One-atom cage effect in collinear I2(B)–Ar complexes: A time-dependent wave packet study

Abstract

Two-dimensional time-dependent wave packet calculations are carried out on a collinear model of the I2(B)–Ar complex to investigate the possible kinematic origin of the one-atom cage effect in small van der Waals molecules. Three different excitation wavelengths are considered (496.5, 488, and 476.5 nm), and the dynamics are assumed to be restricted to the I2 B state electronic surface, with no nonadiabatic transitions following the pump excitation. Good agreement with experiment is obtained. To investigate the sensitivity of observable final state distributions on the weak intermolecular potential between I2 and Ar, three slightly different B state I–Ar interactions are employed for the case of 488 nm excitation. It is found that relatively small changes in the form and magnitude of the weak van der Waals interactions can have a large effect on the final state distributions. These results suggest that the experimental data on I2–Ar photodissociation–recombination can be explained by a purely kinematic one-atom cage effect on the B state electronic surface for a collinear population of I2–Ar clusters, without the need to introduce nonadiabatic electronic effects.