(e,2e) electron spectroscopy of surfaces

In (e,2e) spectroscopy, a primary electron is scattered from a target and detected in coincidence with another electron ejected from the target. We measured such events in electron scattering from a W(100) surface by two time-off-light electron energy analyzers based on position sensitive multi-channel detectors. We analyzed the total energy distribution of correlated electron pairs, as well as the energy-sharing distributions of electrons within a pair with a certain total energy. We found that the correlated electron pairs are created mainly by the primary electron scattering off a valence electron close to the Fermi level. An asymmetry in the energy-sharing distributions of the electrons of the correlated pair appears when the incident electron direction is off-normal. We suggest that most of the correlated pairs from W(100) are created by the specularly reflected or diffracted primary electrons and are due to a single scattering event of the primary electron with a valence electron.