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  Alcorn, F.M.; van der Veen, R.M.; Jain, P.K.: In Situ Electron Microscopy of Transformations of Copper Nanoparticles under Plasmonic Excitation. Nano Letters 23 (2023), p. 6520-6527

10.1021/acs.nanolett.3c01474

Abstract:
Metal nanoparticles are attracting interest for their light-absorption properties, but such materials are known to dynamically evolve under the action of chemical and physical perturbations, resulting in changes in their structure and composition. Using a transmission electron microscope equipped for optical excitation of the specimen, the structural evolution of Cu-based nanoparticles under simultaneous electron beam irradiation and plasmonic excitation was investigated with high spatiotemporal resolution. These nanoparticles initially have a Cu core−Cu2O oxide shell structure, but over the course of imaging, they undergo hollowing via the nanoscale Kirkendall effect. We captured the nucleation of a void within the core, which then rapidly grows along specific crystallographic directions until the core is hollowed out. Hollowing is triggered by electronbeam irradiation; plasmonic excitation enhances the kinetics of the transformation likely by the effect of photothermal heating.