Vibration-to-rotation and vibration-to-vibration energy transfer between diatomic molecules

A classical model for VR and VV energy transfer between two dissimilar diatomic molecules is proposed. For the exponential repulsive potential, in the limit as the rotation of the molecules goes to zero, the present model reduces to the previous results for VT and VV energy transfer. For the hydrogen halides, whose relaxation is generally accepted as being governed by VR energy transfer, the Pr's predicted by the present theory agree reasonably well with the experimental data. In particular, the positive and negative temperature dependence of the VV Pr's for N₂HI and N₂DI are predicted.