3). However, the reasons behind these effects are not well understood and motivate the development of materials that facilitate the systematic study of celltopography interactions. With this in mind, we report two different fabrication processes to build hierarchical structures in a variety of different materials in order to investigate the competitive effects of micro and nanotopographies on cell adhesion, spreading, and morphology.

Materials and Methods Micro and nanofabrication techniques such as ion beam lithography (FIB), electron beam lithography (EBL), photolithography, and reactive ion etching (RIE) were combined to create micro/nano hierarchical structures on silicon. Two distinct strategies were developed in order to create high resolution surface topographies with the chance to build versatile designs. Then, these structures were transferred to a number of biocompatible polymers including polydimethylsiloxane (PDMS), polymethylmethacrylate (PMMA), low density polyethylene (LDPE), and recombinant elastin-like polypeptides (ELP). PMMA samples consisted on four different patterned areas with microchannels, nanochannels and perpendicular and parallel

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micro/nanochannels were fabricated in order to determine the competitive and synergetic effect of the micro- and nano-scale topographies in rat mesenchymal stem cells adhesion and morphology.

Results and Discussion Scanning electron microscopy (SEM) and atomic force microscopy (AFM) observations revealed that hierarchical topographical patterns consisting of perpendicular and parallel micro/nanochannels were fabricated in silicon and then these structures were successfully transferred to the different polymeric materials. Optical, widefield epifluorescence, confocal, and SEM observations revealed that the cells changed their morphology, alignment and elongation, depending on the different surface topographies (Fig. 1). Cell alignment and elongation significantly increased on parallel nano/microchannels (Figs. 1, 2). However, cells did not have a significant preference for micro or nanochannels in perpendicular region (Fig. 2).

Conclusions We have developed two distinct methods to fabricate hierarchical structures with high resolution and accurate topography control in silicon and biocompatible polymers. Due to the opportunity to interact with biology at both the nano and microscale, these types of hierarchical structures could be used for a variety of applications in tissue engineering and regenerative medicine. Surface topographies with hierarchical features expanding from the nano to the macroscale offer the possibility to synergistically improve the bioactivity of materials and control biological processes. september 10-14, 2012

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Abstracts

TNT2012 Figure 1. Representative fluorescence images of cells on (a) micro- (b) perpendicular (c) parallel and (d) nano-channels. (e-f) SEM and (g) fluorescence images (red=vinculin, green=actin cytoskeleton) of cells growing on perpendicular channels. Direction of nanochannels is schematically shown by white lines (b-d, g).

Figure 2. (a) Quantification of cell alignment revealing that cells are aligned preferentially along the micro-, nano- and parallel channels. However, cells sense the competitive effect of the micro- and nanoscale topographies, interacting with both micro- and nano-channels when perpendicular to each other. (b) Quantification of cell elongation revealing that cells sense the synergistic effect of the micro- and nano-topographies on parallel channels. The cells are significantly more elongated on parallel channels compared to the micro- and nano-channels individually.

References [1] M.J. Dalby, N. Gadegaard, R. Tare, A. Andar, M.O. Riehle, P. Herzyk, C. D. W. Wilkinson, R. O. C. Oreffo, Nature Materials 6 (2007) 997â&#x20AC;&#x201C;1003 [2] R. J. McMurray, N. Gadegaard, P. M. Tsimbouri, K. V. Burgess, L. E. McNamara, R.Tare, K. Murawski, E.Kingham, R. O. C. Oreffo, M. J. Dalby, Nature Materials 10 (2011) 637â&#x20AC;&#x201C;644 [3] A. Mata, L. Hsu, R. Capito, C. Aparicio, K. Henrikson, S. I. Stupp, Soft Matter 5(6) (2009) 1228â&#x20AC;&#x201C;1236

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Refractive index sensing based on plasmonic fano-like interference

F. López-Tejeira, R. Paniagua-Domínguez and J. A. Sánchez-Gil

Instituto de Estructura de la Materia (IEM-CSIC) Serrano 121 E-28006 Madrid, Spain

flt@iem.cfmac.csic.es

As Unlike those propagating at metal/dielectric interfaces, localized collective oscillations of charges confined to the surface of metal nanoparticles can be directly excited by external illumination without the need of any additional coupling-in technique, provided that particles are much smaller than the incident wavelength. These oscillations, which can be pictured as a “wave” of electrons moving across the surface of the particle, are referred to as localized surface plasmon resonances (LSPRs) and they are responsible of nanoparticles' bright colors when in colloidal suspension, as a result of their intense absorbing and scattering of light in the visible range. One of the most appealing properties of LSPRs is that their resonant frequency strongly depends on nanoparticles's size, shape and composition, as well as on the refractive index of the surrounding medium. Given that present technological advances allows one to control particle geometry down to nanometer scale, spectral shift of LSPRs can then be used to detect extremely small changes of the immediate dielectric environment. For instance, such as those produced by the binding of some biological molecules with a higher refractive index than that of their aqueous solvent. When assessing the actual performance of a refractive index sensing scheme based on the spectral shift of a given plasmon resonance, we have to first consider its refractive index sensitivity, which is defined as the linear regression slope within a given range for the position of the resonance (either a peak or a dip) as a function of refractive index. This magnitude is usually expressed in terms of wavelength or energy shifts per refractive index unit and it provides a preliminary measure of the sensor quality. However, sensitivity alone cannot characterize the sensor performance but in an ideal scenario of infinitely high spectral resolution and no TNT 2012 madrid (spain)

system noise. Sherry et al. [1] therefore proposed the so-called figure of merit (FoM), which is defined as the plasmon resonance sensitivity divided by its “Full Width at Half Maximum” (FWHM), as the most meaningful indicator for evaluating the performance of LSPR-based sensors. Such dimensionless quantity allows one to directly compare the sensing properties of different systems irrespective of their shape, size and operating wavelength. According to its very definition, the optimal FoM would then be obtained from those resonances exhibiting both high sensitivity to environment and narrow FWHM, which are precisely the main features of spectral line profiles arising from Fano interference [2]. Such an interaction of discrete- and continuum-like states (often labeled as “dark” and “bright” modes) has already been employed for refractive index sensing by means of either propagating or localized plasmon resonances. In this work [3], we propose that the Fano-like interference of longitudinal plasmon resonances occurring at a single nanorod [4] can be employed for refractive index sensing in two different configurations that are reasonably attainable. We also discuss their expected performance in terms of their FoMs, which are calculated under realistic conditions by means of the separation of variables (SVM) and the finite element (FEM) methods [5, 6].

References [1] L. J. Sherry et al., Nano Lett., 5 (2005) 2034. [2] B. Luk’yanchuk et al., Nat. Mater., 9 (2010) 707. [3] F. López-Tejeira, R. Paniagua-Domínguez and J. A. Sánchez-Gil, submitted. [4] F. López-Tejeira et al., New J. Phys., 14 (2012) 023035. [5] N. V. Voshchinnikov and V.G. Farafonov, Astrophys. Space Sci., 204 (1993) 19. [6] COMSOL Multiphysics version 4.2. september 10-14, 2012

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New intermediate band sulphide nanoparticles acting in the full visible light range spectra as an active photocatalyst

Raquel Lucena1, José Carlos Conesa1, Fernando Fresno1, Perla Wahnón2, Pablo Palacios2 and Yohanna Seminovski2 rlucena@icp.csic.es

Instituto de Catálisis y Petroleoquímica, CSIC, Marie Curie 2, 28049 Madrid, Spain. 2 Instituto de Energía Solar, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.

Nowadays one of the challenges of materials science is to find new technologies that will be able to make the most of renewable energies. An example of new proposals in this field are the intermediate-band (IB) materials, which promise higher efficiencies in photovoltaic applications (through the intermediate band solar cells), or in heterogeneous photocatalysis (using nanoparticles of them, for the light-induced degradation of pollutants or for the efficient photoevolution of hydrogen from water).

Figure 1. IB working principle: (a) photons of different energies excite electrons from the VB directly to the CB and also from the VB to the IB and from the IB to the CB. (b) A wider photon energy range is thus used.

Figure 2. Density of states (computed with DFT) of In2S3 with octahedral In partially substituted by V.

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An IB material consists in a semiconductor in which gap a new level is introduced [1], the intermediate band (IB), which should be partially filled by electrons and completely separated of the valence band (VB) and of the conduction band (CB). This scheme (figure 1) allows an electron from the VB to be promoted to the IB, and from the latter to the CB, upon absorption of photons with energy below the band gap Eg, so that energy can be absorbed in a wider range of the solar spectrum and a higher current can be obtained without sacrificing the photovoltage (or the chemical driving force) corresponding to the full bandgap Eg, thus increasing the overall efficiency. This concept, applied to photocatalysis, would allow using photons of a wider visible range while keeping the same redox capacity. It is important to note that this concept differs from the classic photocatalyst doping principle, which essentially tries just to decrease the bandgap. This new type of materials would keep the full bandgap potential but would use also lower energy photons. In our group several IB materials have been proposed, mainly for the photovoltaic application, based on extensively doping known semiconductors with transition metals [2], examining with DFT calculations their electronic structures. Here we refer to In2S3 and SnS2, which contain octahedral cations; when doped with Ti or V an IB is formed according to quantum calculations (see e.g. figure 2). We have used a solvotermal synthesis method to prepare in nanocrystalline form the In2S3 thiospinel and the layered compound SnS2 (which when undoped have bandgaps of 2.0 and 2.2 eV

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a) V:SnS2 30nm 23nm SnS2

100 0.020

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Absorption spectra of In2S3

0.018 0.016

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Figure 3. a) XRD diagram of SnS2 and V:SnS2 synthesized materials, indicating the nanocrystal size deduced from linewidths. b) V:In2S3 HR-TEM image of In2S3 with EDS measurement of the composition at the In2S3 nanocrystals. Kubelka-Munk transform: KM=(1-R)2/2R

k/s (KM function)

Figure 5. Rate constant k measured for aqueous HCOOH photooxidation under light of different wavelengths on In2S3 with and without ≈10% V doping, compared with the respective DR Vis-NIR spectra.

These materials are thus promising not only for degradation of pollutants (or for photovoltaic cells) but also for efficient photoevolution of hydrogen from water; work in this direction is now being pursued.

References 6

V:In2S3

In2S3 0 0.5

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E (eV)

Figure 4. Experimental diffuse reflectance spectrum of pure and V-doped nanocrystalline In2S3.

For both sulphide type nanoparticles (doped and undoped) the photocatalytic activity was studied by following at room temperature the oxidation of

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[1] A. Luque, A. Martí, Phys. Rev. Lett. 78, 1977, 5014. [2] a) P.Palacios et al. Phys. Rev. B 73 (2006) 085206; ibid. J. Chem. Phys. 124 (2006) 014711. b) P. Palacios et al. Thin Solid Films 515 (2007) 6280; ibid. J. Phys. Chem. C 112 (2008) 9525. c) P. Palacios et al. Phys. Rev. Lett. 101 (2008) 046403. [3] a) R. Lucena et al. Chem. Maters. 20 (2008) 5125. b) P. Wahnón et al. Phys. Chem. Chem. Phys.13 (2011) 20401. september 10-14, 2012

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formic acid in aqueous suspension, a simple reaction which is easily monitored by UV-Vis spectroscopy. The spectral response of the process is measured using a collection of band pass filters that allow only some wavelengths into the reaction system. Thanks to this method the spectral range in which the materials are active in the photodecomposition (which coincides with the band gap for the undoped samples) can be checked, proving that for the vanadium substituted samples this range is increased, making possible to cover all the visible light range. Furthermore it is checked that these new materials are more photocorrosion resistant than the toxic CdS witch is a well know compound frequently used in tests of visible light photocatalysis.

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respectively) where the cation is substituted by vanadium at a ≈10% level. This substitution has been studied, characterizing the materials by different physical and chemical techniques (TXRF, XRD, HR-TEM/EDS) (see e.g. figure 3) and verifying with UV spectrometry that this substitution introduces in the spectrum the sub-bandgap features predicted by the calculations (figure 4).

Quantum dot intermediate band solar cells: issues for an attractive concept

Antonio Luque

Instituto de Energía Solar, Universidad Politécnica de Madrid, Spain

The Intermediate Band Solar Cell [1] is formed by sandwiching and Intermediate Band (IB) material between two ordinary semiconductors p- and ndoped. The IB material has an energy band or set of levels (the IB) situated within the bandgap of a semiconductor. In this way, besides the photocurrent generation by photons with enough energy as to pump electrons form the valence band (VB) to the conduction band (CB) a second path of current appears with two photons of less energy that completes the pumping using the IB as stepping stone. The concept is very attractive because this cell is potentially able to increase the photocurrent without decreasing the photovoltage. In this way the detailed balance [1] top efficiency is 63% to compare to the 41% of a single bandgap solar cell. IBSCs can be made with alloys presenting an IB [2] and with IB materials containing Quantum Dot (QD) arrays [3, 4]. In the first case we have to deal with relatively exotic materials in which the device technology is incipient and therefore the cell efficiency measured so far is very small. In the second case, which is the one to present in this talk the device technology is rather developed. Most of the work so far has been done with StranskiKrastanov InAs QDs in GaAs, grown by MBE [4].

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IBSCs of 18% efficiency [5] have been presented, reasonable but below the expectations. The reason for this is that the voltage is usually strongly reduced and the current is increased only slightly. In IBSC the voltage is believed to be controlled [6, 7], like in most devices, by SRH recombination through the ordinary impurities of the solar cell (not the IB levels) but the presence of the IB increases the minority carriers and the cell behaves as with a reduced bandgap. More perfection in the material quality may prevent this reduction and this has actually been attained [8] in InAs/GaAs QD IBSCs made by MOCVD. The reduced current is an intrinsic property of the QDs. VB→IB absorption requires that the initial and final eigenfunctions have strong projection in both the CB and the VB [7, 9]; unfortunately the IB eigenfunctions are almost fully projected on the CB and all the VB eigenfunctions have no or negligible projection on the CB. Controlling the shape and density of the QDs might be a way to overcoming this issue. In summary, the IBSC has become a hot subject in photovoltaics. The concept is very attractive but bringing it into practice will still require efforts.

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[1] A. Luque, A. Martí, Physical Review Letters 1997, 78, 5014. [2] N. Lopez, L. A. Reichertz, K. M. Yu, K. Campman, W. Walukiewic, Physical Review Letters 2011, 106, 028701. [3] A. Martí, L. Cuadra, A. Luque, in Proc. 28th IEEE Photovoltaics Specialists Conference, IEEE, New York 2000, 940. [4] A. Luque, A. Martí, C. Stanley, N. López, L. Cuadra, D. Zhou, A. Mc-Kee, Journal of Applied Physics 2004, 96, 903. [5] S. A. Blokhin, A. V. Sakharov, A. M. Nadtochy, A. S. Pauysov, M. V. Maximov, N. N. Ledentsov, A. R. Kovsh, S. S. Mikhrin, V. M. Lantratov, S. A. Mintairov, N. A. Kaluzhniy, M. Z. Shvarts, Semiconductors 2009, 43, 514. [6] A. Luque, P. G. Linares, E. Antolín, I. Ramiro, C. D. Farmer, E. Hernández, I. Tobías, C. R. Stanley, A. Martí, Journal of Applied Physics 2012, 111, 044502. [7] A. Luque, A. Marti, C. Stanley, Nature Photonics 2012, 6, 142. [8] C. G. Bailey, D. V. Forbes, S. J. Polly, Z. S. B. IEEE, Y. Dai, Chelsea Mackos, R. P. Raffaelle, S. M. Hubbard, IEEE Journal on Photovoltaics 2012, DOI 10.1109/JPHOTOV.2012.2189047. [9] A. Luque, A. Mellor, E. Antolin, P. G. Linares, I. Ramiro, I. Tobias, A. Marti, Solar Energy Materials and Solar Cells 2012, 103, 171.

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References

Silica nanostructures toxicity assessment and their potential for biomedical applications Italian Institute of Technology Center for Bio-Molecular Nanotechnologies@Unile Via Barsanti, 73010 Arnesano, Lecce, Italy

Maria Ada Malvindi, Virgilio Brunetti, Giuseppe Vecchio, Antonio Galeone, Valeria De Matteis, Roberto Cingolani and Pier Paolo Pompa mariada.malvindi@iit.it

Silica nanoparticles are widely used in various industrial fields and recently, they have been exploited also for biomedical research. The impact of SiO2NPs on human health and the environment is thus of great interest. Nowadays, the overall evaluation of the toxicity/biocompatibility of SiO2NPs is extremely difficult, owing to controversial results in the literature and to the lack of standard procedures and/or insufficient characterization of the nanomaterials in biological systems. Therefore the biocompatibility needs to be documented in greater detail. In this study we evaluated the toxicity of different silica nanostructures, both pure and quantum dots (QDs)- or iron oxide-doped, and studied their potential applications in gene delivery. We performed a systematic in vitro study to assess the biological impact of pure SiO2NPs, by investigating 3 different sizes (Fig.1) and 2 surface charges in 5 cell lines. We analyzed the cellular uptake and distribution of the NPs along with their possible effects on cell viability, membrane integrity and generation of reactive oxygen species (ROS). We observed that all the investigated SiO2NPs do not induce detectable cytotoxic effects (up to 2.5 nM concentration) in all cell lines (Fig.2a). Once having assessed the biocompatibility of SiO2NPs we evaluated their potential in gene delivery, showing

their ability to bind, transport and release DNA, allowing the silencing of a specific protein expression (Fig.2b) [1]. The biocompatibility of SiO2NPs and their gene carrier performance were also evaluated and confirmed in primary neuronal cells [2]. Finally, we investigated the toxicity of silica nanoparticles doped with iron oxide nanocrystals. We tested nanoparticles with two surface charges in two cell lines by evaluating their effect on cell viability, cell membrane integrity and induction of ROS. We found that SiO2NPs doped with iron oxide nanoparticles do not induce detectable cytotoxic effects up to 1 nM concentration (Fig.3b) with negatively charged NPs exerting the higher toxicity. This is likely associated to the nanoparticles degradation in lysosomal environment. Overall, we demonstrate that SiO2 nanostructures are quite safe in vitro and have promising potential in biomedical applications.

References [1] M.A. Malvindi et al., Nanoscale, 2012, 4; 4(2), 486-495. [2] G. Bardi et al., Biomaterials, 2010, 31, 65556566.

Figure 1. Representative TEM images of three sizes of SiO2NPs: 25, 60 and 115 nm.

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Figure 2. a) Viability of A549 cells 48 and 96 h after the exposure to increasing doses evaluated of 25 nm SiO2NPs by the WST-8 assay; b) In vitro silencing of tGFP expression.

Figure 3. a) SiO2NPs doped with iron oxide NPs; b) Viability of A549 cells 48 and 96 h after the exposure to increasing doses of SiO2NP doped with iron oxide NPs evaluated by the WST-8 assay; c) Iron release in lysosomal environment.

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Plasmonic nanoparticle chain in a light field: a resonant optical sail

Silvia Albaladejo1, Juan José Sáenz1 and Manuel I. Marqués2

Departamento de Física de la Materia Condensada and Instituto “Nicolás Cabrera”, Universidad Autónoma de Madrid, 28049 Madrid, Spain. 2 Departamento de Física de Materiales and Instituto “Nicolás Cabrera”, Universidad Autónoma de Madrid, 28049 Madrid, Spain.

Metallic Optical trapping and driving of small objects has become a topic of increasing interest in multidisciplinary sciences. We propose [1] to use a chain made of metallic nanoparticles as a resonant light sail, attached by one end point to a transparent object and propelling it by the use of electromagnetic radiation. Driving forces exerted on the chain are theoretically studied as a function of radiation’s wavelength and chain’s alignments with respect to the direction of radiation. Interestingly, there is a window in the frequency

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manuel.marques@uam.es

spectrum in which null torque equilibrium configuration, with minimum geometric cross section, corresponds to a maximum in the driving force.

References [1] S. Albaladejo, J. J. Sáenz and M. I. Marqués, Nanoletters 11, 4597 (2011)

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Imaging the carrier confinement within a single nanowire 1

European Synchrotron Radiation Facility, 38043-Grenoble, France IMM, Instituto de Microelectrónica de Madrid (CNM, CSIC), 28760-Tres Cantos, Spain 3 Department of Applied Physics, Valencia University, 46100-Burjasot, Spain 4 Institute for Electronics, Microelectronics, and Nanotechnology, CNRS-UMR 8520, Department ISEN, F-59652 Villeneuve d’Ascq, France 5 National CRI Center for Semiconductor Nanorods, Department of Physics and Astronomy, Seoul National University, Seoul 151747, Republic of Korea 2

Gema Martínez-Criado1 , A. Homs1, B. Alén2, J. A. Sans3, J. Segura-Ruiz1, A. Molina-Sánchez4, J. Susini1, J. Yoo5 and G.-C. Yi5

gmartine@esrf.fr

The assembly of group-III nitride nanowires into optoelectronics offers a promising approach to improve the performance of light-emitting devices. Two dimensional quantum confinement effects, created by coaxial band structure engineering, lead large spectral tunability and high luminescence quantum yields. Sophisticated core/multishell nanowires have already been designed to produce a large variety of sizedependent phenomena for advanced light-emitting diodes. Although theory suggests that the carrier distributions in nanowires exhibit two dimensional confinement under a cross-section of hexagonal geometry, its direct observation has never been addressed. By combining synchrotron excited optical luminescence with simultaneous energy-disperse X-ray spectroscopy using a nanometre-sized hard X-ray beam, here we show experimental evidence for these carrier localization effects. Applied to single coaxial nGaN/InGaN multiquantum-well/p-GaN nanowires, our hyperspectral imaging method reveals a stronger transition at the hexagon corners, matching theoretical predictions. Based on core-level excitation processes, our experiment opens new avenues for further local structure, and time-resolved studies with both nanometre resolution and optical sensitivity. We anticipate that this methodology will contribute to a greater understanding of the underlying design concepts of photonic nanodevices.

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Reciprocal space and transmission electron microscopy study of heterogeneous GaP: MnP magnetic epilayers containing MnP nanoclusters

S. Lambert-Milot, S. Gaudet, P. Desjardins, and R.A. Masut remo.masut@polymtl.ca

Regroupement québécois sur les matériaux de pointe (RQMP) and Département de génie physique, École Polytechnique de Montréal P.O. Box 6079, Station Centre-Ville, Montréal, Québec H3C 3A7, Canada

Work done in collaboration with: C. Lavoie, IBM T.J. Watson Research Center, Yorktown Heights, NY 10598, USA; C. Lacroix and D. Ménard, Département de génie physique, École Polytechnique de Montréal; M. Garcia-Hernandez, and A. de Andres, Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain.

The integration of magnetic nanoclusters in thin IIIV semiconductor films can enhance magnetoresistance and magneto-optic effects with the potential to be integrated in novel devices for room temperature applications [1-3]. The magnetic properties of heterogeneous films strongly depend on the structural properties of the clusters and film matrix, which are in turn determined by the growth conditions. We show how a three dimensional mapping of reciprocal space by X-ray diffraction combined with transmission electron microscopy measurements can determine the texture of GaP epilayers containing embedded MnxP nanoclusters grown on GaP substrates by metal organic vapor phase epitaxy [4-5]. This systematic approach allows identification of all phases present in the heterogeneous films, in particular showing traces of hexagonal Mn2P precipitates, whose formation can be avoided by lowering the film growth temperature. Growth at 650 oC produces mostly orthorhombic MnP nanoclusters, responsible for the magnetic properties, which are oriented along specific GaP crystallographic directions, forming six well defined families. The population of these families can be quantified and is influenced by the growth temperature and the film thickness. The MnP clusters principally grow on GaP(001) and GaP{111} facets with a small fraction of clusters nucleating on higher-index GaP{hhl} facets. Most epitaxial alignments share a similar component: the

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MnP(001) plane (c-axis plane) is parallel to the GaP{110} plane family. Axiotaxial ordering between the MnP clusters and the GaP matrix has also been observed [5].

Figure 1. The TEM image on the left shows a plan view of a heterogeneous GaP:MnP epilayer containing MnP o nanoclusters grown at a substrate temperature of 650 C [ref. 4]. The heterogeneous films are grown on semiinsulating GaP(001) substrates in a low-pressure coldwall MOVPE reactor, using trimethylgallium, tertiarybutylphosphine, and methyl cyclopentadienyl manganese tricarbonyl as precursors for Ga, P and Mn respectively, and Pd-purified hydrogen as the carrier gas. The reactor pressure was set at 40 Torr with a total flow rate maintained at 4000 sccm. Growth rate is 1.2 μm/ h for GaP(001) at a growth temperature of 650 oC C

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References

The authors acknowledge J. Bouchard for technical support, J.-P. Massé for assistance with TEM measurements, and J. Jordan-Sweet and E. Dimasi for technical assistance at the NSLS X20 and X6B beamlines. This research was supported by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Canada Research Chair Program, and the Fonds Québécois de la Recherche sur la Nature et les Technologies (FQRNT). The research was carried in part at the NSLS, Brookhaven National Laboratory, supported by the U.S. D.O.E., Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886.

[1] G. Monette, C. Lacroix, S. Lambert-Milot, V. Boucher, D. Ménard and S. Francoeur, J. Appl. Phys. 107 (2010) 09A949. [2] C. Lacroix, S. Lambert-Milot, P. Desjardins, R.A. Masut and D. Ménard J. Appl. Phys. 103 (2008) 07D531. [3] C. Lacroix, S. Lambert-Milot, P. Desjardins, R.A. Masut and D. Ménard, J. Appl. Phys. 105 (2009) 07C119. [4] S. Lambert-Milot, C. Lacroix, D. Ménard, R. A. Masut, P. Desjardins, M. Garcia-Hernandez and A. de Andres, J. Appl. Phys. 104 (2008) 083501. [5] S. Lambert-Milot, S. Gaudet, C. Lacroix, D. Ménard, R.A. Masut, P. Desjardins, and C. Lavoie, J.Vac. Sci. & Tech., submitted.

Figure 2. Reciprocal space measurements: were carried out at the National Synchrotron Light Source (NSLS) (Brookhaven National Laboratory) X20A and X6B beam lines. The figure below illustrates the large photon flux provided by the synchrotron source, a key feature to obtain a full 3D reciprocal space map which will allow texture determination.

Figure 3. Texture and phase quantification: is obtained from X-ray diffraction (a set of more than 600 pole figures, as the example illustrated below) combined with transmission electron microscopy (TEM) analysis

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Acknowledgements

Spatial and temporal control of osteoblastic cells proliferation on electroconductive carbon nanotube-based bone grafts

D. Mata1, M. Amaral1,2, A.C. Bastos1, M.A. Neto1, F.J. Oliveira1, M.A. Lopes3, M.H. Fernandes4 and R.F. Silva1 diogomata@ua.pt

CICECO, Dept. of Materials and Ceramic Eng., Univ. of Aveiro, 3810-193 Aveiro, Portugal 2 I3N, Physics Dept., Univ. of Aveiro, 3810-193 Aveiro, Portugal 3 CEMUC, Dept. of Metallurgical and Materials Eng., Univ. of Porto, 4200-465 Porto, Portugal 4 Faculty of Dental Medicine, Univ. of Porto, 4200-393 Porto, Portugal

Biomaterials can still be reinvented to become simple and universal bone regeneration solutions. Following this roadmap, "smart" bone grafts have been designed with new functionalities able to stimulate specific bone cells responses. Regarding the beneficial effects of endogenous electrical signals in natural bone, electron conductivity emerge as an exciting functionality. As opposed to natural piezoelectric bone, electroconductive bone grafts have key advantages: external control over the level and duration of stimulation; confinement of exogenous electrical fields on their surface leading to spatial and temporal control of bone tissue regeneration. Following this, the present work aims to: (1) process MWCNTs-based bone grafts; (2) assess the Îą-MEM-conductive bone grafts interactions under (or not) electrical fields; (3) evaluate in vitro the efficiency of conductive bone grafts in delivering electrical stimulus to osteoblastic cells. Biologically safer carbon nanotubes (CNT) [1-3] presenting outstanding characteristics - nonmetallic phases, bioactive, high aspect-ratio and ultimate electrical conductivity - were used here as fillers to obtain highly conductive biomaterials. Calcium phosphate (CaP)/CNT powders show high interaction being the CNTs decorated with CaP particles (Fig. 1a). Microstructures of fracture (Fig. 1b) and polished surfaces (Fig. 1c) show that CNT are well dispersed combining individual CNT (Fig. 1d) and controlled sized agglomerates (<10 Dm) (Fig. 1c). This CNT 3D network gives an electrical percolation threshold (Pc) in the range of 0.9-1.8 vol.% (Fig. 1e). Pursuing the main goal of this work,

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the selection of the CNT loading should be: low to preserve the biological profile of the matrix; high to give composites with higher conductivity than the biological milieus. The 2.5 wt.% loading is the one that matches this two requisites (Figs. 1e,f).

Figure 1. Microstructure and electrical conductivity of CNT-based composites.

In an in vivo scenario, it is expected that this composite formulation induces the locally increase of the conductivity and confines the exogenous electrical fields on its surface. To evaluate this, two set of experiments were performed in Îą-MEM (12 ml). The presence of six CaP samples show an increase of 0.15 % of the impedance of the medium (Figs. 2a,c). Conversely, six CaP/CNT (2.5 wt.%) samples decrease the impedance in 1.26 % (Figs. 2b,c). Scanning vibrating electrode (SVET) measurements were accomplished under a constant electrical field Exx of 3 mV.cm-1/100 DA, accordingly to the configuration of Fig. 2d. At the

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The current-voltage response of ion channels in osteoblastic cells is shown in Fig. 3a. An action potential of +10 mV for 5 ms is enough to induce a maximum peak of current in the cell. This is followed by a depolarization to the resting state during 20 ms (red line in Fig. 3a). This biological data was used as reference to select the AC electrical signal parameters for the stimulation experiments (Fig. 3b). In vitro stimulation of MG63 osteoblastic cells was accomplished in a homemade apparatus (Fig. 3c, current circuit highlighted by blue arrows) using 12 ml of Îą-MEM solution and six samples per culture plate (same conditions seen in Fig. 2). The frequency was kept constant at 40Hz and the electrical field (5.6 and 15.3 mV.cm1 )/current density (91 and 167 DA.cm-2)/current (100 DA and 200 DA) and time (15 and 30 min) were varied. Potential and density current distributions of the stimulation area of the culture plate (Figs. 3c,d) are presented for the 200 DA stimulus condition in Figs. 3e,f. It can be seen that the samples (black dotted line in Figs. 3e,f) were uniformly stimulated. MTT assay in Fig. 4g shows that electroconductive CaP/CNTs templates under electrical stimulus accelerate the proliferation of osteoblastic cells. For all the stimulation conditions

In conclusion, osteoblastic cells were efficiently stimulated on CNT-based bone grafts. MTT assays showed almost 300% increase in cell proliferation, relatively to the non-stimulated condition, after only 3 days of daily stimulation time of 15 min. These exciting observations are intimately related with the locally increase of the conductivity and the confinement of electrical fields on the surface of the conductive material.

References [1] Mata D, Ferro M, Fernandes AJS, Amaral M, Oliveira FJ, Costa PMFJ, Silva RF. Carbon 48 (2010) 2839-54. [2] Mata D, Amaral M, Fernandes AJS, Oliveira FJ, Costa PMFJ, Silva RF. Carbon 49 (2011) 218196. [3] Mata D, Silva RM, Fernandes AJS, Oliveira FJ, Costa PMFJ, Silva RF. Carbon 50 (2012) 358506.

Figure 2. Îą-MEMMWCNTs-based bone grafts interactions under (or not) electrical fields.

Figure 3. In vitro evaluation of the efficiency of CNT-based bone grafts in delivering electrical stimulus to osteoblastic cells.

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the cell population is higher than the control (nonstimulated material) (Fig. 3g). Conversely, for the dielectric materials the stimulus delivering is less efficient, showing responses equal or lower than the control (Figs. 3h,i). Interestingly, these observations corroborate the results of Fig. 2. SEM and CLSM microscopy images (Figs. 3j,k) show no evident differences in cells morphology between the two conditions and for the three materials.

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borders, it can be seen that the conductive sample induces less distortion of the E lines than the dielectric one (Figs. 2e,f). Also, the Eyy component, perpendicular to the sample surface, is maximized for the conductive sample (Figs. 2 g-j).

Recent advances in fast imaging Raman technology for nano materials characterisation

Sébastien Maussang

Renishaw Ibérica S.A.U, Gavà Park, C. Imaginació, 3, 08850 Gavà, Barcelona, Spain

Raman spectroscopy continues to provide analytical solutions in a variety of material science applications offering chemical specificity on a micrometer scale. The ability to create chemical and stress images by acquiring Raman spectra from an array of positions and then processing them to reveal the parameter of interest is a powerful technique. Traditionally, these spatially-related data have been collected by raster scanning the sample beneath the incident laser spot, typically in micrometer intervals. New approaches to Raman imaging have been developed that enhance the capabilities of modern Raman instruments that now have the ability to produce images on the nano scale. The use of either high precision motorised stages or piezoelectric-controlled sample stages permits accurate and repeatable sample movements in intervals significantly smaller than the diffraction limited laser spot size. When used in conjunction with an atomic force microscope tip, feedback can be applied to ensure the sample’s surface remains in the plane of the laser focus, optimising efficiency. Topographic images of the surface can

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be correlated with Raman images as the data are acquired simultaneously. This approach is proving to be most useful in materials research and the study of semiconductor materials, particularly in assessing carbon nanotube structures, graphene film properties and in stress in silicon devices. Other application areas include biological intracellular structure and tissue imaging. Additionally, a new method of acquiring both 2D and 3D confocal Raman images has been developed – ‘Streamline’. Spectra are collected in parallel, rather than in series using the traditional methods. Shorter total acquisition times result, with high quality individual spectra recorded in the order of fifty milliseconds. The method also benefits from ‘on the fly’ data analysis resulting in real time image creation. This innovative approach allows the technique to succeed where others have failed: producing uncompromised data and images for small or large areas at speeds much greater than possible with competing methods. A number of materials examples will be shown to illustrate the benefits of this method and will demonstrate how information can be achieved on the nanometre scale.

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Unusual nucleic acid structures for DNA-based nanotechnologies

Jean-Louis Mergny

Univ. Bordeaux, IECB, INSERM U869, France

Nucleic acids are prone to structural polymorphism: in addition to the classical DNA double-helix, a number of alternative structures may be formed. Important biological processes require melting of the DNA double-helix and several genetic diseases are mediated by the formation of non B-DNA structures. Among these, G-quadruplexes (G4) represent an exceptional polymorphic class of higher-order nucleic acid structures in which the structural unit is formed by a planar arrangement of four Hoogsteen-bonded guanines known as Gquartets (Fig.1). A vertical π-stacking arrangement of several G-quartets and the presence of monovalent cations provide these structures with remarkable stabilities. Nucleic acids are gaining in popularity and utility for creating new nanomaterials due to their ability to self-assemble. Pairing of double-stranded DNA is being explored by a growing number of researchers to construct extremely sophisticated nanostructures and nanodevices. We believe that G4 offer interesting possibilities for nanotechnology and biotechnology and we are currently seeking new properties for DNA-based logic gates and nanomaterials.

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Figure 1. Presentation of a G-quartet with four coplanar guanines

This work is supported by INSERM, Fondation pour la Recherche Médicale (FRM), University of Bordeaux, Agence Nationale de la Recherche (ANR grants F-DNA, G4-Toolbox & QuantADN), and Région Aquitaine grants. I thank all members of ARNA laboratory as well as L. Yatsunyk (Swarthmore College), P. Alberti (MNHN, Paris) D. Monchaud (Dijon) M.P. Teulade-Fichou (Curie, Orsay) R. Eritja (Barcelona), A. Galeone (Naples) and L. Lacroix (Toulouse) for helpful discussions.

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Evidence for magnetic order in a purely organic 2D layer adsorbed on epitaxial graphene

Rodolfo Miranda1,2

Dep. Física de la Materia Condensada, Universidad Autónoma de Madrid, Cantoblanco 28049, Madrid, Spain 2 Instituto Madrileño de Estudios Avanzados en Nanociencia (IMDEA-Nanociencia), Cantoblanco 28049, Madrid, Spain

Collective magnetic properties are usually associated to d or f electrons which carry the individual magnetic moments. Band magnetism in organic materials based on π electrons has remained an experimental challenge, in spite of rigorous predictions of a fully spin polarized ground state in half-filled flat band organic systems [1].

magnetic moment, which is revealed by a prominent Kondo resonance. The magnetic moment is preserved upon dimer and monolayer formation. The self-assembled 2D monolayer of magnetic molecules develops spatially extended spin-split electronic bands visualized in the real space by STM, where only the majority band is filled, thus becoming a 2D, purely-organic magnet whose predicted spin alignment in the ground state is visualized by spin-polarized STM at 4.6 K.

References [1] Y. Nagaoka, “Ferromagnetism in a narrow, half-filled band”, Phys. Rev. 147, 392 (1966). [2] Manuela Garnica, Daniele Stradi, Sara Barja, Cristina Díaz, Fabian Calleja, Manuel Alcamí, Nazario Martín, Amadeo L. Vázquez de Parga, Fernando Martín, and Rodolfo Miranda (to be published).

Figure 1. Above: STM image of TCNQ/graphene/Ru(0001) at 4.6 K; Belowleft: spin polarized PDOS on different molecules and right: local spin polarized tunnelling spectroscopy on the two molecular domains.

Cryogenic Scanning Tunneling Microscopy (STM) and Spectroscopy in UHV and accurate Density Functional Theory (DFT) simulations show [2] that isolated TCNQ molecules deposited on a monolayer of graphene epitaxially grown on Ru(0001) acquire charge from the substrate and develop a sizeable

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Dirac fermions in HgTe quantum wells Physics Institute, EP3, Wuerzburg University, Am Hubland, 97074 Wuerzburg, Germany

L. W. Molenkamp

laurens.molenkamp@ physik.uni-wuerzburg.de

HgTe quantum wells have a linear band dispersion at low energies and thus mimic the Dirac Hamiltonian. Changing the well width tunes the band gap (i.e., the Dirac mass) from positive, through zero, to negative. Wells with a negative Dirac mass are 2-dimensional topological insulators and exhibit the quantum spin Hall effect, where a pair of spin polarized helical edge channels develops when the bulk of the material is insulating. Our transport data provide very direct evidence for the existence of this third quantum Hall effect. Wells with a thickness of 6.3 nm are zero gap Dirac systems, similar to grapheme. However, zero gap HgTe wells possess only a single Dirac valley, which avoids inter-valley scattering.

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Three dimensional electrodes base on core/shell nanowires for photoelectrochemical cells

Jiandong Fan, C. FĂĄbrega, T. Andreu, Andreu Cabot and Joan Ramon Morante jrmorante@irec.cat

Departament Electronica, Universitat de Barcelona, Barcelona, 08028, Spain Catalonia Institute for Energy Research, IREC, Sant Adria del Besos, 08930, Spain.

Three dimensional arrayâ&#x20AC;&#x2122;s offer an increased active surface area for all type of electrodes, in general, and, in particularly, for higher efficiency in photo electrochemistry devices. In this scenario, coreshell nano hetero or homo structures are the essential brick for built-in these electrodes and they become essential to define advanced photo electrochemistry elements or, even, for a more complex and promising artificial photosynthesis systems that require frontal or back illumination according to the photo reactor design related to the production of sun fuels. However, all their outstanding properties depend on the adequate capability for photon capture and the consequent control of the charge separation. Under these conditions, doping of the inner part of the structure becomes basic for the charge extraction associated with a high transport facility, low internal resistance, as well as the surface conditions are determining for the charge transfer of the other type of carriers. As a consequence, doping management becomes an essential point for energy band engineering and, so, a fundamental key for controlling the overall nanostructure performances. In this contribution, we report on the growth on electrodes of nanowires with controlled doping and how they can be coated for selected shell material with controlled thickness for having homo and hetero structures with modified surface properties and varied electrical field values at the surface. It contributes to enhance the charge carrier transfer

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as well as it presents also excellent transport properties. As demonstration, examples of vertically aligned homostructures ZnO:ZnO and heterostructures ZnO/ZnS or ZnO/TiO2,â&#x20AC;Ś among others core /shell nanowires will be presented like for discussing the functional matching in these coaxial heterojunction including electrical, optical crystallographic and thermo chemical performances related to their degradation and stability. In general, these core/shell nanowires have been grown by a facile and low cost electrodeposition two-step process. In this way, due to the controlled surface electrical field, photoelectrochemical properties of these nanowires have been found to be highly enhanced with the presence of these shell layers and an experimental study as function of their thicknesses will be presented and modelized to explain the promotion the surface-related radiative recombination processes. The enhancement factor is proved to depend on the shell thickness. These performances are associated with the improvement of the photogenerated charge carrier separation and surface to neutral inner part transfer capability achieved when increasing the space charge area within the nanowires with a built-in electric field introduced by the doping profile. These features allow the deduction of practical rules for the design and optimization of these three dimensional photoelectrodes for the production of sun fuels.

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Metal-Carbon Nanohybrid Foams: from Laser Chemistry to Nanochemistry 1

Instituto de Carboquímica ICB-CSIC, Miguel Luesma Castán 4, 50018 Zaragoza, Spain Instituto de Síntesis Química y Catálisis Homogénea, Universidad de Zaragoza-CSIC, Zaragoza, Spain 3 Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, Zaragoza, Spain 4 Departamento de Química Física, Universidad de Zaragoza, 50009 Zaragoza, Spain

Andrés Seral-Ascaso1, Asunción Luquin2, María Luisa Sanjuán3, Rosa Garriga4, Mariano Laguna2, Germán F. de la Fuente3, and Edgar Muñoz1

Metal-carbon nanohybrid foams have been produced by laser irradiation of organometallic precursors [1]. The laser irradiation of aromatic organometallic precursors resulted in milligram quantities of soot exhibiting a fibrous appearance. Scanning electron microscopy (SEM) characterization showed that the microstructure of this material exhibited the porous, foam-like texture which results from the aggregation of ‘‘necklace’’-like ensembles of nanobeads, similar to that observed in other ‘‘spongy’’ carbon materials, such as carbon aerogels [2,3] and carbon nanofoam [4]. Transmission electron microscopy (TEM) studies reveals that these metal-carbon nanohybrids are multi-component materials that consist of metal nanoparticles embedded in amorphous carbon aggregates, amorphous carbon nanoparticles, and graphitic nanostructures, which can be eventually observed as independent, separate components in the produced soots (Fig. 1) [5]. The present work also reports on important experimental parameters toward the controlled synthesis of these carbon foams. Thus, characterization studies indicate that the composition, metal nanoparticle dilution and crystallite size, and structure of the metal-carbon foams can be tailored by suitably tuning the laser parameters used and by choosing the metals and ligands of the irradiated targets [5,6]. It is also demonstrated here that, contrary to carbon aerogels, the employed metals are not required for the growth of the observed graphitic nanostructures [2,3,5] . TNT 2012 madrid (spain)

Figure 1. SEM-(left, scale bar: 100 nm) and TEM (right, scale bar: 10 nm) micrographs of laser-ablation produced Au-carbon foams [1].

This “laser chemistry”, based on the use of molecular precursors, would enable the facile production of multifunctional nanostructured carbon materials with a range of tunable properties. Alternatively to this “laser chemistry” approach, wet chemistry strategies have been designed for the synthesis of metal-carbon nanohybrids based on the in-situ reduction of noble-metal salts in presence of carbon foams produced by laser ablation of metal-free organic compounds. Further physical-chemical characterization studies, chemical processing, and potential technological applications of these metalcarbon nanohybrid foams will be also discussed [6].

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References [1] E. Muñoz, M. de Val, M. L. Ruiz-González, C. López-Gascón, M. L. Sanjuán, M. T. Martínez, J. M. González-Calbet, G. F. de la Fuente, M. Laguna, Chem. Phys. Letters 420 (2006) 86. [2] R.W. Fu, G. Dresselhaus, M.S. Dresselhaus et al., Langmuir 21 (2005) 2647. [3] F.J. Maldonado-Hódar, C. Moreno-Castilla et al., Langmuir 16 (2000) 4367. [4] A.V. Rode et al., Appl. Phys. A 69 (1999) S755. [5] E. Muñoz, M. L. Ruiz-González, A. Seral-Ascaso, M. L. Sanjuán, J. M. González-Calbet, M. Laguna, G. F. de la Fuente Carbon 48 (2010) 1807. [6] A. Seral-Ascaso et al., submitted.

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Understanding Electronic Structure and Charge Transport in Single-Molecule Junctions

Jeffrey B. Neaton

Molecular Foundry Lawrence Berkeley National Laboratory, USA

Interfaces are pervasive in nanostructured materials, and the details of their atomic-scale morphology, electronic structure, and environment dictate the flow of matter, charge, and energy, ultimately determining function. Single-molecule junctions represent the molecular limit of a hybrid interface, and recent transport measurements of well-defined junctions have provided new opportunities to quantitatively understand how interfacial composition and structure is connected to conductance, thermopower, current-voltage (IV) characteristics, and rectifying behavior. In this talk, I will summarize predictive fundamental studies [14], using density functional theory and many-body perturbation theory, of the electronic structure and transport properties of single-molecule junctions. Advantages and limitations of our approaches will

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be discussed in the context of recent calculations and experiments.

References [1] H. J. Choi et al, Phys. Rev. B 76, 155420 (2007) [2] S. Y. Quek et al, Nano. Lett. 9, 3949 (2009) [3] J. B. Neaton et al, Phys. Rev. Lett. 97, 216405 (2006); M. DellAngela et al, Nano Lett. 10, 2470 (2010); I. Tamblyn et al, Phys. Rev. B 84, 201402 (2011); S. Sharifzadeh et al, arXiv:1204.0509 [4] S. Y. Quek et al, ACS Nano 5, 551 (2011); V. Fatemi et al, Nano Lett 11, 1988 (2011); J. Widawsky et al, Nano Lett. 12, 354 (2012); P. Darancet et al, in preparation (2012)

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Measurement of the capacitance across a tunnel barrier 1 2

LT-NanoLab, Department of Applied Physics, University of Alicante, Alicante, Spain Institut für experimentalphysik, Freie Universität Berlin, Berlin, Germany

Bernat Olivera1, Giovanni Sáenz-Arce1, Martina Corso2, Carlos Sabater1, Juan Ignacio Pascual2 and Carlos Untiedt1 bernat.olivera@ua.es

Electronic transport in the process of the formation of nanocontacts between two metallic electrodes can be measured by bringing together two metallic wires made of the same material using different techniques such the Scanning Tunneling Microscope (STM) [1]. Most of the experiments have been focused to measure the conductance of the junctions, however until now very little attention has been paid to other electronic characteristics of this system such as the capacitance[2]. Here we report the measurement of the whole impedance characteristics of a controlled vacuum gap in between two metallic electrodes using a homemade STM. High vacuum and cryogenic conditions are necessary to achieve the desired low mechanic (below 10pm) and thermal noise. Electronics is carefully implemented taking care to reach low electronic noise too. In order to measure the impedance of the atomic junctions, a lock-in amplifier technique has been used. In our experiments we have observed a decrease of capacitance when the tunnel current is increasing, as predicted by theory[2-4]. On an other hand, we also observe such a decrease in the field emission regime when increasing the applied bias voltage in between electrodes (shown at the figure), and when each field emission resonance state (Gundlach oscillations) takes place. This effect has also been independently observed by the measurement of the forces at the junction by the Tuning Fork technique.

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Figure 1. Au>Au measurements taken at 4.2K and cryogenic vacuum using STM where distance between tip and sample is held constant.

References [1] N. Agraït, A. Levy-Yeyati, J.M. Van Ruitenbeek. Phys. Rep. 377, 81 (2003). [2] J. G. Hou et al., Phys. Rev. Lett. 86, 5321 (2001). [3] M. Büttiker, J.Phys.:Condens. Matter 5, 9361 (1993). [4] J. Wang et al. , Phys. Rev. Lett. 80, 4277 (1998).

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Protein-polymer nanoreactors and processors act as artificial organelles

Cornelia G. Palivan Cornelia.Palivan@unibas.ch

Department of Chemistry, University of Basel, Klingelbergstrasse 80, Basel 4056, Switzerland

The combination of biological molecules and synthetic polymer carriers/templates represents a very promising approach for development of efficacious therapies with minimum side effects, diagnostic methods featuring significantly higher sensitivity and selectivity, and personalized diagnostics and therapeutics via theragnostic approaches. In this respect, suitable amphiphilic block copolymers self-assemble into in aqueous media into vesicles with membranes mimicking biological membranes. The properties of such vesicles can be extensively controlled via chemical composition, molecular weight and the hydrophilicto-hydrophobic block length ratio of the polymers, and have the advantage of superior stability and robustness. The combination with suitable biological molecules (proteins, enzymes, DNA, peptides) introduces other well-defined functions, such as molecular recognition, cooperation, and catalytic activity. We exploited the concept of bio-synthetic combination to develop antioxidant nanoreactors that encapsulated superoxide dismutase/mimics in the aqueous cavities of vesicles generated by the self-assembly of poly(2-methyloxazoline)-bpoly(dimethylsiloxane)-poly(2-methyloxazoline), PMOXA-PDMS-PMOXA copolymers [1,2]. By synthesizing appropriately functionalized polymers (e.g. biotin, antibody) we successfully immobilized the nanoreactors on solid support to follow the folding/unfolding of single proteins, and to monitor enzymatic reactions down to the scale of a few molecules [3]. A step further in obtaining multifunctionaliy, is to co-encapsulate enzymes that act in tandem inside the polymer cavity: cascade reactions can therefore take place in situ [4].

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Here we present antioxidant processors designed by simultaneous co-encapsulation of enzymes and channel proteins (Figure 1) [5]. Cascade reaction of co-encapsulated superoxide dismutase and lactoperoxidase allowed for a complete detoxification of superoxide radicals and related H2O2. The polymer membrane was selectively controlled by insertion of channel proteins, which allowed the exchange of substrates and products with the environment, supporting the in situ activity of the enzymes. In addition, the detection of superoxide radicals and related H2O2 was based on a fluorescent product of the second enzyme that strongly favored a dual application of the processor: in biosensing and detoxification of reactive oxygen species. By changing the enzyme/combination of enzymes either to hemoglobin, or to superoxide dismutase - catalase, we enlarged the detoxification approach to other free radicals species, such as nitrogen reactive species, or combination of oxygen and nitrogen reactive species.

Figure 1. Schematic representation of an antioxidant processor based on the co-encapsulation of a combination of enzymes inside polymer nanovesicles.

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Inside cells nanoreactors and processors preserved their integrity over more than 48hours, and did not present toxicity in that interval. After cellular uptake, the nanoreactors/processors retained their function over extended periods of time, thus acting as artificial organelles that continuously exchange molecular information with the host cell. This opens new avenues in protein therapy as well as intracellular sensing approaches.

References [1] F. Axthelm, O. Casse, W. Koppenol, T. Nauser, W. Meier, C. Palivan, J. Phys. Chem. B, 112(28), (2008), 8211. [2] O. Onaca, D.W. Hughes, V. Balasubramanian, M. Grzelakowski, W. Meier, C. G. Palivan, Macromol. Biosci, 10(5), (2010), 531. [3] S. Egli, M. G. Nussbaumer, V. Balasubramanian, M. Chami, N. Bruns, C. G. Palivan, W. Meier, J.Am.Chem.Soc., 133 (12), (2011), 4476. [4] a. D. M. Vriezema, J. Hoogboom, K. Velonia, K. Takazawa, P. C. M. Christianen, J. C.Maan, A. E. Rowan and R. J. M. Nolte, Angewandte Chemie, 115, (2003), 796. b. S. F. M. van Dongen, M. Nallani, J. L. L. M. Cornelissen, R. J. M. Nolte and J. C. M. van Hest, Chem.Eur. J., 15, (2009), 1107. [5] P. Tanner, O. Onaca, V. Balasubramanian, W. Meier, C. G. Palivan. Chem. Eur. J, 17, (2011), 4552.

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Plasmonic nanoparticles for the protection of the final optics in inertial confinement fusion facilities: capabilities and limitations

Ovidio Y. Peña Rodríguez

Instituto de Fusión Nuclear, Universidad Politécnica de Madrid, C/ José Gutiérrez Abascal 2, E-28006 Madrid, Spain

HiPER (High Power Laser Energy Research Facility) is an ESFRI project of the EU for the production of energy using laser-driven Inertial Confinement Fusion (ICF). In this kind of facilities the final optics assemblies are the last element of the main laser system and the first one of the target area systems. The materials of this system are subject to bursts of direct targets of more than 100 MJ injected at 1020 Hz. Currently there are no materials capable of withstanding these conditions for a reasonable camera size (R ∼ 5 m). The use of a certain concentration of gas (typically a few μg/cm3 Xe) or deflecting incident ions by means of electric fields are some of the solutions that have been proposed to mitigate this effect. However, the optimal solution is the development of new materials able to protect the lenses and maintain its transparency in these aggressive conditions. Plasmonic

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nanostructures embedded in thin films look like an ideal candidate for this task because they are able to stop an important part of the radiation and, simultaneously, they offer unprecedented abilities to manipulate electromagnetic waves. For instance, simple spherical silver nanoparticles present a quite low optical density at 350 nm (i.e., the wavelength of HiPER’s lasers). Another possibility worth exploring is the usage of plasmonic Fano resonances to produce a high transparency in some selected spectral regions. Finally, another attractive feature of plasmonic nanostructures is that they can potentially behave as self-healing materials because the mean free path of the vacancies is greater than the material grains, which leads to effective annihilation of vacancies at grain boundaries.

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Functionalizated magnetic nanoparticles for biodetection, imaging and separation of Mytilus galloprovincialis larvae using NIT-zipper® technology.

Daniel Pérez-Estévez*, Christian Sánchez-Espinel, Gonçalo Doria, Sara Puertas, Silvia Lorenzo-Abalde, África González-Fernández, Rubén Santos.

*University of Vigo, Spain

Novel nanomaterials are envisaged to have a major impact on a number of relevant areas. It is anticipated that within the next few years the application of nanomaterials and nanotechnologybased manufacturing will have a crucial role in biomedical, pharmaceutical, cosmetic, veterinary, environmental and agro-food technologies. In this work, several sizes of high-quality monodisperse Fe3O4 Nanoparticles (NPs) were synthesized and functionalizated (or bioconjugated)using NIT-zipper® disruptive technology, following the manufacturer's instructions (Nanoimmunotech), with monoclonal antibodies (mAbs) directed against mussel (Mytilus galloprovincialis) larvae, such as M22.8 and M36.5 (Pérez et al., 2009), and with different labels (fluorescent dyes), that may allow an easier and more specific identification.

larvae collected in the magnet were analyzed by fluorescent and optical microscopy (pictures: A; 20X mussel larvae with Texas Red dye, B; magnetic nanoparticles aggregates inside mussel larvae, and C; 20X mussel larvae with FITC dye) and flow citometry. The obtained results clearly indicate that our successful nanosystem recognise the mussel larvae in field plankton samples from different geographical regions, but not the larvae of any other bivalve species. Thus, it could be used for routine monitoring and purification of mussel larvae in plankton samples from different sources, offering an innovative solution to agro-food markets that could give rise to new processes and solve current problems, like the lack of suitable methods for an unequivocal recognition and a rapid sorting of the bivalve larvae species in plankton samples, in these industries.

Functionalizated Nps were incubated with mussel larvae and magnetic separation was perform. The

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Urchin-inspired zinc oxide as building blocks for nanostructured solar cells

Laetitia Philippe1, Jamil Elias1, Mikhael Bechelany2, Ivo Utke1, Rolf Erni3, Davood Hosseini4 and Johann Michler1

Laboratory for Mechanics of Materials and Nanostructures, EMPA Materials Science & Technology, Feuerwerkstrasse 39, 3602 Thun, Switzerland 2 Institut Européen des Membranes (UMR CNRS 5635), Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier, France. 3 Electron Microscopy Center, EMPA Materials Science & Technology, Ueberlandstrasse 129, 8600 Duebendorf, Switzerland 4 Laboratory for Thin Films and Photovoltaics, EMPA, Materials Science & Technology, Ueberlandstr. 129, CHD-8600 Dübendorf, Switzerland

According to recent studies on the global power plant market, the installed capacity of solar power grew faster than that of any other power technology. Last generation nanostructured photovoltaic devices include dye sensitized (photoelectrochemical, quasisolid, and solidstate) solar-cells and their hybrid and fully inorganic variants as extremely thin absorber (ETA) solar-cells. They appear to have a big light harvesting potential compared to planar thin film photovoltaic devices due to their “built-in” large surface area architecture involving an n-type semiconductor material covered by a light absorber (dye, organic or inorganic films) for collecting photons. After charge separation, electrons are collected by a photoanode for electricity generation. TiO2 and ZnO were agreed to be the most promising materials as wide band gap n-type semiconductors with a preference for ZnO due to its better electronic transport properties and its comparatively easy controllable growth as single-crystal nanowire arrays Better control of light-scattering and electronic transport through this n-type semiconductor is essential for improving the solar efficiency.Among numerous studied architectures, nanoparticles and nanowires are the most employed building-blocks because they either provide high surface areas (nanoparticles) or direct electron transport (nanowires). In direct comparison, single-crystal nanowire arrays offer shorter electron collection paths, thus avoiding charge recombination; but solar cells based on nanoparticles still have a higher solar efficiency due to their larger surface area. Hence, increasing the surface area of planar nanowire carpets by increasing the diameter and length of the

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laetitia philippe@empa.ch

individual nanowire has been proposed in many research reports to enhance the solar light harvesting. As a commonly acquired result, such an increase of the surface area in nanowire carpets leads to an augmentation of charge recombination being detrimental for solar cell efficiency. Therefore, future nanostructured solar-cell architectures need to improve multiple light-scattering while keeping reasonable surface areas with a short electron collection path; in other words, improving the solar light absorption and reducing the electron-hole recombination. To tackle this challenge we have recently developed urchin-like nanostructures by electrodeposition of ZnO nanowires onto surface activated polymer spheres. This structure showed a twofold improvement of light scattering compared to nanowire arrays. However, these nanostructures had a limited mechanical stability and their interspacing could not be varied which prohibited further optimized use in applications. In the present paper, we report on a novel architecture – based on a selfstabilized hollow urchin-like ZnO nanowire buildingblocks using a novel low-costand scalable synthesis route which allows for controlled building-block interspace and tunable nanowire dimensions. We show that the light diffusion and absorption as well as solar cell efficiency can be elegantly controlled and enhanced by engineering the dimensions of such building-blocks.

References [1] J. Elias, C. Levy-Clement, M. Bechelany, J. Michler, G. Y. Wang, Z. Wang, L. Philippe Adv. Mater. 2010, 22, 1607. september 10-14, 2012

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TNT2012 Figure 1. Schematic view of synthesis route for (I) self-stabilized hollow urchin-like ZnO nanowire building blocks and (II) successive fabrication steps for the ETA solar-cell: a) Dip coating for the deposition of an ordered monolayer of polystyrene microspheres onto an FTO covered glass substrate; b) Size reduction of spheres using plasma etching with oxygen plasma; c) Deposition of a uniform conformal thin layer of about 20 nm of ZnO by ALD; d) Electrodeposition of n-type ZnO NWs with controlled length and diameter; e) Formation of hollow u-ZnO by dissolving the polystyrene spheres in toluene; f) Coating of NWs with an absorber film of CdSe by electrodeposition; g) Covering with p-type CuSCN by chemical impregnation, and h) Deposition of a gold thin film electrode by physical vapor deposition.

Figure 2. SEM images of ZnO urchin-like structures after dissolution of the polystyrene sphere monolayers a) without PE and b) with 20 min PE treatment. The insets of a) and b) are the SEM images of the ordered PS before electrodepostion coated with 20 nm of ZnO by ALD. c) Side view of individual u-ZnO structures. Note: the planar NW-carpet between the u-ZnO. d) and e) are views of individual hollow u-ZnO structures from a scratched part of the sample where the structures were reversed upside down. All the scale bars in the figure (except (e)) are 2 Îźm.

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Improving the Direct Electron Transfer Efficiency in Laccase Electrodes for Biofuel Cell Cathodic Reactions

Marcos Pita1, Cristina Gutierrez-Sanchez1, Sergey Shleev2 and Antonio L. De Lacey1

marcospita@icp.csic.es 1

Instituto de Catalisis y Petroleoquimica, Consejo Superior de Investigaciones Cientificas. C/Marie Curie 2 L10, 28049 Madrid, Spain 2 Biomedical Laboratory Science and Technology, Faculty of Health and Society, Malmö University SE-205 06 Malmö, Sweden

Fungal laccases are one of the best candidates for enzymatic biofuel cell cathodes due to its ability to reduce O2 directly to H2O at high potentials; laccases are also suitable for direct electron transfer when appropriately wired toward different electroactive surfaces such as gold or graphite. However, laccase faces several hindering conditions when taking to many in vivo-like environments, being the most relevant chloride inhibition and the functional pH. Chloride anions are a reversible inhibitor of laccase and are present in most biological fluids. Additionally, the typically acidic pH-optima for laccase performance take any laccase-modified electrode out of range for many natural fluids. This presentation will show strategies to improve laccase performance under these nonfavoured environments. It has been shown that specific orientation of laccase for DET can reduce this inhibition source when immobilized on a lowdensity graphite (LDG) electrode [1] and how to extend this immobilization method to gold planar electrodes [2]. We will show the improvement brought to current density and chloride resistance by combining a LDG electrode with gold nanoparticles. The limitations brought by the use of neutral pH can be addressed by generation of a local acidic pH environment. This has been

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achieved by inserting the laccase electrode in a magnetic ring that allows the deposition of magnetic nanoparticles carrying another enzyme able to acidify the environment [3]. For conceptual purposes we have used glucose oxidase (GOx) to produce a gluconic-acid environment, managing to lower pH 2 units while keeping the bulk pH neutral and therefore allowing laccase to work. Catalase was present for oxygen-regeneration purposes.

References [1] Cristina Vaz-Dominguez, Susana Campuzano, Olaf Rüdiger, Marcos Pita, Marina Gorbacheva, Sergey Shleev, Victor M. Fernandez, Antonio L. De Lacey. Biosensors and Bioelectronics, 24, (2008), 531–537. [2] Marcos Pita, Cristina Gutierrez-Sanchez, David Olea, Marisela Velez, Cristina Garcia-Diego, Sergey Shleev, Victor M. Fernandez, Antonio L. De Lacey. Journal of Physical Chemistry C, 27, (2011), 13420-13428. [3] Sylvain Clot, Cristina Gutierrez-Sanchez, Sergey Shleev, Antonio L. De Lacey, Marcos Pita. Electrochemistry Communications, 18, (2012), 37-40.

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Strategies and activities in nano

Photonics Unit - Instituto Tecnológico la Marañosa, Ctra M301 Km 10.500, 28330 San Martín de la Vega, Spain

J. Plaza, R. Almazán, L. Gómez, D. Fernández, M.T. Rodrigo, M.C. Torquemada, V. Villamayor, I. Catalán, C. Sierra, I Génova, F. Rangel, A. Vicioso, C. Gutiérrez, M. Álvarez and M. Magaz jplazao@oc.mde.es

In recent years, emerging technologies are becoming of great interest due to the possibility of developing applications which can improve the features of the existing ones, and even, there is the possibility of developing novel applications that cannot be achieved without these. Usually, there are two different ways of developing applications: a bottom-up approach, starting from the development of science and technology to assess its properties and create an application from them. A top-down approach, on the other hands, starts with a real problem that needs a specific application, and then seeks for the most optimal technology that can create an application to solve that problem. With this end-user point of view, Ministry of Defense has defined several sectors of interest [1], in which different kind of technologies can provide the means to develop the required applications, and among them, nanotechnology, and more specifically photonics and new emerging fields like metamaterials and plasmonics are expected to play an important role. Applications related to light guiding, multispectral sensing, lensing, and reduction of scattered light can be achieved using metamaterials. These are artificial materials [2] whose optical properties are solely determined by the fabricated microstructure, making it possible to the control the dielectric permittivity (ε) and magnetic permeability (μ) to achieve unsual properties such as negative refraction at certain wavelengths. Combined with Transformation Optics [3], these new materials allow an accurate control of the flow of light. This

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unique properties of metamaterials make them also attractive to be used in security features like of bank notes, passports or ID cards. Fast and accurate detection of biological or chemical agents is a topic of great interest in the field of security. IR spectroscopy is one of the most promising technologies for this application, since it allows the detection of IR signatures to be compared with databases to identify the threat. Also, the interaction of agents with sensing surfaces can change the optical properties, making it suitable for the use of plasmons in this kind of detection.

References [1] Ministerio de Defensa. Estrategia de Tecnología e Innovación para la Defensa – ETID (2010) [2] V.G. Veselago, The electrodynamics of substances with simultaneously negative values of ε and μ. Soviet Physics Uspekhi (1968) Vol 10 N4, 509 [3] D. Schurig, J.J. Mock, B.J. Justice, S.A. Cummer, J.B. Pendry, A.F. Starr, D.R. Smith, Metamaterial Electromagnetic Cloak at Microwave Frequencies. Science(2006) 977

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High Precision local electrical Probing: A New Low Temperature 4-Tip STM with Gemini UHV-SEM Navigation

A. Bettac, B. Guenther, J. Koeble, M. Maier and A. Feltz

a.bettac@omicron.de

Instituto Omicron NanoTechnology GmbH, Limburger Str. 75, 65232 Taunusstein, Germany

Developments in commercial surface science instrumentation regularly follow the major trends in science. The variety of instrumental approaches is as wide-ranged as science itself. Therefore, the identification of relevant analysis techniques and their advancement towards ease-of-use and a routinely accessible performance level represent a major challenge for enterprises. Beside OMICRON´s major activities in conventional SPM, electron spectroscopy and thin film techniques, the class of “multitechnique” instruments represents another important R&D line that is in the focus of this presentation. One prominent example in nanotechnology is the development of individual nano-scale devices. A tremendous variety of approaches exist and fundamental questions arise. Comprehensive concepts towards electrically integrated and therefore functional devices are however rare. Individual (metallic) nano-scale contacts represent one of the main challenges. High precision local electrical probing has the potential to increase efficiency in evaluating different approaches. The OMICRON UHV NANOPROBE already meets the involved requirements: (1) Rapid and simultaneous SEM navigation of four local STM probes; (2) Localization of nanostructures by sub-4nm UHV Gemini SEM resolution; (3) Individual probe fine positioning by atomic scale STM imaging; (4) STM based probe approach for “soft-landing” of sharp and fragile probes and controlled electrical contact; (5) suitable low noise signal re-routing for transport measurements; (6) chemical/magnetic analysis by complementary analysis techniques such as SAM, SEMPA, CL and others.

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And although the UHV NANOPROBE represents a flexible solution, especially in combination with complementary techniques, it´s concept is fundamentally limited in terms of lowest temperature and SPM resolution. Together with the Forschungszentrum Jülich, we thus have been developing a completely new design, the Low Temperature UHV NANOPROBE. It represents the evolution from a high performance probing system towards 4 simultaneously operating and high performing low temperature SPMs, navigated by SEM. The major R&D targets have been (1) equilibrium temperature of sample and probes at temperatures T<5K; (2) simultaneous SEM for probe navigation close to base temperatures; and (3) high STM performance of all four probes, truly suitable for manipulation and spectroscopy. First evaluation measurements will be presented: STM on Au(111) with pm stability, STS revealing the supeconducting gab of a Nb tip with approx. 3meV gap size, and first transport measurement at T<5K.

Figure 1. Left: Image of the LT NANOPROBE stage. Right: STM on Au(111) at a temperature of below 5 K. The atomic structure and the herringbone reconstruction are clearly visible.

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S-layer proteins as patterning elements in the life and non-life sciences

Dietmar Pum and Uwe B. Sleytr dietmar.pum@boku.ac.at

Department of Nanobiotechnology, University of Natural Resources and Life Sciences, Vienna, Austria

Crystalline S(urface)-layers are the most commonly observed cell surface structures in prokaryotic organisms (bacteria and archaea) [1]. S-layers are highly porous protein meshworks with unit cell sizes in the range of 3 to 30 nm, and thicknesses of ∼10 nm. S-layers exhibit either oblique (p1, p2), square (p4) or hexagonal (p3, p6) lattice symmetry. One of the key features of S-layer proteins is their intrinsic capability to form self-assembled monolayers in solution, at solid supports such as silicon or gold, at the air-water interface, at planar lipid films and at liposomes and nanocapsules. Basic research on S layer proteins enabled us to make use of the unique self-assembly properties of native and, in particular, genetically functionalized S-layer fusion protein lattices as matrices for the binding of molecules and the templated synthesis of nanomaterials [2]. S-layer proteins were already used as scaffolds for making hybrid organicinorganic nanostructures such as highly ordered nanoparticle arrays or silicified nanoporous biomembranes. In another approach the genetic engineering of fluorescent S-layer proteins allowed to develop novel pH indicators as used in drugtargeting and delivery systems. Further on, advances in elucidating the atomistic structure of Slayer proteins and simulating the self-assembly process opened the door to the design of new biofunctional materials for a diverse range of applications. The overall goal of our research is dedicated towards the development of an S-layer-based biomolecular construction kit. This presentation summarizes the key properties of S-layer proteins, with a focus on the self-assembly process, and describes different applications in the life and nonlife sciences. TNT 2012 madrid (spain)

Figure 1. Confocal micrographs showing the pH dependence of four different fluorescent S-layer fusion proteins.

Acknowledgements: Part of this work was funded by the Air Force Office of Scientific Research (AFOSR) Agreement Awards FA9550-09-0342 and FA9550-10-0223, the Austrian Nano-Initiative (Project Slaysens), and the Erwin Schödinger Society for Nanobiosciences, Vienna, Austria.

References [1] Sleytr, U.B., Schuster, B., Egelseer, E.M., Pum, D., Horejs, C.M., Tscheliessnig, R., Ilk, N., In Progress in Molecular Biology and Translational Science, Horworka, S. (Ed.), Academic Press, Burlington, MA (USA), Vol. 103 (2011) 277. [2] Pum, D., Sleytr, U.B., In Nanobioelectronics – for electronics, biology, and medicine, Offenhäuser, A., Rinaldi, R. (Eds.), Springer, New York, NY (USA), (2009) 167.

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Near field X-ray spectromicroscopies: new tools for nanoscience

Juris Purans purans@cfi.lu.lv

Institute of Solid State Physics, 8 Kengaraga Riga, Latvia

In the last years, the X-ray absorption (XAS) techniques have undergo remarkable development: (i) experiments with unprecedented femtometer accuracy, under extreme conditions of high pressure and temperature [1], (ii) experiments with nanoscale lateral resolution [2]. Nevertheless, investigations of complex nanostructured materials used in modern technologies require special X-ray experimental techniques able to imaging simultaneously topography and chemical mapping (X-ray analysis of matter) on the nanometer scale. Near Field (NF) X-ray Spectromicroscopy (FF illumination and NF detection) is a fully new approach for the detailed investigation of nanostructures down to the nanometer level. The extremely high lateral resolution of Local Probe Microscopies (LPM, AFM,STM) makes them among the most largely used in nanoscience. However, these tools suffer of a lack in chemical sensitivity. On the other hand, far field X-ray spectroscopy probes the chemical and structural properties of materials. A combination of X-ray spectroscopies and LPM is the ideal answer to many problems in nanosciences. This report highlights the most important contributions which were held in the combination of X-ray spectroscopies and LPM techniques. The basics of such approach are circulating since years. The first observations of core-level photoelectrons generated by X-ray irradiation of the tip-surface region of STM have been published by Tsuji [4]. Ishii [5] has measured the capacitance XAS signal with a metal tiny electrode. The combination of XAS and scanning near-field optical microscopy (SNOM) as a local detector was proposed by Purans [6], while a combination of XRF technique and LPM with a cantilever, having a hole of 100 nm, as a

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collimator of X-ray beam was proposed by Nagamura [7]. First STM and SNOM experiments under focused synchrotron-radiation (SR) were performed at ESRF on the microbeam line ID-3 [8]. Detailed STM study using soft SR X-rays was performed by Matsushima et al. [9]. A STM dedicated to in situ experiments under the irradiation of highly brilliant hard-X-rays of synchrotron radiation has been developed by Saito et al. [10] and a current modification was detected at the absorption edge with a spatial resolution of the order of 10 nm. Finally, Ishii and Hamilton et al. [11] has combined electrostatic force microscopy (EFM) with tunable synchrotron x-ray source excitation. Further progress we have achieved in the framework of the European X-TIP project by the focusing SR beam to increase the density of the incident photons. X-ray optics at third generation Synchrotron Radiation facilities have lead to the stable production of X-ray microbeams with extremely high photon densities making this approach feasible. We have started with three types of experiments: (i) XAS-AFM: X-ray excited secondary electrons detection by conductive tip in AFM mode; (ii) XAS-SNOM: X-ray excited optical luminescence (XEOL) detection by SNOM in AFM mode; (iii) XAS-SCM/AFM: X-ray excited capacitance or/and photoconductivity of sample detection by conductive tip in SCM, KFM or AFM mode. The new instrumentation developed within this project offers the possibility to carry out a selective structural analysis of the sample surface with the subwavelength spatial resolution determined by the SNOM probe aperture. In addition, the apex of the optical fibre plays the role of a topographic probe, and chemical and topographic mappings can be simultaneously recorded.

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Abstracts

[1] [2] [3] [4] [5] [6] [7]

J. Purans et al., Phys. Rev. Lett. 100 (2008) 055901 ; R.F. Pettifer et al., Nature 435 (2005) 78. W. Chao et al., Nature 435 (2005) 1210; DT. Attwood, Nature 442 (2006) 642. S. Larcheri and J. Purans, Rev. Sci. Instrum. 79 (2008) 013702. K.Tsuji et al., Surf. and Interface Anal. 27 (1999) 132. M.Ishii, Physica B. 308-310 (2001) 1153 ; M. Ishii et al., Appl. Phys. Lett. 90 (2007) 063101. J.Purans, Proc. TXRF2003 Sat. meeting on micro X-ray beam analysis, 13.09.2003, Osaka, Japan. T. Nagamura, Proceedings TXRF2003 Sat. meeting on micro X-ray beam analysis, 13.09.2003, Osaka, Japan. [8] F.Comin, D. Pailharey, R. Felici, J. Chevrier, J.Purans, ESRF user report on the project SI-956, 2004, Grenoble. [9] T.Matsushima et al., , Rev. Sci. Instr. 75 (2004) 2149. [10] A. Saito et al., J. Synchrotron Rad. 13 (2006) 216. [11] M. Ishii et al., Appl. Phys. Lett. 90 (2007) 063101.

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Unveiling the Landau levels structure of graphene nanoribbons

R.L. Ribeiro1, J.M. Poumirol1, A. Cresti2, W. Escoffier1, J.M. Broto1, S. Roche3,4 and B. Raquet1

Laboratoire National des Champs Magnétiques Intenses, INSA UPS CNRS, UPR 3228, Université de Toulouse, 143 av. de Rangueil, 31400 Toulouse, France 2 IMEP-LAHC, Grenoble-INP, Minatec 3 Parvis Louis Néel, BP 257 38016 Grenoble, France 3 CIN2 (ICN-CSIC) and Universitat Autonoma de Barcelona, Catalan Institute of Nanotechnology, Campus de la UAB, 08193 Bellaterra (Barcelona), Spain 4 ICREA, Institucio Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain

In the present work we show the first experimental evidence of Hall quantization in graphene nanoribbons along with the impact of the 1-D confinement of Dirac fermions. Carbon-based nanoelectronics is, in the actuality, one of the most promising subjects of nanotechnology. The challenging task for technologists is the achievement of clean devices with an engineered energy gap. The lateral confinement in graphene nanoribbons leads to a series of 1-D electronic sub-bands with a confinement gap. In presence of a large enough magnetic field, the band structure evolves to magneto-electric sub-bands and graphene-like Landau levels are expected to develop. The presence of these Landau levels makes itself evident with the appearance of ShubnikovdeHaas (SdH) oscillations and conductance quantization plateaus. Up to now, Hall quantization in graphene nanoribbons (GNRs) remains puzzling since no experimental evidence has been found for widths smaller than 200 nm [1-4]. The absence of Hall quantization in GNRs has been attributed to disorder, which is suspected to crosslink the chiral edge currents and impede the conductance quantization. Lithographically patterned GNRs of 100 and 70 nm widths are made using oxygen plasma etching and a PMMA etching mask. These GNR present a high conductance, a high field effect mobility and a weakly diffusive transport regime with presence of Fabry-Perot oscillations at low temperature. Magneto-resistance (MR) measurements show the first experimental evidence of Hall quantization in

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rebeca.ribeiro@lncmi.cnrs.fr

GNRs (Fig. 1) for filling factors ʋ= 2 and 6. On the other hand, anomalies in the magneto-transport measurements are evidenced: (i)

At high electrostatic doping level SdH oscillations show a clear departure from the regular linear behaviour of the Landau index as a function of 1/B (Fig. 1(a) inset). This is a direct signature of the electronic confinement that starts to overcome the magnetic confinement. (ii) The maxima of MR for all the ribbons, fingerprint of the Landau levels depopulation [5], present an up-shift of several Tesla compared to the theoretical value [6]. (iii) The narrower ribbons exhibit the expected 6G0 conductance maxima for a two-terminal measurement [5] but the 2G0 plateau is absent and the depopulation of the N=2 Landau level goes along with an unusual double peak of the resistance (Fig. 1(b)). To unveil the origin of the singular Landau spectrum we performed numerical simulations of the GNR band structure as a function of the perpendicular magnetic field and self-consistent calculations of the carrier distribution under magnetic field. We directly compared the oscillatory behaviour of the magnetoresistance and the onset of the magneto-electric sub-bands (Fig. 2). The simulations give evidence of magnetooscillations of the Fermi energy (blue line in Fig. 2) which consistently explains the broadening of the magneto-resistance peaks and their up-shift lo larger magnetic field. The presence of a second peak in the MR spectrum (Fig. 2 (b)) also finds a natural explanation: this is the clear signature of the orbital degeneracy lifting enhanced by the magnetic field and the pinning of the Fermi energy. TNT 2012 madrid (spain)

Abstracts

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Figure 1. Two terminal magneto-resistance measurements in a) GNR of 100nm width exhibiting the h/2e and h/6e quantization Hall resistance. Inset: Landau level index as a function of 1/B from: experimental magneto-resistance (circles) at high electrostatic doping, band structure calculations (crosses) and calculations of occupied sub-bands in a hard-wall confinement. b) Magneto-resistance of a GNR of 70nm width with the presence of a double resistance peak in the crossing of N=2 Landau level.

Figure 2. Numerical simulation of the band structure (black lines) in 814-aGNR (100 nm, Sample A) and 571-aGNR (70 nm, Sample B), self-consistent calculations of the Fermi energy under magnetic field (blue curve) and direct comparison with magneto-resistance measurements (red curve).

References [1] [2] [3] [4] [5] [6] [7]

C. Berger et al. Science, 312 (2006) 1191. F. Molitor et al. PRB 79 (2009) 075426. J. B. Oostinga et al. PRB, 81 (2010) 193408. J. M. Poumirol, et al. PRB, 82 (2010) 041413. J. R. Williams et al. PRB, 80 (2009) 045408. N. M. R. Peres et al. PRB, 73 (2006) 241403 R. L. Ribeiro et al. PRL 107 086601 (2011).

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Graphene potentialities for space and defense applications: focus on mechanical properties

Carlos Rivera1,2

carlos.rivera@insa.es

Ingeniería y Servicios Aeroespaciales, S.A., Paseo del Pintor Rosales 34, 28008, Madrid, Spain 2 Unidad de Fotónica, Instituto Tecnológico “La Marañosa”, Crta. San Martín de la Vega, km. 10.5, 28330, Madrid, Spain

The promising properties of graphene have motivated considerable research effort in recent years [1]. Surprisingly, the potential advantages offered by the technology based on graphene structures extend to a great variety of physical phenomena, including those affecting to electrical, optical, magnetic, thermal, chemical and mechanical properties. In some cases, the parameters predicted and measured have reached even the highest values reported for any known material (e.g., the highest carrier mobility at room temperature or the greater strength). However, much work must still be carried out to bring the inherent advantages of graphene to practical applications. Such work comprises the development of an efficient method to synthesize graphene in the proper form for each desired application without degrading its intrinsic properties. Further steps should also ensure the suitability of other technological aspects such as the compatibility with device-oriented fabrication processes, the scalability or the affordability. Here we provide a comprehensive overview of the potential uses of graphene-based devices and components for space and defense sectors. Basically, funded programmes have promoted next generation electronics and fundamental research topics. The development of future radio-frequency (RF) electronics is of paramount importance to improve the ever more demanding systems, especially taking into account the difficulty to maintain the historical trend predicted by Moore's law with traditional Si-based electronics. In addition to the more conventional approach of improving performance parameters of active devices, new functionalities or uses, such as those derived from the ambipolar nature of graphene or the possibility

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to achieve low-resistivity interconnects, respectively, have also been proposed [2]. Nevertheless, the benefits explored have not only been restricted to the utilization of graphene's superb electrical properties. Graphene has also been studied as building block of metamaterials and plasmonic components, as well as for transparent conductors, and high-speed electrooptical modulators and photodetectors [3]. Another remarkable areas which deserve attention in the present work are sensors and coatings (e.g., for inflatable structures or impermeable membranes) [4],[5]. In all cases, the success of graphene-based devices will depend on whether this material can lead to substantial improvement over competing technologies. The case of mechanical properties and the corresponding applications will be discussed in further detail. Three topics, namely, piezoelectricity (both engineered by chemical modification of the surface or introducing stressor structures), graphene papers and graphene composite materials, will be addressed [6],[7]. The analysis performed for the later structures will be focused on determining their effective Young's modulus, intrinsic strains and failure strains, as well as the proper parameters to account for the interlayer and intralayer bond strengths. It is worth noting that graphene composites could be exploited to enhance the macroscopic properties of the matrix material. Therefore, other macroscopic behaviours such as those due to the impact resistance will be assessed for suitable structures. The applications considered regarding mechanical properties will include the use of graphene as filler material, the control of mechanical motion, energy harvesting and sensors (e.g., resonator-based mass sensors). TNT 2012 madrid (spain)

Abstracts

[1] [2] [3] [4]

A. K. Geim and K. S. Novoselov, Nature Materials, 6 (2007) 183–191. J.-S. Moon and D. K. Gaskill, IEEE Trans. Microw. Theory Tech., 59 (2011) 2702–2708. T. Mueller, F. Xia, and P. Avouris, Nature Photonics, 4 (2010) 297–301. J. S. Bunch, S. S. Verbridge, J. S. Alden, A. M. van der Zande, J. M. Parpia, H. G. Craighead, and P. L. McEuen, Nano Lett., 8 (2008) 2458–2462. [5] E. W. Hill, A. Vijayaragahvan, and K. Novoselov, IEEE Sensors J., 11 (2011) 3161–3170. [6] S. Stankovich, D. A. Dikin, G. H. B. Dommett, K. M. Kohlhaas, E. J. Zimney, E. A. Stach, R. D. Piner, S. T. Nguyen, and R. S. Ruoff, Nature, 442 (2006) 282–286. [7] M. T. Ong and E. J. Reed, ACS Nano, 6 (2012) 1387–1394.

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References

Supported nanomaterials for photocatalytic water disinfection at rural areas: from lab. scale to on-site experiments

Juan Rodríguez purans@cfi.lu.lv

Facultad de Ciencias, Universidad Nacional de Ingeniería, P.O. Box 31-139, Av. Túpac Amaru 210, Lima, Perú

In this work, It will be reviewed our experience in the fabrication and characterization of photocatalytic nanomaterials for water purification. The growth of TiO2 nanoparticles fixed onto rigid and flexible substrates will be shown as well as ZnO nanorods supported onto a flat substrate. All of these materials will be discussed as a function of the main parameters used in their preparation and their ability to photocatalytically eliminate bacteria in water. Studies were performed in the laboratory as well as at a greenfield site. For long term on-site experiments, for example, bacteria decontamination under real conditions has been successfully tested at rural places using solar irradiated photocatalytic prototypes of up to 120 L. With these studies, it was demonstrated the feasibility to obtain water disinfection by using supported photocatalytic nanomaterials illuminating it with solar radiation and makes us optimistic for the development of robust technologies for water treatment at rural areas.

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Substantial increase of the critical current on a Spin Transfer Nanopillar by adding an Fe/Gd/Fe trilayer

M. Romera1, J. Grollier2, V. Cros2, S. Collin2, T. Devolver3, M. Muñoz4 and J. L. Prieto1

mromera@fis.upm.es Instituto de Sistemas Optoelectrónicos y Microtecnología, Universidad Politénica de Madrid. Avenida Complutense 30, Madrid, Madrid, Spain. 2 Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 ave. A. Fresnel, 91767 Palaiseau, France. 3 Intitut d’Électronique Fondamentale, Université Paris Sud 11-CNRS, rue André Ampère F 91405 Orsay, France. 4 Instituto de Microelectrónica de Madrid (CNM, CSIC), Isaac Newton 8, Tres Cantos, Madrid 28760, Spain.

Spin Transfer Torque (STT) excitations have created an increasing interest on the last few years due to the technological possibilities of current induced domain wall movement [1], switching nanomagnets [2] or generating radiofrequency signals [3]. However, they can also be detrimental in other applications like magnetic read heads, where stability and signal-to-noise ratio are very important issues in which STT has a negative effect [4]. In consequence, while for many applications the goal is to reduce the critical current density (jC) at which STT is induced, others require just the opposite. The inclusion of Rare Earths (RE) contaminants on a magnetic layer has been one of the main approaches used to affect important magnetic properties like polarization, precessional frequency or damping [5,6,7]. Within RE, Gadolinium (Gd) is of special interest because it is ferromagnetic up to Room Temperature (TC(Gd)=293 K) and it has a very large magnetic moment at low temperatures. As a dopant it has already shown great potential for tuning the resonance frequency of a magnetic domain wall [8] or its velocity in magnetic nanostripes [9], or even controlling the spin polarization of the material [5,9]. In this work we have studied the influence of Gadolinium on the STT in Permalloy based nanopillars. We report a remarkable increase of the jC required to destabilize the Permalloy layer when a Fe/Gd/Fe ferrimagnetic trilayer is added onto the structure. Indeed, other ferrimagnetic structures have been already successfully applied in spin valves in order to increase the critical current for STT [10]. The use of a thin layer of Gd could potentially add

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stability to this kind of structures without detriment of performance.

Figure 1. Stability phase diagram at 10 K corresponding to a reference Py device (a) and to a device with Fe/Gd/Fe (c). Color diagrams have been obtained from the positive branch (i.e. from –Imax to +Imax) of the R-I loops for different fields, and normalized so ΔR=0 corresponds to P state (dark blue in the diagrams). The colored lines on top of the contour plots highlight hysteretic transitions. Brown lines indicate a transition from high to low resistance in the positive branch (–Imax to +Imax), either from AP-state to lower resistance (solid brown line) or from some other intermediate resistance value (I-state) to a lower resistance (dashed brown line). Black lines represent transitions from the P state to a higher resistance state on the negative branch of the R-I loops, either from P to AP state (solid black line) or from P to a I-state (dashed black line). Selected R-I loops at 10 K and different fields for the reference device are represented in (b) and for the device with Fe/Gd/Fe in (d). The current sequence was I=0→ -Imax → +Imax → 0. Arrows in (c) and (d) emphasize minor transitions or instabilities.

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The basic structure used in this study is SiO2// Cu(60)/ CoFe(12)/ Cu(10)/ Py(4)/ AFL/ Cu(8) where Py stands for Permalloy (Ni80Fe20) and AFL is an Artificial Ferrimagnetic Layer of Fe(1)/ Gd(1)/ Fe(1). Numbers between brackets represent thickness in nanometers. In order to understand the effect of the AFL, we have measured also a reference sample with only Py in the free layer (i.e. SiO2// Cu(60)/ CoFe(12)/ Cu(10)/ Py(4)/ Cu(8)). Figure 1 shows the phase diagram and some selected R-I loops measured at 10 K on elliptical pillars (with axis of 50 and 150 nm) patterned on the reference sample (Fig. 1a and 1b) and on the sample with AFL (Fig. 1c and 1d) respectively.

Figure 2. Measurements at RT in a Py(4nm)-film (black symbols) and a Py(4nm)/Fe(1nm)/Gd(1nm)/Fe(1nm)-film (red symbols). (a) Imaginary part of the permeability measured at high fields. (b) FMR data (symbols) adjusted to the Kittel equation (line). (c) P-Moke hysteresis loops with the field applied perpendicular to the sample plane.

In the hysteretic region of the diagrams (at low fields) the jC is observed to increase almost an order of magnitude with the insertion of the AFL (from 2.3·107 A/cm2 to 1.6·108 A/cm2). In the reference device, reversible transitions (usually associated to unstable precession-like motion of the free layer) are predominant out of the hysteretic region and can be observed even for very high fields (~500 Oe). On the other hand, in the device with AFL these reversible transitions are almost no existent in all the range of field applied. In fact, in this device there are not transitions at all for applied fields higher than ~200 Oe.

References

The effect of the Fe/Gd/Fe trilayer on the magnetic properties of the Py layer has been studied through Ferromagnetic Resonance, SQUID and P-Moke measurements (Fig. 2). We observed that the AFL modify the damping, saturation magnetization and thickness on the free layer, but these variations only explain an increase of the critical current by a factor 1.6. On the other hand, Gd has small polarization (~13% [5]), and most of the magnetic moment in the Gd layer comes from strongly localized 4f electrons. Therefore, all the angular momentum carried by the spin polarized current in the Py/Fe free layer must be transferred to the antiparallel Gd layer at the interface between the 3d Py/Fe and the 4f Gd. The effect of this sudden transfer of angular momentum can be observed experimentally in any standard Spin Valve just by inserting a very thin Gd layer between the non-magnetic layer and the free layer. By doing this the magnetoresistance value drops to zero [11]. The large jC enhancement observed in our nanopillars seems to be caused by a reduction of the effective torque on the free layer associated to the sudden transfer of angular momentum at the interface of the antiparallel Gd layer.

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It is also important to highlight the fact that the total ΔR of the device does not change much by adding Fe/Gd/Fe, as the thickness of the Py layer underneath is of the order of its spin diffusion length. Therefore our results with this type of trilayers might constitute a potential solution to the problems of STT instability in some nanometer-size devices.

[1] S. S. P. Parkin, M. Hayashi, L. Thomas, Science, 320 (2008) 190. [2] B. O¨ zyilmaz, A. D. Kent, D. Monsma, J. Z. Sun, M. J. Rooks, and R. H. Koch, Phys. Rev. Lett., 91 (2003) 067203. [3] D. Houssameddine, U. Ebels, B. Delaët, B. Rodmacq, I. Firastrau, F. Ponthenier, M. Brunet, C. Thirion, J.P. Michel, L. Prejbeanu-Buda, M.C. Cyrille, O. Redon and B. Dieny, Nat. Mat., 6 (2007) 447. [4] J.G. Zhu and X. Zhu, IEEE Trans. Magn., 40 (2004) 182. [5] C. Kaiser, A.F. Panchula and S.S.P. Parkin, Phys. Rev. Lett., 95 (2005) 047202. [6] S.G. Reidy, L. Cheng and W.E. Bailey, Appl. Phys. Lett., 82 (2003) 1254. [7] G. Woltersdorf, M. Kiessling, G. Meyer, J.U. Thiele, and C. H. Back, Phys. Rev. Lett., 102 (2009) 257602. [8] S. Lepadatu, J.S. Claydon, D. Ciudad, C.J. Kinane, S. Langridge, S.S. Dhesi and C.H. Marrows, Appl. Phys. Lett., 97 (2010) 072507. [9] R. L. Thomas, M. Zhu, C. L. Dennis, V. Misra and R. D. McMichael, J. Appl. Phys., 110 (2011) 033902. [10] N. Smith, S. Maat, M. J. Carey and J. R. Childress, Phys. Rev. Lett., 101 (2008) 247205. [11] M. Romera, M. Muñoz, P. Sánchez, C. Aroca and J. L. Prieto, J. Appl. Phys., 106, 0239922 (2009).

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New capabilities at the interface of X-rays and scanning tunneling microscopy

Volker Rose

Advanced Photon Source and Center for Nanoscale Materials Argonne National Laboratory, USA

In this talk we will discuss the development of a novel high-resolution microscopy technique for imaging of nanoscale materials with chemical, electronic, and magnetic contrast. It will combine the sub-nanometer spatial resolution of scanning tunneling microscopy (STM) with the chemical, electronic, and magnetic sensitivity of synchrotron radiation. [1,2] Drawing upon experience from a prototype that has been developed to demonstrate general feasibility, current work has the goal to drastically increase the spatial resolution of existing state-of-the-art x-ray microscopy from only tens of nanometers down to atomic resolution. Key enablers for high resolution are insulator-coated “smart tips” with small conducting apex (cf. Fig. 1). [3] The technique will enable fundamentally new methods of characterization, which will be applied to the study of energy materials and nanoscale magnetic systems. A better understanding of these phenomena at the nanoscale has great potential to improve the conversion efficiency of quantum energy devices and lead to advances in future data storage applications. The combination of the high spatial resolution of STM with the energy selectivity afforded by x-ray absorption spectroscopy provides a powerful analytical tool.

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Scan me

Figure 1. X-ray nanotomography surface rendering of a smart scanning tunneling microscope tip. The platinumiridium tip (red) has been coated with a SiO2 insulating layer (green).

References [1] V. Rose, J.W. Freeland, S.K. Streiffer, “New Capabilities at the Interface of X-rays and Scanning Tunneling Microscopy”, in Scanning Probe Microscopy of Functional Materials: Nanoscale Imaging and Spectroscopy, S.V. Kalinin, A. Gruverman, (Eds.), Springer, New York (2011), pg 405-432. [2] M.L. Cummings, T.Y. Chien, C. Preissner, V. Madhavan, D. Diesing, M. Bode, J.W. Freeland, V. Rose, Ultramicroscopy 112, 22 (2012). [3] V. Rose, T.Y. Chien, J. Hiller, D. Rosenmann, R.P. Winarski, Appl. Phys. Lett. 99, 173102 (2011).

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G. Rubio-Bollinger1, A. Castellanos-Gomez1,2, M. Poot3,2, G. A. Steele2, H.S.J. van der Zant2 and N. Agraït1,4

Mechanical properties of freely suspended atomically thin dielectric layers of mica 1

Dpto de Física de la Materia Condensada. Universidad Autónoma de Madrid, Campus de Cantoblanco. E-28049 Madrid, Spain. 2 Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands. 3 Yale University. Department of Engineering Science. Becton 215, 15 Prospect St. New Haven, CT 06520, USA. 4 Instituto Madrileño de Estudios Avanzados en Nanociencia IMDEA-Nanociencia, E-28049 Madrid , Spain.

We study the elastic deformation of freely suspended atomically thin sheets of muscovite mica [1][3] (see Figure 1), a widely used electrical insulator in its bulk form. Using an atomic force microscope, we carried out bending test experiments [1,2] (see Figure 2) to determine the Young’s modulus and the initial pre-tension of mica nanosheets with thicknesses ranging from 14 layers down to just one bilayer. We find that their Young’s modulus is high (190 GPa), in agreement with the bulk value which indicates that the exfoliation procedure employed to fabricate these nanolayers does not introduce a noticeable amount of defects. Additionally, ultrathin mica presents low pre-strain and it can stand reversible deformations up to tens of nanometers without breaking. The low pretension and high Young's modulus and breaking force found in these ultrathin mica layers demonstrates their prospective use as complement for graphene in applications requiring flexible insulating materials or as reinforcement in nanocomposites.

gabino.rubio@uam.es

Figure 1. Optical micrograph of ultrathin two dimensional mica layers deposited on a silicon subtrate patterned with holes, where the mica sheet is suspended. Different colors correspond to different mica sheet thicknesses. The graph shows the optical contrast dependence on the mica sheet thickness.

References [1] A. Castellanos-Gomez et al., Nano Research (accepted) 2012. [2] A. Castellanos-Gomez et al., Advanced Materials, 24 (2012) 772-775. [3] A. Castellanos-Gomez et al., Small, 7 (2011) 2491-2497.

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Figure 2. Force vs. deformation traces measured at the center of the suspended part of mica nanosheets with 2, 6 and 12 layers in thickness. The slope of the traces around zero deflection is marked by a dotted line. (Inset) schematic diagram of the bending test experiment carried out on a freely suspended mica nanosheet.

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An efficient MRI contrast agent based on PEGylated iron oxide nanoparticles Instituto de Ciencia de Materiales de Madrid/CSIC, Cantoblanco, 28049 Madrid, Spain Estudios Avanzados de Cuba, San Antonio de Los Baños km 3½, La Habana, Cuba

Amalia Ruiz, Gorka Salas, Macarena Calero, Yenisel Hernández, Angeles Villanueva, Fernando Herranz, Sabino Veintemillas-Verdaguer, Eduardo Martínez, Domingo F. Barber and María del Puerto Morales amaliaruiz@icmm.csic.es

Superparamagnetic nanoparticles are of special interest for various applications in nanomedicine. Nowadays, one of the most important and rapidly growing ﬁelds is the use of iron oxide particles as contrast agents for magnetic resonance imaging (MRI). Also, the immobilization of poly(ethylene glycol) (PEG) onto the nanoparticles's surface is the most used strategy to avoid opsonisation and cellular recognition, improving biocompatibility and pharmacokinetic. In this study, we developed a MRI contrast agent based on PEGylated iron oxide nanoparticles. Magnetite nanoparticles (12 nm in diameter) were obtained via thermal decomposition of a iron coordination complex to assure nanoparticle homogeneity in size and shape (Fig. 1). Particles were coated with DMSA by a ligand exchange process to remove oleic acid, after which three distinct short-chain PEG polymers were covalently bound to the nanoparticle surface via EDC activation of the carboxylic groups. In all cases, colloidal suspensions had hydrodynamic sizes below 100 nm and low surface charge, demonstrating the effect of PEG coating on the colloidal properties and stability of the magnetic nanoparticles. We tested in vitro the internalization and biocompatibility of these materials in the HeLa human cervical carcinoma cell line. Cells preincubated with PEG-coated iron nanoparticles were visualized outside the cells and their biocompatibility at high Fe concentrations was demonstrated using a standard MTT assay. Finally, we used relaxivity parameters (r1 and r2) to evaluate the efficiency of suspensions as MRI contrast agents; r2 values were four times higher than that for commercial products, probably due to the larger nanoparticle size. The time of residence in blood after coating increased up to hours in New TNT 2012 madrid (spain)

Zealand rabbits and Wistar rats (Fig. 2). Our results suggest that this PEGylation strategy for large magnetic nanoparticles (>10 nm) holds promise for biomedical applications. T2 MRI images of rat liver before and after injecting the synthesized contrast agent showed a significant increase in the contrast with time from 10 min up to 50 minutes (Fig. 3).

References [1] D. Peer, J.M. Karp, S. Hong, O.C. Farokhzad, R. Margalit, R. Langer, Nat. Nanotechnol. 2007, 2, 751 [2] M. Colombo, S. Carregal-Romero, M. F. Casula, L. Gutiérrez, M.P. Morales, I.B. Böhm, J.T. Heverhagen, D. Prosperi, W. J. Parak, Chem. Soc Rev. 2012, DOI:10.1039/c2cs15337h. [3] J. Gao in Biofunctionalization of Nanomaterials (Eds: Ch. Kumar), Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, Germany 2005, Ch. 3. [4] S. Perrault, C. Walkey, T. Jennings, H. Fischer, W. Chan, Nano Lett. 2009, 9, 1909. [5] C. Fang, N. Bhattarai, C. Sun, M. Zhang, Small 2009, 5, (14) 1637. [6] A. G. Roca, S. Veintemillas-Verdaguer, M. Port, C. Robic, C. J. Serna, M. P. Morales, J. Phys. Chem. B 2009, 113, 7033.

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TNT2012 Figure 1. (a) TEM images of magnetite nanoparticles (b) Size-distribution graph. The red line is the log-normal ﬁtting function of the particle size data.

Figure 2. (e, f) ICP quantification of iron concentration in blood after injection into e) rabbits and f) rats. NPDMSA-PEG-NH2 [○], NP-DMSA-PEG-(NH2)2 [■] and NPDMSA-PEG-Prop-(NH2)2) [∆].

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Figure 3. T2 MR images of rat liver before and after injecting the synthesized contrast agent. In the left animal injected with NP-DMSA-PEG-(NH2)2 and in the right control animal (a)T2 image after 10 minutes of injection.(b)T2 image after 50 minutes of injection.

TNT 2012 madrid (spain)

Creating nanowires with atomic precision

C. Sabater, J.J. Palacios, M.J. Caturla, C. Untiedt

University of Alicante, Departamento Física Aplicada, Carretera San Vicente del Raspeig s/n, San Vicente del Raspeig, Spain

carlos.sabater@ua.es

Measuring the conductance between gold electrodes and limiting the indentation depth between the two electrodes up to a conductance value of approximately 5G0 in the case of gold we can obtain the same conductance behavior for hundreds of cycles of formation and rupture of the nanocontact. Furthermore, when two metals approach, the first contact between them occurs abruptly in most cases. This phenomenon is called “jump-to-contact”. It is well known that the conductance in a nanocontact is related to the smallest area of the contact between the two electrodes. Therefore, variations of the conductance should be related to changes in the atomic structure at the contact. Similarly, a jump in the conductance is observed when the two electrodes are pulled apart and the contact is broken, in what is called "jump-out-of-contact". Both experiments are rationalized using molecular dynamics simulations together with density functional theory transport calculations which show how: a)

after repeated indentations (mechanical annealing), the two metallic electrodes are shaped into tips of reproducible structure. certain atomic contact structures are most likely to occur.

Figure 1. Experimental traces obtained for Au nanocontacts during formation and rupture when limiting the conductance to (a) 5G0 and (b) 8G0. The inset shows a 3D figure of the rupture where the third axis is each individual trace.

These results provide a crucial insight into fundamental aspects relevant to nano-tribology or scanning probe microscopies.

References [1] C.Sabater, C. Untiedt, J.J.P, Phys. Rev. Lett. 108, 205502 (2012). [2] C. Untiedt, M. J. Caturla, M. R. Calvo, J. J. Palacios, R. C. Segers, and J. M. van Ruitenbeek, Phys. Rev. Lett. 98, 206801 (2007)

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Figure 2. Snapshots of the MD simulations of rupture and formation of a nanocontact in gold for the initial configuration and before cycles 2, 5, 10, 15 and 20 (top). Number of atoms in the top nanoelectrode (in %) that were initially on the second one, and viceversa, as a function of the number of cycles(bottom). Temperature was not fixed in this calculation.

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TNT2012 Figure 3. Traces of conductance from DFT (open circles are calculations with 1 electron and diamonds are calculations with 11 electrons) and estimates from MD minimum cross section (lines) for calculations with 525 atoms. (a) Rupture trace during first cycle and (b) rupture trace for cycle number 10 for a maximum indentation of 5 atoms in cross section.

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Figure 4. (color online) Analysis of the steepest jump of conductance before the formation of a metallic contact for the case of gold, made from more than 300 000 conductance traces. The left panel shows a density plot, where the horizontal axes represents the conductance at which the jump takes place and the vertical axes shows the conductance of the contact formed. We have artificially changed the colors of the peak above (gray scale) to make it visible. The right panel shows the corresponding histogram of the conductance of the contact formed after the jump.

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Nanoscale elemental analysis and applications using STM combined with brilliant hard X-rays 1

Department of Precision Science & Technology, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan 2 RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148, Japan 3 Institute for Molecular Science, Myodaiji-cho, Okazaki 444-8585, Japan 4 WPI center, National Institute for Materials Science,Tsukuba 305-0003, Japan

Analyses by scanning tunneling microscopy (STM) combined with brilliant X-rays from synchrotron radiation (SR) can provide various possibilities of original and important applications. The STM observation under inner-shell excitation at a specific core-level enables us to analyze the elements or control the local reaction with the high spatial resolution of STM [1]. We have recently demonstrated the elemental analyses with a spatial resolution lower than 2 nm on semiconductor surfaces [2]. The principle of our analyses is not to collect the secondary electrons by STM tip (that may damage the spatial resolution), but to extract the element-specific modulation of the â&#x20AC;?tunneling currentâ&#x20AC;? succeeding the core-excitation process, which contains truly local information. A key to accomplish successful results is to effectively increase the signal to noise (S/N) ratio. On this purpose, we developed a special SR-STM system. The experimental setup is shown in Fig.1. To surmount a tiny core-excitation efficiency by hard X-rays, we focused two-dimensionally an incident beam having the highest photon density at the SPring-8. Many problems derived from the high brilliance (thermal and electrical noise, damage of STM scanner, instability such as thermal drift, etc.) were solved by the special apparatus and system [1]. Furthermore, we developed a special tip [3] (that can eliminate the noisy electrons coming from a wide area) and signal acquisition system that realizes a high signal to noise ratio to obtain a small modification of the tunneling current originating from the core excitation. After first results on a semiconductor hetero-interface (Si(111)7x7-Ge) [1], second results on the nanoscale elemental analysis were acquired for metalsemiconductor interface (Ge(111)-Cu nano-domains) [2]. For both cases, the spatial resolution of the analysis was estimated to be 1~4 nm, and it is worth noting that

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Akira Saito1,2, T. Tanaka1, H. Matsuno1, H. Miki1, Y. Furudate1, Y. Takagi3, M. Akai-Kasaya1, Y. Tanaka2, Y. Kohmura2, T. Ishikawa2, Y. Kuwahara1,2 and M. Aono4 saito@prec.eng.osaka-u.ac.jp

the measured domains had a thickness of less than one atomic layer (Fig.2).

Figure 1. Schematic view of experimental setup.

Figure 2. (a) Line profile of beam-induced tip current image along the line shown in the bottom image. (b) Topographic image and (c) beam-induced tip current image of Ge (111)-Cu (-2V, 0.2 nA).

After progresses of the measurement system and techniques, we succeeded in obtaining a series of successive STM images at an atomically same area

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without serious drift or sample damages. Accordingly, we could acquire a linear dependence of the element contrast on the incident photon density. The photon density dependence of the elemental contrast will give an important clue to know the origin of the element contrast. Actually, our result on the linear dependence of the element contrast on the photon density suggests that we can deny a possibility of the local potential change derived from the core excitation, because the potential should give an exponential dependence of the contrast on the incident photon density.

irradiation, our atomic motion occurs at very low temperature in comparison with the past report.

Also we could recently measured scanning tunneling spectroscopy (STS), which have long been impossible because of instability due to brilliant X-ray irradiation. STS information gives us more direct hint to approach the mechanism of contrast to obtain a higher resolution. It is notable that the image in Fig. 2(c) shows the contrast originating from the chemical difference (that is not based on the surface step height), presenting the structures different from the conventional topographic (Fig. 2(b)) image.

On the other hand, the above mentioned results will allow us to study the element-specific atomic control of local reaction with the spatial resolution of STM, giving hope of wide application. For example, the dense X-rays are suggested to have new applications, such as direct X-ray lithography. In other viewpoint, our results show a new application of the in situ SR-STM system. Our method for observing the atomic track will serve to provide new information not only for the radiation effects on various optical devices in new X-ray generators, but also for basic science by observing photon-matter interactions.

Next, we have recently achieved a direct observation of the â&#x20AC;&#x153;X-ray induced atomic motionâ&#x20AC;? with the track of the atomic motion at an atomic scale using the SR-STM system under the incident photon density of ~2x1015 photon/sec/mm2 [4]. This observation was enabled only by use of the in situ SR-STM system, because the STM images in the atomically same area should be compared before and after X-ray irradiation. In our STM images, the low-magnification images showed that the X-ray induced atomic motion rate is so low that structural changes are hardly detectable by other surface analysis techniques such as diffraction analysis. However, the magnified STM images revealed a clear change in the atomic structures after X-ray irradiation. Then, we developed a technique to recognize atomic motions directly to comprehend their behavior. By merging the STM images obtained before and after X-ray irradiation, the atomic motion track could be newly presented as several continuous lines (Fig. 3), whereas other stable atoms are shown as spheres. The appeared atomic track is the direct evidence and visualized information of the atomic diffusion at an atomic scale. It is worth comparing our results with past conventional thermal STM observations on the same surface [5], where the atomic motion was found to occur in the form of 2dimensional domain and begin at ~220Â°C. However, our results show the atomic track having a local chain distribution. This locality in diffusion can be attributed to the anisotropy of the surface structure, and probably the origin of atomic motion, to core excitation. In fact, considering the temperature increase of 92 K from the room temperature estimated from the X-rays

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Apart from the result on the elemental analysis, this finding on the atomic motion will serve to study the initial radiation effect on the optical devices such as mirror or grating at the X-ray sources of new generation such as X-ray free electron laser (XFEL). Also our observation of the damage barrier has potential importance as an indicator for a damage threshold in the near future for analyzing tiny materials using strong X-rays.

Figure 3. Atomic motion tracks newly presented by merging the STM images before and after X-ray irradiation.

References [1] A.Saito, et al.: J.Synchrotron Rad.13 (2006) 216. ;Jpn.J.Appl.Phys.45 (2006) 1913.; Curr. Appl.Phys. (2012) in press. [2] A.Saito et al.: Surf. Interface Anal. 40 (2008) 1033.; "Nano-imaging" (NTS publisher, 2008) p.278. [3] A.Saito et al.: Surf. Sci. 601 (2007) 5294. [4] A.Saito et al.: J. Nanosci. Nanotechnol. 11 (2011) 1873. [5] R.M. Feenstra et al.: Phys. Rev. Lett. 66 (1991) 3257. TNT 2012 madrid (spain)

Biorthogonal chemistry for the functionalization of superparamagnetic nanoparticles: cross olefin metathesis

B. Salinas1,2, J. Ruiz-Cabello1,2, M.P. Morales3 and F. Herranz2 bsalinas@cnic.es

Unidad de Imagen Avanzada. Centro Nacional de Investigaciones Cardiovasculares (CNIC).Madrid, Spain 2 Dpto.QuĂmica-FĂsica II, Facultad de Farmacia Universidad Complutense, CIBERES, Madrid, Spain 3 Biomaterials and Bioinspired Materials Instituto de Ciencia de Materiales de Madrid,Madrid, Spain

The use of magnetic nanoparticles in biomedical applications has witnessed an exponential growth last years. Iron oxide nanoparticles (NP), particularly, have gained a dominant role because of their physicochemical properties and low toxicity. Due to their superparamagnetic behavior these particles are of paramount importance in imaging techniques like Magnetic Resonance Imaging (MRI) and Magnetic Particle Imaging (MPI). In order to provide stability and targeting these NPs require specific coating. The association of one or more biologically relevant molecules at the interface of a NP defines a NP-bioconjugate, which combines the unique physicochemical properties of NP materials with biological activity such as selective binding. To date, researchers have largely relied upon the traditional chemistries associated with protein labeling for the preparation of NPbioconjugates. However, the range of bioconjugation techniques used with NPs has lagged behind the multitude of biological applications proposed. Although traditional bioconjugate chemistries have been adequate for proof-of-concept studies, the optimization of NPbioconjugates for real applications (e.g., clinical) will require much greater control than these chemistries can offer. Rather, clean, efficient, and bioorthogonal conjugation reactions are required to eliminate undesirable side reactions, minimize nonspecific NP-bioconjugate activity, improve reproducibility in production, and maximize efficacy [1-3]. Within this group of bioorthogonal chemistry,

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olefin metathesis offers many of these features thanks to the new family of catalysts, especially Hoveyda-Grubbs 2nd generation. The metathesis mechanism reorganizes the carbon atoms of two C=C bonds, generating two new ones in the presence of a catalyst. This kind of reaction allows access from the easily prepared olefins to those that are cumbersome to obtain, being an efficient and stereoselective synthesis of the more substitute olefins in mild conditions. All of these advantages make the metathesis of alkenes one of the most powerful tools in synthetic chemistry, but as far as we know, it has not been applied for the functionalization of iron oxide superparamagnetic. Here we present our results in the functionalization of superparamagnetic iron oxide nanoparticles with four different terminal olefins through metathesis reaction [4]. First, we synthesized iron oxide nanoparticles by the decomposition of organic precursor obtaining hydrophobic Fe3O4 NPs, with oleic acid as surfactant. The olefin metathesis was made between the double bond in oleic acid structure and four different molecules with a terminal double bond; methyl acrylate, 6hexenetirile, allyltrifluoroacetate and 3-allyloxi-1,2propandiol, in presence of catalytic amounts (4%mol) of Hoveyda-Grubbs second generation catalyst. These new NPs were fully characterized by TEM, VSM, MS and FTIR, showing the success of the reaction and quite good values for the hydrodynamic size and PDI as can be seen in figure 1.

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TNT2012 Figure 1. General metathesis synthesis and summary of the averaged sizes.

Figure 2. Hydrolysis of NPs (2) with methyl acrylate, generating hydrophilic NPs.

After the metathesis the ester bond in 2 was hydrolyzed rendering water stable sample 6 due to the presence of the terminal carboxylic acid, with a Z average of 28 ± 10 nm (PDI 0.30 ± 0.07, N=3). These NPs were fully characterized. The physicochemical properties of the inorganic core were studied by TEM and VSM, which demonstrated the superparamagnetic behavior of the sample [4]. The presence of the acid was probed through the FTIR spectrum and the ζ potential profile, which exhibit their stability in physiological conditions, with a value of -37 ± 5 mV at pH 7, and the typical profile for NPs stabilized by a carboxylic acid.

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For biomedical applications the nanoparticles must show high stability in solutions with high ionic strength. To this end metathesis is especially well suited as it allows such modifications in one single step from the hydrophobic particles if the right olefins are used. For this reason once demonstrated the possibility of using the metathesis in USPIO the second stage was the direct bioconjugation with hydrophilic polymers bearing a terminal olefin. On this regard we will focus in the results obtained with Polyethylene glycol (PEG) and different proteins from the extracellular matrix. First, the biopolymers were modified to show a terminal olefin through a substitution reaction. The metathesis was applied as shown before over the sample 1, rendering hydrophilic NPs. These NPs were fully characterized by FTIR, MS, VSM and TEM, showing the success of the reaction keeping the superparamagnetic behavior of the NPs, which allow their possible use as MRI contrast agent. In this work we demonstrate, for the first time, the use of the cross olefin metathesis reaction for bioorthogonal functionalization of iron oxide nanoparticles with different ligands, allowing the incorporation of different functional groups and biomolecules. Using appropriate catalyst and reaction conditions it is possible to modify the structure of the surfactant without self-metathesis, as demonstrated with the hydrodynamic size, TEM images and FT-IR spectra reported here. This simplifies the synthesis of hydrophobic and hydrophilic nanoparticles with applications in different fields.

References [1] Russ Algar W., Prasuhn D. E., Stewart M. H., Jennings T. L., Blanco-Canosa J. B., Dawson P. E., Medintz I. L. 2011 Bioconjugate Chem., 22, 825–858. [2] Herranz F., Morales M.P., Roca A.G., Desco M., Ruiz-Cabello J. 2008 Chemistry- A European Journal, 14(30), 9126-9130. [3] Herranz F., Almarza E., Rodríguez I., Salinas B., Rosell Y., Desco M., Bulte J.W.M., Ruiz-Cabello J. 2011 Microsp. Res. Tech. 74 (4), 577-591. [4] B. Salinas, J. Ruiz-Cabello, M.P. Morales, F. Herranz. 2012 Bioinspired, Biomimetic and Nanomaterials. 1, 166-172.

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AC Josephson effect in finite-length nanowire junctions with Majorana modes

Pablo San Jose

Instituto de Estructura de la Materia (CSIC) Serrano 123, 28006 Madrid (SPAIN)

It has been predicted that superconducting junctions made with topological nanowires hosting Majorana bound states (MBS) exhibit an anomalous 4Ď&#x20AC;-periodic Josephson effect. Finding an experimental setup with these unconventional properties poses, however, a serious challenge: for finite-length wires, the equilibrium supercurrents are always 2Ď&#x20AC; periodic as anticrossings of states with the same fermionic parity are possible. We show, however, that the anomaly survives in the transient regime of the ac Josephson effect. Transients are, moreover, protected against decay by quasiparticle poisoning as a consequence of the quantum Zeno effect, which fixes the parity of Majorana qubits. The resulting long-lived ac Josephson transients may be effectively used to detect MBS.

References [1] Phys. Rev. Lett. 108, 257001 (2012)

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Thermal and mechanical effects of different excitation modes based on low frequency laser modulation in optical hyperthermia Centre for Biomedical Technology (CTB), Technical University of Madrid (UPM), Campus Montegancedo, Pozuelo de Alarcón (Madrid), Spain

Recently, gold nanoparticles, in combination with laser light, have been used successfully to achieve controlled thermal damage in tumor tissue [1] [2]. Gold nanostructures show a unique optical property, ie, they efficiently absorb light due to the surface plasmon resonance phenomenon and then convert the absorbed light into localized heat [3]. Our first work was aimed at obtaining a proof of concept of an optical hyperthermia system [4]. The instrument was similar to others currently being used [5] [6], but with the possibility of using different excitation methods by changing the light exposure pattern from continuous wave light to pulsed light. The system was developed to evaluate the effectiveness of gold nanorods designed to work in the optimal tissue window for light absorbance (808 nm) used to produce cellular death in glioblastoma cell lines (1321N1). The obtained results showed that the use of gold nanorods in hyperthermia therapy is very effective (Figure 1) but in order to develop an optimal treatment, many parameters still need to be optimized, concerning both laser irradiation and gold nanorods characteristics. After these first results, our work is focused on the development of new excitation methods with the aim of increasing the effectiveness of the hyperthermic treatment thanks to the well known thermal effects and to other mechanical effects that are being studied and could influence the cell death process. The low frequency modulation of the laser source (<30KHz) allows the generation of a pulsed signal that intermittently excites the gold nanorods. The

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Cristina Sánchez, Julio Alberto Ramos, Tamara Fernández, Milagros Ramos, Alberto Martínez, Francisco del Pozo, José Javier Serrano cristina.sanchez@ctb.upm.es

temperature curves obtained for different frequencies and duty cycles of modulation but with equal average power and identical laser parameters, show that the thermal behavior in continuous wave and modulation modes are the same (Figure 2). However, the cell death experiments suggest that the percentage of death is higher in the cases of modulation (Figure 3). This observation allows us to conclude that there are other effects in addition to temperature that contribute to the cellular death.

Figure 1. Photothermal treatment of 1321N1. The cells were stained with propidium iodide and then fixed and analyzed on a flow cytometer. The graph shows the percentages of dead cells (IP+-cells) over total cells, calculated for each condition. Control: 1321N1 basal cell death rate. AuNRs: 1321N1 cells incubated with gold nanorods. Laser: 1321N1 cells subjected to laser irradiation. Laser + AuNRs: 1321N1 cells subjected to laser irradiation in the presence of gold nanorods.

The mechanical effects like sound or pressure waves are expected to be generated from thermal expansion of gold nanorods. In order to study the behavior and magnitude of these processes we have developed a measure device based on ultrasound piezoelectric receivers (25KHz) and a lock-in amplifier that is able to detect the sound

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The first results (Figure 4) show that the pressure measurements are directly proportional to the concentration of gold nanorods and the laser power, therefore, our present work is focused on determine the real influence of these effects in the cell death process.

Abstracts

References [1] Huff TB, Tong L, Zhao Y, Hansen MN, Cheng JX, Wei A. Hyperthermic, Nanomedicine (Lond), 2 (2007) 125-132. [2] Kuo WS, Chang CN, Chang YT, et al., Angew Chem Int Ed Engl., 49 (2010) 2711-2715. [3] Jain PK, El-Sayed IH, El-Sayed MA, Nano Today, 2 (2007) 16-27. [4] Fernández T, Sánchez C, Martínez A, del Pozo F, Serrano JJ, Rarmos M, Int. J. Nanomed, 7 (2012) 1511-1523. [5] Fourkal E, Vlechev I, Taffo A, Ma C, Khazak V, Skobeleva N., IFMBE Proc., 25 (2009) 761-763. [6] Rozanova N, Zhang JZ, Science in China Series B: Chemistry, 52 (2009) 1559–1575.

Figure 2. Temperature curves of gold nanorods suspension for different duty cycles of modulation in comparison to the continuous wave mode (CW). The parameters of the laser are fixed in an average power of 381 mW and a frequency of modulation of 5KHz.

Figure 3. IP/calcein essay 24h after irradiation: Comparison between different times and excitation modes (modulation and CW).

Figure 4. Voltage levels for different laser intensitiy values (linearly proportional to the power source) in a duty cycle sweep.

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waves generated in samples of gold nanorods during laser irradiation providing us a voltage level proportional to the pressure signal.

Maximal entanglement out of transport through double quantum dots

Rafael Sánchez and Gloria Platero rafael.sanchez@icmm.csic.es

Instituto de Ciencia de Materiales de Madrid (ICMM-CSIC), Sor Juana Inés de la Cruz 3, Madrid, Spain

Double quantum dots connected in series to source and drain electronic reservoirs can be tuned to contain up to two electrons. In such configuration, current suppression due to Pauli exclusion principle has been detected [1]. This effect is known as spin blockade. Driving the system with time dependent magnetic fields allows the coherent manipulation of the two electron states. Single spin rotations remove Pauli correlations and restore the flow of current [2,3]. Analyzing the current spectrum as a function of the driving frequency, we find dark resonances where spin blockade is restored due to collective rotations of the two spins. Then, the two electrons are spatially separated, each one kept in a different quantum dot. Furthermore, for such frequencies the system evolves towards a maximally entangled stationary state [4]. We find robust Rabi oscillations of two positive parity Bell states for weak coupling to the reservoirs. We investigate the influence of the magnetic field polarization.

References [1] K. Ono, D.G. Austing, Y. Tokura, S. Tarucha, Science 297 (2002) 1313. [2] F.H.L. Koppens, C. Buizert, K. J. Tielrooij, I. T. Vink, K. C. Nowack, T. Meunier, L. P. Kouwenhoven, L. M. K. Vandersypen, Nature 442 (2006) 766. [3] R. Sánchez, C. López-Monís, G. Platero, Phys. Rev. B 77 (2008) 165312. [4] R. Sánchez, G. Platero, in preparation.

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TDDFT simulations of the energy loss of moving projectiles in solids and nanostructures

Daniel SĂĄnchez-Portal sqbsapod@ehu.es

Centro de FĂsica de Materiales UPV/EHU-CSIC, Paseo Manuel de Lardizabal 5, 2018 San SebastiĂĄn, Spain

We have recently developed a code to perform real time time-dependent density-functional theory simulations [1,2,3]. Our method is based on the SIESTA code [4] and uses a linear combination of atomic orbitals as a basis set. Previous versions of our code had been used to study the optical response of finite systems [1], i.e., electron dynamics was followed after the system was initially perturbed while nuclei were kept fixed in their initial positions. Our most recent version, however, allows performing coupled electronnuclear dynamics within the Ehrenfest approximation and has been applied to study the problem of radiation damage in solids and nanostructures.

Figure 1. Electronic stopping power of H and He projectiles in gold as a function of projectile velocity. Results of our simulations are compared with the experimental data from on single and polycrystalline thin gold films.

Although radiation damage processes are of extraordinary fundamental and technological importance, ab initio simulations of these effects in solids are still very scarce to date. Most simulations for solids and condensed systems are based on TNT 2012 madrid (spain)

semi-empirical approaches, like SRIM [5]. The energy transferred to the solid goes both onto displacements of the target ions (nuclear stopping) and electronic excitations (electronic stopping). While at very low velocities nuclear stopping can we dominant, at moderate, intermediate and high energies the most efficient energy loss mechanism is the electronic stopping. The effect of electronic stopping is frequently incorporated in simulations through an ion and target dependent friction coefficient. Thus, the electronic stopping is assumed to depend linearly on velocity. This is generally true for simple metals, for which the friction coefficient can be estimated very efficiently using a jellium model plus scattering theory [6]. However, it has been recently observed that there are significant deviations from linearity at low velocities in insulators and noble metals, both showing different kinds of threshold effects. Understanding of such effects demands an explicit treatment of the electronic stopping in the presence of the actual atoms and actual electronic structure of the host system. Our simulations using time-evolving TD-DFT could reproduces the anomalies in the stopping power observed experimentally for projectile velocities below 0.3 a.u., for insulators and noble metals [2,3]. In addition, we could analyze the Barkas effect (difference in stopping between protons and antiprotons) in LiF [2], and the He/H anomaly in Au [3] (the stopping is larger for He at all velocities, contrary to expectations based on free electron models). Our approach has quite general applicability and we plan to apply it to other radiation damage problems. As an example, we have recently studied the influence of the electrons being excited on the effective internuclear forces when an Al target is bombarded with protons [7].

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of these issues. In particular, I will present some of our recent semi-classical results on the influence of the localized-hole screening on the energy losses during photoemission from metal clusters [10].

References [1]

Figure 2. Screening of a localized hole during photoemission from a metal (jellium) clusters. The induced electronic density is shown close to the symmetry z-axis (r = 0.02 a.u., the electron is emitted along the z-axis and r is the perpendicular coordinate). The time evolves along the vertical axis. The color map shows the change in density in units of the background density. The color scale is limited to a maximum value of in order to reveal the effects in the regions where the induced density is small. The induced density above this value is shown in green. The actual maximum value of the induced density is about 50 in units of background density. It corresponds to the small region around the position of the hole. (a) Shows the results of the TDDFT calculation of the complete system. In (b) the induced density is calculated as a sum of two separate contributions, screening of the hole and screening of the moving electron. The cluster contains 106 electrons and has radius of 18.93 a.u., with density corresponding to rs = 4.The velocity of the electron is constant and is equal to 1 a.u. Insets: profile of the plot along the time axis at (r= 0.02 a.u., z= 0.2 a.u.)

A. Tsolakidis, D. Sánchez-Portal, and R. M. Martin Phys. Rev. B 66 (2002) 235416. [2] J. M. Pruneda, D. Sánchez-Portal, A. Arnau, J. I. Juaristi, and Emilio Artacho Phys. Rev. Lett. 99 (2007) 235501. [3] M. A. Zeb, J. Kohanoff, D. Sánchez-Portal, A. Arnau, I. Juaristi and E. Artacho, Phys. Rev. Lett. 108 (2012) 225504. [4] J. M Soler, E. Artacho, J. D. Gale, A. García, J. Junquera, P. Ordejón and D. Sánchez-Portal, J. Phys.: Condens. Matter 14 (2002) 2745. [5] J. F. Ziegler, J. P. Biersack, and U. Littmark, “The Stopping and Range of Ions in Matter”, New York, 1985. Pergamon. ISBN 0-08022053-3. [6] P. M. Echenique, R. M. Nieminen, J. C. Ashley and R. H. Ritchie, Phys. Rev. A 33 (1986) 897. [7] A. A. Correa, J. Kohanoff, E. Artacho, D. Sánchez-Portal and A. Caro, Phys. Rev. Lett. 108 (2012) 213201. [8] E. V. Chulkov, A. G. Borisov, J. P. Gauyacq, D. Sánchez-Portal, V. M. Silkin, V. P. Zhukov and P. M. Echenique Chemical Reviews 106 (2006) 4160. [9] R. D. Muiño, D. Sanchez-Portal, V. M. Silkin, E. V. Chulkov and P. M. Echenique, PNAS 108 (2011) 971. [10] N. Koval, D. Sánchez-Portal, A. G. Borisov, R. D. Muiño, to appear on Nanoscale Research Letters.

Finally, the dependence of the electron dynamics on the size and dimensionality is an important issue in many fields. For example, it determines the efficiency and time scale of the screening of interactions, the rate of many chemical reactions at surfaces and the optical response of nanoobjects. We plan to use our methods to investigation some

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WaveGuide's u-NMR and magnetic nanoswitches for security and defense applications

Marcus Semones marcus@waveguidecorp.com

WaveGuide Corporation

One Broadway, 14th floor Cambridge, MA 02142, USA

The uNMR, innovative technology combined with proprietary Magnetic Nanoswitches enables low cost rapid, on-site screening for Security and Defense Applications. Product applications include point of testing of suspicious samples to determine if a biothreat agent is present, anti-counterfeiting, adulteration and product diversion in industries as diverse as petroleum, pharmaceuticals and beverages. WaveGuide Corporation is a Harvard University spin out that is commercializing a handheld nuclear magnetic resonance spectrometer (uNMR) and proprietary Magnetic Nanoswitches.

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Fluorescence and Raman characterization of a transport system formed by the anti tumoral drug emodin, silver nanoparticles and porous silicon

Paz Sevilla1,2, Margarita Hernandez2, Gonzalo Recio3, E. Corda2, Raúl J. Martín-Palma3, José V. García-Ramos2 and Concepción Domingo2 paz@farm.ucm.es

Dep. Química Física II, Facultad de Farmacia, UCM, 28040 Madrid, Spain Instituto de Estructura de la Materia, CSIC, Serrano 121, 28006 Madrid, Spain 3 Departamento de Física Aplicada, Facultad de Ciencias, UAM, 28049 Madrid, Spain 2

Emodin is an orange crystalline solid that belongs to the anthraquinone family (fig. 1). It has shown anticancer effect in breast and prostate tumors. It presents high solubility in organic solvents but it is insoluble in water. To overcome this limitation design of advanced drug delivery systems are necessary in order to deliver the drug at the target site with the adequate rate and concentration. Between the new materials that have recently revealed a lot of promise in drug delivery, porous silicon (PSi) is an interesting one (fig. 2). It is biocompatible and biodegradable and is able to form micro devices to carry the drugs until the site of interaction [1-3]. If the molecules do not remain inside the pores it is necessary to functionalize the silicon surface. As this is the case of emodin, we have solved the problem by using silver nanoparticles. These metal nanostructures present additional advantages derived from the Localized Surface Plasmon Resonances (LSPR) they support. The principal benefit is related with the obtaining of surface enhanced spectroscopy such as SERS (surface enhanced Raman scattering) and SEF (surface enhanced fluorescence) that can be used as potent and high sensitive techniques for molecular detection.

Figure 1. Structure and acid-base equilibrium of emodin.

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Figure 2. Cross section of a porous silicon layer.

Understanding and knowledge of the physicochemical properties of the systems used to transport and release the drugs constitute a prerequisite in designing advanced drug delivery systems. Interaction of emodin with silver nanoparticles has been previously studied in our group [4-5]. In the present work we have used Raman and SEF spectroscopy to perform a characterization of emodin adsorbed on silver nanoparticles and loaded on PSi. Besides optimization of pore size and impregnation conditions of PSi, enhancement factor of fluorescence signal of emodin has been obtained (fig. 3). It varies between 5 and 24 for diverse conditions used. Preliminary Raman and fluorescence studies of other non steroidal anti inflammatory drugs (NSAIDS), in particular ketorolac and indomethacin, in solution and adsorbed on silver nanoparticles will also be presented. Conclusion collected in this study TNT 2012 madrid (spain)

20000

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Figure 3. Fluorescence spectra of nanostructured porous silicon: a) loaded with the antitumoral drug emodin, b) loaded with the antitumoral drug emodin adsorbed on silver nanoparticles. Excitation laser wavelength used was 532 nm. All spectra were normalized to the Raman signal from the Si at 547 nm.

References [1] N. J. Halas, Nanomedicine, 4 (2009) 369. [2] R. J. Martín-Palma, M. Manso-Silván, and V. Torres-Costa, J. Nanophotonics, 4 (2010) 042502. [3] A. Muñoz-Noval, V. Sánchez-Vaquero, V. Torres-Costa, D. Gallach, V. Ferro-Llanos, J. J. Serrano, M. Manso-Silván, J.P. García-Ruiz, F. del Pozo, and R.J. Martín-Palma, J. Biomedical Optics, 16 (2011) 025002. [4] P. Sevilla, F. García-Blanco, J.V. García-Ramos and S. Sánchez-Cortes, Phys. Chem. Chem. Phys., 11 (2009) 8342. [5] R. De-Llanos, S. Sánchez-Cortés, C. Domingo, J. V. García-Ramos and P. Sevilla, J. Phys. Chem. C, 115 (2011) 12419.

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constitutes a first step in the design of a new drug delivery system to be used with emodin or with other drugs like ketorolac or indomethacin.

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Manipulation of molecular quantum states in an STM tunneling junction using classical metal atom inputs

We–Hyo Soe wh-soe@imre.a-star.edu.sg

IMRE, A*STAR, 3 Research Link, 117602, Singapore

Digital logic gates are basic functional units in any digital electronic circuit performing arithmetic logic operations. The most straightforward approach for improving the performance of digital logic gates is the further miniaturization of solid state transistors as their primordial building blocks. However those downsizing encounters several fundamental problems at the atomic scale, i.e. leakage currents, heat dissipation, fabrication limitations, etc. AtMol is a project pioneering a new proposed paradigm to implement molecular electronics and quantum computing. The final goal of this project is to fabricate a fully functional molecular chip, whose chip core will be made of atom wires interconnecting a single logic processing molecule. A low-temperature scanning tunneling microscope (STM) is a very suitable tool not only for surface science but also to investigate single molecule electronics. STM differential conductance (dI/dV) measurement is a very effective technique to gain access to the low lying electronic states of single molecules. To have access to those states, a molecule has to be electronically decoupled or weakly coupled, i.e. physisorbed, to the metal surface. We present here how the electron probability distributions of molecular states are imaged in real space using a pentacene molecule directly adsorbed on a gold surface. [1] STM dI/dV conductance images taken at voltages corresponding to the resonances near the substrate Fermi level were found to be very close to the mono-electronic molecular orbitals (MO), in contrast high-order resonance states images were composed also with MO components from loworder resonance states. dI/dV conductance maps of other molecules will be also presented. [2,3]

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Quantum states of a molecule can be modified by light irradiation, external fields, structural transformation, etc. Here, we show that is possible to manipulate the quantum states of a trinaphthylene molecule by using classical metal atom contacts. [4] Herein two naphthylene branches of the trinaphthylene molecule are used to set atom input terminals and the remaining one functions as the signal output terminal. One Au atom in contact with an input branch carries 1-bit of classical information input that is converted into quantum information throughout the molecule. The Au-trinaphthylene electronic interactions give rise to measurable energy shifts of the molecular electronic states demonstrating a NOR logic gate functionality. The NOR truth table of the single molecule logic gate was characterized by STM dI/dV measurements. How far the quantum information is transferred through will also be discussed. [5]

References [1]

W –H Soe, C Manzano, A De Sarkar, N Chandrasekhar and C Joachim, Phys. Rev. Lett. 102 (2009) 176102. [2] W –H Soe, C Manzano, H S Wong and C Joachim, J. Phys.: Condens. Matter (2012) in press. [3] W –H Soe, H S Wong, C Manzano, M Grisolia, M Hliwa, X Feng, K Müllen and C Joachim, ACS Nano 6 (2012) 3230. [4] W –H Soe, C Manzano, N Renaud, P de Mendoza, A De Sarkar, F Ample, M Hliwa, A M Echavarren, N Chandrasekhar and C Joachim, ACS Nano 5 (2011) 1436. [5] C Manzano, W –H Soe, P de Mendoza, A M Echavarren C Joachim, to be submitted.

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Disorder-induced randomization of spin polarization and interfacially protected surface states in three-dimensional models of topological insulators 1 2

David Soriano1, Frank Ortmann1 and Stephan Roche1,2 David.soriano@icn.cat

CIN2 (ICN-CSIC), Campus UAB, 08193, Bellaterra (Barcelona), Spain Instituci贸 Catalana de Recerca i Estudis Avan莽ats (ICREA), 08010, Barcelona, Spain

The growing interest on topological insulators (TI) relies on their fascinating electronic properties, namely, a non-trivial insulating bulk which guarantees the formation of highly robust Dirac-like states at the surface holding a chiral spin texture.[1-3] This new topological phase of condensed matter is governed by strong spin-orbit coupling and their surface states are protected against disorder preserving time-reversal symmetry (non-magnetic). Here we use a three-dimensional model of TI on a diamond lattice, described by the Fu-Kane-Mele (FKM) Hamiltonian,[4] and show how Dirac cone characteristics can be tuned on opposite surfaces upon differentiation of atomic-scale surface terminations. In particular, when the outermost surface layers are removed, the number of Dirac cones in the surface Brillouin zone (SBZ) changes from three at the three equivalent M-points to a single one at Gamma. This result extends the applicability of the FKM model to real TI such as the frequently studied Bi2Se3, Bi2Te3 or Sb2Te3. More interestingly, when opposite surfaces are geometrically differentiated by removing the outermost layer from only one surface, Dirac cones develop at the M-points in one surface and at the Gammapoint in the other and remain uncoupled and gapless down to few bulk layers (see Fig.1(b,e) for 11 and 3 layers thickness respectively).[5,6] Our findings are consistent with recent experimental observations by Bian et al.[7] and open the way to controlled engineering of thin 3D-TI with highly robust chiral states. TNT 2012 madrid (spain)

Figure 1. Band structure of slabs of various thicknesses (layers L) and surface terminations (T1 is the default termination and T2 is the one obtained by removing the outermost layer as explained in the text). When opposite surfaces are geometrically differentiated (b,e) the surface states remain gapless down to few bulk layers.

Additionally, by introducing Anderson bulk disorder,[8-11] we investigate the changes in the spin texture with increasing disorder in the slab in order to determine the extent to which the topological protection of surface states is reduced. As disorder strength is increased, spin polarization becomes smaller and spread over a wider range of vector length, evidencing randomization of the spin texture fingerprint (see Fig. 2; blue and red arrows correspond to the clean and disordered cases respectively). Our findings suggest ways to analyze the bulk crystalline quality of TI by inspecting the spin texture features through spin-resolved ARPES experiments.

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References

Figure 2. Spin texture of a T2-T2 slab (12 layers) in presence (red) and in absence (blue) of bulk Anderson disorder. The randomization of the spin texture in presence of bulk disorder is evident.

Acknowledgements. This work is supported by the TRAIN2 project of the SUDOE Territorial Cooperation Programme.

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[1] J. E. Moore, Nature, 464 (2010) 194. [2] [2] M. Z. Hasan and C. L. Kane, Rev. Mod. Phys., 82 (2010) 3045. [3] X.-L. Qi and S.-C- Zhang, Rev. Mod. Phys., 83 (2011) 1057. [4] L. Fu, C. L. Kane and E. J. Mele, Phys. Rev. Lett., 98 (2007) 106803. [5] Y. Zhang, C.-Z. Chang, C.-L. Song, L.-L. Wang, X. Chen, J.-F. Jia, Z. Fang, X. Dai, W.-Y. Shan, S.-Q. Shen, Q. Niu, X.-L. Qi, S.-C. Zhang, X.-C. Ma and Q.-K. Xue, Nature, 464 (2010) 194. [6] A. A. Taskin, S. Sasaki, K. Segawa and Y. Ando, arXiv:1204.1829. [7] G. Bian, X. Wang, Y. Liu, T. Miller and T. C. Chiang, Phys. Rev. Lett., 108 (2012) 176401. [8] A. M. Black-Schaffer and A. V. Balatsky, Phys. Rev. B, 85 (2012) 121103(R). [9] G. Schubert, H. Fehske, L. Fritz and M. Vojta, Phys. Rev. B, 85 (2012) 201105(R). [10] J. Henk, A. Ernst, S. V. Eremeev, E. V. Chulkov, I. V. Maznichenko and I. Mertig, Phys. Rev. Lett., 108 (2012) 206801. [11] H. Beidenkopf, P. Roushan, J. Seo, L. Gorman, I. Drozdov, Y. S. Hor, R. J. Cava and A. Yazdani, Nature Phys., 7 (2011) 939. [12] D. Soriano, F. Ortmann and S. Roche (submitted)

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Atomically precise construction and electronic properties of danglingbond nanostructures on hydrogen passivated Ge(001) surface

Marek Kolmer1, Szymon Godlewski1, Bartosz Such1, Hiroyo Kawai2, Mark Saeys2,3, Christian Joachim2,4 and Marek Szymonski1

Centre for Nanometer-Scale Science and Advanced Materials (NANOSAM), Department of Physics, Astronomy, and Applied Computer Science, Jagiellonian University, Reymonta 4, PL 30-059, Krakow, Poland 2 Institute of Materials Research and Engineering, 3 Research Link, Singapore 117602, Singapore 3 Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Drive 4, Singapore 117576, Singapore 4 Nanosciences Group & MANA Satellite, CEMES-CNRS 29 rue Jeanne Marvig, F-31055 Toulouse, France

We report on studies concerning preparation of well organized atomic wires and 2D nanopads by tip-induced hydrogen desorption from hydrogen passivated Ge(001) surface. Dangling-bond (DB) nanostructures on the passivated surface are fabricated using atomically precise STM tip-induced dimer-by-dimer hydrogen desorption. We have developed new, very efficient protocol allowing for at will fabrication of pre-designed DB structures. Their geometrical structure is characterized with atomic resolution by means of LT-STM. High resolution STM images of wires of different orientation and lengths are in good agreement with ESQC/SGFM calculations. Furthermore, the electronic properties of the fabricated nanostructures are examined by scanning tunneling

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spectroscopy (STS) measurements allowing for acquisition of the density of states spatial distribution, which can be measured successfully with a lateral resolution reaching an individual dangling-bond. Deeper understanding of experimental observations is provided by calculations of surface electronic structure and electron transport properties performed with semiempirical method fitted to first principles density functional theory (DFT). Based on the example of short DB wires we discuss the effect of through surface and through space electronic coupling between the created DBs, which results in narrowing of the surface band gap with increasing DB wire length.

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Efficient biexciton emission in single CdSe nanocrystals

Philippe Tamarat, Yann Louyer, Mark Fernée, Louis Biadala and Brahim Lounis

LP2N, Université de Bordeaux, Institut d’Optique Graduate School & CNRS, 351 cours de la libération, 33405 Talence, France

Quantum-confined nanoparticles have been increasingly investigated over the past decade due to the superior efficiency and tunability of their emission wavelength from the ultraviolet to the near infra red. Among those nanoparticles, colloidal CdSe nanocrystals (NC) are particularly attractive for many applications such as nanoscale electronics, laser technology, quantum cryptography, and biological fluorescent labeling. A detailed understanding of the NCs band-edge exciton fine structure is crucial for these applications. While intensive experimental and theoretical work has been performed to describe the size dependence of the exciton fine structure in nearly spherical NCs, the shape dependence has received much less attention despite recent advances in NC growth methods which lead to a greater control over shape distribution. Pioneering theoretical and experimental investigations [1, 2] have indicated that the shape dependence of NCs can be as important as the size dependence in terms of tuning their electronic and optical properties. The elucidation of these shape effects remains an experimental challenge which can be addressed by the optical study of individual NCs, where ensemble averaging over shape and size distributions is suppressed. Shape and size effects also govern the optical response of NCs in the multiexcitonic regime, where potential applications such as optical gain are envisaged [3]. Despite the important role that biexcitons play in the optics of NCs, it has been practically impossible to observe the biexciton recombination line in the PL of CdSe NCs under continuous wave excitation, because of efficient nonradiative Auger recombination [4].

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philippe.tamarat@institutoptique.fr

This presentation will be focused on our recent magneto-optical and time-resolved spectroscopic investigations of single commercial qdot655 streptavidin conjugates NCs (comprising a core of CdSe capped by a ZnS layer) as a function of temperature. The remarkable photostability of these NCs at low temperature led us to unveil the spectral and temporal signatures of the emission from the lowest exciton-fine-structure states [5,6], trion emission [7] and biexciton emission [8]. Because of the NCs shape distribution, we find various band-edge exciton fine structures that are consistent with theoretical predictions for elongated NCs. Furthermore, contrarily to what was anticipated for “standard” CdSe-based core shell NCs, we show evidence for spectral and temporal signatures of highly efficient radiative biexcitonic recombinations in this type of NCs. Special attention will also be paid to the attractive trion (charged exciton) emission properties for potential applications in quantum information processing.

References [1] A. L. Efros et al., Physical Review B 54, 4843 (1996). [2] J. T. Hu et al., Science 292, 2060 (2001). [3] V. I. Klimov et al., Science 290, 314 (2000). [4] V. I. Klimov et al., Science 287, 1011 (2000). [5] L. Biadala et al., Physical Review Letters 103, 037404 (2009). [6] L. Biadala et al., Physical Review Letters 105, 157402 (2010). [7] Y. Louyer et al., Applied Physics Letters 96, 203111 (2010). [8] Y. Louyer et al., Nano Letters 11, 4370 (2011).

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Microemulsions as reaction media for the synthesis of bimetallic nanoparticles

C. Tojo and F. Barroso ctojo@uvigo.es

Physical Chemistry Department, University of Vigo, E-36200 Vigo, Spain

Bimetallic nanoparticles are particularly attractive due to their properties often differ markedly from either of the constituent metals. Nowadays it is wellknown that the design and control of spatial arrangement of both metals in bimetallic nanoparticles are critical for exploiting their potential applications. The properties of bimetal nanoparticles strongly depend on their size, structure and morphology, so it is of the utmost importance to fully elucidate the mechanism underlying the nucleation and growth of nanoparticles. The fact that the nucleus evolves to a particle by accumulating new layers implies that the differences in nucleation rates of both metals would strongly affect the metals segregation and final nanoparticle sizes. Because the synthetic route seems to be crucial to determine final sizes and structures of bimetallic nanoparticles, our study is focused on a concrete method: the reverse microemulsion route. This method is one of the most important methods to control the particle size, because the surfactantstabilized droplets provide a microenvironment for the preparation of nanoparticles by exchanging their contents and preventing the excess aggregation of particles. But microemulsion itself is a very complicated system, and the dynamics of intermicellar exchange plays an important role in the kinetics [1, 2]. In line with our ongoing effort to study the formation of simple and bimetallic nanoparticles in microemulsions, we have aimed here to investigate the nucleation and growth of bimetallic nanoparticles and to provide a detailed insight into the factors affecting nanoparticle structure and size. The main concept used to describe nucleation is related to the critical radius. Above this size, it is favorable for the new phase to form; below this size, the clusters will tend to dissolve rather than grow.

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Monte Carlo simulations were carried out to investigate the influence of critical nucleus sizes on the structure and sizes of final bimetallic nanoparticles. Because bimetallic particles are composed by two different metals (A and B), which can need a different minimum number of atoms to form a stable nucleus, the algorithm distinguish two critical nucleation numbers (nA* and nB*). In addition, the possibility of heterogeneous nucleation (nucleus composed by different metals) has also been considered by including a new parameter (nAB*), defined as the minimum number of metal atoms (A or B) inside the same droplet needed to form a heterogeneous nucleus capable of further growth. In relation to the nanoparticle structure, core-shell structures are expected when one metal reduces faster than the other [3]. The study reveals that, keeping equal the reduction rates of the two metals, the final structure is also sensitive to changes in the critical nucleus numbers, because these parameters determine the rate of nucleation. Figure 1A shows simulation results using equal reduction rates, a low value of concentration (〈cA〉=〈cB〉=4 molecules of reactant per droplet), a rigid film (f=5, kex=1) and different critical nucleus sizes (nA* =1, nB* =9, nAB* =4). In this figure the number of particles containing different percentages of one of the metals (A: faster nucleation metal) is monitored from the nanoparticle core to the outside (layer by layer). One can observe that the inner layers are composed by the metal which nucleates faster, and composition shows a progressive improvement towards a mix of both metals as the process advances (from the inner to the outer layers). Finally, the outer layers show an enrichment in the slower nucleation metal. Therefore this kind of structure can be considered a core-shell, although it was obtained simulating two metals with the same reduction rate. An increase in the difference between nucleation rates of both TNT 2012 madrid (spain)

In relation to the nanoparticle sizes, three different experimental behaviours have been found: bimetallic nanoparticles can be significatively smaller (negative deviation [4-7]), larger (positive deviation [8]) or equal than individual monometallic nanoparticles (no deviation [9, 10]). Because these results were ascribed to a difference in the nucleation process, we have carried out computer simulations to study how nanoparticle sizes change by using different combinations of the three critical nucleus numbers. Our results show that a negative deviation is obtained when heterogeneous critical size nAB*, is smaller than the two homogeneous ones (nA* and nB*), i.e., heterogeneous nucleation rate is the fastest nucleation. On the contrary, to obtain positive deviations the heterogeneous nucleation must be slower than the homogeneous ones. Both kind of deviations were obtained only if a rigid surfactant film was used. Also relevant to the discussion is the observation that no kind of deviation could be obtained when different reduction rates ratios were simulated. Therefore,

[1] R.P. Bagwe, K.C. Khilar, Langmuir, 16 (2000) 905. [2] M.A. López-Quintela, C. Tojo, M.C. Blanco, L. García-Río, J.R. Leis, Curr. Opin. Colloid Interface. Sci., 9 (2004) 264. [3] C. Tojo, M. de Dios, M.A. López-Quintela, J. Phys. Chem. C, 113 (2009) 19145. [4] M. Wu, D. Chen, T. Huang, Langmuir, 17 (2001) 3877. [5] A. Habrioux, W. Vogel, M. Guinel, L. Guetaz, K. Servat, B. Kokoh, N. Alonso-Vante, Phys. Chem. Chem. Phys., 11 (2009) 3573. [6] M. Wu, D. Chen, T. Huang, Chem. Mater., 13 (2001) 599. [7] M. Wu, L. Lai, Coll. Surf.A, 244 (2004) 149. [8] J. Santhanalakshmi, P. Venkatesan, J. Nanopart. Res., 13 (2011) 479. [9] L.M. Magno, W. Sigle, P.A.v. Aken, D.G. Angelescu, C. Stubenrauch, Chem. Mater., 22 (2010) 6263. [10] F.J. Vidal-Iglesias, J. Solla-Gullón, V. Montiel, J.M. Feliu, A. Aldaz, J. Power Sources, 171 (2007) 448.

rigid film

The simulation results are expected to contribute to developing advanced strategies for the design nanostructured particles.

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the only factor affecting nucleation which can explain the sizes deviations is the different rate in heterogenous and homogeneous nucleation. Direct comparison between experimental and simulation results is not possible, because to the best of our knowledge, no experiment has ever directly measured the size of the critical nucleus.

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metals gives rise to a better segregation of metals in the final nanoparticle. Likewise, as long as the formation of heterogeneous seeds is faster, the degree of alloying is greater. In addition, it is observed that the difference in nucletion rates of both metals is not the only parameter to determine the metals segregation, playing the interdroplet channel size a relevant role. In agreement with experimental observations, the results also suggest that the metal segregation can be avoid by using a more flexible surfactant (see figure 1). These results allow us to tune the experimental conditions for designing specific bimetallic structures.

Small molecule organic photovoltaics at the nanoscale McGill University, Montreal, Canada

Organic photovoltaics (OPVs) are a sustainable method of solar energy harvesting with possible fabrication advantages over more developed inorganic semiconductor solar cells. However, the power conversion efficiency of OPV devices is currently about 8.6%, compared to over 20% for crystalline silicon and up to 43.5% for triple junction inorganic solar cells [1-4]. The structure of solar harvesting device active layers is crucial to performance [5-7], but little is currently known about the specific loss mechanisms responsible. We present a preliminary study of structure-function relationships in thin films of organic photovoltaic materials by simultaneous non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM). Thin films of small electron donor and electron accepter molecules were thermally evaporated on KBr (001) surfaces under ultra-high vacuum. Local contact potential difference and topography were mapped with simultaneous KPFM and NC-AFM to investigate corresponding optoelectronic and structural properties at the nanometre scale. Light may be coupled into the UHV AFM system to illuminate samples during imaging, thus allowing characterization of active OPV materials during the generation of excitons and charge carriers. Our early results demonstrate that combined NC-AFM and KPFM is a powerful approach to studying

J.M. Topple, Z. Schumacher, A. Tekiel and P. Grutter topplej@physics.mcgill.ca

fundamental physical processes in photovoltaic power generation. Understanding structurefunction relationships in OPVs will contribute to the advancement of renewable energy light harvesting devices that are clean, efficient and affordable.

Figure 1. Illustration depicting possible structuredependent OPV efficiency loss mechanisms under investigation. (a) Charge flow dependent on molecular anisotropy and bottleneck structure, (b) recombination loss structure and the influence of defects.

References [1] L. Kazmerski, Best Research-Cell Efficiencies Report, National Renewable Energy Laboratory (2011). [2] S. H. Park, A. Roy, S. Beaupre, S. Cho, N. Coates, J.S. Moon, D. Moses, M. Leclerc, K. Lee, A.J. Heeger, Nature Photonics 3 (2009) 297. [3] Y. Liang, Z. Xu, J. Xia, S.T. Tsai, Y. Wu, G. Li, C. Ray, L. Yu, Adv. Mater. 22 (2010) E135. [4] Martin A. Green, Keith Emery, Yoshihiro Hishikawa and Wilhelm Warta, Prog. Photovolt: Res. Appl. 18 (2010) 346. [5] P.G. Nicholson and F.A. Castro, Topical Review, Nanotechnology 21 (2010) 492001. [6] A. Liscio, V. Palermo and P. Samori, Accounts of Chemical Research 43 (2010) 541. [7] D.C. Coffey and D.S. Ginger, Nature Materials 5 (2006) 735.

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TNT2012 Figure 2. Volmer-Weber growth of islands of CuPc (electron donor) and PTCDI (electron accepter) molecules on KBr (001). (a,c) 3D-rendered topography imaged by NC-AFM, (b,d) local contact potential difference imaged by KPFM.

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Atomistic models of charge separation and recombination in organic photovoltaics interfaces

Alessandro Troisi, Tao Liu, Domenico Caruso, David L. Cheung and David P. McMahon

Department of Chemistry, University of Warwick, U.K.

a.troisi@warwick.ac.uk

The key process in organic photovoltaics cells is the separation of an exciton, close to the donor/acceptor interface into a free hole (in the donor) and a free electron (in the acceptor). In an efficient solar cell, the majority of absorbed photons generate such hole-electron pairs but it is not clear why such a charge separation process is so efficient in some blends (for example in the blend formed by poly(3-hexylthiophene) (P3HT) and a C60 derivative (PCBM)) and how can one design better OPV materials. The electronic and geometric structure of the prototypical polymer:fullerene interface (P3HT:PCBM) is investigated theoretically using a combination of classical and quantum simulation methods. It is shown that the electronic structure of P3HT in contact with PCBM is significantly altered compared to bulk P3HT. Due to the additional free volume of the interface, P3HT chains close to PCBM are more disordered and, consequently, they are characterized by an increased band gap. Excitons and holes are therefore repelled by the interface.

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This provides a possible explanation of the low recombination efficiency and supports the direct formation of â&#x20AC;&#x153;quasi-freeâ&#x20AC;? charge separated species at the interface. This idea is further explored by using a more general system-independent model Hamiltonian. This talk will discuss how and when a combination of computational and theoretical models can truly contribute to organic electronics and will provide few examples of genuine material properties predictions based on computational models.

References [1] T. Liu, D.L. Cheung and A. Troisi A, Phys. Chem. Chem. Phys. 2011, 13, 21461. [2] D.P. McMahon, D.L. Cheung, Troisi A, J. Phys. Chem. Lett. 2011, 2, 2737. [3] A. Troisi, Chem. Soc. Rev. 2011, 40, 2347. [4] A. Troisi, Organic Electronics 2011, 12, 1988.

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Present and perspectives on dissemination and training in nanotechnology in IberoAmerica: Red NANODYF – CYTED

Joaquín Tutor Sánchez

Mechanical Engineering Department, ETSI-ICAI Universidad Pontificia Comillas Coordinator of NANODYF Network, Area 6 Science and Society, CYTED Program

Promoting the assimilation of contents of Nanotechnology involves action in dissemination, and formal education in schools and universities. Iberoamerican countries have not specific plans in this important line of action, which will result in a delay of their citizens compared to other regions. IberoAmerica cannot be excluded from this process of dissemination and training in Nanotechnology because the future economy trends will be structured around advances in nanotechnology, and because there is already a significant Iberoamerican presence in research and development in Nanotechnology. So, that is the purpose and mission of the "Jose Roberto Leite" Network of Dissemination and Education in Nanotechnology (NANODYF) from the CYTED Program, which in its first year of work (2011) has detected what the current state of the Outreach and Training nanotechnology in a group of countries representing the Iberoamerican region is; and it aims to draw a future strategy to improve and enhance areas that are weak or even absent in the region.

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Superconductivity at adatom/molecule-induced silicon surfaces and interfaces

Takashi Uchihashi UCHIHASHI.Takashi@nims.go.jp

National Institute for Materials Science, 1-1, Namiki, Tsukuba, Ibaraki 305-0044, Japan

The state-of-the-art nanotechnology has enabled fabrication of ultrathin superconductors of high crystallinity and with atomically controlled thicknesses and interfaces. This has opened ways to tune superconductivity [1,2] and to investigate the thinnest crystalline layers for its emergence [3,4]. Notably, superconductivity was found to exist for silicon surface reconstructions with metal adatoms [5], which are the ultimate forms of thin epitaxial films. This finding is, however, based on spectroscopic evidence of superconducting energy gaps observed by scanning tunneling microscopy (STM). The very existence of supercurrent through these surfaces has not been clarified yet and important information such as critical current density has been missing. We have performed direct and macroscopic electron transport measurements on a silicon surface reconstruction with In adatoms (Si(111)(√7×√3)-In) in UHV at low temperatures [6]. The superconducting transition is evidenced by observations of the zero resistance state and of I − V characteristics exhibiting sharp and hysteretic switching below 2.8 K ( ≡ Tc) (see Fig.1 and Fig.2). This macroscopic supercurrent also shows a significant robustness; the two-dimensional (2D) critical current density J2D,c is estimated to be as high as 1.8 A/m at 1.8 K. If the thickness of Si(111)(√7×√3)-In is assumed to be double the covalent radius of In (= 0.30 nm), this corresponds to a 3D critical current density of 6.1×109 A/m2, comparable to those of practical bulk superconductors. The precise values of Tc and J2D,c are dependent on sample preparation, suggesting the importance of crystallinity of the surface reconstruction layer. The observed temperature dependence of critical current density J2D,c indicates

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that the surface atomic steps serve as strongly coupled Josephson junctions. The analysis based on the Josephson junction model using the standard Ambegaokar-Baratoff equation [7] allows us to obtain the resistance of the atomic step. The value is found to be consistent with that deduced from normal sample resistance.

Figure 1. Temperature dependence of zero bias dependence of the Si(111)-(√7×√3)-In reconstruction. The insets show the configurations of the four-terminal measurements and an STM image of the sample surface.

The present study demonstrates that various surface reconstructions of silicon and related semiconductors could be used as practical superconducting materials. To achieve this aim, however, the surface metal-adatom layer should be passivated and buried under a capping layer while the superconductivity remains intact, which poses a new technical challenge. We present a trial for passivation of surface superconducting layer with molecular assembly [8]. We find that Cophthalocyanine molecules can be assembled in a

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Abstracts

References [1] [2] [3] [4] [5] [6]

[7] [8] [9]

Y. Guo et al., Science 306 (2004) 1915. M. M. Özer et al., Nature Phys. 2 (2006) 173. S. Qin et al., Science 324 (2009) 1314. C. Brun et al., Phys. Rev. Lett. 102 (2009) 207002. T. Zhang et al., Nature Phys. 6 (2010) 104. T. Uchihashi et al., Phys. Rev. Lett. 107, 207001 (2011); also see Viewpoint in Physics 4, 92 (2011). V. Ambegaokar and A. Baratoff, Phys. Rev. Lett. 10 (1963) 486. B. N. Cotier et al., Appl. Phys. Lett. 78 (2001) 126. T. Gang et al., Nature Nanotech. 7 (2012) 232.

Figure 2. Temperature dependence of I-V characteristics of the same sample, from which critical current Ic can be determined. The inset shows that temperature dependence of Ic.

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highly ordered fashion on the Si(111)-( √7×√3)-In surface by a simple sublimation method, while the resulting layer still exhibits a signature of superconducting transition. The fabrication of a molecular interface could also be used to tune the properties of superconductivity by modifying the phonon spectrum and by introducing magnetic moments into molecules [9].

Microstructural change of li(NiCo)O2 based materials of Li ion battery during charge and discharg

Yoshio Ukyo, Yoji Takeuchi and Yoshinari Makimura

TOYOTA Central Research & Development Laboratories Inc., 480-1192 Yokomichi, Nagakute, Aichi Japan

1. Introduction During charge and discharge of lithium-ion batteries with Li(NiCo)O2 based positive active materials, electrochemical reaction with lithium intercalation /deintercalation proceeds reversibly. The performance of Li(Ni,Co)O2 materials has been studied by many authors. For example, we have reported the fading mechanism of lithium ion batteries with on LiNi0.8Co0.15Al0.05O2 as the positive material and pointed out that the reaction and diffusion resistances of positive electrode drastically increased during durability test at high temperatures. It was revealed that the microstructural change of positive material played a important role for resistance increase. In this presentation, the microstructural change of LiNi0.8Co0.15Al0.05O2 material investigated by various methods, such as electrochemical techniques, STEM, EELS, and XAFS. The cylindrical cells (18650type) of LiNi0.8Co0.15Al0.05O2 and artificial graphite with carbonate electrolyte were used for durability tests at high temperatures. The electrodes taken out of the cells before and after durability tests were evaluated by using various methods. The LiNi0.8Co0.15Al0.05O2 materials before and after 1 cycle were also evaluated by STEM-EELS to compare with the materials after long durability test.

2. STEM analysis The microstructural change near grain boundaries before and after 1 cycle observed by using low magnification STEM is shown in Fig.1. The grain boundaries have thin grain boundary layers which produce bright contrast indicate by arrows in Fig.1 (a). As shown in this figure, the thickness of some

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grain boundary layers (indicated by arrows in b) increased drastically and some microcracks are found at triple points and grain boundaries. According to the observation by high resolution STEM, EELS and ED, it was revealed that the crystal structure changes from ordered layer structure (bulk) to disordered rock-salt structure (surface) through partially ordered structure. The thickness of grain boundary layer changed from about 5 nm before first cycle to about 25 nm after first cycle. This means that phase transition occurred especially near at grain boundary (surface) during intercalation / deintercation of lithium.

Figure 1. Low magnification STEM images fresh (a) and after first cycle. The thickness of the grain boundary layer (white contrast indicate by arrows) increased drastically after first cycle [8].

3. XAFS analysis The determination of the Ni valence before and after durability test was conducted by using XAFS method. The Ni K-edge spectra (XANES) after durability test are shifted to lower energy. Fig.2 shows Ni valence determined by the energies from the half-step heights of the Ni K-edge spectra as a function of x in Li1-xNi0.8Co0.15Al0.05O2. As shown in this figure, the Ni valence after durability test

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Abstracts

References [1] Y. Itou et al, J. Power sources, 146 (2005) 39. [2] T. Nonaka et al, J. Electrochem. Soc., 154 (2007) A353. [3] T. Sasaki et al, J. Electrochem. Soc., 154 (2007) A289. [4] S. Muto et al, J. Electrochem. Soc., 154 (2007) A371. [5] T. Sasaki et al, J. Electrochem. Soc., 158 (2011) A1214. [6] T. Nonaka et al, J. Power sources, 162 (2006) 1329. [7] H. Kondo et al, J. Power sources, 174 (2007) 1131. [8] S. Zheng et al, J. Electrochem. Soc., 158 (2011) A357.

Figure 2. The dependence of Ni valence before and after cycle test at high temperature on SOC (x in Li1-xNi0.8Co0.15Al0.05O2) [2].

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decreased, especially near surface (CEY).In my presentation, the fading mechanism of Li-ion battery with Li1-xNi0.8Co0.15Al0.05O2 will be discussed in detail based on the results obtained.

Monitoring the oxygen content in graphene oxide Universidad de Alicante, 1Chemical Engineering Department, University of Alicante, 03080 Alicante, Spain

Helena Varela-Rizo, Iluminada RodriguezPastor, Gloria RamosFernández Ignacio Martín-Gullón helena.varela@ua.es

The chemical derivation of graphene oxide emerged as an easy route to obtain atomically thin carbon sheets with the aim to obtain graphene in a large scale. This graphene oxide (G-O) is decorated with different oxygen groups that disrupt the electronical properties of pristine graphene. The real structure of graphene oxide has not yet been fully understood, same as its predecessor, the graphite oxide, which has been studied over hundred years. Most of the studies, based in bulk analysis of the graphene oxide such as TGA or XPS, stated C/O ratios of 2:1 and variable oxygen contents that range from 20 to 33% [1]. We have developed a particular synthesis method to produce graphene oxide from helical ribbon carbon nanofibers (HR-CNF). Our studies of the quantification of the oxygen content comprised XPS and TGA of the bulk powder and EDS and EELS of single G-O sheets. XPS results were consistent with the literature providing C/O ratios up to 2, while the analysis of the sheets showed much less oxygen content and, therefore, a higher C/O ratio. This difference between the bulk and the sheet analysis agrees with some recent studies that state that most of the oxidation of the graphene oxide is due to some debris attached to the sheets and not to the oxygen covalently bonded [2].

Here, we monitor by different techniques the oxygen content in powder and exfoliated samples of graphene oxide. We tried to find the composition if a single graphene oxide sheet and compared it with the content in the all bulk.

References [1] Bagri, A., C. Mattevi, M. Acik, Y.J. Chabal, M. Chhowalla, and V.B. Shenoy, Structural evolution during the reduction of chemically derived graphene oxide. Nat Chem, 2010. 2(7): p. 581-587. [2] Rourke, J.P., P.A. Pandey, J.J. Moore, M. Bates, I.A. Kinloch, R.J. Young, and N.R. Wilson, The Real Graphene Oxide Revealed: Stripping the Oxidative Debris from the Graphene-like Sheets. Angewandte Chemie International Edition, 2011. 50(14): p. 3173-3177.

This revelation indicates that the existing models of graphene oxide, based on the results of bulk analysis, should be submitted to debate. The knowledge of the structure could lead to a better enhancement of the properties of the graphene oxide.

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Postsynthetic asymmetric transformation of boronic-acid-protected gold nanoclusters studied by magnetic circular dichroism (MCD) and electronic circular dichroism (ECD)

Hiroshi Yao and Masanori Saeki yao@sci.u-hyogo.ac.jp

Graduate School of Material Science, University of Hyogo, Hyogo 678-1297, Japan

Investigations of monolayer-protected metal nanoclusters, possessing typically less than 100 atoms, are largely motivated in the past decade due to their intriguing size-dependent physicochemical properties. Much attention is recently paid on inducing chirality in metal nanoclusters owing to their widespread catalytic use of chirally-modified metal surfaces. Postsynthetic asymmetric transformation is one of the notable techniques for facile control of symmetry-breaking [1]. Our approach here is to use gold nanoclusters bearing an achiral boronic acid group that can bind to chiral cis-diols such as fructose [2]. In addition, we also apply magnetic circular dichroism (MCD) spectroscopy to gain a better understanding of the nanoclusters’ electronic structures as well as their chiroptical signals induced by their surface fructose complexation. A relationship between the MCD and normal (induced) CD responses is also examined, both of which distinctly stem from the cluster’s electronic transitions. We also find that this asymmetric induction is pH-sensitive, suggesting that the gold cluster-fructose complex formation has a great advantage for some biological applications. We synthesized 3-mercaptophenylboronic acid (3-MPB)protected gold clusters with a mean core diameter of 1.1 nm (gel fractioned), and examined their electronic absorption, MCD and chiroptical responses induced by the reaction of boronic acid-chiral fructose binding (Figure 1). Note that the mean core size of the cluster was determined by a solution-phase SAXS measurement. Figures 2a and 2b show absorption and MCD spectra (at a magnetic field of –1.6 T) of the gold nanocluster compound in methanol/aqueous buffer (pH = 10.0) mixture, respectively. It is well known that small gold nanoparticles (< ~2 nm) no longer support the plasmon excitation characteristic, so the structured absorption comes from molecule-like electronic transitions. On the other hand, the MCD spectrum shows overall positive features in the metal-based electronic transition region at –1.6 T. The MCD signals were very weak at > ~500 nm, probably arising from transitions out of the HOMO into LUMO (essentially intraband transitions), whereas

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relatively strong MCD signals were detected at higher energy transitions (< ~500 nm) that involve more or less character of thiolate ligands. Hence it is expected that the MCD responses of the thiolate-protected gold clusters would primarily arise from the electronic state mixing of the ligands and gold atoms. Note that the sign of the MCD signal was completely reversed when the field is switched (+1.6 T), confirming that signatures are not from an experimental artifact but originate from real MCD signals. Based on the MCD features, we deem that magnetic fieldinduced mixing of electronic states of the ligands and surface gold atoms would bring about the Faraday B-term, because (i) a ground-state Zeeman splitting (at H = 1.6 T) is in the order of 0.2 meV (if present), smaller than the energy of room temperature (~26 meV), so the C-term contribution should be trivial; (ii) the MCD response does not contain any derivative line shape with respect to the absorption peak, so the A-term contribution would be also negligible [3].

Figure 1. Reaction scheme for the postsynthetic binding between surface 3-MPB and chiral fructose bearing diols in basic solution.

Figure 2. Absorption and MCD spectra (at -1.6 T) of the gold nanocluster compound. Deconvoluted Gaussian band fits of the electronic absorption and MCD spectra are also shown.

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We next performed spectral deconvolution analysis of both the absorption and MCD data to quantitatively estimate accurate transition energies and their spectral linewidths in the nanocluster since the MCD features must correspond to electronic transitions (even unresolved) in the electronic absorption. The Gaussian fits of MCD as well as electronic absorption spectra are also shown in Figure 2. For deconvoluting the experimental data, we assumed that the analysis is constrained by the requirement that a “single set” of Gaussian components be used for the fitting of both the absorption and the MCD spectra. For the excellent (satisfactory) agreement between the measure and calculated spectra, eight Gaussian components were necessary. Importantly, the two different spectral patterns have made the spectral deconvolution analysis successful. The pristine gold nanocluster had no optical activity. However, D-/L-fructose addition to the nanocluster solution altered CD responses. Figure 3a shows the CD spectra of the gold nanocluster compound in the presence of D-/L-fructose at pH=10.0. Note that fructose did not induce significant absorption changes of the gold nanocluster, strongly indicating that complexation between the surface 3-MPB ligand and chiral fructose hardly influenced the electronic states of the clusters, and consequently, the gold core rearrangement or size growth was unlikely to take place upon complexation. On the other hand, the nanocluster showed an appreciable Cotton effect with complicated coupling patterns when complexed with D- or L-fructose (that is, asymmetric induction). Additionally, an almost perfect mirror-image relationship was obtained in the region of metal-based electronic transitions, implying enantiomeric complexation. To gain a better understanding of the structure (shape) of CD spectra, we compare them with the peakseparated bands obtained by the deconvolution analysis. Figure 3b shows the induced CD and the deconvoluted absorption spectra of the gold nanocluster with D-fructose (10–3 M) plotted against energy in wavenumber. For the guide of eyes, vertical dash lines are drawn at the same energy positions. The induced CD response is distinctly related to the peakseparated bands; for example, the deconvoluted spectra of 2, 3, 5, 6, and 7 exhibited negative, positive, negative, positive, and negative peaks in the CD response, respectively (see Figure 3b). The band 4 showed (+/–) split-type CD signal, implying an interaction between the inclusive electronic transitions. The spectrum 1 (the lowest energy component) seems to be CD silent. In conclusion, the induced CD

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signatures can be successfully correlated with the isolated (separated) electronic transitions obtained by deconvolution analysis based on the absorption and MCD spectra. This spectral analysis is expected to benefit better understanding of the electronic states and the origin of the optical activity in chiral metal nanoclusters.

Figure 3. (a) Effects of D-L- fructose on the CD spectrum of the 3-MPB-protrctrd gold nanocluster in the methanolic base solution. Green and red curves indicate the spectra obtained upon addition of D- and L-fructose, respectively. Mirror imagen relationship can be seen between them. (b) Electronic absorption and CD spectra of the gold cluster in the presence of chiral D-fructose (10-3 M). The data were plotted against wavenumber. The deconvoluted spectra with Gaussian function are also shown for ease of comparison. (c) CD spectra of the nanocluster in the presence of D-/L-fructose (10-3 M) in the methanolic acid solution (pH = 1.68). Green and red curves indicate the spectra obtained upon addition of D- and L-fructose, respectively.

At the end, to confirm that the induced CD responses are controllable by external parameters, we examined pH-dependent optical activity of the 3-MPB-protected gold cluster in the presence of chiral fructose. The binding constant of the anionic boronate-diol is very much larger than that of the neutral boronic acid-diol [2], so that significant decomposition of the complexes is highly expected in acidic conditions. Figure 3c shows (induced) CD spectra of the gold nanocluster compound in the presence of D-/L-fructose (10–3 M) in methanol/aqueous oxalate buffer (pH=1.68). In contrast to Figure 3a, no CD signals were detected, suggesting no complexation of surface 3-MPB moieties with chiral fructose. Interestingly, optical activity of the gold nanoclusters can be simply controlled by external parameters such as the pH value. This method will be a powerful strategy to quantitatively induce optical activity in a controlled manner.

References [1] Yao, H. Kitaoka, M.; Sasaki, A. Nanoscale, 4 (2012) 955. [2] Yao, H.; Saeki, M.; Kimura, K. J. Phys. Chem. C, 114 (2010) 15909. [3] Stephens, P. J. Ann. Rev. Phys. Chem., 25 (1974) 201.

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Laser heating control with polarized light in isolated multi-walled carbon nanotubes

Mariusz Zdrojek, Jarosław Judek and Michał Wąsik zdrojek@if.pw.edu.pl

Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland

We are proposing a novel method of laser heating control only through change in polarization of the incident light, keeping its power density constant [1]. The idea combines antenna effect found in isolated multi-walled carbon nanotubes and the possibility of their heating by light illumination. To observe this we used Raman spectroscopy technique (see fig. 1), where the heating manifests itself in a pronounced downshift of the Raman G and 2D lines as a function of the polarization angle (see fig. 2). To our knowledge, this is the first experimental demonstration of polarization dependent heating effect in carbon nanotubes probed by Raman spectroscopy or by any other technique. Interpretation of the observed phenomena will be discussed.

Figure 1. (a) Schematic of the experimental setup used for exploring the dependence of the inelastic scattering amplitude and phonon energy on the angle φ between the carbon nanotube axis and the direction of the electric field vector of the incident and scattered light. (b) Raman spectrum from an isolated multiwalled nanotube. (c) Atomic force microscopy image of isolated MWCNT (d~ 30 nm) on the SiO2/Si substrate.

Our method can be useful in field electron emission devices or in selective nanotubes heating and TNT 2012 madrid (spain)

destruction. It can also be extended to other one dimensional nanoobjects, if only certain conditions are fulfilled. We expect that the effect presented here can be found in other high aspect ratio nanoobjects, if only localization of the electronic states is high enough and/or they stay within the electrostatic limit.

Figure 2. Angular evolution of G and 2D band positions for two polarization configurations (VV and VH). Four data series in a plot (a) acquired for the different laser power densities (p1 >p2 >p3 >p4) prove the thermal origin of the Raman shift change. Experimental data (open symbols) were fitted with the cos2(φ) function (lines).

References [1] M. Zdrojek, J. Judek, M. Wąsik, Phys. Rev. Let. 108, 225501 (2012)

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Late Abstracts

Optical antennas: nanoscience meets quantum optics

Stephan GĂśtzinger stephan.goetzinger@mpl.mpg.de

Department of Physics, Friedrich-Alexander University Erlangen-NĂźrnberg & Max Planck Institute for the Science of Light, GĂźnther-Scharowsky-Str. 1 /Bldg. 24, 91058 Erlangen, Germany

The ultimate control of light-matter interaction is achieved when a single emitter strongly interacts with a single photon. A manipulation at the level of single quanta is not only of fundamental interest but is of special importance for emerging quantum technologies, such as quantum information processing. In this talk I will first briefly review our experimental progress on the interaction of strongly focused photons with a single molecule [1, 2]. Then I will discuss how optical antennas can be used to enhance light-emitter interaction and how the emission properties of a single emitter can be dramatically altered. Two types of antennas are presented. With a metallic nanoantenna [3], we experimentally achieved a two orders of magnitude reduction in the fluorescence lifetime of a single molecule [4]. In another experiment we embedded a single organic molecule in a planar dielectric antenna, which directs the emission towards the collection optics. We realized a single-photon source with near-unity collection efficiency and a record count rate of 50x106 photons per second [5]. With the current design we collect 96% of the photons emitted by a single molecule. Metallodilectric antennas promise photon collection rates exceeding 99% [6].

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References [1] J. Huang et al., Nature 460, 76 (2009). [2] Y. Rezus et al., Phys. Rev. Lett. 108, 093601 (2012). [3] H. Eghlidi et al., Nano Lett. 9, 4007 (2009). [4] K.G. Lee et al., arXiv:1208.1113v1 (2012). [5] K.G. Lee et al., Nat. Phot. 5, 166 (2011). [6] X.-W. Chen et al., Opt. Lett. 36, 3545 (2011).

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Environmental Effects in Carbon Nanotube and graphene-based Transistors

Richard Martel

r.martel@umontreal.ca

Département de Chimie, Université de Montréal, Montréal, Canada

Charge transfer doping by atmospheric gas is ubiquitous in carbon-based field-effect transistors (FETs), but this important phenomenon is yet poorly understood. This talk will mainly discuss our recent investigation on the origin of air doping and on its signatures in the electrical, optical and thermoelectric properties of carbon nanotube and graphene devices.

the air doping using plastic substrates was provided and the kinetics of the charge transfer process was monitored using graphene FETs [1,2]. The results are quantitatively described using the MarcusGerischer theory on charge transfer. Here we will present the results and conclusions of our studies and provide hint for controling the air-doping effect in nanotube [1] and graphene devices [2,3].

Figure 2. Air effect on graphene FET with different substrates. (A) Graphene on SiO2 and (B) graphene on parylene. — (Red) Transfer characteristics of graphene FETs measured in vacuum at room temperature after a 4 hour anneal at 400K. — (Cyan) Characteristics measured after 30 minutes in air.

Figure 1. Transfer characteristics for a 1 μm long individual SWNT FETs in air. (a) A device on SiO2 and (b) on parylene. In black is the forward gate voltage scan and in red the reverse scan. The source-drain bias voltage was Vsd = -1 V.

By using both carbon nanotube (Figure 1) and graphene layers (Figure 2) as testbeds, we first measured the influence of the chemical nature of the substrate and the impact of different gas exposure on the switching behaviour of both nanoscale and thin-film FETs. Our studies revealed that electrochemical charge transfer doping by the water/oxygen redox couple is the underlying mechanism behind the environmental effects in most nanodevices (Figure 3). A solution to control

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In a second study, we report the observation of the optical signatures of doping and disorder in the mid-infrared (MIR) absorption spectra of singlewalled carbon nanotubes (SWNTs) [4]. An asymmetric line shape of the SWNT phonon modes at ~870 and ~1600 cm-1 is characteristic of a Fano resonance (Figure 4). This kind of resonance is indicative of the presence of a strong e-ph interaction and stems from the scattering of an electronic continuum onto a phonon discrete mode. The π phase shift of the wavefunction in the neighborhood of the resonance creates destructive interferences, which are seen as a dip in the spectrum. According to theoretical calculations, the bands at ~870 and ~1600 cm-1 are ascribed to oTO and iTO infrared active phonon modes, respectively

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Figure 4. MIR spectra of an intrinsic and doped SWNT film. Arrows indicate the phonon modes and the presence of the Fano resonance. Inset: NIR-vis spectra of the SWNT film.

This work was done in collaboration with Pierre Lévesque, François Lapointe, Carla M. Aguirre, Benoit Cardin-St-Antoine, Patrick Desjardins, David Ménard and T. Szkopek.

References

Figure 3. Electron-transfer mechanism within the Marcus-Gerischer theory. Schematic of the water/oxygen redox couple density of states (DOS) for an equivalent concentration of oxidizing and reducing species and a comparison with the SWNT DOS (left) and graphene DOS (right). The arrow indicates the direction of the charge transfer reaction.

In a third study, P-doping by air exposure and Ndoping by local potassium (K) deposition was used to prepare a suspended carbon nanotube film having a PN doping profile between two metal contacts. The electrical response of this PN device was studied using laser excitation and temperature gradients. The device response is best described in terms of a thermal mechanism that is independent of the nanotube-metal barrier. Moreover, we show using estimates of the local Seebeck coefficients that a PN junction in a suspended nanotube film

TNT 2012 madrid (spain)

[1] C. M. Aguirre, P. Levesque, M. Paillet, F. Lapointe, B. C. St-Antoine, P. Desjardins and R. Martel, Adv. Mat.. 21, 3087-3091 (2009). [2] S. S. Sari, P. Lévesque, C. M. Aguirre, J. Guillemette, R. Martel and T. Szkopek, Appl. Phys. Lett. 95, 242104 (2009). [3] P. L. Lévesque, S. S. Sabri, C. M. Aguirre, J. Guillemette, M. Siaj, P. Desjardins, T. Szkopek, R. Martel, Nano Letters, 11, 132-135 (2011). [4] F. Lapointe, E. Gaufrès, I. Tremblay, N. Y-Wa Tang, P. Desjardins and R. Martel, Phys. Rev. Lett. 109, 097402 (2012). [5] Jeon, G. S. & Mahan, G. D. Phys. Rev. B 72 155415 (2005). [6] Bantignies, J.-L. et al. Phys. Rev. B 74 195425 (2006). [7] B. C. St-Antoine and D. Ménard, Nano Letters, 11, 609-613 (2011); B. C. St-Antoine, David Ménard and R. Martel, Nano Research, 5, 7381 (2012).

september 10-14, 2012

| 201

Abstracts

behaves as a thermopile. The performances of the novel nanotube thermopile will be presented and compared to state-of-the-art SWNT bolometers [7].

TNT2012

[5]. A supplementary mode is observed at ~1260 cm-1, which corresponds to a defect mode, the so-called "D-band" in Raman spectroscopy. Our results are in agreement with previous studies of SWNTs in the MIR, though prior works failed to recognize the role of e-ph interactions on these infrared bands [6]. We also found that the e-ph coupling broadens the phonon modes, which also shifts to higher energy compared to the uncoupled state. Finally, the influence of defects on the MIR cross-section of Fano resonances was explored by functionalization of SWNTs with bromophenyl moieties. We measured that the absorption crosssection increases when defects are induced in the wall in comparison to undamaged SWNTs in the same doping state. We therefore propose that the Fano resonances are activated in two ways: First, increasing the number of charge carriers leads to an increase in the number of scattering events and in intraband continuum absorption; second, the creation of defects lowers the symmetry and relaxes the selection rules. Similar Fano resonances in single layer graphene will also be discussed.

Mohsen Mohsen-Nia

Borhani, Bahareh

J. Espada, J.C. Stockert, F. Agulló-López, A. García-Cabañes and M. Carrascosa

Blázquez Castro, Alfonso

E. Flahaut and J. González

Belandria, Edgar

Y. Miyahara , J. A. J. Burgess, O. IglesiasFriere and P. Grutter

Bates, Jeffrey R

María Muñoz , Dmitri N Muraviev, Patricia Ruiz

Bastos, Julio

Gunes Alp Yakaboylu, Hatice Genc, Kenan Isik, A. Tansu Koparal, Ender Suvaci

Barutca, Banu

U.L. Fulco, C.A. Barboza, and E. Moreira

Albuquerque, Eudenilson

M.A. Vicente, R. Trujillano, S.A. Korili, A. Gil

Albeniz, Saioa

B. Santos, A. Mascaraque, M. Maicas, L. Pérez, E. Miralles, A. Quesada, A. T. N´Diaye, A. K. Schimd and J. de la Figuera

Abuin, Manuel

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Iran

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Posters list: alphabetical order

"Synthesis and characterization of nanofillers based on modified clay materials"

"Magnetic domain structure of Co ultra-thin islands on Ru”

poster title

NanoChemistry

Nanobiotechnologies & Nanomedicine

senior

student

"Phototoxicity induced by Iron-doped LiNbO3 nanoparticles in human tumor cells" "Preparation and characterization of polypropylene/ MgAl2O4.MgO nanocomposites"

senior

student

"Morphological changes of gel–type functional polymers after intermatrix synthesis of polymer stabilized silver nanoparticles"

"Unintended Consequences of Focused Ion Beam Milling on Nanostencil Lithography"

student

senior

student

student senior

"Evaluation of the Cytotoxic and Genotoxic Potential of TiO2 Nanoparticles"

Low dimensional materials (nanowires, clusters, "Raman effect in carbon nanotubes filled with nanowires" quantum dots, etc.)

Nanofabrication tools & nanoscale integration

NanoChemistry

Risks-toxicity-regulations

Low dimensional materials "Electronic Spectra of Calcium Carbonate Porous Nanostructured (nanowires, clusters, Material" quantum dots, etc.)

Nanofabrication tools & nanoscale integration

Nanomagnetism and Spintronics

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Lin Xiaoyang, Li Weiwei, Kaili Jiang, Dafiné Ravelosona, Claude Chappert, Weisheng Zhao

Deng, Chenxing

Carole Fauquet, Anna Reymers, Vladimir Gevorgyan, Alain Ranguis, Damien Chaudanson, Artak Karapetyan and Wladimir Marine

Dehlinger, Maël

V. Vega, L. Iglesias, J. García, D. Görlitz, K. Nielsch, E. Díaz Barriga-Castro, R. Mendoza-Résendez, A. Ponce, C. Luna

De la Prida, Victor Manuel

Yeong-Eun Yoo, Jae-Sung Yoon

Choi, Doo-Sun

Prashant, C.K., Madhusudan Bhatt, Manoj Gautam, A.K.Dinda

Chandravilas, Prashant

Daniel Calle,Elizabetta Agostinelly, Gaspare Varvaro, Viviana Negri, Sebastián Cerdán, Paloma Ballesteros

Cerpa, Arisbel

Shibing Long, Carlo Gagli, Riccardo Rurali, Enrique Miranda, David Jiménez, Julien Buckley, Ming Liu and Jordi Suñé

Cartoixa, Xavier

S. Carrasco,F. Navarro-Villoslada, M.C. Capel-Sánchez, J.L. García Fierro, M.C. Moreno-Bondi, C.A. Barrios

Canalejas Tejero, Víctor

F. Z.Benabid, F.Zouai, S.Bouhelal and D. Benachour

Cagiao, Mª Esperanza

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India

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"Optical and structural properties of Al doped ZnO nanostructured films formed by Sol-Gel processing"

"Observation of low-field magnetoresistance in graphene at room temperature"

Nanostructured and nanoparticle based materials Graphene / Carbon nanotubes based Nanoelectronics and field emission

"Electroplating and magneto-structural characterization of multilayered Co50Ni50/Co80Ni20 nanowires from single electrochemical bath in anodic alumina templates"

"Coloring of injection molded plastic plate by surface nanostructures without pigment"

NanoOptics NanoPhotonics Plasmonics

Nanomagnetism and Spintronics

"Size Dependent Differential Immune Response with Poly-εcaprolactone Nanoparticles-An in vitro study"

"Hysteresis loops and magnetic susceptibility for different orientation angle of oriented carbon nanotubes using VSM and SQUID"

"Conductance Quantization in Resistive Switching"

"Ultrasensitive Non-Chemically Amplified Negative-Tone Electron Beam Lithography Resist"

"Study of weather effect on pvdf/pmma based blend coatings ageing: influence of artificial ageing (xenotest) and neutral saline fog"

poster title

Nanobiotechnologies & Nanomedicine

Nanomagnetism and Spintronics

Other

Nanostructured and nanoparticle based materials

topic

student

senior

student

senior

student

senior

student senior

Adéla Galandáková, Hana Vágnerová, Bohumil Zálešák and Jitka Ulrichova

Frankova, Jana

Georgia Ibanescu, Elena Matei, Nicoleta Preda, Monica Enculescu, Maria Eugenia Toimil Molares, Ionut Enculescu

Florica, Camelia

Gamze Çetintaş, Asiye Aslıhan Avan, Serkan Naci Koç, İsmail Boz

Filik, Hayati

Víctor Fernàndez-Altable and Andrea Falqui

Figuerola, Albert

Ana L. Daniel-da-Silva, Noémi Jordão, Ana Barros-Timmons, Tito Trindade

Fateixa, Sara

Vassilios Yannopapas, Emmanuel Paspalakis

Evangelou, Sofia

E. Matei, I. Enculescu, C. Trautmann

Enculescu, Ionut

Ali Shokuhfar, Amin Hosseini-Sadegh, Abolfazl Zare-Shahabadi

EbrahimiNejad, Salman

Doshi, Nilay

K. Ziegler, J. Macanás, F. Carrillo, M. Muñoz, D.N. Muraviev

Domènech García, Berta

R. Gutierrez, R. Raaman and G. Cuniberti

Díaz García, Elena

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Czech Republic

Romania

Turkey

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Portugal

Greece

Romania

"Preparation of PlatinumNanoparticles-Graphene Modified Electrode and Sensitive Determination of Paracetamol"

"Gold-Catalyzed Growth of Colloidal Cadmium Chalcogenide Worm-like Nanostructures"

"Effect of noble metal nanoparticles on the glass transition temperature of poly(t-butylacrylate) composites"

"Effects of a Plasmonic Nanostructure on Kerr Nonlinearity in a Four-Level Quantum System"

"Influence of metallic nanostructures on the optical properties of dye-doped polymer thin films"

"Compressive Buckling of Boron Nitride Nanotubes with Hydrogen Storage"

"Nano fabrication of nanoscaled integrated circuit chips"

"Development of new Polymer-Metal-Nanocomposites based on activated foams and textile fibers and their catalytic evaluation."

"Spin selective transport through helical molecular systems"

poster title

Nanobiotechnologies & Nanomedicine

"Influence of silver nanoparticles on in vitro wound healing model"

Low dimensional materials "Electrical properties of ZnO single nanowires contacted by FIBID (nanowires, clusters, and EBL" quantum dots, etc.)

NanoChemistry

Low dimensional materials (nanowires, clusters, quantum dots, etc.) NanoOptics NanoPhotonics Plasmonics Nanostructured and nanoparticle based materials Low dimensional materials (nanowires, clusters, quantum dots, etc.)

Nanomaterials for Energy

Nanofabrication tools & nanoscale integration

United Arab Emirates

Iran

NanoChemistry

Nanomagnetism and Spintronics

topic

Spain

country

senior

student

senior

student

senior

student

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M. Nieto-Vesperinas and J. J. Sáenz

Gómez-Medina, Raquel

T. Campo, F. Márquez, E. Elizalde, C. Morant

Gomez, Arancha

Q. Gu, F. Grillot, S. Loualiche, J. Le Pouliquen, T. Batte, O.Dehaese, A. Le Corre,L. Bramerie, D. Bosc,L. Bodiou, J.-C. Simon, Y. Battie, A. Loiseau,B. L. Liang, D.L. Huffaker

Gicquel-Guézo, Maud

Silvia Maria Martelli, Clarice Fedosse Zornio,Thiago Caon, Cláudia Maria Oliveira Simões and Valdir Soldi

Gava Marini, Vanderleia

F. Sousa, RO Louro, JA Queiroz, IJ Correia

Gaspar, Vitor

Andrés Seral-Ascaso, Asunción Luquin, Mariano Laguna, Germán F. de la Fuente and Edgar Muñoz

Garriga, Rosa

Yahya Moubarak Meziani, Jesús Enrique Velázquez-Pérez and Jaime Calvo-Gallego

García-García, Enrique

N. Bion, S. Royer, D. Duprez, D. Sidabra

Galdikas, Arvaidas

Jana Franková, Klára Habartová, Bohumil Zálešák, Jitka Ulrichová

Galandáková, Adéla

E.L. Albuquerque and M.S. Vasconcelos

Fulco, Umberto

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Spain

France

Brazil

Portugal

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Lithuania

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"Photonics based on carbon nanotubes"

"Zein nanoparticles as a carrier system for terpinen-4-ol"

"Cell Internalizing and pH-responsive Chitosan Nanoparticles for Improved Delivery of DNA Biopharmaceuticals"

"Gold Nanoparticle Decoration of Carbon Nanotubes and Graphene: Synthesis, Physical-Chemical Characterization, and Applications"

"Terahertz Time Domain Spectroscopy for molecules inspection: water vapor and drugs"

senior

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senior

student

senior

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"Modeling of Diffusion Process in Nanosized Perovskite LaCoO3 Powder Catalysts"

Low dimensional materials (nanowires, clusters, "Controlled synthesis of si nanowires on si substrates" quantum dots, etc.) NanoOptics "Non-conservative electric and magnetic optical forces on NanoPhotonics semiconductor particles" Plasmonics

NanoOptics NanoPhotonics Plasmonics

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Nanobiotechnologies & Nanomedicine

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High spatial resolution spectroscopies under SPM probe

NanoChemistry

senior

student

student senior

"Biological effects induced by silver and gold nanoparticles: in vitro study."

"Electronic Transport in Quasiperiodic Graphene p–n–p Junctions"

Graphene / Carbon nanotubes based nanoelectronics and field emission

Nanobiotechnologies & Nanomedicine

poster title

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Alicja Bachmatiuk,Bernd Büchner,Mark H. Rümmeli, Gianaurelio Cuniberti

Ibrahim, Imad

D. Schmid, P. Stiller and C. Strunk

Hüttel, Andreas K.

A. Gallego, O. Castillo, I. Berlanga, C. Gómez, E. Mateo, J. I. Martínez , F. Flores, A. Houlton, B. R. Horrocks, C. Gómez Navarro, J. Gómez-Herrero, S. Delgado and F. Zamora

Hermosa, Cristina

M.Ramezani, M. Rahimizadeh, H. Eshghi, Kh. Abnoos

Hashem Nia, Azadeh

Manolo Perlado and Santiago CuestaLópez

Guerrero Contreras, Carlos Luis

Dušan Nohavica, Petar Gladkov

Grym, Jan

J. Ruiz-Cabello and F. Herranz

Groult, Hugo

F. Domínguez-Adame, R. A. Römer

González-Santander, Clara

N. Gordillo, M. Panizo-Laiz, A. Rivera, F. Munnik, K. Saravanan and J. M. Perlado

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José Ignacio Eguiazábal

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Germany

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"Growth of high yield metallic-free horizontally aligned single wall carbon nanotubes nucleated from fullerene"

"Single wall carbon nanotubes as highly sensitive nanoelectromechanical hybrid systems: driving, braking, detection"

"Solvent-induced Delamination of a Multifunctional Two Dimensional Coordination Polymer"

"Efficient Gene Delivery Nanovectors Based on Functionalization Of Single wall Carbon Nanotubes (SWNT) with Polyethylenimine (PEI)"

"Nanocrystals in the Manufacture of Target for Inertial Confinement Fusion."

"Liquid-phase epitaxial growth on nanoporous substrates"

student

senior

student

senior

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"Micellar approach for the design of new up-converting nanophosphors and superparamagnetic nanoparticles for optical imaging and in vivo MRI"

NanoChemistry

student

"Localization of states on graphene-type lattices "

Theory and modelling at the nanoscale

senior

student senior

"H diffusion in nanoestructured as compared to massive W"

"Nanocomposites based on poly(ether imide) by the addition of a poly(butylene terephthalate)/carbon nanotube masterbatch: Electrical conductivity and mechanical performance"

poster title

Nanomaterials for Energy

Nanostructured and nanoparticle based materials

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"The Effect of Electrochemical Methods on The Shape of Zinc Oxide Nanostructures"

Nanostructured and nanoparticle based materials

Viviana Negri, Sebastián Cerdán and Paloma Ballesteros

Lado Touriño, Isabel

O. Vikhrova, Yu. Danilov, I. Kalentieva, B. Zvonkov

Kudrin, Alexey

Michał Krasodomski, Michał Wojtasik, Kamil Pomykała

Krasodomski, Wojciech

Gulyaev Yu.V., Kosakovskaya Z.Ya., Blagov E.V.,Latyshev Yu.I.,Orlov A.P., Smolovich A.M.

Kosakovskii, German

G. Greene-Diniz, G. Fagas, M.G. Haverty, S. Shankar, C. Martinez-Lacambra, J.C. Greer

Jones, Sarah

Gloria Platero

Spain

Russia

Poland

Russia

Ireland

Spain

Theory and modelling at the nanoscale

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"Molecular modeling of aromatic interactions between pyrene derivatives and carbon nanotubes"

"The features of carrier transport in the ferromagnetic semiconductor quantum well structures"

"Modified graphene and graphite oxide dispersions in petroleum fractions"

"Quantum Effects At Field Emission From Carbon Quasi-1D Cathodes"

"The Effect of Vacancy Defects on Electron Scattering in Carbon Nanotubes"

"Microwave-induced resistance oscillations and zero-resistance states in 2D bilayer systems"

Low dimensional materials "Off-resonance magnetoresistance spike in irradiated ultraclean (nanowires, clusters, 2DES" quantum dots, etc.)

Spain

Iñarrea, Jesús

Nanomaterials for Energy

"High efficiency electrodes based on nanostructured materials for energy devices"

"Non-Covalent Biofunctionalization of Graphene with Cage-like Multi-Enzyme Complexes for Sensing"

poster title

Nanobiotechnologies & Nanomedicine

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Italy

Turkey

United Kingdom

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Serena Randazzo, Maria Chiara Mistretta, Salvatore Piazza, Carmelo Sunseri

Inguanta, Rosalinda

Y.Sahin, E. Suvaci

Imamoglu, Gamze

Abeer Alshammari, Mareike G. Posner, Abhishek Upadhyay, Frank Marken, Stefan Bagby

Ilie, Adelina

authors

senior

student

senior

student

senior

student senior

Victor Sorribas, Martin Gutierrez, Rosa Cornudella, José Antonio Moreno, Rafael Piñol, Lierni Gabilondo, Angel Millán, Fernando Palacio

Lamiaa, M.A.Ali

R. Mendoza-Reséndez

Luna, Carlos

Giulio Fracasso, Marco Colombatti, María Antonia Herrero, Maurizio Prato and Ester Vázquez

Lucio, Maria Isabel

A. Ballestar, J. Baryola-Quiquia, P. Esquinazi

Lorite, Israel

M. N. Piña, J. Morey, R. Alemany, B. O. Vögler, F. M. L. Barceló

López, Kenia A.

Rosa Lopez and David Sanchez

Lim, Jong Soo

Ralitsa Georgieva and Adrian Neagu

Lighezan, Liliana

Christian Sarra-Bournet, Myriam LaprisePelletier, Marc-André Fortin

Létourneau, Mathieu

José Luis Costa-Krämer, Carlo Guerrero and Marisel Díaz

León, Natalia

Marcela Urzúa, Maximiliano Pino and Deodato Radic´

Leiva, Angel

Jean-Luc Bridot,Rémy Guillet-Nicolas, Freddy Kleitz ,MarcAndré Fortin

Laprise-Pelletier, Myriam

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Spain

Mexico

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Spain

Romania

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country "Mesoporous Silica Nanoparticles (MSNs) as MRI/PET DualModality Imaging Probes"

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Nanobiotechnologies & Nanomedicine

Nanomagnetism and Spintronics

"Toxicity studies of polymer based superparamagnetic iron oxide nanoparticles "

"Microstructural and Magnetic Properties of Hematite Submicron Pseudo-Cubes Obtained by Nanocrystal Oriented Attachment"

"New selective drugs based on carbon nanohorns"

"Study of the transport properties frequency dependence of multilayer graphene by Impedance Spectroscopy"

Graphene / Carbon nanotubes based nanoelectronics and field emission

Nanobiotechnologies & Nanomedicine

"Antifolates-Modified Iron Oxide Nanoparticles for Targeting Cancer Cells"

"Fluctuation relations for spintronics"

Nanomagnetism and Spintronics Nanobiotechnologies & Nanomedicine

"Thermal properties of the S-layer protein from Lactobacillus salivarius"

"Plasma-liquid Electrochemistry : a Fast Method for Synthesizing Magnetic Nanoparticles"

Nanobiotechnologies & Nanomedicine

Nanostructured and nanoparticle based "Thin Films of Polyelectrolytes with Adsorbed Gold Nanoparticles" materials Low dimensional materials "Shell structures in aluminium nanocontacts at elevated (nanowires, clusters, temperatures" quantum dots, etc.)

Nanobiotechnologies & Nanomedicine

topic

student

senior

student

senior

student

senior

student

senior

student

student senior

N.O. Nuñez, C. Luna

Mendoza-Reséndez, Raquel

E. Pichonat, S. Frégonèse, A. Ouerghi and H. Happy

Mele, David

Wojciech Krasodomski, Michał Pajda, Kamil Pomykała, Leszek Ziemiański

Mazela, Wojciech

M.L. Vasconcelos and E.L. Albuquerque

Mauriz, Paulo

Ionut Enculescu,Camelia Florica, Monica Enculescu, Victor Kuncser, Maria Eugenia Toimil Molares

Matei, Elena

M.K. Keshavartz, J. Arreguin-Zavala, D. Vasilevskiy and S. Turenne

Masut, Remo

F.M. Alberti, D. Marquardt, H. Meyer, C. Rutz, K. Schütte, C. Vollmer, C. Janiak

Marcos Esteban, Raquel

Adrian E. Flood, Suchitra Phithaksoemsak

Maneedaeng, Atthaphon

A. L. Alvarez, C. Coya, J. Jimenez-Trillo , M. García-Velez, G. Alvarado

Mallavia, Ricardo

Kh.Kabgov, F.Sharipov, Ju.M. Yu, M.Shulga

Makhsuda, Abdusalyamova

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Mexico

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Germany

Thailand

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Tajikistan

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Graphene / Carbon nanotubes based nanoelectronics and field emission Nanostructured and nanoparticle based materials

Nanostructured and nanoparticle based materials

"Green Synthesis of Silver Nanoparticles Mediated by Bee Products"

"High Frequency Epitaxial Graphene Fields Effect Transistors (GFET) on SiC"

"Evaluation of carbon nanotubes - oil dispersion stability"

senior

student

senior

student

"Optical transmission spectra in Fibonacci photonic multilayers with mirror symmetry"

NanoOptics NanoPhotonics Plasmonics

senior

student

senior

"Nanostructured thermoelectric alloys obtained by mechanical alloying followed by hot extrusion or by microwave sintering "

"“Ligand-Free” Metal-Nanoparticles in Ionic Liquids"

Low dimensional materials "Effect of the deposition conditions on the properties of magnetic (nanowires, clusters, nanowires" quantum dots, etc.)

Nanomaterials for Energy

NanoChemistry

"Size-Controllable Calcium Carbonate Crystals by Homologous Series of Anionic Surfactants"

Nanostructured and nanoparticle based materials

senior

"Proposal of a low-cost, mask-less procedure for patterning electrodes of organic devices at nanoscale using electrodischarges"

Nanofabrication tools & nanoscale integration

student senior senior

poster title "The preparation and investigation of properties of Er2O3"

NanoChemistry

topic

Keijo Riikjärv, Kelli Hanschmidt, Aile Tamm, Hugo Mändar,Gunnar Nurk,Kaupo Kukli, Tanel Tätte

Part, Marko

Jin-Wo Kim, Jae-Kang Kim, Sang-Ki Kang, Yeon-Tae Yu

Park, Kyoung-Geun

P. Wahnón , B. Mari

Palacios, Pablo

Banu Barutca, Kenan Isik, Ender Suvaci, A. Tansu Koparal, Yucel Sahin

Ozogut, Ugur Can

Ana María Calle, Mónica Pacheco

Orellana, Pedro

Abdolreza Rezaeifard, Maasoumeh Jafarpour

Naeimi, Atena

Munawar Hussain, Peter A Lieberzeit

Mustafa, Ghulam

C. Gaul, A. V. Malyshev, P. A. Orellana, C. A. Müller and F. Domínguez-Adame

Munárriz, Javier

María de las Nieves Piña and Kenia A. López

Morey, Jeroni

A. Dolati, E.Jabbari

Mohajeri, Soha

F.Ebrahimi,V.Ebrahimi

Mirasmouri, Moslem

authors

Estonia

Korea

Spain

Turkey

Chile

Spain

Austria

Spain

Iran

country

"Copper (II) Tetrasulfonated Phthalocyanine Immobilized on Superparamagnetic Nanoparticles"

"Nanoparticles and nanocomposites as VOC recognition materials"

"Spin-dependent transport in graphene nanoribbons with a periodic array of ferromagnetic strips"

"Chemical remediation: Squaramide Magnetic Iron Nanoparticles for Removal of Toxic Metals ions in Water"

"Electrodeposition of Polyaniline nanowires"

"The surface Plasmon\'s frequencies of two Metallic Nanospheres by Bloch-Jensen Hydrodynamical Model"

poster title

Nanostructured and nanoparticle based materials

"Novel method in synthesis of YSZ microtubes and their application as ALD substrates"

Low dimensional materials (nanowires, clusters, "Fano and Andreev Reflection in Quantum dots" quantum dots, etc.) Nanostructured and "Shape and Size Controlled ZnO Particles and Their Cytotoxic nanoparticle based Behaviour" materials "Theoretical study of band alignment in nano-porous ZnO Nanomaterials for Energy interacting with substituted Phthalocyanines" Nanostructured and "Synthesis of nano-sized SiC and Si/SiC from silicon and carbon nanoparticle based powders by non-transferred arc thermal plasma" materials

Nanomagnetism and Spintronics

Graphene / Carbon nanotubes based nanoelectronics and field emission Nanostructured and nanoparticle based materials

NanoChemistry

NanoOptics NanoPhotonics Plasmonics Nanostructured and nanoparticle based materials

topic

student

senior

student

senior

student senior

Moritz Nazarenus, Sumaira Ashraf, Wolfgang J. Parak

Rivera Gil, Pilar

José Manuel López-Alonso , Ashod Aradian

Rico-García, José María

Jurriaan Huskens, Willem Verboom

Ricciardi, Roberto

Jakub Koktan, and Vladimír Král

Rezanka, Pavel

Gerard Macias Sotuela, Maria Alba, Lluís F. Marsal, Josep Pallarès and Josep FerréBorrull

Rahman, Mohammad Mahbubur

C. T. Sousa, J. Escrig, J. Ventura, M. Vázquez, J. P. Araújo

Proenca, Mariana

Flora Sánchez, Carmen Mansilla, Pablo Ibort, Sol Cuenca, Marta Aguado, César F. Cruz, Ivonne González

Ponz, Fernando

M. Maaza and E. Iwuohag

Philander, Ghouwaa

Esther Jódar and Fernando Rojas

Pérez-Garrido, Antonio

J.L. Costa-Kramer , E. Medina, A. Donoso

Peralta, Mayra

J. Ruiz-Cabello, S. Veintemillas-Verdaguer, M. Puerto Morales, I. Rodríguez, F. Herranz

Pellico Sáez, Juan

authors

Germany

Spain

Nanobiotechnologies & Nanomedicine

NanoOptics NanoPhotonics Plasmonics

NanoChemistry

Czech Republic

Netherlands

NanoOptics NanoPhotonics Plasmonics

Nanomagnetism and Spintronics

Nanostructured and nanoparticle based materials

NanoChemistry

Nanofabrication tools & nanoscale integration Graphene / Carbon nanotubes based nanoelectronics and field emission

NanoChemistry

topic

Spain

Portugal

Spain

South Africa

Spain

Venezuela

Spain

country

"Polymeric Capsules as multifunctional tool for intracellular ion concentration"

"Effect of short-range order vs. long-range disorder on the effective properties of a 1D "metamaterial" chain of resonant particles "

"Systematic circular dichroism study of systems containing cysteine and silver nanoparticles" "Heterogeneous catalysis inside a microreactor containing acidfunctionalized polymer brushes"

"3D nanostructuring of nanoporous anodic alumina for photonic applications"

"Crossover between magnetic reversal modes in ordered arrays of electrodeposited nanotubes"

"A nanoplatform based on self-assembled plant-made nanoparticles with multiple applications"

"Properties of Vanadium Dioxide Coatings for Smart Window Applications"

"Graphene structures with circular shape: a study of the influence of topological defects in transport properties"

"A Three dimensional e-beam lithography technique for the construction of high density micro and nanocoils"

"Synthesis & Functionalization of Fe3O4 Nanoparticles for Magnetic Particle Imaging”

poster title

senior

student

senior

student

senior

student

senior

student

student senior

J.G. Vilhena, Ricardo García, Rubén Pérez

Serena, Pedro A.

Pablo Palacios, Perla Wahnón, and Ricardo Grau-Crespo

Seminovski, Yohanna

Jose Ignacio Eguiazábal

Santamaría, Pablo

M. Timusk, M. Järvekülg, R. Lõhmus, I. Kink and K. Saal

Salundi, Aigi

Rodriguez-Tapiador M.I., Alcázar C., Moreno R. and Ferrito R.

Sainz, Raquel

Tamanaco Francisquez and Carlos Untiedt

Sabater, Carlos

Uthumporn Arsawang, Thanyada Rungrotmongkol and Supot Hannongbua

Rungnim, Chompoonut

Gibrán Amparán and Antonio PérezGarrido

Rojas, Fernando

Iago Rodríguez-Palmeiro, Adrián Sánchez, Eva Rodil, Ana Soto, Alberto Arce

Rodríguez-Cabo, Borja

C. Kanyinda-Malu and R.M. de la Cruz

Rodríguez Rodríguez, Pedro

P. Perna, M. Muñoz, J. L. Prieto, A. Bollero, J. L. F. Cuñado, M. Romera, J. Akermann, E. Jiménez, N. Mikuszeit, V. Cros, J. Camarero and R. Miranda

Rodrigo, Cecilia

authors

Spain

Estonia

Spain

Thailand

Spain

country

"First Principles calculations of SnS2 layered semiconductor, taking into account the Van der Waals interactions." "Towards a molecular dynamics description of the mechanical properties of antibodies as measured with a force microscope"

Theory and modelling at the nanoscale

"Improved mechanical and barrier properties of amorphous polyamide films by the addition of a highly exfoliated nanoclay"

Nanostructured and nanoparticle based materials

Theory and modelling at the nanoscale

"Development of high performance electro-optical films by sol-gel method"

"Colloidal stability of Graphene Oxide and derivatives in water"

Other

NanoChemistry

Low dimensional materials "Investigation of Plastic and Elastic Deformations of Gold (nanowires, clusters, Nanowires under Uniaxial Strain with Point-Contact Spectroscopy" quantum dots, etc.)

senior

student

senior

student

"Insight into molecular dynamics properties of gemcitabine anticancer drugs loaded inside an open-ended single-walled carbon nanotube"

Nanobiotechnologies & Nanomedicine

senior

"Genetic Algorithms in the control and design of charge one qubit quantum gates in circular graphene quantum dots"

Graphene / Carbon nanotubes based nanoelectronics and field emission

student

"Phosphonium-based ionic liquids for the formation of nanoparticles"

"Phonons Contribution to the Infrared and Visible Spectra of II-VI Semiconductor Nanoshells"

NanoOptics NanoPhotonics Plasmonics

student

student senior

NanoChemistry

"Disentangling the magnetoresistance response through the magnetization reversal in magnetic multilayers"

poster title

Nanomagnetism and Spintronics

topic

R. Iglesias, M.A. Rivas, F. Coelho and T.P. Iglesias

Vilão Ramos, Gina

Valter Reedo, Ants Lõhmus and Irina Hussainova

Umalas, Madis

Chadchawan Supachitra, Hannongbua Supot and Akasit Sanong

Thuesombat, Pakvirun

L. Escoda, J. Saurina, A. Carrillo, E. Bosch, B. Hernando

Sunyol, Joan Josep

Irene Yeriskin, Jim Greer

Szepieniec, Mark

V. Kusigerski, M. Rosic, J. Blanusa, M. Perovic, A. Mrakovic, B. Antic, and B. Matovic

Spasojevic, Vojislav

T. Malwela, L. Vayssieres, E. Iwuoha and M. Maaza

Sone, Bertrand

Jesus M. Corres, Ignacio Del Villar, Francisco J. Arregui, Ignacio R. Matias

Socorro, Abian

Dr. Kvitek Libor

Slovak, Petr

Ahamd Kompanya, Ali Khorsand Zaka, Majid Abrishamia, Maryam Javidib, Majed Mortazavib

Shayani Rad, Maryam

Mona Basha Ahmed and Sameh Hossan Eldil

Shamma, Rehab

authors

Portugal

Estonia

Thailand

Spain

Ireland

Yugoslavia

South Africa

Nanostructured and nanoparticle based materials Nanostructured and nanoparticle based materials

Risks-toxicity-regulations

Nanostructured and nanoparticle based materials

Theory and modelling at the nanoscale

Nanomagnetism and Spintronics

Nanostructured and nanoparticle based materials

Nanobiotechnologies & Nanomedicine

Czech Republic

Spain

Nanobiotechnologies & Nanomedicine

Nanostructured and nanoparticle based materials

topic

Iran

Egypt

country

"Electrical conductivity and relative permittivity of 15 nm Al2O3water nanofluids"

"Synthesis of ZrC-TiC nanostructures"

"Effect of Silver Nanoparticles on Rice Oryza Sativa L. KDML 105 seedlings"

"Nanocrystalline magnetic shape memory alloys: Ni-Mn-(In,Sn)"

"Influence of Electron Correlations on Quasiparticle Energies and Lifetimes"

"Magnetic properties of nanostructured Ca1-xGdxMnO3 obtained by glycine-nitrate procedure"

"Nanostructured tungsten trioxide thin films by aqueous chemical growth for applications in gas sensing and electrochromism"

"Nanocomposite carbon material – silver nanoparticles: Preparation and antibacterial activity" "Immunoglobulin G sensor by means of lossy mode resonances induced by a nanostructured polymeric thin-film deposited on a tapered optical fiber"

"Characterization and in vitro evaluation of microleakage and antibacterial properties of prepared ZnO and ZnO:Ag nano sealers"

"A novel nanovesicular carrier system for ocular delivery of clotrimazole"

poster title

student

senior

student

senior

student

student senior

Miroslav Veverka, Pavel Veverka, Karel Knížek, Karel Závěta, Ondřej Kaman,Vladimír Král, Etienne Duguet, Graziella Goglio and Emil Pollert

Zvatora, Pavel

A. Dolati, I. Imanieh

Yousefi, Elahe

Kyeongjun Ko, Kyeonggeun Park

Yu, Yeontae

S. McDermott, R. J. Bartlett, G. Fagas and J.C. Greer

Yeriskin, Irene

Jan Grym

Yatskiv, Roman

Hiroyuki Ishii, Nobuhiko Kobayashi and Kenji Hirose

Yamamoto, Kohei

Burkhard Raguse, Lech Wieczorek, Edith Chow, James S. Cooper, Lee J. Hubble

Webster, Melissa

Valter Reedo, Uno Mäeorg, Andres Hoop, Ants Lõhmus

Välbe, Raul

authors

Czech Republic

Iran

Korea

Ireland

Czech Republic

Japan

Australia

Estonia

country

NanoChemistry

"Structural and magnetic properties of nanocrystalline La1-xSrxMnO3+d"

"Morphology study of the electrodeposited platinum nanotube"

Nanofabrication tools & nanoscale integration

student

senior

"Light scattering effect of nano-sized hollow TiO2 layer on conversion efficiency of DSSC"

Nanomaterials for Energy

senior

student

"Influence of ZnO surface polarity on the electrophoretic deposition of metal nanoparticles."

student

senior

"Detecting oil seeps in seawater, sensing bacteria in milk, and identifying disease states from a patient’s urine: New applications for gold nanoparticle chemiresistors"

"Thermal Conductance Calculations of Silicon Nanowires"

student

student senior

"Preparation of R-methyl Imidazolium-Sodium Hexaflorosilicate Complex Crystals"

poster title

"Electronegativity and Electron Currents in Molecular Tunnel Junctions"

Theory and modelling at the nanoscale

Nanostructured and nanoparticle based materials Nanostructured and nanoparticle based materials Low dimensional materials (nanowires, clusters, quantum dots, etc.) Nanostructured and nanoparticle based materials

topic

Edited by

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