Ultrafast Electron Microscopy Visualizes Acoustic Vibrations of Plasmonic Nanorods at the Interfaces

By integrating a direct electron detector with ultrafast electron microscopy and controlling the quality of the pulsed electron beam, unprecedented spatiotemporal resolution in real-space imaging was achieved under practical pump-probe measurements. As a proof-of-principle demonstration of this new technique, the acoustic vibrations of plasmonic nanorods that were one nanometer amplitude or less and picosecond period upon femtosecond-pulsed photoexcitation were studied at the frictional interfaces. The subnanometer sensitivity in visualizing individual mechanical movement captures new details about acoustic vibrations such as the initial launching of the vibrations and the suppression and release of the vibration at the interfaces