The influence of the attractive well on near-resonant vibrational energy transfer in the gas phase: the importance of third body collisions

In a recent paper we postulated that for both non-resonant and near-resonant (VV) energy transfer orbiting collisions become important at temperatures below the Lennard-Jones well depth. We show here that the rate constants for near-resonant (VV) processes are affected by the third body collision partners H-2, He and Ne, which stabilise the collision complex and reduce the probability for energy transfer. The reverse behaviour has been found for argon which may form dimers with the excited molecules, increasing the collision cross-section. (C) 1997 Elsevier Science B.V.