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

The transition state region of the F + H-2 reaction is studied by photoelectron spectroscopy of FH2-. The photoelectron spectra consist of overlapping electronic bands with different angular distributions. The ground state band shows partially resolved features which differ depending on whether the anion is made from normal or para hydrogen. This dependence on the anion nuclear spin statistics implies that these features are due to progressions in bending levels of the neutral FH2 complex. In order to confirm this, and to determine the sensitivity of the photoelectron spectrum to the bend potential near the F + H-2 transition state. three-dimensional simulations of the FH2- photoelectron spectrum were performed assuming various potential energy surfaces for the F + H-2 reaction. We found that the London-Eyring Polanyi-Sato surface proposed by Takayanagi and Sato gave better agreement than either the T5a or 5SEC surfaces. From the higher energy band, we can extract information on the F + H-2 excited electronic states, and several approximate simulations on model surfaces for these states are presented.