The mobilities of the positive ions ${\mathrm{H}}^{+}$, ${\mathrm{H}}_3^{+}$, and ${\mathrm{H}}_5^{+}$ in ${\mathrm{H}}_2$ gas have been measured, using the "four-gauze" electrical shutter method. The ions have been identified mass-spectrometrically. Measurements were made over a range of $\frac{E}{p_0}$ ($E=\mathrm{electric}\mathrm{field}\mathrm{intensity}$, $p_0=\mathrm{normalized}\mathrm{pressure}$) from 5.5 to 100 V per cm×mm Hg and in a pressure range of from 0.5 to 1.6 mm Hg. The predominant ion is ${\mathrm{H}}_3^{+}$. The mobility ${\mu }_0$ corrected to 0°C for the ${\mathrm{H}}^{+}$ ions was 14.4, for the ${\mathrm{H}}_3^{+}$ ions 10.2 and for the ${\mathrm{H}}_5^{+}$ ions 9.6 ${\mathrm{cm}}^2$/V×sec at $\frac{E}{p_0}=10\mathrm{}$ V/cm×mm Hg. With increasing $\frac{E}{p_0}$, the mobility of the ${\mathrm{H}}^{+}$ ions decreases, that of the ${\mathrm{H}}_3^{+}$ ions increases to a maximum of 14.7 ${\mathrm{cm}}^2$/V sec at $\frac{E}{p_0}=60\mathrm{}$ V/cm×mm Hg and then decreases, and that of the ${\mathrm{H}}_5^{+}$ ions increases.

• Received 25 February 1965

DOI:https://doi.org/10.1103/PhysRev.139.A349