A5083608612- Gold and Silver Nanoparticles Synthesis and Applications
- nanoparticles nucleation surface interactions
- Advanced Chemical Physics Studies
- Plasmonic and Surface Plasmon Research
- Laser-Ablation Synthesis of Nanoparticles
- Spectroscopy and Quantum Chemical Studies
- Catalytic Processes in Materials Science
- Nanocluster Synthesis and Applications
- Surface and Thin Film Phenomena
- Electron and X-Ray Spectroscopy Techniques
- Protein Interaction Studies and Fluorescence Analysis
- Atomic and Molecular Physics
- Nonlinear Optical Materials Studies
- Molecular Junctions and Nanostructures
- Advanced Physical and Chemical Molecular Interactions
- Quantum Dots Synthesis And Properties
- Nanoparticles: synthesis and applications
- Laser Material Processing Techniques
- Theoretical and Computational Physics
- Fullerene Chemistry and Applications
- Nanomaterials for catalytic reactions
- Ion-surface interactions and analysis
- Iron oxide chemistry and applications
- Electrocatalysts for Energy Conversion
- Graphene research and applications
Université Claude Bernard Lyon 1
2014-2024
Centre National de la Recherche Scientifique
2014-2024
Institut Lumière Matière
2013-2024
Forum Réfugiés - Cosi
2014-2018
Laboratoire de Spectrométrie Ionique et Moléculaire
2004-2013
Laboratoire de physique de la matière condensée
2005
Freie Universität Berlin
1999
We report experiments on gold clusters in the size range 2--4 nm, embedded an alumina matrix. The metallic particles are produced with a laser vaporization source and codeposited dielectric vapor as thin film substrate. Our technique allows varying cluster at given metal concentration. These composite materials studied through optical absorption ellipsometric measurements, allowing determination of their complex index refraction. Various complementary techniques provide information about...
Electron-lattice energy exchanges are investigated in gold and silver nanoparticles with sizes ranging from 30 to 2.2 nm embedded different environments. Femtosecond pump-probe experiments performed the low-perturbation regime demonstrate a strong increase of intrinsic electron-phonon interaction for smaller than 10 due confinement effect.
The internal thermalization dynamics of the conduction electrons is investigated in silver nanoparticles with radius ranging from 13 to 1.6 nm using a femtosecond IR pump-UV probe absorption saturation technique. A sharp increase electron energy exchange rate demonstrated for smaller than 5 nm. results are consistent electron-electron scattering acceleration due surface induced reduction Coulomb interaction screening by and core electrons.
The optical extinction spectra of single silver nanoparticles coated with a silica shell were investigated in the size range 10−50 nm. Measurements performed using spatial modulation spectroscopy technique which permits independent determination both metal nanoparticle under study and width its localized surface plasmon resonance (LSPR). These parameters can thus be directly correlated at particle level for first time. results show linear increase LSPR inverse diameter small regime (less...
Absolute extinction cross sections of individual silver nanocube dimers are measured using spatial modulation spectroscopy in correlation with their transmission electron microscopy images. For very small interparticle distances and an incident light polarized along the dimer axis, we give evidence for a clear splitting main dipolar surface plasmon resonance which is found to be essentially induced by cube edge rounding effects. Supported discrete dipole approximation finite element method...
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,...
The conduction electron energy exchanges are investigated in gold and silver nanoparticles with average size ranging from 2 to 26 nm, embedded different matrices. experimental studies were performed by following the internal thermalization dynamics of photoexcited nonequilibrium electrons a femtosecond pump-probe technique. probe wavelength dependent measurements qualitative agreement results theoretical model based on bulk metal kinetics band-structure modeling. In both metals, measured...
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...
The impact of quantum confinement on the width surface plasmon resonance a metal nanoparticle is theoretically investigated in model system formed by silver nanosphere different environments. Calculations are performed using time-dependent local density approximation (TDLDA) for diameters up to about 11 nm, permitting precise quantification broadening due size reduction. As expected, this found be inversely proportional particle diameter, but with an amplitude strongly depending environment...
The stable structures and melting behaviors of silver-rich bimetallic clusters ${({\mathrm{Ag}}_{0.75}{M}_{0.25})}_{N}$, where $M=\mathrm{Au}$, Pt, Ni, containing up to $N=309$ atoms, were investigated by exchange Monte Carlo simulations. Ag-Au are as a solid solution equilibrium phase below their point. Ag-Pt exhibit continuous transition from core/shell alloy core/pure Ag shell. Ag-Ni display peculiar transformation prolate shapes before the nickel core melts alloying with silver at higher...
We have studied the spectral response of individual pairs gold nanoparticles chemically synthesized and stabilized on a transparent thin film. Very interspacing distances are explored by taking advantage residual layer surfactant molecules at metal surface. Absolute extinction cross section measurements spatial modulation spectroscopy technique correlated to corresponding high magnification images independently obtained from transmission electron microscopy. The signature transition isolated...
Absolute extinction measurements on individual silver nanoparticles under illumination show a steady evolution of their localized surface plasmon resonance. Their progressive transformation during light exposure and the influence various parameters such as nature stabilizers, local environment (oxygen rate), spectral range incident light, shape nanoparticle (spheres or nanocubes) have been carefully investigated in correlation with transmission electron microscopy imaging. A combination...
Homodimers of noble metal nanocubes form model plasmonic systems where the localized plasmon resonances sustained by each particle not only hybridize but also coexist with excitations a different nature: surface polaritons confined within Fabry-Perot cavity delimited facing cube surfaces (i.e., gap plasmons). Destructive interference in strong coupling between one these highly modes and radiating longitudinal dipolar dimer is responsible for formation Fano resonance profile opening spectral...
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...
Low-frequency Raman-scattering experiments have been performed on thin films consisting of nickel-silver composite nanoparticles embedded in alumina matrix. It is observed that the Raman scattering by quadrupolar modes, strongly enhanced when light excitation resonant with surface dipolar excitation, mainly governed silver electron contribution to plasmon excitation. The results are agreement a core-shell structure nanoparticles, shell being loosely bonded nickel core.
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...
A great number of works focus their interest on the study gold nanoparticle plasmonic properties. Among those, sharp nanostructures appear to exhibit more interesting features for further developments. In this paper, a complete bipyramidal-like is presented. The nano-objects are prepared in high yield using an original method. This chemical process enables precise control shape and size particles. specific photophysical properties bipyramids suspension ripened by recording response single...
A great number of works have focused their research on the synthesis, design and optical properties gold nanoparticles for potential biological applications (bioimaging, biosensing). For this kind application, sharp nanostructures appear to exhibit more interesting features since surface plasmon bands are very sensitive surrounding medium. In paper, a complete study PEGylated nanostars bipyramidal-like is presented. The prepared in high yield surfaces covered with biocompatible polymer....
We show that the optical properties of a particle above plane dielectric interface differ dramatically from those same embedded in homogeneous matrix. Calculations for gold and silver spheres have been carried out using exact multipole expansion method, providing thus benchmark results testing accuracy available numerical methods. For spheres, dependence extinction cross-section has studied detail as function parameters characterizing particle/interface system, namely, radius sphere,...
Optical properties of copper clusters $3\phantom{\rule{0.5em}{0ex}}\text{to}\phantom{\rule{0.5em}{0ex}}5\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ in diameter, produced by laser vaporization and embedded alumina, are investigated compared to a semi-quantal model [based on time-dependent local-density approximation (TDLDA) density functional theory (DFT)], including the absorption screening ionic core background surrounding matrix. To begin with, experiments show that alumina trapped oxidized if...
This article describes a high sensitivity spectrophotometer designed to detect the overall extinction of light by single nanoparticle (NP) in 10(-4)-10(-5) relative range, using transmission measurement configuration. We focus here on simple and low cost scheme where white lamp is used as source, permitting easy broadband measurements (300-900 nm). Using microscope, confocal geometry, an increased reached thanks modulation NP position under spot combined with lock-in detection. Moreover, it...