Metallization of Warm Dense SiO2 Studied by XANES Spectroscopy

• Published in: Physical review letters Vol. 113; no. 11
• Main Authors: Denoeud, A, Benuzzi-Mounaix, A, Ravasio, A, Dorchies, F, Leguay, P M, Gaudin, J, Guyot, F, Brambrink, E, Koenig, M, Le Pape, S, Mazevet, S
• Format: Journal Article
• Language: English
• Published: 12-09-2014
• Subjects: Beams (radiation); Broadband; Delay; Density; Laser beams; Metallizing; Nanostructure; Silicon dioxide
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.113.116404

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/cm3 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.