The ionization processes in CCl4and SF6have been studied for both positive and negative ions in a mass spectrometer, and in a total ionization tube. The appearance potential of Clminus;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 Clminus;a value of 3.30plusmn;0.07 ev is obtained forD(CCl3sngbnd;Cl). The appearance potential curves for CCl3+and SF5+near threshold indicate structure which may be associated with energy states of these ions.
展开▼
