Mechanisms and rate constants of the collisional deactivation of CO+(A 2Π,v) by He and Ar

Abstract

Collisional deactivation processes of CO+(A 2Π,v) by He and Ar are investigated in detail using both a time-resolved laser induced fluorescence and a threshold electron-secondary ion coincidence technique. Three deactivation mechanisms, pure vibrational relaxation, internal conversion, and charge transfer reaction, are identified. The time-resolved fluorescence from both the initially photoexcited and vibrationally relaxed levels of CO+ A 2Π makes clear the two distinct vibrational relaxation mechanisms: indirect two-step population of the lower levels in the CO+ (A)+He system and direct transition to the lower levels in the CO+(A)–Ar system. Threshold electron-secondary ion coincidence (TESICO) experiments demonstrate that the charge transfer reactions CO+ (A,v)+Ar→Ar++CO contribute significantly to the overall fluorescence quenching by Ar.