Nonadiabaticity in ion–molecule reactions: Coupling of proton and charge transfer in the H+2 and D+2+Ar system

Abstract

An experimental study of proton and charge transfer in H+2+Ar and D+2+Ar has been carried out as a function of kinetic and vibrational energy. The data show that charge transfer is predominantly long range, having a weak translational, but strong vibrational dependence. The existence of near-resonant energy levels is very important in determining the magnitude of the cross sections, while favorable Franck–Condon factors between the states is found to be less critical. Undulations in the charge transfer cross sections for both H+2 and D+2(v = 0) as a function of kinetic energy have been observed for the first time. As kinetic energy increases, the resemblence between the vibrational dependences of the proton and charge transfer channels becomes quite pronounced. This indicates that the two channels are closely coupled, especially above ∼3 eV.