Vibrational Energy Transfer from DF(1) to Toluene. Competition between the Benzene Ring CH and Methyl Group CH Stretches

Abstract

Vibrational energy transfer from DF(1) to toluene has been studied by use of the WKB semiclassical procedure in the distorted-wave approximation. Both methyl stretches (ν4, ν17, ν28) and benzene ring CH stretches (ν1, ν2, ν3) are within 200 cm-1 of the DF vibrational frequency. Transfer of this energy mismatch from translation to toluene accompanies the vibration-to-vibration energy exchange step (i.e., VVT). Energy transfer to these two groups of CH modes is treated in both long-range and short-range interactions. At 300 K, the most favored VVT channel is the energy transfer pathway from DF(1) to the ν4 mode of the methyl CH stretch taking place at long interaction range. The ring CH modes suffer stronger perturbation by DF, but their excitation is not very efficient because they proceed with a larger energy mismatch. However, when the ring mode vibrational frequencies are changed to alter the energy mismatch toward the resonant case, energy transfer to the ring modes at long range becomes the principal ...