Development and Application of Ultrafast Low-Energy Electron Microscopy

This proposal aims at the development and application of Ultrafast Low-Energy Electron Microscopy (ULEEM), a new experimental technique for studying dynamics at surfaces. It addresses a key question in ultrafast surface science, namely the observation of rapid structural changes with high spatial and temporal resolution, and with ultimate surface sensitivity down to the monolayer level. In order to achieve this goal, a number of conceptual and technological challenges will need to be addressed.This project is designed to support a comprehensive approach to the successful implementation of ULEEM. Pulsed electron source concepts and electron pulse compression schemes will be realized for the conditions of low-energy electron microscopy. Furthermore, tailored contrast mechanisms will be employed to enhance the time-resolved mapping of specific structural features and domains.With this newly established methodology, we will study a selected set of model systems and nonequilibrium phenomena to explore ultrafast surface imaging of the dynamics and control of phase transformations, interlayer energy transfer in van der Waals heterostructures, and the excitation and propagation of collective modes.