The dynamics of the prototype abstraction reaction Cl(2P3/2,1/2) + H2: A comparison of crossed molecular beam experiments with exact quantum scattering calculations on coupled ab initio potential energy surfaces

To investigate the relative reactivity of the two spin–orbit states of atomic Cl with molecular hydrogen, we have measured laboratory-frame differential cross sections (DCSs) using an atomic Cl beam with a known concentration of the ground (2P3/2) and excited (2P1/2) spin–orbit states. The experimental results are compared with a complete determination of the appropriate centre-of-mass DCSs from quantum mechanical scattering calculations on the Capecchi–Werner coupled ab initio potential energy surfaces (PESs). The multi-electronic-state quantum scattering prediction differs somewhat from the experimental results. This disagreement is likely due to an underestimation of the degree of rotational excitation of the HCl product, due to residual imperfections in the exit channel of the ab initio PESs. In particular, an increase in the reactivity of the excited spin–orbit state would result in poorer agreement with experiment.