Study of Negative Ion Formations by Electron Impact I. Negative Ions Produced from Acrylonitrile

抄録

Utilizing a conventional electron gun and mass spectrometer, the formation of negative ions at wide electron energies(0 to 100 ev)have been investigated for an acrylonitrile. The ionization efficiency curves have been obtained for the negative ions including C^-, CH^-, C₂^-, C₂H^-, CN^-, HCN^-, C₃^-, CCN^-, CHCN^-, C₂CN^-, C₂HCN-and C₂H₂CN^-. The appearance potentials of these negative ions have been determined for both processes of the dissociative resonance capture and ion-pair production, and some of the ions have two or more appearance potentials in each processes. The O^-ions produced from O₂ and CO were used for an energy calibration establishing the appearance potentials, and SF₆^-ions from SF₆ were also used on energy calibra tion for the electron energy near zero ev. The pressure effects of the formation of these negative ions have been studied in various electron energies over the whole pressure ranges(presumably from10^-4to 10^-7 mmHg in the ionization chamber). From the studies of the pressure effects the negative ion formation, it has been observed that the intensities of the negative ions produced by the processes of all dissociative resonance capture were increased lineary for pressure increased, but on the other hand the processes of the ion-pair production indicated more complicated depen dency, that the dependencies of the ion intensity on the pressure have various mode among the ions from 1st to 4th order against the pressure. Possible explanations of the formation mechanisms of the negative ions are discussed.