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 D–H–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.