The kinetic and dynamic characteristics of the reaction of H atoms with electronically excited O2 were studied using the quasiclassical trajectory (QCT) method and the potential energy surface of Li et al. (J. Chem. Phys. 2010, 133, 144306-144314). The reaction takes place via a deep potential well that can be entered by climbing a barrier in the reactant valley and can be left without a barrier on the product side. In this reaction, the basic assumptions of statistical rate theories are not fulfilled: (i) 80% of the trajectories cross the barrier region twice and are nonreactive; (ii) the energy is not equilibrated in the HO2 potential well. The QCT cross sections agree well with those from the existing exact quantum-mechanical data and extend them to vib-rotationally excited reactants. The thermal rate coefficients agree well with measurements of pure reactive quenching of O2(1Δg) and are lower than those involving both reactive and electronic quenching. The temperature dependence is described as k2 = 5.81 × 10-16 T1.45 exp(-2270/T) cm3 molecule-1 s-1. On the basis of a comparison of the QCT data with the two kinds of experiments, we estimate that electronic quenching is faster than reaction by a factor of about 10 at low and 2 at high flame temperatures.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry