Differential cross section for the $H+D2→HD(v′=1,j′=2,6,10)+D$ reaction as a function of collision energy

We have measured differential cross sections (DCSs) for the HD $(v′=1,j′=2,6,10)$ products of the $H+D2$ exchange reaction at five different collision energies in the range $1.48⩽Ecoll⩽1.94eV$⁠. The contribution from the less energetic H atoms formed upon spin-orbit excitation of Br in the photolysis of the HBr precursor is taken into account for two collision energies, $Ecoll=1.84$ and $1.94eV$⁠, allowing us to disentangle the two different channels. The measured DCSs agree well with new time-dependent quantum-mechanical calculations. As the product rotational excitation increases, the DCSs shift from backward to sideward scattering, as expected. We also find that the shapes of the DCSs show only a small overall dependence on the collision energy, with a notable exception occurring for HD $(v′=1,j′=2)$⁠, which appears bimodal at high collision energies. We suggest that this feature results from both direct recoil and indirect scattering from the conical intersection.