Vibrational Energy Transfer Probabilities of Highly Vibrationally Excited Dichloroethane with Argon, Krypton, Xenon, and Sulfur Hexafluoride

Abstract

The competition between unimolecular reaction and collisional deactivation of chemically activated 1,2-C2H4Cl2, 〈 E〉 = 88 kcal mol−1, was studied using Ar, Kr, Xe, and SF6 as bath gases. Sufficient data were collected to establish the high pressure rate constant and the increase in the rate constant with declining pressure for each gas. The results were fitted to a cascade deactivation scheme using gas kinetic collision diameters to define the collision frequency. Exponential transition probability models were assigned to argon and krypton with average down transition probabilities per collision of 3.5–4.5 kcal mol−1, which is substantially larger than the average energy removed by He and Ne. Xenon could be fitted by this model, or by a stepladder model with 〈Δ E〉 = 5 kcal mol−1. A stepladder model with an average down transition probability of 7 kcal mol−1 was assigned to SF6. The experimental results that have been accumulated (12 gases) for collisional deactivation of 1,2-C2H4Cl2 are summarized.