On the unexpected oscillation of the total cross section for excitation in He2+ + H collisions

Recent calculations and measurements have revealed unexpected oscillations of the total cross section for excitation in low- to intermediate-energy He2+ + H collisions. A physical explanation of this behavior is given here stemming from analysis of classical trajectory Monte Carlo simulations, molecular orbital close coupling calculations, and solution of the time-dependent Schroedinger equation on a numerical lattice. These results indicate that the observed behavior should be characteristic of a wide range of reactions in ion-atom collisions