Femtosecond electron diffraction: application to electron-phonon coupling in metals and comparison with time resolved x-ray techniques

Summary form only given. Twenty years ago, the technique of electron diffraction was introduced and made for the first time possible the direct observation of structural changes in the picosecond time scale. This simple technique is based on the photoelectric effect and provides a perfectly synchronized electron "replica" of the incident pulse. The technique was originally demonstrated with a 20 picosecond resolution and was used to investigate the dynamic of melting. Later it was used at the 100 ps level to investigate surface melting. The technique was further pushed to the subpicosecond time scale to study light induced chemical reactions in gas phase. At the University of Michigan the electron diffraction technique is used to directly study electron-phonon coupling in the femtosecond time scale using the Debye-Waller effect and surface dynamics. We show the experimental set up of the electron diffraction system and give results for a [111] transmission electron diffraction pattern of a 30 nm thick gold single crystal.