Vibrational energy transfer and relaxation processes in CH₃Br. A detailed kinetic analysis of the lower vibrational levels

Energy transfer processes among the lower vibrational levels in CH₃Br have been examined in an attempt to obtain information about the magnitude of the rate constants coupling these levels with one another and coupling ν₃ and ν₆ to the ground state. We conclude that there is a significant direct deactivation of both ν₃ and ν₆ to the ground state for CH₃Br-CH₃Br collisions. The magnitude of V-V rate constants for CH₃Br-CH₃Br and CH₃Br-rare gas interactions are discussed. In the course of these studies, a numerical method has been developed which allows for the determination of kinetic rate constants from measured rates by iterative solution of the coupled set of kinetic equations. Propagation of error from experimental rates to kinetic rate constants has been explicitly considered. The impact of our kinetic analysis and resulting conclusions on previous studies of the methyl halides is also discussed.