Visualizing the acoustic vibration of plasmonic nanorods in ultrafast electron microscopy

Abstract

With advances in spatial resolution reaching the atomic scale, 2 and 3 dimensional (D) imaging in transmission electron microscopy (TEM) has become an essential methodology in various fields of research providing static structural information. Now it has become possible to integrate the ultrahigh temporal resolution (fourth dimension) to the 3D spatial resolution of TEM.1-5 Here, presented is the concept and recent application of time-resolved imaging in ultrafast electron microscopy (UEM), which made it possible to directly visualize a single gold nanorod (Au NR) undergoing plasmonic-acoustic vibration of sub-nanometer amplitude and picosecond period, upon femtosecond-pulsed light excitation for the first time. The unique integration of a direct electron detection camera6to ultrafast electron microscopy in combination of achieving control over the quality of pulsed electron beam enabled the unprecedented spatiotemporal resolutions with selective and characteristic vibrations of a single Au NR being unveiled in contrast to conventional optical spectroscopic measurements on ensembles.