Publications

2013

• Loss spectroscopy of molecular solids: combining experiment and theory
  
  • Roth Friedrich
  • Cudazzo Pierluigi
  • Mahns Benjamin
  • Gatti Matteo
  • Bauer Johannes
  • Hampel S.
  • Nohr Markus
  • Berger Helmuth
  • Knupfer Martin
  • Rubio Angel
  New Journal of Physics, Institute of Physics: Open Access Journals, 2013, 15 (12), pp.125024. The nature of the lowest-energy electronic excitations in prototypical molecular solids is studied here in detail by combining electron energy loss spectroscopy (EELS) experiments and state-of-the-art many-body calculations based on the Bethe-Salpeter equation. From a detailed comparison of the spectra in picene, coronene and tetracene we generally find a good agreement between theory and experiment, with an upshift of the main features of the calculated spectrum of 0.1-0.2 eV, which can be considered the error bar of the calculation. We focus on the anisotropy of the spectra, which illustrates the complexity of this class of materials, showing a high sensitivity with respect to the three-dimensional packing of the molecular units in the crystal. The differences between the measured and the calculated spectra are explained in terms of the small differences between the crystal structures of the measured samples and the structural model used in the calculations. Finally, we discuss the role played by the different electron-hole interactions in the spectra. We thus demonstrate that the combination of highly accurate experimental EELS and theoretical analysis is a powerful tool to elucidate and understand the electronic properties of molecular solids. (10.1088/1367-2630/15/12/125024)
  DOI : 10.1088/1367-2630/15/12/125024
• Local-field effects on the plasmon dispersion of two-dimensional transition metal dichalcogenides
  
  • Cudazzo Pierluigi
  • Gatti Matteo
  • Rubio Angel
  New Journal of Physics, Institute of Physics: Open Access Journals, 2013, 15, pp.125005. Two-dimensional transition-metal dichalcogenides (TMDs) are gaining increasing attention as alternative to graphene for their very high potential in optoelectronics applications. Here we consider two prototypical metallic 2D TMDs, NbSe$_2$ and TaS$_2$. Using a first-principles approach, we investigate the properties of the localised intraband $d$ plasmon that cannot be modelled on the basis of the homogeneous electron gas. Finally, we discuss the effects of the reduced dimensionality on the plasmon dispersion through the interplay between interband transitions and local-field effects. This result can be exploited to tune the plasmonic properties of these novel 2D materials. (10.1088/1367-2630/15/12/125005)
  DOI : 10.1088/1367-2630/15/12/125005
• Influence of Yb3+ and Er3+ ions environment on the evolution of its' luminescent properties in oxide glasses under ionizing irradiation
  
  • Pukhkaya V.
  , 2013. We have investigated the effects of ionizing irradiation (e¯- and γ-) on the Yb3+ and Er3+ luminescent properties in aluminosilicate (AS) and phosphate glasses by trying to understand the impact of initial Yb3+ environment and mostly the role of Yb cluster. For that, AS and phosphate glasses containing different amount of Yb clusters were irradiated in 104-2∙109 Gy dose range. At first, we have shown that the point defect fading is slow down by a clustering effect in the glass. We have obtained a 2-step dependence of point defects quantity versus lg(dose). The cluster presence limits the defect production in the high dose range, whatever the glass composition (AS or phosphate). Consequently, we observed the same two-regions trends for the 2F5/2 lifetime as a function of the lg(dose). But for high content of cluster, the lifetimes value decreases linearly within lg(dose). This result does not depend on the glass type nor on the rare earth element (Er3+), implying a more general mechanism that implying one type of defect in particular. Secondly, we have interpreted the strong variation of the complex EPR signal in phosphate glasses within glass composition, dose and time with the formation of at least 8 point defects. In addition, the origin of the luminescent diamagnetic defect is discussed.
• Frenkel versus charge-transfer exciton dispersion in molecular crystals
  
  • Cudazzo Pierluigi
  • Gatti Matteo
  • Rubio Angel
  • Sottile Francesco
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2013, 88 (19), pp.195152. By solving the many-body Bethe-Salpeter equation at finite momentum transfer, we characterize the exciton dispersion in two prototypical molecular crystals, picene and pentacene, in which localized Frenkel excitons compete with delocalized charge-transfer excitons. We explain the exciton dispersion on the basis of the interplay between electron and hole hopping and electron-hole exchange interaction, unraveling a simple microscopic description to distinguish Frenkel and charge-transfer excitons. This analysis is general and can be applied to other systems in which the electron wave functions are strongly localized, as in strongly correlated insulators. (10.1103/PhysRevB.88.195152)
  DOI : 10.1103/PhysRevB.88.195152
• Imaging flux distributions around superconductors: Geometrical susceptibility in the Meissner state
  
  • Grisolia Mathieu
  • Badia-Majos Antonio
  • van Der Beek Cornelis Jacominus
  Journal of Applied Physics, American Institute of Physics, 2013, 114, pp.203904. Experiment and analytical calculations show that the demagnetizing field of a superconductor is a sensitive probe of quantities otherwise difficult to measure, such as the sample-probe distance in flux-density imaging experiments, and the field of first flux penetration Hp. In particular, the ratio of the maximum field measured above the superconductor edge and the applied field can be determined unambiguously so as to define a linear "geometric" susceptibility. The evolution of this susceptibility with field depends on the regime of flux penetration, and can be used as a means to determine Hp and the effect of a parallel field component in magneto-optical imaging experiments. (10.1063/1.4834519)
  DOI : 10.1063/1.4834519
• Interaction of intense femtosecond laser pulses with KDP and DKDP crystals in the short wavelength regime
  
  • Duchateau Guillaume
  • Geoffroy Ghita
  • Belsky Andrei
  • Fedorov Nikita
  • Martin Patrick
  • Guizard Stéphane
  Journal of Physics: Condensed Matter, IOP Publishing [1989-....], 2013, 25 (43), pp.435501. (10.1088/0953-8984/25/43/435501)
  DOI : 10.1088/0953-8984/25/43/435501
• Exciton dispersion from first principles
  
  • Gatti Matteo
  • Sottile Francesco
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2013, 88 (15), pp.155113. We present a scheme to calculate exciton dispersions in real materials that is based on the first-principles many-body Bethe-Salpeter equation. We assess its high level of accuracy by comparing our results for LiF with recent inelastic x-ray scattering experimental data on a wide range of energy and momentum transfer. We show its great analysis power by investigating the role of the different electron-hole interactions that determine the exciton band structure and the peculiar "exciton revival" at large momentum transfer. Our calculations for solid argon are a prediction and a suggestion for future experiments. These results demonstrate that the first-principles Bethe-Salpeter equation is able to describe the dispersion of localized and delocalized excitons on equal footing and represent a key step for the ab initio study of the exciton mobility. (10.1103/PhysRevB.88.155113)
  DOI : 10.1103/PhysRevB.88.155113
• Mesures de solubilité en CO2 supercritique par méthode gravimétrique en dynamique
  
  • Hung L.
  • Hertz Audrey
  • Hartmann Daniel
  • Charton F.
  • Boutin Olivier
  , 2013, 114. no abstract
• Orbital quantization in a system of edge Dirac fermions in nanoperforated graphene
  
  • Latyshev Yu. I.
  • Orlov A.P.
  • Frolov A.V.
  • Volkov V.A.
  • Zagorodnev I.V.
  • Skuratov V.A.
  • Petrov Yu.V.
  • Vyvenko O.F.
  • Ivanov D. Yu.
  • Konczykowski Marcin
  • Monceau Pierre
  JETP Letters, Springer Verlag, 2013, 98 (4), pp.214-218. The dependence of the electric resistance R of nanoperforated graphene samples on the position of the Fermi level E (F), which is varied by the gate voltage V (g), has been studied. Nanoperforation has been performed by irradiating graphene samples on a Si/SiO2 substrate by heavy (xenon) or light (helium) ions. A series of regular peaks have been revealed on the R(V (g)) dependence at low temperatures in zero magnetic field. These peaks are attributed to the passage of E (F) through an equidistant set of levels formed by orbitally quantized states of edge Dirac fermions rotating around each nanohole. The results are in agreement with the theory of edge states for massless Dirac fermions. (10.1134/S0021364013170098)
  DOI : 10.1134/S0021364013170098
• Electrochemical Behaviour of Stainless Steel under Radiation and Exposed to Representative Chemistry in Pressurised Water Reactor Conditions
  
  • Wang Mi
  , 2013. The dissertation focuses on the behaviour of stainless steel under irradiation and exposed to primary PWR conditions. The electrochemical potential of austenitic 316L stainless steel and the environmental parameters (hydrogen pressure, temperature, etc.,) have been measured continuously at high temperature (HT) and high pressure (HP) under irradiation, using a unique experimental HTHP working cell. Two sources of irradiation, proton and electron beams, have been employed in the study. A high similarity of electrochemical behaviour under both types of irradiations has been observed: (i) an oxidative potential response under irradiation (few tens of millivolts); (ii) an increase in the hydrogen pressure reduces the oxidative potential response; (iii) a synergetic effect of thermal ageing and fluence leading to a decrease of the oxidative response under irradiation. The observations of the oxide film showed that without irradiation, metallic nickel in the inner and outer oxide films has been observed under a high hydrogen pressure. Under irradiation, um scale cavities (pits) have been observed in the strongly electron irradiated oxide film formed on 316L stainless steel. These defects are induced by the effect of irradiation of the passive film and water radiolysis. It is also shown that water radiolysis influences the PWR water chemistry by making it become a stronger oxidant at the oxide/solution interface. As a result, the release of metallic cations is increased and a-Fe2O3 hematite has been observed on the irradiated outer oxide film where cavities were formed.
• Circular Dichroism and Superdiffusive Transport at the Surface of BiTeI
  
  • Mauchain Julien
  • Ohtsubo Y
  • Hajlaoui M
  • Papalazarou E
  • Marsi M
  • Taleb-Ibrahimi A
  • Faure Jérôme
  • Kohk K A
  • Tereshchenko O E
  • Eremeev S V
  • Chulkov E V
  • Perfetti L
  Physical Review Letters, American Physical Society, 2013, 111, pp.126603. We investigate the electronic states of BiTeI after the optical pumping with circularly polarized photons. Our data show that photoexcited electrons reach an internal thermalization within 300 fs from the arrival of the pump pulse. Instead, the dichroic contrast generated by the circularly polarized light relaxes on a timescale shorter than 80 fs. This result implies that orbital and spin polarization created by the circular pump pulse rapidly decays via manybody interaction. The remnant dichroic contrast at longer delay times is due to the helicity dependence of superdiffussive transport. We ascribe it to the lack of inversion symmetry in an electronic system far from equilibrium conditions. (10.1103/PhysRevLett.111.126603)
  DOI : 10.1103/PhysRevLett.111.126603
• Influence of Electronic Irradiation on Failure and Hardness Properties of Pure Silica Glasses
  
  • Barlet M.
  • Delaye J-M.
  • Gennisson M.
  • Caraballo R.
  • Boizot B.
  • Bonamy Daniel
  • Rountree C.L.
  , 2014, 7, pp.286-293. This paper’s focus is the failure and hardness properties of pure amorphous silica (Corning 7980) after β-irradiation at different doses (0-2 GGy). Crack propagation takes place in the SCC regime (10−7-10−10 m.s−1) and Vickers indentation techniques probe the hardness properties of the samples. Irradiation is found to create point defects which mainly include E’ centers, Non-Bridging Oxygen Hole Centers and Peroxy Radicals. β-irradiation herein invokes minor changes in the structure. A small effect of β- irradiation on SCC and hardness variations cannot be eliminated, despite minute variations in the SCC and the hardness properties. (10.1016/j.mspro.2014.10.037)
  DOI : 10.1016/j.mspro.2014.10.037
• Circular Dichroism and Superdiffusive Transport at the Surface of BiTeI
  
  • Kokh K.A.
  • Eremeev S. V.
  • Perfetti Luca
  Physical Review Letters, American Physical Society, 2013, 111, pp.126603. We investigate the electronic states of BiTeI after the optical pumping with circularly polarized photons. Our data show that photoexcited electrons reach an internal thermalization within 300 fs of the arrival of the pump pulse. Instead, the dichroic contrast generated by the circularly polarized light relaxes on a time scale shorter than 80 fs. This result implies that orbital and spin polarization created by the circular pump pulse rapidly decays via manybody interaction. The persistent dichroism at longer delay times is due to the helicity dependence of superdiffussive transport. We ascribe it to the lack of inversion symmetry in an electronic system far from equilibrium conditions.
• High-energy collective electronic excitations in free-standing single-layer graphene
  
  • Wachsmuth P.
  • Hambach R.
  • Kinyanjui Mk
  • Guzzo Matteo
  • Benner G.
  • Kaiser U.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2013, 88, pp.075433. In this joint experimental and theoretical work, we investigate collective electronic excitations (plasmons) in free-standing, single-layer graphene. The energy- and momentum-dependent electron energy-loss function was measured up to 50eV along two independent in-plane symmetry directions (ΓM and ΓK) over the first Brillouin zone by momentum-resolved electron energy-loss spectroscopy in a transmission electron microscope. We compare our experimental results with corresponding time-dependent density-functional theory calculations. For finite momentum transfers, good agreement with experiments is found if crystal local-field effects are taken into account. In the limit of small and vanishing momentum transfers, we discuss differences between calculations and the experimentally obtained electron energy-loss functions of graphene due to a finite momentum resolution and out-of-plane excitations. (10.1103/PhysRevB.88.075433)
  DOI : 10.1103/PhysRevB.88.075433
• Direct observation of electron thermalization and electron-phonon coupling in photoexcited bismuth
  
  • Faure Jérôme
  • Mauchain Julien
  • Papalazarou E
  • Marsi M
  • Boschetto Davide
  • Timrov I
  • Vast N
  • Ohtsubo Y
  • Arnaud B.
  • Perfetti L
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2013, 88 (7), pp.075120. We investigate the ultrafast response of the bismuth (111) surface by means of time resolved photoemission spectroscopy. The direct visualization of the electronic structure allows us to gain insights on electron-electron and electron-phonon interaction. Concerning electron-electron interaction , it is found that electron thermalization is fluence dependent and can take as much as several hundreds of femtoseconds at low fluences. This behavior is in qualitative agreement with Landau's theory of Fermi liquids but the data show deviations from the behavior of a common 3D degenerate electron gas. Concerning electron-phonon interaction, our data allows us to directly observe the coupling of individual Bloch state to the coherent A1g mode. It is found that surface states are much less coupled to this mode when compared to bulk states. This is confirmed by ab initio calculations of surface and bulk bismuth. (10.1103/PhysRevB.88.075120)
  DOI : 10.1103/PhysRevB.88.075120
• Water radiolysis in exchanged-montmorillonites: the H2 production mechanisms.
  
  • Fourdrin Chloé
  • Aarrachi H.
  • Latrille C.
  • Esnouf S.
  • Bergaya F.
  • Le Caër S.
  Environmental Science and Technology, American Chemical Society, 2013, 47 (16), pp.9530. The radiolysis of water confined in montmorillonites is studied as a function of the composition of the montmorillonite, the nature of the exchangeable cation, and the relative humidity by following the H2 production under electron irradiation. It is shown that the main factor influencing this H2 production is the water amount in the interlayer space. The effect of the exchangeable cation is linked to its hydration enthalpy. When the water amount is high enough to get a basal distance higher than 1.3 nm, then a total energy transfer from the montmorillonite sheets to the interlayer space occurs, and the H2 production measured is very similar to the one obtained in bulk water. For a basal distance smaller than 1.3 nm, the H2 production increases with the relative humidity and thus with the water amount. Lastly, electron paramagnetic resonance measurements evidence the formation of a new defect induced by ionizing radiation. It consists of a hydrogen radical (H2 precursor) trapped in the structure. This implies that structural hydroxyl bonds can be broken under irradiation, potentially accounting for the observed H2 production. (10.1021/es401490t)
  DOI : 10.1021/es401490t
• Effect of polycarboxylate and crushed quartz in UHPC: Microstructural investigation
  
  • Courtial Mireille
  • de Noirfontaine Marie-Noëlle
  • Dunstetter Frédéric
  • Signes-Frehel Marcel
  • Mounanga Pierre
  • Cherkaoui Khalid
  • Khelidj Abdelhafid
  Construction and Building Materials, Elsevier, 2013, 44, pp.699-705. The context of this study was to find an extrudable formulation of Ultra High Performance Concretes usable in an aggressive environment. In the five mixtures of this study, the only variable parameters are the polycarboxylate (PCE) dosage and the crushed quartz to micro silica ratio. This paper is devoted to a systematic microstructural study using Scanning Electronic Microscopy (SEM), with the idea to link the microstructure with the macroscopic results. Through this study, the effect of the polycarboxylate on the hydration of the type of cement used here is pointed out. From 1.8% to 2% polycarboxylate content, we observe a change in the hydration time for the two calcium silicates, the major phases of anhydrous cement. In the presence of microsilica and with 2 wt.% PCE, we observe a higher consumption of dicalcium silicate, which should not have reacted with such a low water content (Water/Cement = 0.16). (10.1016/j.conbuildmat.2013.03.077)
  DOI : 10.1016/j.conbuildmat.2013.03.077
• Development of New Kinds of Plasmonics Materials Through Swift Heavy Ion Shaping Technique
  
  • Cardin Julien
  • Dufour Christian
  • Khomenkov Vladimir
  • Fafin Alexandre
  • Monnet Isabelle
  • Rizza Giancarlo
  • Coulon Pierre-Eugène
  • Slablab Abdallah
  • Mailly Dominique
  • Ulysse Christian
  • Lafosse Xavier
  • Perruchas Sandrine
  • Gacoin Thierry
  , 2013. In recent years, an innovative technique of ion-shaping of matter at the nanoscale has been proposed based on the deformation of embedded metallic nanoparticles (NPs) induced by host amorphous matrix deformation and nanoparticle melting during swift heavy ions irradiation. This technique allows the deformation of spherical metallic particles embedded in a silica matrix into several original classes of ion-shaped nanoparticles: i) facetted-like NPs, ii) nanowires iii) chromosome-like particles. The fundamental aspect of ion-matter interaction has been investigated through the modeling of the temperature profile within the nanoparticle by implementing the thermal-spike model for three-dimensional anisotropic and composite media. A straight correlation has been found between the spatial distribution of molten matter and the deformation path followed by the nanoparticles during the irradiation. Localized Surface Plasmon Resonances (LSPR) are generated along ion-shaped nanoparticles through electron excitation in a Scanning Transmission Electron Microscope. This has been investigated through nanometer-scale Electron Energy Loss Spectroscopy (EELS) analysis. The near field response of nanoparticles was investigated experimentally for different kinds of ion-shaped objects. We confirmed the near field distribution and the identification of LSPR modes of nanoparticles by modeling with a home developed Auxiliary Differential Equations-Finite Difference Time Domain (ADE-FDTD) code. This work demonstrates the possibility to use ion irradiation as a tool for the controllable fabrication of plasmonic nanostructures with topologically tunable optical properties. These ion-beam shaped composite media have potential applications spanning from plasmonic photovoltaics to Surface-Enhanced Raman Scattering (SERS) and Surface enhanced infrared absorption (SEIRA) spectroscopies.
• Nanopore size tuning of polymeric membranes using the RAFT-mediated radical polymerization
  
  • Barsbay Murat
  • Güven Olgun
  • Bessbousse Haad
  • Beuneu François
  • L. Wade Travis
  • Clochard Marie-Claude
  Journal of Membrane Science, Elsevier, 2013, pp.135-145. Poly(acrylic acid) (PAA) was grafted into the nanochannel walls of track-etched β-PVDF membranes in a controlled manner by RAFT polymerization. PAA-g-PVDF copolymers with various degrees of grafting from 5% to 63% were characterized by ATR-FTIR, X-ray photoelectron spectroscopy and atomic force microscopy (AFM). The controlled fashion of RAFT mediated grafting was demonstrated by size exclusion chromatography (SEC) and AFM. It was observed that the pore diameter decreases steadily with the degree of grafting (DOG) and pores start to be filled by the grafted PAA beyond $ 40 wt% DOG, based on AFM measurements and $ 15 wt% DOG, based on electrochemical analysis. The synthesized nanoporous membranes were later transformed into highly sensitive functionalized membrane electrodes (FMEs) by deposition of a thin gold ($ 50 nm) layer onto the membrane surfaces without blocking the nanochan-nels. The synthesized FMEs have been found to be sensitive to sub-ppb concentrations of Pb 2+ in square-wave anodic stripping voltammetry (SW-ASV) measurements. The sensitivities of RAFT mediated FMEs compared to those synthesized by conventional free-radical polymerization were found to be almost three times higher at sub-ppb concentrations of Pb 2+ in SW-ASV analysis. & (10.1016/j.memsci.2013.05.029)
  DOI : 10.1016/j.memsci.2013.05.029
• Role of localized electrons in electron-hole interaction: The case of SrTiO3
  
  • Sponza Lorenzo
  • Véniard Valérie
  • Sottile Francesco
  • Giorgetti Christine
  • Reining Lucia
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2013, 87 (23), pp.235102. Strontium titanate SrTiO3 is an extensively studied material. Of particular interest are its electronic properties. Here we present a theoretical study of its optical spectrum on the basis of state-of-the-art calculations including many-body effects. The latter are evaluated by solving the Bethe-Salpeter equation within the GW approximation for the self-energy. Excitonic effects are strong at the onset and at higher energies up to 10 eV. Agreement between theory and experiment is excellent at the onset, but only qualitative at higher energies, where excitonic effects are stronger in theory than in experiment. The origin of structures in the spectrum, as well as the remaining discrepancy between theory and experiment, are discussed. We also present benchmark results for calculations using more approximate ways to determine the spectra, including simplified time-dependent density-functional theory. (10.1103/PhysRevB.87.235102)
  DOI : 10.1103/PhysRevB.87.235102
• Irradiated Assisted Corrosion of Stainless Steel in Light Water Reactors - Focus on Radiolysis and Corrosion Damage
  
  • Wang Mi
  , 2013. This working report concerns bibliography related to irradiation induced suface reactions at water leached metallic structures in light water reactors.
• Dynamical screening in correlated metals: Spectral properties of SrVO3 in the GW approximation and beyond
  
  • Gatti Matteo
  • Guzzo Matteo
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2013, 87 (15), pp.155147. (10.1103/PhysRevB.87.155147)
  DOI : 10.1103/PhysRevB.87.155147
• Des polymérisations classiques en solution aux polymérisations radio-induites contrôlées en milieu confiné
  
  • Clochard Marie-Claude
  , 2013. Le manuscrit HDR de Mme Marie-Claude Dubois-Clochard relate les principaux résultats acquis en synthèse et structuration à l'échelle nanométrique de polymères fonctionnels. Si la synthèse de polymères fonctionnels est à la base des études abordées, l'ordre chronologique des activités de Recherche de 1995 à 2013 montre une évolution des polymérisations classiques en solution vers des polymérisations radio-induites contrôlées par mécanisme RAFT en milieu confiné. L'innovation porte sur le développement de nouveaux objets polymères et composites organique/inorganique façonnés à l'échelle nanométrique aux propriétés physiques et physico-chimiques originales. Trois domaines d'application se détachent : l'Energie-Environnement (Moteurs, Piles à combustible, Capteurs pour la qualité de l'Eau), la Santé (Nanovecteurs pour Thérapie cancéreuse et imagerie, translocation d'ions ou de molécules à travers un nanopore unique dans une membrane polymère) et les Nanotechnologies (Magnétorésistance d'un nanofil magnétique unique de forme cylindrique ou biconique). Les résultats marquants ont été : - l'établissement d'isothermes d'adsorption de type bi-langmuir à l'interface solide/liquide organique pour des macromolécules tensioactives à faible concentration, et, à forte concentration, un comportement particulier de réorganisation de ces mêmes macromolécules, non pas en couches alternées, mais sous forme d'hémicelles inverses. - la synthèse d'un polymère pH-dégradable innovant permettant une dégradation hydrolytique en passant de pH 7.4 (Sang) à pH 5.5 (Lysosome intracellulaire) en vue de délivrer des toxines dans les cellules tumorales (Santé). - la démonstration de l'effet coopératif solvant/polymère en croissance pour la pénétration du greffage induit par irradiation dans des films fluoropolymères. - la synthèse de membranes polymères nanoporeuses à traces attaquées bi-fonctionnelles ayant une fonctionnalité dans les pores et une autre en surface. Cette membrane, après transformation en électrode par simple métallisation aura fait l'objet de projets de valorisation en vue d'une création de start-up et/ou de transfert de technologie pour le développement d'un détecteur de traces métaux lourds dans l'eau traitée (Environnement). Dans la même thématique, la fonctionnalisation directe des traces dans les films de polymères irradiés aux ions lourds rapides du GANIL a permis de développer de nouvelles membranes conductrices de protons pour les piles à combustible (Energie) - l'observation non-décrite d'effets coopératifs sur la mobilité des ions dans un milieu confiné créé par un nanopore cylindrique unique dans une membrane fine de fluoropolymère. L'effet accélérateur ou décélérateur de la mobilité des ions confinés dans le pore aux parois chargées semble dépendre uniquement de la nature chimique des ions et de leur concentration. - L'observation de sauts de résistance bien au-delà de la magnétorésistance d'un nanofil magnétique biconique (constriction de l'ordre de la dizaine de nanomètre) sous champ magnétique ayant une dépendance à la fois en angle et en intensité de courant injecté. Effets de relaxations avant et après saut montrant un système énergétiquement activé. - Le contrôle de taille des nanopores d'une membrane polymère par polymérisation radio-induite contrôlée par mécanisme RAFT.
• Carbon nanotube electrodes in organic transistors
  
  • Valitova Irina
  • Amato Michele
  • Mahvash Farzaneh
  • Cantele Giovanni
  • Maffucci Antonio
  • Santato Clara
  • Martel Richard
  • Cicoira Fabio
  Nanoscale Research Letters, SpringerOpen, 2013, pp.C3NR33727H. The scope of this Minireview is to provide an overview of the recent progress on carbon nanotube electrodes applied to organic thin film transistors. After an introduction on the general aspects of the charge injection processes at various electrode-semiconductor interfaces, we discuss the great potential of carbon nanotube electrodes for organic thin film transistors and the recent achievements in the field. (10.1039/C3NR33727H)
  DOI : 10.1039/C3NR33727H
• Analysis of dissociated dislocations in a deformed bicrystal close to the rhombohedral twin orientation in -alumina
  
  • Lartigue-Korinek S.
  • Hardouin Duparc Olivier
  • Lagerlof K.P.D.
  • Moulahem S.
  • Hallil A.
  Philosophical Magazine, Taylor & Francis, 2013, 93, pp.1182-1196. A bicrystal close to a rhombohedral twin orientation in -alumina has been deformed by compression at high temperature. After deformation the twin contained a periodic array of intrinsic dislocations. This configuration is interpreted by the decomposition of incoming basal lattice dislocations into interfacial disconnections and further interactions between sessile and glissile products. The dislocations are widely dissociated and the separation width between partials being close to 30 angstrom. The translation state of the interfacial structure between partials is different from those of the perfect twin. Possible structural models are envisaged and simulated using ab initio calculations and the less efficient Streitz and Mintmire modelling. One model in particular fits the experimental image rather well. The interfacial energies are higher than those estimated using elasticity theory. (10.1080/14786435.2012.752885)
  DOI : 10.1080/14786435.2012.752885