Ionization Processes in CCl4 and SF6 by Electron Beams

Abstract

The ionization processes in CCl₄ and SF₆ have been studied for both positive and negative ions in a mass spectrometer, and in a total ionization tube. The appearance potential of Cl⁻ is 0+0.05 ev with a very sharp energy dependence. A second process with an onset at about 0.4 ev and a maximum at about 0.7 ev, exhibits a much broader energy dependence. The relative intensities of these two processes are found to be extremely sensitive to the energy distribution of the electron beam, but do not appear to exhibit a temperature dependence. From the appearance potentials and kinetic energy measurements of Cl⁻ a value of 3.30±0.07 ev is obtained for D(CCl₃–Cl). The appearance potential curves for CCl₃⁺ and SF₅⁺ near threshold indicate structure which may be associated with energy states of these ions.