The Mass of Positive Ions in a Glow Discharge

Preliminary results are presented here in an attempt to determine directly the mass of gas ions in air, ${\mathrm{N}}_2$, ${\mathrm{O}}_2$, and S${\mathrm{O}}_2$. The ions were formed in a glow discharge, allowed to drift at low velocity through a distance of 2.5 cm, and passed as a molecular beam through a slit 0.01 mm by 5.0 mm where the mass spectrum was analyzed with a positive ray analysis apparatus of the Dempster type. The pressure in the discharge and drift spaces was maintained at 0.1 to 0.5 mm of mercury. The following ions appeared in relatively large quantities: ${\mathrm{N}}^{+}$, $\mathrm{N}_3^{}{}_{}{}^{+}{}_2{}^{}{}_{}{}^{}$, ${\mathrm{O}}^{+}$, $\mathrm{N}_2^{}{}_{}{}^{+}$, $\mathrm{O}_2^{}{}_{}{}^{+}$, $\mathrm{O}_3^{}{}_{}{}^{+}$, S$\mathrm{O}_2^{}{}_{}{}^{+}$, and ${\mathrm{H}}_2$S$\mathrm{O}_3^{}{}_{}{}^{+}$. In addition a smear of heavier ions appeared in smaller numbers, though the intensity was greater in air than in the pure gases and, in air, became relatively larger at high pressures. Peaks corresponding to molecular weights of 56-64, 76, 80, 96, 108, 138, 140, 168 and 200 were the most prominent indicating the presence of such ions as 2$\mathrm{N}_2^{}{}_{}{}^{+}$, ${\mathrm{N}}_2$ $\mathrm{O}_2^{}{}_{}{}^{+}$, 2$\mathrm{O}_2^{}{}_{}{}^{+}$, ${\mathrm{N}}_2$ $\mathrm{O}_3^{}{}_{}{}^{+}$ and heavier combinations. $\mathrm{N}_3^{}{}_{}{}^{+}$ and $\mathrm{O}_3^{}{}_{}{}^{+}$ ions apparently play an important role in gas ion phenomena though the $\mathrm{N}_3^{}{}_{}{}^{+}$ is relatively unstable since it breaks up in the magnetic field into $\mathrm{N}_2^{}{}_{}{}^{+}$ + N. In view of the results it seems likely that air ions aged over a considerable period of time are of a complex and heterogeneous nature, due probably to the formation of nitric oxides, while the ions in pure gases remain monatomic, diatomic and triatomic except for attachment to impurities.