State-resolved differential and integral cross sections for the reaction H+D2→HD(v′=3,j'=0-7)+D at 1.64 eV collision energy

A 212.8 nm laser initiates the reaction H+D-2-->HD+D in a mixture of HBr and D-2. A second laser state-selectively ionizes the HD(v'=3,j') reaction product, allowing a determination of the speed distribution and the relative cross section in a velocity-sensitive time-of-flight mass spectrometer. From these measurements we construct differential and integral cross sections for H+D-2-->HD(v'=3,j'=0-7)+D at 1.64+/-0.05 eV collision energy. Although the integral cross sections do not show any unusual features, the differential cross sections reveal forward-scattered features that have not been observed in crossed-beam experiments. An analysis of the scattering features in HD(v'=3,j'=1-4) suggests that these states are dominated by classical hard-sphere scattering. This hard-sphere (direct recoil) mechanism, however, cannot account for the dominant forward scattering observed in HD(v'=3,j'=0). (C) 2002 American Institute of Physics.