Theory of Rapidly Oscillating Electron Angular Distributions in Slow Ion-Atom Collisions

Abstract

A general expression for the ionization amplitude in slow ion-atom collisions is derived. The expression is inverted to obtain adiabatic electronic wave functions at complex values of the internuclear distance. It is shown that beating between $\ensuremath{\sigma}$ and $\ensuremath{\pi}$ components of electronic wave functions gives rise to rapid oscillations of electron angular distributions with ion velocity $v$. These rapid oscillations measure the real part of that eigenvalue whose imaginary part gives the well-known Wannier exponent.