Ultrafast Electron Microscopy: An Instrument of the XXI Century

• Published in: Crystallography reports 2021-07, Vol.66 (4), p.553-569
• Main Authors: Aseev, S. A., Mironov, B. N., Ryabov, E. A., Avilov, A. S., Girichev, G. V., Ischenko, A. A.
• Format: Article
• Language: English
• Subjects: Crystallography and Scattering Methods; Electron microscopy; Femtosecond pulsed lasers; Laser beams; Laser pumping; Lasers; Microscopy; Motion pictures; Nanoparticles; Phase transitions; Photoelectrons; Physics; Physics and Astronomy; Pulsed lasers; Reviews; State-of-the-art reviews; Temporal resolution; Thin films; Time dependence; Time synchronization
• ISSN: 1063-7745; 1562-689X
• DOI: 10.1134/S1063774521040040

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.