ONE-ATOM CAGE EFFECT IN I2-AR COMPLEXES - CAN IT BE EXPLAINED BY LINEAR GROUND-STATE ISOMERS

We have performed three-dimensional quasiclassical trajectory calculations to study the fragmentation and recombination dynamics (one-atom cage effect) of the I2-Ar van der Waals complex following excitation above the dissociation limit of the I2(B) electronic state. In particular, we have studied the influence of the ground electronic state equilibrium geometry on the recombination probabilty. For this, trajectories have been calculated using two different sets of initial conditions corresponding to linear and T-shaped ground state isomers. The potential energy surface for the I2(B) excited state was taken as a sum of pairwise interactions with semiempirical parameters taken from the literature. It was found that, although the initially linear isomers have (as expected) a higher probability to recombine than the T-shaped ones, the amount of vibrational to translational energy transfer is still far too small as compared to the experimental findings. It is concluded that a pure ballistic mechanism for the one-atom cage effect in I2-Ar is not consistent with experiments.