SELECTIVELY BREAKING EITHER BOND IN THE BIMOLECULAR REACTION OF HOD WITH HYDROGEN-ATOMS

We have deter-mined the branching ratio for the reaction of hydrogen atoms and HOD with either the O-H bond excited or the O-D bond excited. In both cases, the initially excited bond reacts preferentially. Excitation of the third O-H stretching overtone, 4nu(OH), favors breaking the O-H bond by a factor of approximately 200, and excitation of the fourth O-D stretching overtone, 5nu(OD), favors breaking the O-D bond by a factor of approximately 220. Thus vibrational excitation can control the H+HOD reaction to produce either product almost exclusively. A simple model using the calculated wave function for each state and the measured reaction cross section for a particular vibrational excitation predicts the high selectivity observed for the two reactions.