Analysis of final-state momentum distributions of ionization products in ion-atom collisions

A general formulation utilizing three-body kinematics was developed to analyze the final-state momentum distributions of the electron, the recoil, and the projectile ion, for the ionization process in ion-atom collisions. Information on ionization dynamics can be identified and analyzed from the perspective of momentum distributions. The mechanism of electron capture into the projectile continuum was found to contribute a finite value at the kinematical threshold in the longitudinal recoil-ion momentum distribution. Detailed calculations using the continuum distorted wave-eikonal initial state approximation are compared with two recent measurements on momentum distributions of the recoiling ion and the ionized electron in single ionization of He by protons and by highly charged projectiles.