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
Laboratoire pour l'Utilisation des Lasers Intenses (LULI), Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau, France.
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.
Phys Rev Lett. 2014 Sep 12;113(11):116404. 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/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.
我们使用时间分辨X射线吸收光谱法研究了致密等离子体状态下熔融石英的电子结构演变。我们使用纳秒（ns）激光束在样品中产生强烈的均匀冲击波，并使用皮秒（ps）脉冲在Si K边附近产生宽带X射线源。通过改变两束激光之间的延迟以及纳秒激光束的强度，我们探索了一个大的热力学区域，其密度从1到5 g/cm³不等，温度高达5 eV。与正常条件下二氧化硅是具有8.9 eV宽带隙的著名绝缘体不同，我们发现受冲击的二氧化硅在整个热力学区域内表现出作为半金属的赝能隙。这与使用广义梯度近似进行的密度泛函理论预测在定量上是一致的。
