The Generation and Characterization of Ultrashort Electron Pulses and their Application to Time-Resolved Electron Diffraction.

Abstract

Abstract : This report describes the progress that has been made over the last years toward the generation of ultrashort electron pulses, and their application to time resolved electron diffraction. We have generated electron pulses of picosecond duration using an ultrafast laser system, tested a number of photocathode materials, built an apparatus to measure electron pulse durations in the femtosecond domain, and designed and built an electron diffractometer for time resolved electron diffraction. We demonstrated that the diffractometer, which uses a novel one dimensional detection scheme, is well capable of determining atomic distances in molecules to better than on hundredth of an Angstrom. A sophisticated noise suppression system maintains a signal to noise ratio sufficient for pump probe experiments. Further developments include the design of a reflectron electron gun for femtosecond electron pulses, and a two dimensional electron diffraction detector. Finally, significant progress has been made in the interfacing of adaptive optics to a learning algorithm, and the generation of spectrally tunable ultrashort laser pulses at 200 nm.