Laboratorium für Physikalische Chemie, ETH Zürich, Zürich, Switzerland.
Science. 2020 Aug 21;369(6506):974-979. doi: 10.1126/science.abb0979.
Electronic dynamics in liquids are of fundamental importance, but time-resolved experiments have so far remained limited to the femtosecond time scale. We report the extension of attosecond spectroscopy to the liquid phase. We measured time delays of 50 to 70 attoseconds between the photoemission from liquid water and that from gaseous water at photon energies of 21.7 to 31.0 electron volts. These photoemission delays can be decomposed into a photoionization delay sensitive to the local environment and a delay originating from electron transport. In our experiments, the latter contribution is shown to be negligible. By referencing liquid water to gaseous water, we isolated the effect of solvation on the attosecond photoionization dynamics of water molecules. Our methods define an approach to separating bound and unbound electron dynamics from the structural response of the solvent.
液体中的电子动力学具有重要的基础性意义，但时间分辨实验迄今为止仍然局限于飞秒时间尺度。我们报告了将阿秒光谱学扩展到液相。我们在光子能量为 21.7 到 31.0 电子伏特时，测量了液态水和气态水的光电子发射之间的 50 到 70 阿秒的时间延迟。这些光电子发射延迟可以分解为对局部环境敏感的光致电离延迟和源自电子输运的延迟。在我们的实验中，证明后一个贡献可以忽略不计。通过将液态水参考到气态水中，我们分离了溶剂化对水分子阿秒光致电离动力学的影响。我们的方法定义了一种从溶剂的结构响应中分离束缚和非束缚电子动力学的方法。
