Cl + HD (v=1; J=1,2) reaction dynamics: Comparison between theory and experiment

Vibrationally state-resolved differential cross sections (DCS) and product rotational distributions have been measured for the Cl+HD(v=1, J=1)--> HCl( DCl)+D(H) reaction at a mean collision energy of 0.065 eV using a photoinit iated reaction ("photoloc") technique. The effect of HD reagent rotational alignment in the Cl+HD(v=1, J=2) reaction has also been investigated. The e xperimental results have been compared with exact quantum mechanical and qu asiclassical trajectory calculations performed on the G3 potential energy s urface of Allison [J. Phys. Chem. 100, 13575 (1996)]. The experimental meas urements reveal that the products are predominantly backward and sideways s cattered for HCl(v'=0) and HCl(v'=1), with no forward scattering at the col lision energies studied, in quantitative agreement with theoretical predict ions. The experimental product rotational distribution for HCl(v'=1) also s hows excellent agreement with quantum-mechanical calculations, but the meas ured DCl+H to HCl+D branching ratio is near unity, which is at variance wit h the theoretical calculations that predict about 3 times larger yield of H Cl+D at these collision energies. The reactivity shows a marked dependence on the direction of the HD(v=1, J=2) rotational angular momentum, and exper imental measurements of this reagent alignment effect are in good agreement with theoretical predictions. (C) 2000 American Institute of Physics. [S00 21-9606(00)02002-X].