Ultrafast modulation of electronic structure by coherent phonon excitations.
Ultrafast modulation of electronic structure by coherent phonon excitations.
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DOI：
10.1103/physrevb.95.081101
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发表时间：
2017-02
期刊：
影响因子：
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通讯作者：
Jannick Weisshaupt;A. Rouzée;M. Woerner;M. Vrakking;T. Elsaesser;E. L. Shirley;A. Borgschulte
中科院分区：
文献类型：
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作者：
Jannick Weisshaupt;A. Rouzée;M. Woerner;M. Vrakking;T. Elsaesser;E. L. Shirley;A. Borgschulte
采用激光驱动高次谐波源的飞秒 X 射线吸收光谱可通过飞米级相干声子位移来绘制 X 射线吸收的超快变化。在 LiBH4 中，脉冲拉曼激发会引起 10 THz 下 Ag 声子模式的位移，并引起 Li K 边缘处 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显示，泵浦脉冲的电场诱导电荷从 BH4- 转移到相邻的 Li+ 离子，从而产生微分库仑力，驱动该虚拟过渡态的晶格振动。
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 LiBH4, displacements along an Ag 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 BH4- to neighboring Li+ ions, resulting in a differential Coulomb force that drives lattice vibrations in this virtual transition state.