Mobilities and Longitudinal Diffusion Coefficients of Mass-Identified Potassium Ions and Positive and Negative Oxygen Ions in Oxygen

Abstract

Measurements at room temperature of the mobility and longitudinal diffusion coefficient have been made for low-energy mass-identified potassium ions and positive and negative oxygen ions in oxygen gas in a drift-tube mass spectrometer. The zero-field reduced mobilities of ${\mathrm{K}}^{+}$, ${\mathrm{O}}_2^{+}$, and ${\mathrm{O}}_4^{+}$ in ${\mathrm{O}}_2$ were found to be 2.68 ± 0.07, 2.24 ± 0.07, and 2.16 ± 0.08 ${\mathrm{cm}}^2$/V sec, respectively. ${\mathrm{O}}^{-}$, ${\mathrm{O}}_2^{-}$, ${\mathrm{O}}_3^{-}$, and ${\mathrm{O}}_4^{-}$ were determined to have zero-field reduced mobilities of 3.20 ± 0.09, 2.16 ± 0.07, 2.55 ± 0.08, and 2.14 ± 0.08 ${\mathrm{cm}}^2$/V sec, respectively. The longitudinal diffusion coefficients were measured for ${\mathrm{O}}_2^{+}$, ${\mathrm{K}}^{+}$, ${\mathrm{O}}^{-}$, and ${\mathrm{O}}_2^{-}$ in ${\mathrm{O}}_2$. The longitudinal diffusion coefficients of all investigated ionic species at low $\frac{E}{N}$ were at least within 16% of the values predicted from the mobilities by the Einstein relation. At higher $\frac{E}{N}$, the coefficients increased, in some cases quite rapidly, as $\frac{E}{N}$ was increased.