Mass Spectrograph Analyses, and Critical Potentials for the Production of Ions by Electron Impact, in Nitrogen and Carbon Monoxide

The dissociation products formed by bombarding nitrogen and carbon monoxide with electrons of a definite velocity have been studied with a mass spectrograph.Nitrogen.---N₂^_⁺ and N⁺ ions appear at 15.8±{}0.1 and 24.5±{}0.1 volts respectively. The N⁺ ion has kinetic energy and is attributed to N₂→N⁺+N+e. Increases in the efficiency of production of the N⁺ ion appear at 40.0±{}1.0 and 47.0±{}1.0 volts. The largest percentage of the total positive ion current carried by kinetic energy ions is approximately 28 percent at 140-160 volts. Efficiency curves of total ionization and of N₂^_⁺ exhibit maxima at 100.0±{}5.0 and 60.0±{}5.0 volts respectively.Carbon monoxide.---CO⁺, C⁺ and CO⁺⁺ ions appear at 13.9±{}0.2, 22.5±{}0.2, and 43.0±{}1.0 volts respectively. Maximum numbers of CO⁺, C⁺, and CO⁺⁺ ions formed per electron per cm path per mm pressure at 0^∘{}C are 10.13, 0.50, and 0.14 at 102, 105, and 125 volts respectively. The C⁺ ion possesses kinetic energy and is probably due to CO→C⁺+O+e. Assuming that the CO⁺⁺ ion would dissociate into C⁺⁺+O the energy of dissociation cannot be less than from 2 to 3 volts. O^- ions are formed between 9.5±{}1.0 and 16.5±{}1.0 volts, and again beginning at 22.5±{}1.0 volts and reach a maximum at 33 volts. The first group is evidently due to the attachment of an electron to the CO molecule followed by a dissociation CO^-→C+O^-. The second group may be due to CO→C⁺+O^-. O^- ions are only 2.7 percent as numerous as C⁺ ions at 30 volts.