Intermolecular potential effects in trajectory calculations of collisions between large highly excited molecules and noble gases

Quasiclassical trajectory calculations have been applied to study intermolecular potential effects in the collisional deactivation of highly vibrationally excited aromatic molecules by noble gases. For benzene + helium and benzene + argon several potential functions of Lennard-Jones 12-6 and EXP-6 type were used. At low well depths epsilon (for benzene + helium) energy transfer is dominated by the exact shape of the intermolecular potential, especially of the repulsive part, whereas the dependence on E itself is less important. At higher well depths (for benzene + argon) the energy transfer parameters [Delta E] and [Delta E(2)] scale with epsilon and are much less sensitive to details of the interaction. New potential parameters based on experimental scattering data for the benzene + helium system are presented, which provide very good agreement with experimental energy transfer parameters for the deactivation of benzene and azulene by helium. (C) 1996 American Institute of Physics.