Stereodynamics of the vibrational channel O(1D)+H2O→OH(v′=2)+OH

Abstract

The state-selected differential cross section (DCS) and rotational angular momentum polarization for the reaction O(1D)+H2O→OH+OH have been measured by utilizing the polarized Doppler-resolved laser-induced fluorescence probing technique. Stereodynamics of the reaction channel forming the newly formed OH in the specific vibrational level v′=2 is discussed on the basis of the vector properties. A nearly isotropic DCS for the product OH(2Π3/2, v′=2, j′=5.5) most probably indicates that the reaction is dominated by an insertion mechanism involving a collisional HOOH complex with a lifetime comparable to its rotational period. The extremely asymmetrical energy partitioning between the two OH fragments, therefore, suggests that the redistribution of the available energy does not occur on a time scale comparable to the rotational period of the complex. Furthermore, it has been found that the product rotational angular momentum vector j′ is predominantly perpendicular to the collision plane spanned by k and k′ (the relative velocity vectors of the reactants and products, respectively) both for the forward- and backward-scattered products. It suggests that the initially excited bending motion of the H–O–O moiety in the collisional HOOH complex primarily contributes to the product rotation.