TEMPORAL DEPENDENCE OF COLLISIONAL ENERGY-TRANSFER BY QUASI-CLASSICALTRAJECTORY CALCULATIONS OF THE TOLUENE-ARGON SYSTEM

The average energy transferred per collision and its dependence on col lision duration were evaluated by using quasiclassical trajectory calc ulations with valance force field intramolecular potential for toluene and pairwise Lennard-Jones intermolecular potential for argon-toluene interactions. The average energy transferred in up, down, and overall collisions were sorted according to the duration of the collisions. I t was found that, on average, collision durations, for collisions last ing longer than zero, are 0.68 and 0.23 ps at 300 and 1500 K, respecti vely, and this is the time in which energy transfer takes place. Most collisions of duration longer than 0 are impulsive, and the number of complex-forming collisions is negligible. The average minimal distance at which the collisional event manifests itself in internal energy ch ange in the molecule is similar to 0.31 nm at both 300 and 1500 K. One in 800 collisions is a supercollision. The implications of these find ings on energy transfer models are discussed.