QUASI-CLASSICAL TRAJECTORY STUDY OF COLLISIONAL ENERGY-TRANSFER IN TOLUENE SYSTEMS .2. HELIUM BATH GAS - ENERGY AND TEMPERATURE DEPENDENCES, AND ANGULAR-MOMENTUM TRANSFER

The collisional deactivation of highly vibrationally excited toluene-d 0 and toluene-d8 by helium bath gas has been investigated using quasiclassical trajectory simulations. Collisional energy transfer was found to increase with initial toluene internal energy, in agreement with the experiments of Toselli and Barker [J. Chem. Phys. 97, 1809 (1992), and references therein]. The temperature dependence of 〈ΔE 2〉1/2 is predicted to T(0.44±0.10), in agreement with the experiments of Heymann, Hippler, and Troe [J. Chem. Phys. 80, 1853 (1984)]. Toluene is found to have no net angular-momentum (rotational-energy) transfer to helium bath gas, although 〈ΔJ 2〉1/2 has a temperature dependence of T (0.31±0.07). Re-evaluation of earlier calculations ["Paper I:" Lim, J. Chem. Phys. 100, 7385 (1994)] found that rotational energy transfer could be induced by increasing the mass of the collider, or by increasing the strength of the intermolecular interaction: in these cases, angular-momentum transfer depended on the initial excitation energy. In all cases, the final rotational distributions remained Boltzmann. © 1994 American Institute of Physics.