THE IONIZATION AND DISSOCIATION OF SOME HALOGEN MOLECULES BY ELECTRON IMPACT

Abstract

The ionization and dissociation of chlorine, bromine, iodine, iodine monochloride, and iodine monobromide by electron impact have been studied in a mass spectrometer which uses a monoenergetic electron source. Many ionization potentials have been observed for these molecules which, of course, refer to the formation of the parent molecular ions in different excited states. These experimental results are discussed in terms of simple molecular orbital theories of the electronic structures of the different halogen molecules.Electron-induced dissociative ionization processes for the different substances have also been studied. Where possible, appearance potentials of both the positive and negative ions have been determined. These results have been used to construct potential energy diagrams illustrating the origin of some of the negative ion and dissociation processes observed.