EXPERIMENTAL AND THEORETICAL-STUDY OF THE O-STATE REGION BY PHOTODETACHMENT OF OHCL-(HCL TRANSITION)

We present measured and calculated photodetachment spectra of OHCl-, a nd we interpret the results in terms of the vibrational structure of t he transition state of the O+HCl-->OH+Cl reaction. The measured spectr a exhibit two distinct features-an intense broad peak at high electron kinetic energies and a less intense shoulder at lower energies. Super imposed on these broad features are several sharper structures, but th ey are barely discernible from noise in the spectrum. To interpret the se spectra, we have used a recently developed global (3)A'' potential surface for the O+HCl reaction to calculate Franck-Condon factors, usi ng an L(2) method (i.e., expansion in terms of square integrable basis functions) to approximate the scattering wave functions on the reacti ve surface. Assignment of the spectrum has been assisted using the res ults of quantum coupled channel calculations for the same surface. The resulting calculated spectrum shows the same broad features as the me asured spectrum. There is also fine structure with spacings and energi es that are similar to the experiment, but specific features do not ma tch. To interpret both the broad and fine features in the theoretical spectrum, a hierarchical analysis is applied wherein this spectrum is decomposed by a tree construction into components of increasingly high er resolution. The physical meaning of each of these components is the n determined by plotting ''smoothed states'' that are obtained from th e tree coefficients. This leads to the conclusion that the two broad f eatures in the spectrum are made up of progressions in hindered rotor states of the Cl-OH complex, with the most intense feature correspondi ng to OH(v=0) and the weaker shoulder corresponding to OH(v=1). There is evidence for Feshbach resonance features in the v=1 feature, but it appears that most of the fine structure is due to hindered rotor stat es.