Collisional Deactivation of CO2(00o1) and N2O(00o1) by Toluene Isotopomers: Near-Resonant Energy Transfer for N2O(00o1)

Abstract

The time-resolved infrared fluorescence (IRF) technique has been used to study the vibrational deactivation of CO2(00°1) and N2O(00°1) by C6D5CH3 and C6H5CD3 at ambient temperature (295 ± 2 K). The bimolecular deactivation rate constants were found to be (242 ± 17) × 103 and (145 ± 5) × 103 Torr-1 s-1, respectively, for the deactivation of CO2(00°1), and (253 ± 13) × 103 and (376 ± 20) × 103 Torr-1 s-1, respectively, for the deactivation of N2O(00°1). Experimental deactivation probabilities are calculated and compared with our previous data for deactivation of the same two excited molecules by the colliders C6H6, C6D6, C6H5CH3, and C6D5CD3. All deuterated species show enhanced deactivation relative to the respective nondeuterated species, with the largest effects being exhibited by the deactivation of N2O(00°1) by C6D5CD3 and C6H5CD3. The results indicate that the C-D stretch mode in the methyl group of the toluene isotopomers is the major factor responsible for the considerably enhanced deactivation of N2O(00°1), probably as a result of near-resonant intermolecular V-V energy transfer.