Dependence of the probability of VT-VV coupled transitions on vibrational quantum numbers

Abstract

The dependence of the probability of v - 1 → v vibrational excitations in molecule-molecule collisions on the vibrational quantum number v has been studied for v up to 7. This nominally VT energy transfer process can be strongly affected by the participation of VV mode particularly among high-lying states. The dependences of the probabilities on v among such states are shown to be non-linear largely due to the VT-VV intermode coupling. A sample calculation of the dependence in iodine molecules shows that the coupling is very strong when the temperature is high and that the probabilities seriously deviate from the linear relation P v - 1.0 → v.0 = vP 0.0 → 1.0, where molecule 1 undergoes transition from v - 1 to v, while molecule 2 remains in the ground state.