A5085366547- High-pressure geophysics and materials
- Atomic and Molecular Physics
- Advanced Chemical Physics Studies
- Astro and Planetary Science
- Laser-induced spectroscopy and plasma
- Stellar, planetary, and galactic studies
- Cold Atom Physics and Bose-Einstein Condensates
- Diamond and Carbon-based Materials Research
- X-ray Spectroscopy and Fluorescence Analysis
- Quantum, superfluid, helium dynamics
- Electron and X-Ray Spectroscopy Techniques
- Geological and Geochemical Analysis
- Astronomy and Astrophysical Research
- Planetary Science and Exploration
- Laser-Matter Interactions and Applications
- Mass Spectrometry Techniques and Applications
- Astrophysics and Star Formation Studies
- Ion-surface interactions and analysis
- Atomic and Subatomic Physics Research
- Laser Material Processing Techniques
- Energetic Materials and Combustion
- Scientific Research and Discoveries
- Surface and Thin Film Phenomena
- Gamma-ray bursts and supernovae
- Space Science and Extraterrestrial Life
Lagrange Laboratory
2024
Institut de Mécanique Céleste et de Calcul des Éphémérides
2020-2024
Laboratoire Univers et Théories
2011-2023
Centre National de la Recherche Scientifique
2009-2023
Université Côte d'Azur
2022-2023
Observatoire de la Côte d’Azur
2022-2023
Université de Lille
2020-2022
Université Paris Sciences et Lettres
2015-2022
Sorbonne Université
2020-2022
Arcetri Astrophysical Observatory
2022
The effect of intense ultrashort irradiation on interatomic forces, crystal stability, and possible melting transition the underlying lattice is not completely elucidated. By using ab initio linear response to compute phonon spectrum gold, silicon, aluminum, we found that silicon gold behave in opposite ways when increasing radiation intensity: whereas a weakening bond induces instability, undergoes sharp increase its temperature, while significantly smaller observed for aluminum electronic...
Measurements of iron-plasma transmission at 156+/-6 eV electron temperature and 6.9+/-1.7 x 10(21) cm(-3) density are reported over the 800-1800 photon energy range. The is more than twice that in prior experiments, permitting first direct experimental tests absorption features critical for understanding solar interior radiation transport. Detailed line-by-line opacity models excellent agreement with data.
We present a new equation of state (EOS) for dense hydrogen/helium mixtures which covers range densities from $10^{-8}$ to $10^6$ g.cm$^{-3}$, pressures $10^{-9}$ $10^{13}$ GPa and temperatures $10^{2}$ $10^{8}$ K. The calculations combine the EOS Saumon, Chabrier & vanHorn (1995) in low density, temperature molecular/atomic domain, Potekhin (1998) high-density, high-temperature fully ionized limits differ H He, ab initio quantum molecular dynamics (QMD) intermediate density regime,...
Using ab initio molecular dynamics simulations, we calculate the equation of state iron in solid phase for both hcp and bcc structures as well high-pressure melting curve up to 15 Mbars. We first find that temperature increases 11 000 K at highest pressures investigated following a semiempirical law over entire pressure domain. also investigate stability beyond Earth's core conditions (3 Mbars) which is mechanically stabilized with density. Finally, provide simple fits these results...
Using quantum molecular dynamics simulations, we show that the optical properties of aluminum change drastically along nonmetal metal transition observed experimentally. As density increases and many-body effects become important, response gradually evolves from one characteristic an atomic fluid to a simple metal. We combined with Kubo-Greenwood formulation naturally embodies two limits provides powerful tool calculate benchmark various systems as they evolve into warm dense matter regime.
We report dynamical and optical properties of hydrogen (deuterium) around the region principal Hugoniot that starts from cryogenically cooled molecular liquid. These were determined by finite-temperature density functional (FTDF) dynamics (MD) simulations within local generalized gradient approximations. The Hugoniot, calculated FTDF-MD equation state, agrees with gas-gun recent laser-shock experiments for pressures up to 50 GPa. However, maximum compression (4.6 at 52 GPa) significantly...
We construct a multiphase equation of state (EoS) hydrogen in the range 0.2 to 5 g/cc and up 10 eV based on ab initio electronic structure calculations. In molecular solid, cold curve phonon spectra calculations are performed for various structures, proposed literature, cover stability field 500 GPa. A weak structural dependence is observed, solid EoS averaged over these data. dissociating fluid dense plasma, made complete abundant data set literature. Two physical models used fit...
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...
We present a model to describe thermophysical and optical properties of two-temperature systems consisted heated electrons cold ions in solid lattice that occur during ultrafast heating experiments. Our is based on ab initio simulations within the framework density functional theory. The are obtained by evaluating Kubo-Greenwood formula. By applying material parameters our we able temperature relaxation process femtosecond-laser-heated gold its same theoretical framework. Recent...
Using ultrafast x-ray probing, we experimentally observed a progressive loss of ordering within solid-density aluminum as the temperature raises from 300 K to >10{4} K. The Al sample was isochorically heated by short ( approximately ps), laser-accelerated proton beam and probed broadband source around edge. short-range is detected through smoothing time-resolved absorption near-edge spectroscopy (XANES) structure. results are compared with two different theoretical models warm dense matter...
By use of high intensity XUV radiation from the FLASH free-electron laser at DESY, we have created highly excited exotic states matter in solid-density aluminum samples. The is sufficiently to excite an inner-shell electron a large fraction atoms focal region. We show that soft-x-ray emission spectroscopy measurements reveal electronic temperature and density this system immediately after excitation pulse, with detailed calculations structure, based on finite-temperature functional theory,...
The electronic structure evolution of highly compressed aluminum has been investigated using time resolved $K$ edge x-ray absorption spectroscopy. A long laser pulse (500 ps, ${I}_{L}\ensuremath{\approx}8\ifmmode\times\else\texttimes\fi{}{10}^{13}\text{ }\text{ }\mathrm{W}/{\mathrm{cm}}^{2}$) was used to create a uniform shock. second ps (${I}_{L}\ensuremath{\approx}{10}^{17}\text{ generated an ultrashort broadband source near the Al edge. main target designed probe at reshocked conditions...
Taking advantage of the new opportunities provided by x-ray free electron laser (FEL) sources when coupled to a long pulse as available at Linear Coherent Light Source (LCLS), we have performed absorption near-edge spectroscopy (XANES) shock compressed iron up 420 GPa ($\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...
Abstract The history of the Earth has been marked by major ecological transitions, driven metabolic innovation, that radically reshaped composition oceans and atmosphere. nature magnitude earliest hundreds million years before photosynthesis evolved, remain poorly understood. Using a novel ecosystem-planetary model, we find pre-photosynthetic methane-cycling microbial ecosystems are much less productive than previously thought. In spite their low productivity, evolution methanogenic...
Abstract Terrestrial planets in the habitable zone (HZ) of Sun-like stars are priority targets for detection and observation by next generation space telescopes. Earth's long-term habitability may have been tied to geological carbon cycle, a process critically facilitated plate tectonics. In modern Earth, motion corresponds mantle convection regime called mobile lid. The alternate, stagnant-lid is found on Mars Venus, which lacked strong enough weathering feedback sustain surface liquid...
We present the first large-scale simulations of an ultracold neutral plasma, produced by photoionization laser-cooled xenon atoms, from creation to initial expansion, using classical molecular-dynamics methods with open boundary conditions. reproduce many experimental findings such as trapping efficiency electrons increased ion number, a minimum electron temperature achieved on approach threshold, and recombination into Rydberg states anomalously low principal quantum number. In addition,...
We calculate the equation of state dense deuterium with two ab initio simulations techniques, path integral Monte Carlo and density functional theory molecular dynamics, in range 0.67 < rho 1.60 g/cc. derive double shock Hugoniot compare recent laser-driven wave experiments by Mostovych et al. [1]. find excellent agreement between types microscopic but a significant discrepancy measurements.
We investigate the physical properties of warm dense helium under conditions found in atmospheres cool white dwarfs using both a chemical model and ab initio simulations. A is developed for low-ionization limit that includes species He, ${\mathrm{He}}^{+}$, $\mathrm{He}_{2}{}^{+}$, electrons, interactions between them. The calculations consist quantum molecular dynamics (QMD) use generalized gradient approximation (GGA) to calculate equation state electrical optical within linear response...
Using a combination of classical and ab-initio molecular dynamics simulations, we calculate the structure electrical conductivity warm dense gold during first picoseconds after short-pulse laser illumination. We find that ions remain in their initial fcc for several picoseconds, despite electron temperatures ranging from few to eV The conductivities calculated under these nonequilibrium conditions using latter assumption are remarkable agreement with recent measurements interacting thin films.