Quasiclassical trajectory studies of the dynamics of the F + I2→ IF + I reaction

Abstract

The reaction F + I₂ has been studied using quasiclassical trajectory methods on several empirical surfaces all possessing a constant well depth corresponding to the reaction intermediate, I₂F, which is known to be a stable species. A greater attraction on the potential surface decreases the product vibrational excitation whilst an increase in the initial translational energy causes an increase in the product rotation at the expense of vibration, also enhancing slightly the translational energy of the products. A percentage of the reactive trajectories involve attractive secondary encounters, with migration of the F atom occurring in a few cases; these trajectories produce IF with less vibrational energy, more translational energy and more forward scattering than do trajectories with direct collisions. This study suggests that attractive secondary encounters may explain the bimodal vibrational product state distribution observed in experimental studies; direct collisions lead to the formation of highly vibrationally excited IF whilst indirect collisions with attractive secondary encounters create a monotonically decreasing population distribution within low vibrational levels.