Post-collision interaction in inelastic ion-atom scattering

Abstract

The ion-atom inelastic scattering processes including (i) excitation of autoionization states of atoms by ion impact, and (ii) ionization of inner atomic shells are considered. The Coulomb interaction of particles in the final state of such resonance processes (the post-collision interaction — PCI) exerts a strong influence on the energy and angular distributions of the particles. The theoretical models of PCI and experiments that make it possible to observe the PCI effects in different kinematic regions are discussed in this survey. The characteristics of PCI are considered by comparing photon and electron impact processes. Coincidence and noncoincidence experiments as well as the dependence of the lineshift on the incoming ion energy are discussed. The PCI effects are considered also in the kinematic region, where the relative velocity of a scattered ion and an autoionization electron is close to zero. In this case PCI results in the so-called Coulomb focusing of the autoionizing electrons and the oscillatory structure of the cross section. The interference between the direct and resonance scattering processes is considered, and possibilities of its experimental observation are discussed.