A5080539822- Advanced X-ray Imaging Techniques
- Laser Material Processing Techniques
- Diamond and Carbon-based Materials Research
- Laser-Plasma Interactions and Diagnostics
- Laser-induced spectroscopy and plasma
- Advanced Surface Polishing Techniques
- X-ray Spectroscopy and Fluorescence Analysis
- Laser-Matter Interactions and Applications
- High-pressure geophysics and materials
- Ion-surface interactions and analysis
- Laser Design and Applications
- Advanced Chemical Physics Studies
- Electron and X-Ray Spectroscopy Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Particle Accelerators and Free-Electron Lasers
- Mass Spectrometry Techniques and Applications
- Advanced Electron Microscopy Techniques and Applications
- Astro and Planetary Science
- Phase-change materials and chalcogenides
- Esophageal and GI Pathology
- Chalcogenide Semiconductor Thin Films
- Laser-Ablation Synthesis of Nanoparticles
- Nuclear Physics and Applications
- Gastrointestinal disorders and treatments
- Ocular and Laser Science Research
Centre National de la Recherche Scientifique
2013-2025
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2013-2025
Centre Lasers Intenses et Applications
2016-2025
Université de Bordeaux
2013-2025
Santé et Agroécologie du Vignoble
2020
École Nationale Supérieure des Sciences Agronomiques de Bordeaux-Aquitaine
2020
Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement
2020
European X-Ray Free-Electron Laser
2009-2019
Centre Hospitalier Universitaire de Poitiers
2008-2015
Airbus (France)
2010-2014
Fifty years after its discovery, the ovonic threshold switching (OTS) phenomenon, a unique nonlinear conductivity behavior observed in some chalcogenide glasses, has been recently source of real technological breakthrough field data storage memories. This was achieved because successful 3D integration so-called OTS selector devices with innovative phase-change memories, both based on materials. paves way for class memories as well neuromorphic circuits. We elucidate mechanism behind by new...
We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula.As generalization beam spot area we apply and refine definition so called effective (A eff ) [1] in order to avoid using full-width at half maximum (FWHM) parameter is inappropriate beams.Furthermore, demonstrate practical utilization our femtosecond soft X-ray free-electron laser.The ablative imprints poly(methyl methacrylate) -PMMA amorphous carbon (a-C) are...
We present an overview of some recent theoretical and experimental results obtained on the properties iron silica at conditions encountered in planetary interiors. The first part is concerned with development x-ray absorption near edge spectroscopy dynamical experiments using high-energy lasers as a tool to investigate phase transitions structural changes extreme pressure–temperature for these two key constituents. second focuses quasi-isentropic compression technique achieve anticipated...
Abstract High-order harmonic generation in polyatomic molecules generally involves multiple channels of ionization. Their relative contribution can be strongly influenced by the presence resonances, whose assignment remains a major challenge for high-harmonic spectroscopy. Here we present multi-modal approach investigation unaligned molecules, using SF 6 as an example. We combine methods from extreme-ultraviolet spectroscopy, above-threshold ionization and attosecond metrology....
A method for the detection of dust particles occurring in silane–argon gas mixture plasmas is presented. It based on spectral analysis radio-frequency current. The amplitudes fundamental (13.56 MHz) and second harmonics (40.68 are very sensitive to presence earlier nanoparticles when their size range 2–3 nm even if influence capacitive character impedance negligible. This nonperturbative, with a temporal resolution microsecond range, easy implement, can thus be used industrial reactors.
We studied experimentally and theoretically the structural transition of diamond under an irradiation with intense femtosecond extreme ultraviolet laser (XUV) pulse 24--275 eV photon energy provided by free-electron lasers. Experimental results obtained show that irradiated undergoes a solid-to-solid phase to graphite, not amorphous state. Our theoretical findings suggest nature this is nonthermal, stimulated change interatomic potential triggered excitation valence electrons. Ultrashort...
Taking advantage of the new opportunities provided by x-ray free electron laser (FEL) sources when coupled to a long pulse as available at Linear Coherent Light Source (LCLS), we have performed absorption near-edge spectroscopy (XANES) shock compressed iron up 420 GPa ($\ifmmode\pm\else\textpm\fi{}50$) and 10 800 K ($\ifmmode\pm\else\textpm\fi{}1390$). Visible diagnostics with hydrodynamic simulations were used infer thermodynamical conditions along Hugoniot release adiabat. A modification...
The surface chemistry of gold nanoparticles produced by the pulsed laser ablation in liquids method is investigated X-ray photoelectron spectroscopy (XPS). presence oxide expected on these systems using synchrotron radiation conditions close to their original state solvent but free from substrate or effects which could affect interpretation spectroscopic observations. For that purpose we performed experiment a controlled free-standing nanoparticle beam combination an atomizer and aerodynamic...
Time-resolved valence band photoelectron spectroscopy with a temporal resolution of 135 fs is used to map the entire occupied electronic structure photoexcited gas-phase Br2 molecules during dissociation. The observed shifting and mixing energy levels defines transition period where system appears be intermediate between atoms molecules. surprisingly short bond breaking or dissociation time determined by monitoring in real how multiplet free atom arises from states molecule.
The efficiency and uniformity of heating induced by hard x-ray free-electron laser pulse is investigated for 0.5 μm silver foils using the X-ray Pump Probe instrument at Linac Coherent Light Source facility. Intense 8.9 keV pulses 60 fs duration deposit energy predominantly via inner-shell ionization to create a non-equilibrium Ag solid density plasma. are focused 14 × 17 μm2 means beryllium lenses varying total beam energy, deposition varied over range irradiances from 4.4 6.5 1015 W/cm2....
X-ray Free Electron Lasers (XFELs) have the potential to contribute many fields of science and enable new avenues research, in large part due their orders magnitude higher peak brilliance than existing future synchrotrons. To best exploit this brilliance, these XFEL beams need be focused appropriate spot sizes. However, survivability optical components intense, femtosecond radiation conditions is not guaranteed. As mirror optics are routinely used at facilities, a physical understanding...
Pulsed laser ablation in liquid (PLAL) is a powerful method for producing nanoparticle colloids with long-term stability despite the absence of stabilizing organic agents. The colloid involves different reactivities and chemical equilibria complex ionic-specific effects at nanoparticle/solvent interface which must be strongly influenced by their composition. In this work, surface composition PLAL-produced gold nanoparticles alkaline saline (NaBr) water investigated X-ray photoelectron...
In gold nanoparticle colloids produced by the pulsed laser ablation in liquid method, surface oxidation can be controlled adjusting bromide coverage when synthesized halide saline solutions.
Exciton-exciton interaction is experimentally revealed and quantitatively analyzed in a wide band-gap scintillator material ${\text{CdWO}}_{4}$. Under high-intensity femtosecond vacuum ultraviolet excitation, the ${\text{CdWO}}_{4}$ luminescence quenched, while its decay becomes essentially nonexponential. We propose an analytical model, which successfully reproduces kinetics recorded range of excitation densities. The dipole-dipole between excitons leading to their nonradiative shown be...
A laser-based tabletop approach to femtosecond time-resolved photoelectron spectroscopy with photons in the vacuum-ultraviolet (VUV) energy range is described. The VUV pulses are produced by high-order harmonic generation (HHG) of an amplified Ti:sapphire laser system. Two generations same setup and results from gas phase discussed. In both generations, a toroidal grating monochromator was used select one photon 20–30 eV. first perform determine bandwidth source. We find that our HHG source...
We present the results of an experiment where amorphous carbon undergoes a phase transition induced by femtosecond 830 eV x-ray free-electron laser pulses. The threshold fluence is found to be 282 \ifmmode\pm\else\textpm\fi{} 11 mJ/cm${}^{2}$. Atomic force microscopy, photoelectron and micro-Raman spectroscopy give experimental evidence for in terms volume expansion, graphitization, change local order irradiated sample area. interaction modeled accurate time-dependent treatment ionization...
We investigate the evolution of electronic structure fused silica in a dense plasma regime using time-resolved x-ray absorption spectroscopy. use nanosecond (ns) laser beam to generate strong uniform shock wave sample and picosecond (ps) pulse produce broadband source near Si $K$ edge. By varying delay between two beams intensity ns beam, we explore large thermodynamical domain with densities from 1 $5\text{ }\text{ }\mathrm{g}/{\mathrm{cm}}^{3}$ temperatures up 5 eV. In contrast normal...
Abstract Laser interaction with solids is routinely used for functionalizing materials' surfaces. In most cases, the generation of patterns/structures key feature to endow materials specific properties like hardening, superhydrophobicity, plasmonic color‐enhancement, or dedicated functions anti‐counterfeiting tags. A way generate random patterns, by means wrinkles on surfaces resulting from laser melting amorphous Ge‐based chalcogenide thin films, presented. These similar fingerprints, are...
We present results of damage studies conducted at the Free Electron LASer in Hamburg (FLASH) facility with 13.5 nm (91.8 eV) and 7 (177.1 radiations. The laser beam was focused on a sample 890-nm-thick amorphous carbon coated silicon wafer mimicking x-ray mirror. fluence threshold for graphitization determined different grazing angles above below critical angle. observed angular dependence Fth is explained by variation absorption depth reflectivity. Moreover, absorbed local dose needed phase...
Materials used for hard x-ray-free-electron laser (XFEL) optics must withstand high-intensity x-ray pulses. The advent of the Linac Coherent Light Source has enabled us to expose candidate optical materials, such as bulk B4C and SiC films, 0.83 keV XFEL pulses with pulse energies between 1 μJ 2 mJ determine short-pulse damage thresholds. fluence required onset single is around melt slightly lower multiple We observed strong mechanical cracking in which may be due larger penetration depths x-rays.
We present an extended theoretical background of so-called fluence scan (f-scan or F-scan) method, which is frequently being used for offline characterization focused short-wavelength (EUV, soft X-ray, and hard X-ray) laser beams [J. Chalupský et al., Opt. Express 18, 27836 (2010)]. The method exploits ablative imprints in various solids to visualize iso-fluence beam contours at different and/or clip levels. An f-scan curve (clip level as a function the corresponding contour area) can be...
The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes unprecedented time resolution bringing the so called "molecular movie" within reach. absorption spectroscopy is one of most powerful x-ray techniques providing both local order and electronic structure when coupled ad-hoc theory. Collecting spectra few pulses possible only in a dispersive setup. We demonstrate time-resolved measurements LIII-edge near-edge irreversibly laser excited Molybdenum using an...
The chemical and geometrical structure of free-standing carbon dots (Cdots) prepared from the pyrolysis N-hydroxysuccinimide (NHS) have been characterized using X-ray photoelectron spectroscopy (XPS). An aerodynamic lens system was used to generate a sufficient particle density monodispersed Cdots for XPS studies at PLEIADES beamline SOLEIL synchrotron facility. Varying excitation energy between 315 755 eV allows probing surface toward their core, owing kinetic dependence inelastic mean free...
The time evolution of the electron structure is investigated in a molybdenum foil heated up to warm dense matter regime by femtosecond laser pulse, through time-resolved x-ray absorption near-edge spectroscopy. Spectra are measured with independent characterizations temperature and density. They successfully compared ab initio quantum molecular dynamic calculations. We demonstrate that observed white line ${L}_{3}$ edge reveals density state from solid hot (a few eV) expanding liquid. data...