A time-of-flight study of H+ fragments produced by low-energy electron bombardment of the hydrogen halides

Time-of-flight and kinetic energy distributions were obtained for H+ fragments resulting from electron bombardment of HF, HCl, HBr, and HI at electron energies between 21.2 and 51.2 eV. Several distinct features were observed in these spectra for each molecule and the corresponding threshold electron bombarding energies were obtained. Some of these features are proposed to originate from dissociation of HX+ which is excited by removing an inner σ-shell electron in the corresponding molecule. Results from recent (e,2e) experiments support this proposal.