Journal of Chemical Physics, Vol.101, No.5, 3696-3703, 1994
Electron-Impact Dissociation of HCl - Translational Energy and Angular-Distributions of Excited Hydrogen-Atoms
Electron-impact dissociation of HCl for the formation of excited hydrogen atoms (n=4) has been investigated by measuring Doppler profiles of the Balmer lines and their angular dependence at a high optical resolution using a Fabry-Perot interferometer. The translational energy distribution (TED) and the angular difference Doppler profile were obtained. There are five major dissociation processes for the formation of H* (n=4). The threshold energy and the TED peak of the five components are (1) 19 and 2.5; (2) 25 and 7.2; (3) 29 and 1.7; (4) 36 and 5.1; and (5) >40 and 8-12 eV, respectively. Formation of components 1 and 4 is anisotropic and parallel with respect to the electron beam. Component 1 should be produced by predissociation through the Rydberg slates with the Sigma symmetry converging to either the (4) Sigma or (2) Sigma(-) state and then those converging to the A (2) Sigma(+) state. The asymmetry parameter (beta of component 1 was determined to be about 0.62, and the intermediate excited state for the formation of component 1 has a lifetime equal to the rotational period. Component 2 would be produced through the Rydberg states converging to the (2) Pi state. Component 3 would be produced through high-lying doubly excited Rydberg states converging to either the (4)(2) Pi or (4)(2) Sigma(+) state. Component 4 should be produced through doubly excited repulsive states with the Sigma symmetry.
Keywords:DIFFERENCE DOPPLER PROFILES;PHOTOELECTRON-SPECTRUM;PRODUCTION MECHANISM;BALMER LINE;H-STAR;COLLISIONS;PHOTODISSOCIATION;DYNAMICS;CHLORIDE;DEPENDENCE