Differential cross section for dissociative attachment in HCl: Cl^-and H^-formation

Abstract

A modified electron impact spectrometer is used to study Cl- and H- formation in HCl by dissociative attachment. It is shown that the Cl- ion yield exhibits a small, new structure located at the maximum of the main peak in addition to the well known structure on the high-energy tail at the vibrational levels of HCl. The H- ion yield exhibits two peaks at 7.1 and 9.3 eV. The first one is structureless with a non-vertical onset and the angular distribution of the H- is characteristic of a d sigma wave. These results indicate that H- formation in the energy range of this peak proceeds via a repulsive 2 Sigma + HCl- state. The second peak, which proceeds via a 2 Pi HCl- state, exhibits a structure on the high-energy tail and the angular distribution of the H- ions is characteristic of a d pi wave. The structures in this peak are attributed to the interaction of the 2 Pi state of HCl- with the series of Feshbach resonances associated with Rydberg states of HCl.