Photodetachment spectrum of OHF-: Three-dimensional study of the heavy–light–heavy resonances

Abstract

In this work a simulation of the OHF- photodetachment spectrum is performed in a three-dimensional potential energy surface recently developed for OHF(3A''). The ground 2A' state potential of the anion is calculated in three dimensions based on accurate ab initio calculations and the reaction dynamics is studied using a wave packet method. The calculated spectrum shows a sequence of bands associated to vibrational HF(ν) up to ν = 3. Each band is formed by a continuous spectrum and resonant structures. These resonances are associated to the OH–F channel well of the 3A'' PES, in which fragmentation occurs through vibrational predissociation. Above the OH(ν = 0) threshold a new resonant pattern appears corresponding to heavy–light–heavy resonances. Special attention is paid to the assignment of these resonances because they mediate the reaction dynamics in the OH + F collision at low kinetic energies. The sequence of bands is in rather good agreement with that appearing in the experimental spectrum, especially at higher electron kinetic energies. At low kinetic energies, however, some other electronic states may contribute. The resonance structures might be washed out by the rotational average and the relatively low energy resolution of the experiment.