Interaction of Electronically Excited CO(a^3 Π_r) Molecules with H, H2, and H2O: Potential Energy Surfaces and Reaction Kinetics

The kinetics of elementary reactions of H, H2, and H2O species with electronically excited CO(triplet Π state) is theoretically studied using the multireference second-order perturbation theory. The corresponding thermodynamically and kinetically favored reaction pathways are identified. It has been revealed that the reactivity of CO(a3Πr) to these small H-containing species is much higher than that of the ground state CO(X1Σ+) molecule. Appropriate thermal rate constants for specified reaction channels with CO(a3Πr) are calculated using the Rice–Ramsperger–Kassel–Marcus theory-based master equation approach and the capture approximation. The obtained temperature-dependent rate coefficients can be incorporated into the future kinetic submechanisms aimed to describe the CO(a3Πr−X1Σ+) ultraviolet flame chemiluminescence. The corresponding Arrhenius-type expressions are reported for a wide temperature range (T=200−3000 K), relevant to atmospheric and combustion chemistry.