Exact Classical Calculations on Collisional Energy Transfer to Diatomic Molecules with a Rotational and a Vibrational Degree of Freedom

Abstract

Exact classical calculations are carried out on energy transfer from the translational degree of freedom to the vibrational and rotational degrees of freedom in nonreactive atom–diatomic-molecule collisions. The diatomic molecule is either a harmonic or a Morse oscillator and the interaction potential is exponentially repulsive in the interatomic distances. The exact calculations are used to test the validity of a number of approximations which have been applied in theoretical treatments of this type of system. It is shown that the dynamic interaction between molecular rotational and vibrational motion during collision can introduce important differences between noncolinear and colllinear collisions; as a result, great care must be exercised in drawing conclusions from calculations on collinear systems.