Classical trajectory study of energy transfer in pyrazine-CO collisions

Classical trajectory calculations for collisions between vibrationally hot pyrazine (E = 40332 cm(-1)) and room-temperature CO are compared with recent diode laser experiments. Ab initio calculations were carried out to determine parameters fur the pairwise Lennard-Jones intermolecular potential. The trajectory results appear to show good qualitative agreement with preliminary experimental results. The highest DeltaE collisions occur when the CO happens to lie above the pyrazine plane just as the underlying CI-I wag executes an unusually high amplitude motion. Artificially doubling the length of the CO produces results for the angular momentum transfer to the CO molecule that look quite similar to those for angular momentum transfer to CO2 in analogous pyrazine-CO2 experiments.