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 recen t diode laser experiments. Ab initio calculations were carried out to deter mine parameters fur the pairwise Lennard-Jones intermolecular potential. Th e trajectory results appear to show good qualitative agreement with prelimi nary experimental results. The highest DeltaE collisions occur when the CO happens to lie above the pyrazine plane just as the underlying CI-I wag exe cutes an unusually high amplitude motion. Artificially doubling the length of the CO produces results for the angular momentum transfer to the CO mole cule that look quite similar to those for angular momentum transfer to CO2 in analogous pyrazine-CO2 experiments.