Quantum infinite order sudden approximation for ion-molecule reactions: Treatment of the He + H2+ system

Abstract

In this work the ion-molecule reaction He + H (vi) → HeH+ (vf) + H (vi = 0–7, vf = 0–2) was studied quantum mechanically in the energy range 1.3 eV ⩽ Etot ⩽ 1.8 eV. The calculations were carried out employing the Reactive Infinite Order Sudden Approximation (RIOSA). The two features characteristic of this system in the above energy range, namely the strong enhancement of the reaction rate with the initial vibrational energy (at a fixed total energy) and the relatively weak dependence of the cross sections on translational energy, were found to be well reproduced in the numerical treatment. The results also revealed the existence of two mechanisms of the exchange process: one is the ordinary mechanism and the other is probably related to the spectator stripping model.