Time-Resolved Investigation of Coherently Controlled Electric Currents at a Metal Surface
Time-Resolved Investigation of Coherently Controlled Electric Currents at a Metal Surface
复制标题
DOI：
10.1126/science.1146764
复制
发表时间：
2007-11
期刊：
影响因子：
56.9
通讯作者：
J. Güdde;M. Rohleder;T. Meier;S. Koch;U. Höfer
中科院分区：
文献类型：
--
作者：
J. Güdde;M. Rohleder;T. Meier;S. Koch;U. Höfer
固体中电流动力学的研究一直受到不够短暂的触发信号和电子检测速度的阻碍。通过将相干控制方案与光电子能谱相结合，我们利用无接触实验装置在飞秒时间尺度上产生并检测金属表面的横向电子电流。我们采用光频率为ωa和ωa/2的相干光激励来感应电流，其方向由锁相激光激励脉冲之间的相对相位控制。时间和角度分辨光电子能谱提供了激发态电子动量随时间分布的直接图像。对于Cu（100）的第一个（n = 1）像势态，我们发现由于台阶和表面缺陷的电子散射，衰减时间为10飞秒。
Studies of current dynamics in solids have been hindered by insufficiently brief trigger signals and electronic detection speeds. By combining a coherent control scheme with photoelectron spectroscopy, we generated and detected lateral electron currents at a metal surface on a femtosecond time scale with a contact-free experimental setup. We used coherent optical excitation at the light frequencies ωa and ωa/2 to induce the current, whose direction was controlled by the relative phase between the phase-locked laser excitation pulses. Time- and angle-resolved photoelectron spectroscopy afforded a direct image of the momentum distribution of the excited electrons as a function of time. For the first (n = 1) image-potential state of Cu(100), we found a decay time of 10 femtoseconds, attributable to electron scattering with steps and surface defects.