Abstraction versus exchange in the reaction of H with DBr

Publisher Website
Google Scholar
Abstract
The photolysis of DBr−H2−Br2 mixtures at 185 nm furnishes data which can be analyzed to provide the abstraction to exchange rate coefficient ratio k8/k9 for reactive collisions of H with DBr where H is a translationally hot atom with an average energy of about 1 eV. The results of such experiments are reported here and are analyzed using (1) an assumed mechanism, (2) available independent experimental data, (3) some quasiclassical trajectory data, and (4) an isotope effect model based on collision frequencies to give 0.2 ? k8/k9 ? 0.8. In addition quasiclassical trajectory calculations have been used to generate model data for direct comparison with the experimental data. These calculations, using potential energy surfaces which have been very successful in accounting for a variety of other experimental data, give k8/k9 = 0.24, as well as values for the other rate coefficients in the mechanism. With a single adjustable parameter used to fit the intercept in one experiment, these trajectory calculations are in quite satisfactory agreement with the experimental data provided D−atom exchange with DBr is incorporated as a significant mechanism for thermalization of hot D atoms. It is also shown that the photolysis data are consistent with trajectory calculations that give an abstraction to exchange ratio for thermal H atoms that lies in the range 0.2−1.0.

This publication has 31 references indexed in Scilit: