An electron-impact ionization study of molecular selenium beams

We describe the method and presents results of a mass-spectrometric investigation of the yield of positive ions formed as a result of the dissociative ionization of a molecular selenium beam by electron impact. Appearance energies of fragment ions have been determined from the ionization efficiency curves. The dynamics of formation of the molecular ions of selenium in a temperature interval of 420–495 K has been studied. The energy dependences of the efficiency of formation of singly charged Sе$_{n}^{+}$ ($n$ = 1–3) and doubly charged Se$^{++}$ ions are analyzed.