A three dimensional quantum reactive scattering study of the I+HI reaction and of the IHI− photodetachment spectrum

Abstract

In this paper, we present the results of coupled channel hyperspherical reactive scattering calculations on the reaction I+HI→IH+I using a semiempirical potential surface. Only the J=0 partial wave is considered. The bimolecular reaction probability is found to exhibit two sharp resonant peaks at energies below threshold for direct reaction. The resonances are associated with transition state quantum numbers (ν1ν2ν3)=(100) and (200), and their energies are in excellent agreement with the result of L2 calculations due to Clary and Connor, and to Bowman and Gazdy. At higher energy the reaction is dominated by rotational threshold effects, and then below the HI(ν=1) energetic threshold, additional resonances are found which correspond to quantum numbers (002), (102), (202), and (302). Franck–Condon factors associated with photodetachment of IHI− have also been calculated, and these show mainly direct scattering threshold behavior at low energies (E<0.30 eV), with the (100) and (200) resonances contributing only slightly. Resonant behavior is dominant at higher energies (0.3–0.4 eV) where the (002) resonance especially contributes. Agreement of our calculated photodetachment spectra with experimental results due to Neumark and co-workers is good provided that an 0.08 eV energy shift is made in the calculated spectra. This shift is probably due to an incorrect energy barrier on the semiempirical surface.