CALCULATION OF COLLISION-INDUCED ENERGY-TRANSFER RATES IN TETRAHEDRALMOLECULES - APPLICATION TO (CH4)-C-12 PERTURBED BY ARGON

The semi-classical calculation of collisional energy transfer rates in spherical top molecules has been investigated. Multipolar transition moments are expressed in fully symmetrized tensorial form to allow rea listic eigenfunctions (corresponding to the polyad structure of such m olecules) to be easily incorporated. The short range intermolecular po tential has been chosen as an atom-atom Lennard-Jones potential, follo wing earlier studies in the framework of the semi-classical line broad ening theory of Robert and Bonamy. A preliminary application to the be nding dyad of methane perturbed by argon is reported. A sixth order ex pansion of the intermolecular potential has been used. The parameters were adjusted to fit observed line width measurements in the v(4) band . The results obtained for line widths and state to state energy trans fer rates are discussed.