Weisshaupt J, Rouzée A, Woerner M, Vrakking M J J, Elsaesser T, Shirley E L, Borgschulte A
Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie, D-12489 Berlin, Germany.
National Institute of Standards and Technology, Gaithersburg, MD 20899-8441, USA.
Phys Rev B. 2017 Feb 1;95(8). doi: 10.1103/PhysRevB.95.081101.
Femtosecond x-ray absorption spectroscopy with a laser-driven high-harmonic source is used to map ultrafast changes of x-ray absorption by femtometer-scale coherent phonon displacements. In LiBH, displacements along an phonon mode at 10 THz are induced by impulsive Raman excitation and give rise to oscillatory changes of x-ray absorption at the Li K-edge. Electron density maps from femtosecond x-ray diffraction data show that the electric field of the pump pulse induces a charge transfer from the to neighboring Li ions, resulting in a differential Coulomb force that drives lattice vibrations in this virtual transition state.
利用激光驱动的高谐波源进行的飞秒X射线吸收光谱，用于绘制由飞米尺度的相干声子位移引起的X射线吸收的超快变化。在LiBH中，沿10太赫兹的 声子模式的位移由脉冲拉曼激发诱导，并在Li K边产生X射线吸收的振荡变化。飞秒X射线衍射数据的电子密度图表明，泵浦脉冲的电场诱导电荷从 转移到相邻的锂离子，产生一个驱动该虚拟跃迁态晶格振动的微分库仑力。
