Potential energy surface effects on differential cross sections for polyatomic reactions

The effect on differential and integral cross sections of varying the potential energy of the entrance channel to a polyatomic reaction is investigated theoretically. The rotating bond approximation (RBA) is used for the CH₄+OH → CH₃+H₂O reaction. The reaction exhibits peripheral dynamics, with a higher reactivity at higher impact parameters. Due to the significant potential barrier the scattering of the products is however sideways and not forward. It is found that varying the long-range isotropic terms in the potential has almost no effect on the opacity function or the cross sections. The addition of long range anisotropic terms induces rotational transitions of the OH reactant and thereby reduces the reactivity at higher impact parameters, resulting in backward scattering.