Atom-Molecule Reaction D+H2 → HD+H Studied by Molecular Beams

Abstract

Collisions between deuterium atoms and hydrogen molecules have been studied in a modulated crossed beam experiment. The relative signal intensity and the signal phase for product HD from reactive collisions allowed determination of both the angular distribution and HD mean velocity as a function of angle. From these a relative differential reactive scattering cross section in center‐of‐mass coordinates was deduced. The experiment indicates that reactively formed HD having little or no internal excitation, departs from the collision anistropically, with maximum amplitude 180° from the direction of the incident D beam in c.m. coordinates, which shows that the $\mathrm{D}–\mathrm{H}–\mathrm{H}$ reacting configuration is short‐lived compared to its rotation time. Nonreactive scattering of D by H₂ was used to assign absolute values to the differential reactive scattering cross sections.