The Ionization and Dissociation of Water Vapor and Ammonia by Electron Impact

Abstract

The results of a mass-spectrometric study of the products of ionization and dissociation of water vapor and ammonia by electron impact are given. The ionizing potential of the ${\mathrm{H}}_2$O molecule is found to be 13.0±0.2 volts, and of the N${\mathrm{H}}_3$ molecule 10.5±0.1 volts. The possible processes responsible for the formation of the various ions observed, both positive and negative, are discussed. Ions observed in ${\mathrm{H}}_2$O vapor are ${\mathrm{H}}_2$ ${\mathrm{O}}^{+}$, O${\mathrm{H}}^{+}$, ${\mathrm{O}}^{+}$, ${\mathrm{H}}^{+}$, $\mathrm{H}_2^{}{}_{}{}^{+}$, ${\mathrm{H}}_3$ ${\mathrm{O}}^{+}$, ${\mathrm{O}}^{-}$, and ${\mathrm{H}}^{-}$. Ions observed in N${\mathrm{H}}_3$ are N$\mathrm{H}_3^{}{}_{}{}^{+}$, N$\mathrm{H}_2^{}{}_{}{}^{+}$, N${\mathrm{H}}^{+}$, ${\mathrm{N}}^{+}$, ${\mathrm{H}}^{+}$, N$\mathrm{H}_3^{}{}_{}{}^{++}$, N$\mathrm{H}_2^{}{}_{}{}^{-}$, and ${\mathrm{H}}^{-}$.