Local Ionization Dynamics Traced by Photoassisted Scanning Tunneling Microscopy: A Theoretical Approach

For tracing the spatiotemporal evolution
of electronic systems,
we suggest and analyze theoretically a setup that exploits the excellent
spatial resolution based on scanning tunneling microscopy techniques
combined with the temporal resolution of femtosecond pump–probe
photoelectron spectroscopy. As an example, we consider the laser-induced,
local vibrational dynamics of a surface-adsorbed molecule. The photoelectrons
released by a laser pulse can be collected by the scanning tip and
utilized to access the spatiotemporal dynamics. Our proof-of-principle
calculations are based on the solution of the time-dependent Schrödinger
equation supported by the ab initio computation of the matrix elements
determining the dynamics.

为追踪电子系统的时空演化过程，我们从理论上提出并分析了一种实验装置：该装置依托扫描隧道显微术（scanning tunneling microscopy）的优异空间分辨率，结合飞秒泵浦-探测光电子能谱（femtosecond pump–probe photoelectron spectroscopy）的时间分辨率。作为示例，我们研究了表面吸附分子的激光诱导局域振动动力学。激光脉冲释放的光电子可由扫描探针收集，并用于获取该时空动力学信息。我们的原理验证计算基于含时薛定谔方程（time-dependent Schrödinger equation）的求解，并辅以决定该动力学过程的矩阵元的从头算（ab initio）计算。