The Ionization of Hydrogen by Single Electron Impact

From an analysis of the theoretical potential energy curves for the ${\mathrm{H}}_2$ molecule as outlined by Condon the theoretical predictions for the types of ions resulting from primary impacts with electrons are described. These predictions include the formation of ${\mathrm{H}}_2^{+}$ at 15.25 volts, ${\mathrm{H}}^{+}$ at 17.9 volts, ${\mathrm{H}}_2^{+}$ at about 30 volts which then dissociates with several volts kinetic energy, and ${\mathrm{H}}_2^{++}$ at about 50 volts which also dissociates with kinetic energy. Using a mass spectrograph the experimental results of a study of the primary ions in hydrogen indicate the formation of ${\mathrm{H}}_2^{+}$ at 15.4±0.1 volts, ${\mathrm{H}}^{+}$ at 18.0±0.2 volts, and ${\mathrm{H}}^{+}$ at 26 to 30 volts, the last having various amounts of kinetic energy.