Effect of collision energy on the reaction mechanism of C((3)P) + OH(X(2) Π) → CO(X(1) Σ(+)) + H((2)S).

Quasiclassical trajectory calculations based on a fully global ab initio potential energy surface of the rotational angular momentum polarisation of the product CO in the title reaction are reported. The alignment and orientation of the rotational angular momentum of the CO fragment in the scattering frame were found to be sensitive to the initial collision energy chosen. Differences in the angular momentum polarization at different collision energies were traced to differences in the microscopic reaction mechanism. The results of this study suggest that the title reaction is mainly dominated by an abstraction reaction mechanism (involving the short-lived and metastable intermediate complex COH) at low collision energies; however, at relatively high energies, an insertion reaction mechanism (involving the long-lived and stable intermediate complex HCO) plays a role.