The effect of reagent excitation on the dynamics of the reaction O(1D2)+H2→OH(X 2Π)+H

Abstract

The effect of H2 translational, rotational, and vibrational excitation on the dynamics of the O(1D2)/H2 reaction are explored in a semiclassical trajectory study involving both of the energetically accessible potential energy surfaces of the system. Landau–Zener probabilities determine surface hopping. At low reagent excitation, the deep H2O potential minimum dominates the dynamics, causing the reagents to reorient towards a H–O–H (insertion) configuration and form the H2O intermediate, irrespective of the initial approach geometry. High vibrational excitation enhances the probability for transitions onto the excited state potential during the interaction. Reactions which sample the excited state potential have fundamentally different dynamics from those which remain on the lower state. For reactions involving H2(v=4), the OH product has a bimodal vibrational distribution, peaking in OH(v′=2) and OH(v′=9). The lower peak is due to reactions which access the excited state potential; the higher peak results from those which remain on the lower state for the entire interaction. High translational excitation shortens the interaction time and reduces the effect of the potential minimum to reorient the reagents. Rotational excitation also reduces the effect of the potential minimum by causing the system to rotate out of the insertion geometry before entering the potential minimum.