Isotopic branching in (He, HD(super +)) collisions

The isotopic branching in the reaction He + HD(super +)(v = 0, 1, 2, 3; j=0) --> HeH(D)(super +) + D(H), over a range of translational energy (E(sub trans)) is plotted on two different ab initio potential energy surface. The isotopic branching ratio for the reaction decreases in going from v=0 to v=1 and then becomes nearly v-independent in going from v = 1 to v = 3 in both the surface.