Vibrational relaxation of C2H2 and C2D2 by vibration–rotation, translation (V–R, T) energy transfer

Abstract

The collisional probabilities of relaxation and self-relaxation of the ν₂, ν₄ and ν₅ modes in C₂H₂ and of the ν₄ and ν₅ modes in C₂D₂ have been calculated using the ‘effective mass theory’, which includes the effects of molecular rotation in facilitating vibrational energy transfer. The experimental data for C₂D₂ can be reproduced quite satisfactorily. However, the calculations do not support the previously proposed interpretation of experimental measurements on C₂H₂, and an alternative interpretation is suggested.