Negative Ions in the Gas Phase Observed in Electron Transmission and Electron Attachment Spectroscopy

A new electron transmission spectrometer is applied to study the formation of negative ions in ethylene and the fluoroethylenes. It is found that the electron attachment energy in the fluoroethylenes observed in electron transmission completely coincides with the energy of the resonances associated with the formation of F − (and various other stable negative fragments) observed in dissociative electron attachment. This demonstrates that the combination of electron transmission and dissociative electron attachment spectroscopy yields information on the formation and decomposition of molecular negative ions in the gas phase.