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

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 Ep₀ in volts/(cm×{}mm Hg) starts with a slope near unity which gradually decreases to one-half at high values of Ep₀. The mobility, extrapolated to zero field and atmospheric pressure is 2.25 cm²/volt-sec. Nitrogen and carbon monoxide both show a novel characteristic; the drift velocity first rises with Ep₀ but reaches a maximum and actually decreases, then finally resumes a more normal rise with Ep₀ as described for oxygen. It is believed that at high Ep₀ the drift velocity is characteristic of N₂⁺ ions and CO⁺ ions, respectively. At low fields the ion in nitrogen is believed to be N₄⁺. In CO the ion at low fields is believed to be CO⁺, with (CO)₂⁺ being formed at intermediate fields. The results are complicated by an additional ion which appears in the range of Ep₀ from 95 to 250 and which has a higher speed than the other ion. It is suspected of being C⁺.