Flow tube studies of the deactivation of HF(v) by selected polyatomic molecules

A large diameter, medium pressure flow tube has been used to study deactivation processes by selected polyatomic molecules potentially relevant in chemical laser systems. Effective vibrational deactivation rate constants for HF(v = 1,2,3) relaxed by H2S, CO2, N2O, CH4, CF4, and SF6 have been determined. Rate constants for chaperones H2S, CO2, and CH4 are found to be about 102−103 times larger than for the CF4 and SF6. The fast rates are order 1012 cm3/mol−1·sec−1. The N2O rates are intermediate. The rates for a given chaperone increase with ascending v. The agreement with results for HF(1) + M reported from laser-induced fluorescence experiments is generally good. The role of HF rotational energy in absorbing a vibrational energy defect is examined. An empirical correlation with adjusted vibrational energy defect is suggested.