Temperature Dependence of the Mobility of Positive Ions in Argon and Krypton

The mobilities of positive ions of argon and krypton in the parent gases have been measured at room temperature and at one lower temperature, 77.4°K in argon and 90°K in krypton. In each case the atomic ions were found to have a higher mobility at the lower temperature. For ${\mathrm{A}}^{+}$ in A, the mobility, extrapolated to zero field, at 77.4°K was 1.36 times the value at 300°K. Extrapolation could not be carried out accurately in krypton, but evidence is found that the ratio of the mobility at 90°K to the value at 300°K is somewhat larger than 1.2. The change in temperature was found to have no effect on the mobilities of the molecular ions. Agreement of the room temperature results with those of other investigators is good except for a large disagreement with Biondi and Chanin on the molecular ions. The disagreement is particularly large for ${\mathrm{A}}_2^{+}$ at low $\frac{E}{p_0}$ and suggests a difference in the ions measured in the two experiments.