title: Metallization of warm dense SiO(2) studied by XANES spectroscopy.
abstract: We investigate the evolution of the electronic structure of fused silica in a dense plasma regime using time-resolved x-ray absorption spectroscopy. We use a nanosecond (ns) laser beam to generate a strong uniform shock wave in the sample and a picosecond (ps) pulse to produce a broadband x-ray source near the Si K edge. By varying the delay between the two laser beams and the intensity of the ns beam, we explore a large thermodynamical domain with densities varying from 1 to 5  g/cm^{3} and temperatures up to 5 eV. In contrast to normal conditions where silica is a well-known insulator with a wide band gap of 8.9 eV, we find that shocked silica exhibits a pseudogap as a semimetal throughout this thermodynamical domain. This is in quantitative agreement with density functional theory predictions performed using the generalized gradient approximation.
authors.affiliation: Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau, France.
authors.forename: A
authors.initials: A
authors.lastname: Denoeud
authors.affiliation: Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau, France and LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 92195 Meudon, France.
authors.forename: A
authors.initials: A
authors.lastname: Benuzzi-Mounaix
authors.affiliation: Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau, France and LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 92195 Meudon, France.
authors.forename: A
authors.initials: A
authors.lastname: Ravasio
authors.affiliation: Centre Lasers Intenses et Applications (CELIA), CNRS, CEA, Université Bordeaux 1, 33405 Talence, France.
authors.forename: F
authors.initials: F
authors.lastname: Dorchies
authors.affiliation: Centre Lasers Intenses et Applications (CELIA), CNRS, CEA, Université Bordeaux 1, 33405 Talence, France.
authors.forename: P M
authors.initials: PM
authors.lastname: Leguay
authors.affiliation: Centre Lasers Intenses et Applications (CELIA), CNRS, CEA, Université Bordeaux 1, 33405 Talence, France.
authors.forename: J
authors.initials: J
authors.lastname: Gaudin
authors.affiliation: Institut de Minéralogie et de Physique des Milieux Condensés (IMPMC), MNHN, CNRS, UPMC, IRD, Sorbonne Universités, 75005 Paris, France.
authors.forename: F
authors.initials: F
authors.lastname: Guyot
authors.affiliation: Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau, France.
authors.forename: E
authors.initials: E
authors.lastname: Brambrink
authors.affiliation: Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau, France.
authors.forename: M
authors.initials: M
authors.lastname: Koenig
authors.affiliation: Lawrence Livermore National Laboratory, Livermore, California 94550, USA.
authors.forename: S
authors.initials: S
authors.lastname: Le Pape
authors.affiliation: LUTH, Observatoire de Paris, CNRS, Université Paris Diderot, 92195 Meudon, France and Département de Physique Théorique et Appliquée, CEA, 91680 Bruyère-le-Chatel, France.
authors.forename: S
authors.initials: S
authors.lastname: Mazevet