Stereodynamics of the vibrational channel O(D-1)+H2O -> OH(v '=2)+OH

The state-selected differential cross section (DCS) and rotational angular momentum polarization for the reaction O(D-1) + H2O-->OH+OH have been measu red 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 upsilon' = 2 is discussed on t he basis of the vector properties. A nearly isotropic DCS for the product O H((2)Pi(3/2), upsilon' = 2, j' = 5.5) most probably indicates that the reac tion is dominated by an insertion mechanism involving a collisional HOOH co mplex with a lifetime comparable to its rotational period. The extremely as ymmetrical energy partitioning between the two OH fragments, therefore, sug gests that the redistribution of the available energy does not occur on a t ime 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' (th e relative velocity vectors of the reactants and products, respectively) bo th for the forward- and backward-scattered products. It suggests that the i nitially excited bending motion of the H-O-O moiety in the collisional HOOH complex primarily contributes to the product rotation. (C) 1999 American I nstitute of Physics. [S0021-9606(99)00816-8].