Ultrafast time-resolved photoemission electron microscopy and its applications

Photoemission electron microscopy (PEEM) is a type of electron microscopy based on the photoelectric effect, in which the difference of photoemission yield in space is used as the image contrast. Owing to its outstanding features such as high speed imaging, ultra-high spatial resolution and nondestructive measurement, extensive applications of PEEM have been reported in surface physics, surface plasmonics and semiconductor science. In addition, ultrafast pump and probe techniques provide sufficient time resolution for kinetic studies with high spatiotemporal resolution. PEEM with multidimensional and intuitive measuring methods has opened up new venues for researchers. In this paper we first review the development of microscopic imaging and current progress in the application of PEEM to surface plasmonics and semiconductor science. We then describe the femtosecond-time resolved PEEM system and relevant research in Peking University, followed by a discussion of future prospects.