Abstract

Ultrafast electron microscopy (UEM) has made it possible to visualize laser-induced time-dependent processes in materials with a high spatial and temporal resolution. This analytical method is based on sample excitation (pumping) by a pulsed laser beam and its probing by time-synchronized photoelectron bunches in a transmission electron microscope column. Using a digital 2D detector in an experimental setup, one can record a “molecular movie” as a sequence of images representing the behavior of material in the space–time continuum. High temporal resolution is of particular interest in the problems related to detailed analysis of various laser-induced transient processes occurring in thin films, observation of the response of adsorbed molecules to nonequilibrium structural changes of the surface, surface and volume dynamics in semiconductors, generation of coherent acoustic and optical phonons, surface melting of nanoparticles, and nonequilibrium structural dynamics of phase transformations. This review presents the state of the art of the UEM method, where picosecond, femtosecond, and subfemtosecond probe pulses are used to reveal the structural dynamics of condensed matter.

中文翻译：

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超快电子显微镜：二十一世纪的仪器

摘要

超快电子显微镜 (UEM) 使在具有高空间和时间分辨率的材料中可视化激光诱导的时间相关过程成为可能。这种分析方法基于脉冲激光束的样品激发（泵浦）和透射电子显微镜柱中时间同步光电子束的探测。在实验装置中使用数字 2D 探测器，可以将“分子电影”记录为一系列图像，表示材料在时空连续体中的行为。高时间分辨率在与薄膜中发生的各种激光诱导瞬态过程的详细分析、观察吸附分子对表面非平衡结构变化的响应、半导体中的表面和体积动力学相关的问题中特别感兴趣，相干声学和光学声子的产生，纳米粒子的表面熔化，以及相变的非平衡结构动力学。本综述介绍了 UEM 方法的最新技术，其中使用皮秒、飞秒和亚飞秒探测脉冲来揭示凝聚态物质的结构动力学。