Photoelectron-photofragment coincidence study of OHF-: transition state dynamics of the reaction OH + F --> O + HF.

A photoelectron-photofragment coincidence (PPC) study of the dissociative photodetachment of OHF at a photon energy of 4.80 eV is presented. The correlated electron kinetic energy (eKE) and translational energy release (E(T)) into the O + HF + e- products yield information on the potential energy surface close to the transition state of the neutral reaction OH + F --> O + HF. The correlation spectrum shows two different features in the energetically allowed O + HF product channel: (a) diagonal ridges, resulting from direct dissociative photodetachment (DPD) and (b) areas with higher E(T) in the neutral fragments from nonadiabatic dissociation. The total translational energy spectrum (E(TOT) = eKE + ET) reveals a vibrationally resolved product state distribution. These results are discussed in the context of recent theoretical studies of the dissociative photodetachment of OHF-.