Reactive scattering from double minimum potentials: Li+ catalyzed elimination reactions of alkyl halides

We present a study of the dehydrohalogenation reactions of Li+ with isopropyl chloride (IPC), n-propyl chloride (NPC), and isopropyl bromide (IPB) over the collision energy range from 0.6 to 1.7 eV. Full differential cross sections at collision energies up to 1.2 eV show increasing asymmetry in the angular distributions as a function of initial collision energy and suggest that the reactions take place on a time scale of 0.2 ps. The observation of Li+ nonreactively ejected from the initial encounter complex formed by approaching reactants is consistent with a double minimum reaction coordinate and a comparison of the nonreactive flux with the flux for elimination products allows an estimate of the heights of intermediate isomerization barriers separating the wells on the potential surface. The barrier heights are in the order IPC