Femtosecond electron gun for diffraction experiments

Abstract

The concept of an electron gun for generating pulses with a duration <10 fs at energies suitable for electron diffraction experiments is presented. The principle is based on an rf cavity oscillating in the TMoio mode. Laser pulses for photoemission are injected at a well-defined phase of the rf oscillation such that electrons with different initial velocities and different time delays arrive at a target within a very small temporal window. Coulomb broadening is prevented by reducing the number of electrons to the level of a single electron per pulse while increasing the repetition rate to the MHz range. The fs-electron pulses generated will advance the time-resolution of electron diffraction experiments to the level of a vibrational period of molecules.