Vibrational Mode-Specific Dynamics of the OH + XO→ H + XO2 (X = C/S) Reactions: Similar Topologies, Different Dynamics.

The prototypical complex-forming reactions of OH + CO and OH + SO are critical elementary processes in atmospheric chemistry and combustion systems. The vibrational mode-specific quasi-classical trajectory (QCT) investigations for these two reactions were performed on full-dimensional globally accurate potential energy surfaces (PESs). Integral cross-sections (ICS), differential cross-sections (DCS), and product energy distributions for different vibrational excitation modes were calculated and analyzed. Although both exothermic oxygen-transfer reactions share similar topological features in their PES profiles, their energy landscapes exhibit pronounced differences, giving rise to entirely distinct dynamic and kinetic behaviors. This work will advance our understanding of how PES topology, collision energy, and mode-specific vibrational excitation jointly govern reactivity and energy dissipation in radical oxidation processes involving carbon- and sulfur-containing oxides.