Studies of Simple Chemical Reactions in Solution: Iodine Photodissociation, Recombination, and Relaxation and the Development of Autoregressive Procedures for Application to Stochastic Simulations.

摘要

Picosecond time-resolved experimental studies of the iodine photodissociation and recombination reaction were performed in order to clarify the early time dynamics of the dissociation and solvent caging processes. Results suggest that predissociation is much more rapid ((le) 1 ps) than previously thought, and also indicate that geminate recombination may be rapid ((le) 2 ps). A simple theoretical model for vibrational relaxation of diatomic molecules in solution, based on the generalized Langevin equation (GLE), was also developed. In this model, the memory function in the GLE is determined directly form equilibrium force autocorrelation functions for the individual atoms of the diatomic dissolved in the solvent of interest. The vibrational relaxation model was tested on the system of iodine in liquid xenon, and through comparison with molecular dynamics simulations was shown to perform very well. Results are discussed in terms of simplifying assumptions that the solvent interaction with the diatomic can be characterized by equilibrium dynamics of single atoms in solution. 117 refs., 17 figs., 3 tabs.