THE EFFECT OF VIBRATIONAL EXCITATION OF H₂⁺ ON ITS COLLISION-INDUCED DISSOCIATION

Abstract

A study is reported of the production of fast protons resulting from the collision-induced dissociation of H 2 + in collision with H 2 . Ion energies between 0.6 and 2 kev are considered. For fixed ion energy, a direct relationship is observed between the relative population of the vibrational levels (a function of the ionizing electron energy) and the cross section. As the electron energy is increased, the relative population of the upper states is increased, which gives rise to a marked increase in total cross section. Several mechanisms of ion collisional dissociation obtain. One involves a vertical Franck–Condon transition between electronic states; the other appears to involve a diagonal transition which may occur when Franck–Condon conditions do not apply.