SPECTROSCOPY OF THE TRANSITION-STATE - ELEMENTARY REACTIONS OF THE HYDROXYL RADICAL STUDIED BY PHOTOELECTRON-SPECTROSCOPY OF O-(H2O) AND H3O2-

The transition state regions of the OH+OH→O(3P)+H 2O and the OH+H2O→H2O+OH reactions are studied by photoelectron spectroscopy of the O-(H2O) and H3O2- anions and their deuterated analogs. The spectra show resolved vibrational progressions attributed to H-atom vibrational motion in the unstable neutral complexes formed by photodetachment. The positions and intensities of the peaks change markedly upon isotopic substitution. One-dimensional Franck-Condon calculations using ab initio potentials for the anion and neutral are used to interpret the peak spacings and intensities, as well as the strong isotopic effects. The results are discussed in the context of previously obtained transition state spectra for heavy+light-heavy reactions. © 1995 American Institute of Physics.