EXPERIMENTAL AND THEORETICAL-STUDIES OF THE F-2 TRANSITION-STATE REGION VIA PHOTOELECTRON-SPECTROSCOPY OF FH2-(H)

The transition state region of the F + H-2 reaction is studied by phot oelectron spectroscopy of FH2-. The photoelectron spectra consist of o verlapping electronic bands with different angular distributions. The ground state band shows partially resolved features which differ depen ding on whether the anion is made from normal or para hydrogen. This d ependence on the anion nuclear spin statistics implies that these feat ures are due to progressions in bending levels of the neutral FH2 comp lex. In order to confirm this, and to determine the sensitivity of the photoelectron spectrum to the bend potential near the F + H-2 transit ion state. three-dimensional simulations of the FH2- photoelectron spe ctrum were performed assuming various potential energy surfaces for th e F + H-2 reaction. We found that the London-Eyring Polanyi-Sato surfa ce proposed by Takayanagi and Sato gave better agreement than either t he T5a or 5SEC surfaces. From the higher energy band, we can extract i nformation on the F + H-2 excited electronic states, and several appro ximate simulations on model surfaces for these states are presented.