Drift Velocity of Ions in Oxygen, Nitrogen, and Carbon Monoxide

Abstract

The drift velocities of ions of the parent gas in oxygen, nitrogen, and carbon monoxide have been measured as a function of field strength to pressure ratio by techniques previously reported. Oxygen gave results similar to those in the rare gases reported previously. A log-log plot of drift velocity against $\frac{E}{p_0}$ in volts/(cm×mm Hg) starts with a slope near unity which gradually decreases to one-half at high values of $\frac{E}{p_0}$. The mobility, extrapolated to zero field and atmospheric pressure is 2.25 ${\mathrm{cm}}^2$/volt-sec. Nitrogen and carbon monoxide both show a novel characteristic; the drift velocity first rises with $\frac{E}{p_0}$ but reaches a maximum and actually decreases, then finally resumes a more normal rise with $\frac{E}{p_0}$ as described for oxygen. It is believed that at high $\frac{E}{p_0}$ the drift velocity is characteristic of ${\mathrm{N}}_2^{+}$ ions and C${\mathrm{O}}^{+}$ ions, respectively. At low fields the ion in nitrogen is believed to be ${\mathrm{N}}_4^{+}$. In CO the ion at low fields is believed to be C${\mathrm{O}}^{+}$, with (C${\mathrm{O})}_2^{+}$ being formed at intermediate fields. The results are complicated by an additional ion which appears in the range of $\frac{E}{p_0}$ from 95 to 250 and which has a higher speed than the other ion. It is suspected of being ${\mathrm{C}}^{+}$.