MECHANISMS AND RATE CONSTANTS OF THE COLLISIONAL DEACTIVATION OF CO+(A(2)PI,V) BY HE AND AR

Collisional deactivation processes of CO+ (A 2PI,v) by He and Ar are i nvestigated in detail using both a time-resolved laser induced fluores cence and a threshold electron-secondary ion coincidence technique. Th ree deactivation mechanisms, pure vibrational relaxation, internal con version, and charge transfer reaction, are identified. The time-resolv ed fluorescence from both the initially photoexcited and vibrationally relaxed levels of CO+ A 2PI makes clear the two distinct vibrational relaxation mechanisms: indirect two-step population of the lower level s in the CO+ (A) + He system and direct transition to the lower levels in the CO+ (A)-Ar system. Threshold electron-secondary ion coincidenc e (TESICO) experiments demonstrate that the charge transfer reactions CO+ (A,v) + Ar --> Ar+ + CO contribute significantly to the overall fl uorescence quenching by Ar.