Stereodynamical control of cold HD + D 2 collisions.

We report full-dimensional quantum calculations of stereodynamic control of HD( v = 1, j = 2) + D 2 collisions that has been probed experimentally by Perreault et al. using the Stark-induced adiabatic Raman passage (SARP) technique. Computations were performed on two highly accurate full-dimensional H 4 potential energy surfaces. It is found that for both potential surfaces, rotational quenching of HD from with concurrent rotational excitation of D 2 from is the dominant transition with cross sections four times larger than that of elastically scattered D 2 for the same quenching transition in HD. This process was not considered in the original analysis of the SARP experiments that probed Δ j HD = -2 transitions in HD( v HD = 1, j HD = 2) + D 2 collisions. Cross sections are characterized by an l = 3 resonance for ortho -D 2 ( j D 2 = 0) collisions, while both l = 1 and l = 3 resonances are observed for the para -D 2 ( j D 2 = 1) partner. While our results are in excellent agreement with prior measurements of elastic and inelastic differential cross sections, the agreement is less satisfactory with the SARP experiments, in particular for the transition for which the theoretical calculations indicate that D 2 rotational excitation channel is the dominant inelastic process.