Four-Dimensional Ultrafast Electron Microcopy
Abstract: Four-dimensional (4D) ultrafast electron microscopy (UEM), pioneered by Ahmed Zewail at Caltech since 2004, enables scientist to explore ultrafast events and process that occur at the atomic scale and in femtoseconds, which is 10 orders of magnitude better than that of conventional microscopes limited by the video-camera rate of recording. 4D UEM has been used in the study of ultrafast dynamics from atomic motions during structural dynamics to ultrafast phase transitions, nanomechanical oscillations, chemical bonding dynamics, crystallization dynamics, charge density wave, and plasmonics.
I have focused on developing on novel methods using 4D UEM and their applications in studying ultrafast dynamics of light-matter interactions. In this talk, I will introduce the development and progress made in 4D UEM, such as ultrafast phase-transition dynamics of single-particle vanadium dioxide embedded in ensemble, development of diffraction PINEM to improve energy resolution and study near-field plasmon dynamics in the infrared range, photon-gating to improve temporal resolution in UEM, and a multiple-cathode 4D UEM.