A5034806994- nanoparticles nucleation surface interactions
- Advanced Chemical Physics Studies
- Diamond and Carbon-based Materials Research
- Ion-surface interactions and analysis
- Magnetic properties of thin films
- Fullerene Chemistry and Applications
- Graphene research and applications
- Theoretical and Computational Physics
- Quantum Dots Synthesis And Properties
- High-pressure geophysics and materials
- ZnO doping and properties
- Silicon Nanostructures and Photoluminescence
- Boron and Carbon Nanomaterials Research
- Advanced Materials Characterization Techniques
- Catalytic Processes in Materials Science
- Semiconductor materials and devices
- Surface and Thin Film Phenomena
- Chalcogenide Semiconductor Thin Films
- Gold and Silver Nanoparticles Synthesis and Applications
- Electronic and Structural Properties of Oxides
- Atomic and Molecular Physics
- Laser-Ablation Synthesis of Nanoparticles
- Physics of Superconductivity and Magnetism
- Ga2O3 and related materials
- Nanocluster Synthesis and Applications
Université Claude Bernard Lyon 1
2013-2022
Centre National de la Recherche Scientifique
2012-2022
Institut Lumière Matière
2013-2022
Université Sorbonne Nouvelle
2020
Institut polytechnique de Grenoble
2018
Forum Réfugiés - Cosi
2014-2017
Canadian Nautical Research Society
2015
Laboratoire des Technologies de la Microélectronique
2014
Laboratoire de physique de la matière condensée
2003-2012
Laboratoire de Physique Théorique de la Matière Condensée
2003-2012
Using a new micro-SQUID setup, we investigate magnetic anisotropy in single 1000-atom cobalt cluster. This system opens fields the characterization and understanding of origin such nanoparticles. For this purpose, report three-dimensional switching field measurements performed on 3 nm cluster embedded niobium matrix. We are able to separate different contributions evidence dominating role surface.
The low-energy cluster beam deposition technique (LECBD) is applied to produce assembled films with hitherto unknown nanostructured morphologies and properties. Neutral clusters having the very low energy gained in supersonic expansion at exit of inert gas condensation-type source are deposited without fragmentation upon impact on substrate. Depending conditions (nature, size flux incident clusters, nature temperature substrate, vacuum conditions), granular nanostructures resulting from...
In this paper the specific properties of free clusters and formation new cluster-assembled materials using low energy cluster beam deposition (LECBD) technique are discussed. Recent results obtained for summarized with special attention to observed structures. As structures materials, two main aspects specially emphasized: memory effect leading phases nanostructure related random stacking mechanism characteristic LECBD. These effects corresponding potential applications illustrated some...
Optical properties of mixed clusters Ni/Ag, Co/Ag, and Ni/Au 2--5 nm in diameter, produced by laser vaporization embedded an alumina matrix, are investigated. The first part is devoted to $({\mathrm{Ni}}_{x}{\mathrm{Ag}}_{1\ensuremath{-}x}{)}_{n}$ whose photoabsorption spectra reveal a surface plasmon resonance, damped, broadened, blueshifted as compared pure silver clusters. For given mean size, blueshift the resonance band well damping broadening with increasing nickel proportion observed,...
We report on the synthesis of ${\mathrm{C}}_{2n\ensuremath{-}q}{\mathrm{Si}}_{q}$ clusters with $2n\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}32\ensuremath{-}100$ and $q<4$. The analysis abundance distribution photofragmentation spectra provides clear evidences that such remain in fullerene geometry Si atoms are located close to each other network. These results corroborated by ab initio calculations within density functional theory. stability electronic properties these...
The magnetic measurements on single cobalt and iron nanoclusters containing almost 1000 atoms are presented. Particles directly buried within the superconducting film of a micro-SQUID (superconducting quantum interference device) which leads to required sensitivity. angular dependence switching field in three dimensions turns out be good agreement with uniform rotation cluster magnetization. Stoner Wohlfarth model yields therefore an estimation anisotropy cluster. In particular, uniaxial,...
The high pressure evolution of silicon clathrates is studied at room temperature by x-ray diffraction up to 15 GPa. Remarkably, no transition towards the diamond structure observed and clathrate phase transforms directly into $\ensuremath{\beta}$-tin metallic 11 Further, bulk modulus found be $90\ifmmode\pm\else\textpm\fi{}5\mathrm{GPa}$, that is, only $(8\ifmmode\pm\else\textpm\fi{}5)%$ smaller than one phase. These results are in good agreement with ab initio calculations which predict...
We present a joint experimental and theoretical study of the superconductivity in doped silicon clathrates. The critical temperature Ba(8)@Si-46 is shown to strongly decrease with applied pressure. These results are corroborated by ab initio calculations using MacMillan's formulation BCS theory electron-phonon coupling constant lambda calculated from perturbative density functional theory. Further, I(8)@Si-46 gedanken pure diamond clathrate phases within rigid-band approach show that an...
The interaction between a monokinetic and mass resolved low-energy gold cluster beam (111) surface is studied in detail at room temperature by means of molecular dynamics. model makes use the classical second moment tight-binding approximation to estimate interatomic forces. A described account for electron-phonon coupling. Clusters nanometer size are modeled slow down one after other on until nanostructured layer about 7 nm thick formed. slowing consequences diffusionless accumulation...
Mixed $({\mathrm{Au}}_{x}{\mathrm{Ag}}_{1\ensuremath{-}x}{)}_{n}$ clusters of various relative compositions are produced in a laser vaporization source, and embedded an alumina matrix. The size concentration effects the optical properties investigated for different stoichiometries (from $x=0$ up to 1 steps 0.25), diameter range 1.5--5 nm which evolution is ruled by quantum effects. For given size, we measure steady surface plasmon frequency versus x. composition, blueshift (relative...
Free carbon clusters with various selected sizes (${\mathrm{C}}_{20}$,${\mathrm{C}}_{60}$,${\mathrm{C}}_{900}$) have been deposited on different substrates to obtain continuous thin films (thickness \ensuremath{\sim}100 nm). The characterization of nanostructures and electronic structures the performed using complementary techniques (atomic force microscopy, transmission electron energy loss spectroscopy, Raman Fourier transform infrared spectroscopy). A memory effect free cluster properties...
In this paper, we report on structural, magnetic, and magnetoresistive properties of Co-Ag granular films made by low-energy cluster beam deposition (LECBD). With technique, can grow cobalt clusters embedded in silver or other matrix materials, with independent control the size concentration clusters. Moreover, show, from TEM, grazing-incidence small-angle x-ray diffraction, magnetic measurements, that is same, whatever matrix. We measured giant magnetoresistance (GMR) silver, found them...
We study by means of ab initio calculations the ideal tensile and shear strengths C-46 clathrate phase. While its bulk modulus elastic constants are smaller than in diamond, strength is found to be all directions larger critical stresses associated with diamond ${111}$ planes easy slip. This can related frustration cage structure graphite instability under hydrostatic stress conditions. The criteria for designing strong materials discussed.
The optical properties of bimetallic silver-gold clusters are investigated in the size range 1.9--2.8 nm. Clusters, produced by laser vaporization an alloy target Au-Ag (50%-50% atomic composition) embedded with a low concentration alumina matrix. mixed particles have same stoichiometry as rod. Absorption spectra exhibit plasmon resonance band between those pure Au and Ag clusters, shifting towards higher energies decreasing cluster size. Theoretical calculations frame...
Functional cluster-assembled nanostructures with original structures and properties are prepared using the Low Energy Cluster Beam Deposition method (LECBD). This technique consists in depositing supersonic clusters produced gas phase a combined laser vapourisation-inert condensation source. energy typical sizes ranging from ∼1 to few nm not fragmented upon impact on substrate (soft landing regime) leading formation of which retain incident free clusters. Model nanostructured systems any...
We investigate the origin of band at 3.31 eV (A band) commonly observed in emission spectra various ZnO samples. This is prime importance for confirmation $p$ doping nanostructures. check validity three main hypotheses generally evoked to explain it undoped ZnO, namely, surface states, 1LO phonon replica free exciton and a defect-related transition. Using samples structured different scales, from macro nano through meso (i.e., single crystal, nanoparticles assembly, microcrystalline pellet),...
Silicon carbon binary clusters are generated in a laser vaporization source from SixC1−x mixed targets (x=0 to 50%). We have first analyzed stoichiometric (SiC)n (n⩽40) grown silicon carbide target (x=50%). Both high fluence photoionization of neutral and photofragmentation size-selected (SiC)n+ natural positive ions show that silicon-doped fullerenes emerge as stable photoproducts through the induced annealing these clusters. They detected species soon sufficient amount is eliminated...
Our recent studies on Co clusters embedded in various matrices reveal that the co-deposition technique (simultaneous deposition of two beams: one for preformed and matrix atoms) is a powerful tool to prepare magnetic nanostructures with any couple materials even though they are miscible. We study both structure magnetism Co/Nb system, which intimately related. Because such heterogeneous system needs be described at different scales, we used microscopic macroscopic techniques, addition local...
We study PdPt bimetallic clusters in both free and supported phases. These have been produced with a laser vaporization source. Free directly by the source are studied time of flight mass spectrometry photofragmentation technique. observed sequential evaporation Pd atoms mixed consistent palladium segregation process. This tendency has also on particles from which structure composition determined high resolution transmission electron microscopy energy dispersive x-ray analysis. A main result...
Low-energy cluster-beam deposition is a technique that allows the growth of thin films via mechanism different from conventional molecular-beam technique. These differences have been recently demonstrated in case antimony. This work shows rate and mean size incident clusters Sb evaporated on amorphous carbon are two crucial parameters. Crystalline aspect coverage deposits depends strongly these Transmission-electron-microscopy studies allow us to determine optimum conditions under which,...
Supported Au and Ni clusters as well bimetallic AuNi have been produced by laser vaporization of both pure bulk metals alloy. Transmission electron microscopy (TEM) energy dispersive X-ray spectroscopy (EDS) experiments show that they a narrow distribution size centered around 2.5 nm the same composition vaporized Au0.5Ni0.5 photoemission (XPS) has used to measure core level binding shifts 4f7/2 Ni2p3/2. The observed in system combined effects alloying surface local order relation with...