Orientation dependence in the reaction of Xeast; with photodissociation polarized IBr

摘要

The reaction of metastable Xeast; with IBr to produce XeIast; and XeBrast; excimers was studied in crossed molecular beams. The IBr beam was rotationally polarized by using laser photodissociation to selectively remove most of theMstate distribution. The reaction cross section was found to be largest when the Xeast; approaches parallel to the plane of rotation of the IBr, and smallest when the Xeast; approaches perpendicular to the plane of rotation. Reaction models for excimer formation are discussed, and it is concluded that the observed steric effect results from the anisotropy of the ionic Xe+/IBrminus;(2Pgr;) potential surface, involving the first excited state of IBrminus;, which is the intermediate state in the formation of XeIast;.