Université Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33400 Talence, France.
Ecole Polytechnique, LULI (Laboratoire d'Utilisation des Lasers Intenses), UMR 7605, F-91128 Palaiseau, France.
Phys Rev Lett. 2013 Dec 13;111(24):245004. doi: 10.1103/PhysRevLett.111.245004. Epub 2013 Dec 11.
We have probed, with time-resolved x-ray absorption near-edge spectroscopy (XANES), a femtosecond-laser-heated aluminum foil with fluences up to 1 J/cm2. The spectra reveal a loss of the short-range order in a few picoseconds. This time scale is compared with the electron-ion equilibration time, calculated with a two-temperature model. Hydrodynamic simulations shed light on complex features that affect the foil dynamics, including progressive density change from solid to liquid (∼10 ps). In this density range, quantum molecular dynamics simulations indicate that XANES is a relevant probe of the ionic temperature.
我们利用时间分辨的 X 射线吸收近边光谱（XANES）探测了激光烧蚀的铝箔，激光能量密度高达 1 J/cm2。光谱显示在几皮秒内短程有序度降低。这一时间尺度与电子-离子平衡时间进行了比较，电子-离子平衡时间是用双温模型计算出来的。流体动力学模拟揭示了影响箔片动力学的复杂特征，包括从固态到液态的密度渐进变化（约 10 ps）。在这个密度范围内，量子分子动力学模拟表明 XANES 是离子温度的一个相关探针。
