RADIATIVE LIFETIMES OF VIBRATIONALLY EXCITED HCL+ (UPSILON = 1) AND DCL+ (UPSILON = 1) IONS

Vibrational radiative lifetimes of positive ions have been measured for the first time in a selected ion flow tube. Values determined are HCl+ (υ = 1), τ = 4.5 ± 1 ms and DCl+ (υ = 1), τ = 17 ± 4 ms. A reaction with N2 to produce N2H+, which is endothermic and slow for υ = 0 and exothermic and fast for υ > 0 is used to monitor the population of vibrationally excited ions as a function of distance in a helium buffered tube. There is agreement within experimental error of lifetimes measured in low pressure experiments at Orsay and with the calculated lifetimes. Vibrational quenching rate constants for both ions by helium are found to be less than 10-14 cm3 s-1 at 300 K. © 1990.