Steric effect on o–p conversion of a H2 interacting with a 3d impurity sitting on a metal oxide surface

Steric effect on the o–p conversion of a H2 interacting with a 3d impurity sitting on a metal oxide surface is investigated by comparing the o–p conversion yield/rate for a H2 doing cartwheel-like rotation (i.e., the rotational axis of H2 is parallel to the surface) with that for a H2 doing helicopter-like rotation (i.e., the rotational axis of H2 is perpendicular to the surface). The yield of o–p H2 conversion is calculated by using the perturbation theory, where Fermiʹs contact interaction (intra-molecular hyperfine contact interaction) and the H2-surface electron exchange interaction (Coulomb interaction) represent the perturbation terms. On the basis of the calculated results, for the transition from the lowest rotational state of an ortho H2 (with rotational quantum number j=1) to the lowest rotational state of a para H2 (j=0), the o–p H2 conversion yield shows that for a H2 doing cartwheel-like rotation is higher than that for a H2 doing helicopter-like rotation.