Resonant Two-Electron Processes in Ion–atom Collisions

A review of some of the recent results in an effort to obtain electron–ion differential scattering cross sections using fast ion–atom collisions is given. In the projectile frame, if we neglect the effects from the target nucleus, the ion–atom collision can be described as an electron–ion scattering process where the energy distribution of the impinging quasi-free electrons is determined by the Compton-profile of the target. In this electron scattering model (ESM), in addition to the direct electron scattering, doubly excited state formation of the projectile ion is also possible. This is a resonant process in which the doubly excited states can subsequently decay by ejecting Auger-electrons. We have studied elastic, inelastic and superelastic electron scattering as a function of incoming electron energy by observing the outgoing electron energy in the ion–atom collision emission spectra.