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\ifmmode\pm\else\textpm\fi{}0.2 volts, and of the N${\mathrm{H}}_{3}$ molecule 10.5\ifmmode\pm\else\textpm\fi{}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}}^{+}$, ${\mathrm{O}}^{\ensuremath{-}}$, and ${\mathrm{H}}^{\ensuremath{-}}$. 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$\mathrm{H}_{2}^{\ensuremath{-}}$, and ${\mathrm{H}}^{\ensuremath{-}}$.