Translational Energy Distribution and Relative Emission Cross Section of Excited Hydrogen Atom Produced in Electron-chloroform Collisions

Abstract

Abstract Dissociative excitation of CHCl3 and CDCl3 has been investigated by means of the controlled electron impact and the high resolution emission spectroscopy. The emission spectrum shows such excited species as H, CH, CH+, Cl+, CCl, and HCl+. The excitation function of H* has two thresholds, 20.5 and 41.0 eV. The emission cross spections of H* and D* reveal an isotope effect, which is dependent on the excitation energy and the principal quantum number. Translational energy distributions of H* and D* have been determined from the Doppler line shape of the Balmer-β line, and average translational energies from the half-width of the Balmer-α, β, γ, and δ lines. There are no noticeable isotope effect for the translational energy; their major peaks lie at 0–1, 4, and 6–12 eV. These findings indicate that there are at least three major processes for the formation of the excited hydrogen atom. They are assigned to dissociative excitation through the Rydberg states converging to the (2a1)1 ionic states and through excited Rydberg states.