Biomedical subjects

E Schwegler

Publications and source records attributed to E Schwegler.

3 recordsLinked to original sources

PubMed2006

Broadband dielectric function of nonequilibrium warm dense gold.

We report on the first single-state measurement of the broadband (450-800 nm) dielectric function of gold isochorically heated by a femtosecond laser pulse to energy densities of 10(6) - 10(7) J/kg. A Drude and an interband component are clearly seen in the imaginary part of the dielectric function. The Drude component increases with energy density while the interband component shows both enhancement and redshift. This is in strong disagreement with predictions of a recent calculation of dielectric function based on limited Brillouin zone sampling.

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PubMed2001

Dissociation of water under pressure.

The dissociation of water under pressure is investigated with a series of ab initio molecular dynamics simulations at thermodynamic conditions close to those obtained in shock wave experiments. We find that molecular dissociation occurs via a bimolecular process similar to ambient conditions, leading to the formation of short-lived hydronium ions. Up to twofold compression and 2000 K, the oxygen diffusion coefficient is characteristic of a fluid. Our findings do not support models used to estimate the liquid electrical conductivity and interpret Raman spectra that assume the presence of free protons.

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PubMed2000

Water under pressure

Water under pressure is investigated by first principles molecular dynamics, with a focus on the changes in hydrogen bonding and the oxygen network in the nondissociative regime. At a pressure of 10 GPa and a temperature of 600 K, which is close to the freezing point, no appreciable molecular dissociation is observed in the simulations. However, the structure of water is substantially altered from that at ambient conditions. The liquid exhibits a much larger coordination of oxygen atoms, an essential weakening of hydrogen bonding, and sizable changes in the density of electronic states close to the Fermi level. Our results provide new structural data for direct comparison with future experiments.

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