Dissociative charge transfer reactions of acetylene Part 1. Ar +/C 2H 2

Abstract

The techniques of Total Charge Collection, Mass Analysis, and Time-Resolved Mass Spectrometry (TRMS) have been used to investigate dissociative charge transfer reactions as a function of reactant ion translational energy. In this paper a study of the system Ar +/C 2H 2 over the translational energy range 100–2000 eV is reported. Evidence is provided for the occurrence of two types of collision leading to reaction: (i) long range interactions without momentum transfer, producing excited parent ions, and (ii) close collisions involving different degrees of momentum transfer, producing fragment ions. The Near-Adiabatic Maximum Rule appears to be valid in interpreting the translational energy dependence of the long range interactions, and on this basis the principal product ion of the reaction is postulated to be the 2Σ 6 + electronic state of C 2H + 2 excited in low vibrational levels. The TRMS technique has proved useful in distinguishing between the different momentum transfer processes leading to the production of particular fragmentations.