Journal of Physical Chemistry A, Vol.119, No.28, 7180-7189, 2015
A Quasiclassical Trajectory Study of the Reaction of H Atoms with O-2((1)Delta(g))
The kinetic and dynamic characteristics of the reaction of H atoms with electronically excited O-2 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 O-2((1)Delta(g)) and are lower than those involving both reactive and electronic quenching. The temperature dependence is described as k(2) = 5.81 X 10(-16) T-1.45 exp(-2270/T) cm(3) 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.