MODE-SELECTIVE AND BOND-SELECTIVE REACTIONS OF CHLORINE ATOMS WITH HIGHLY VIBRATIONALLY EXCITED H2O AND HOD

The measured OH product state distribution from the Cl + H2O (\04](-)) --> HCl + OH reaction reveals an energy disposal pattern that is similar to that in the analogous H + H2O (\04](-)) --> H-2 + OH reaction. Of the 9700 cm(-1) available energy, approximately 6% appears in internal OH excitation, approximately 21% in product translation, and the remainder (about 73%) appears as internal HCl excitation. The result that most of the available energy appears as internal energy of the newly formed diatomic molecule supports a spectator picture in which the old bond does not participate in the reaction. We measure the bond-selective branching ratio for the Cl + HOD (4 upsilon(OH)) reaction and fmd that initial excitation of the O-H bond favors the HCl + OD product channel by at least a factor of 40. Measurements of the relative reactivity of water molecules prepared in the \04](-), \04](+) and \03](-)\2] local mode vibrational states suggest that all three vibrational modes enhance the reactivity by approximately the same factor.