Rotational Distributions in the Photodetachment of IHI − and in the I + HI Reaction: The Influence of IHI Transition State Resonances

Franck‐Condon factors which determine IHI − photodetachment spectra have been calculated using a three‐dimensional coupled‐channel reactive scattering program. These Franck‐Condon factors show peaks as a function of energy that are in reasonable agreement with measured spectra due to Neumark and co‐workers. Some of these peaks are due to IHI transition state resonances and others are due to direct scattering reactive threshold effects. An analysis of the rotational distributions associated with the Franck‐Condon factors indicates that when direct scattering is dominant, the distributions peak at the rotational state which is nearest to its effective reaction threshold. At energies where IHI transition state resonances are important, the rotational distribution changes, thus providing a characteristic signature of resonance formation. The I + HI bimolecular rotational distributions are also considered, and they also show important differences between direct and resonant energies.