Collisional dissociation of dimers by monomers in rare gases

Cross sections and thermal rate coefficients for single-collision dissociation in ground-state Rg2 by Rg (Rg = Ne,Ar,Kr, and Xe) were computed using Monte Carlo quasiclassical trajectories. The influence of vibrational and rotational excitation of the dissociation cross sections and rate coefficients was investigated for Ar+Ar2. The following conclusions are reached. At high collision energies the cross section for dissociation of ground-state dimers is given by πR2/sub e/ (where R/sub e/ is the equilibrium internuclear separation of the dimer). Initial vibrational excitation greatly enhances dissociation; initial rotation also enhances dissociation but not to the extent that vibration does. The temperature dependence of the rate coefficients for dissociation of ground-state dimers is shown to be well described by k = CT/sup -1/3/. The rate of Ar2 dissociation by Ar is found to be orders of magnitude greater than previously reported values