The Recombination of Ions in Air and Oxygen in Relation to the Nature of Gaseous Ions

Coefficient of recombination of ions produced by x-rays as a function of the age and initial concentration of the ions. Measurement of the coefficient of recombination of ions in air and oxygen has been continued, with an improved form of the apparatus previously described by L. C. Marshall. Marshall's results in air have been checked, showing a sharp initial drop in the coefficient $\alpha$ for short time intervals ascribed to initial non-random distribution of the ions. Further measurements at longer time intervals have been made, using a new system of calculation whereby $\alpha$ is found as a function of $\tau$, the age of the ions, rather than $t$, the total time of recombination. In this case $\alpha$ does not drop to a constant value of about 0.8 to 0.9 × ${10}^{-6\mathrm{}}$ as indicated by Marshall's results, but continues to drop off to values of 0.5 to 0.6 × ${10}^{-6\mathrm{}}$ after the ions have aged for one second, and 0.3 to 0.4 × ${10}^{-6\mathrm{}}$ after two seconds. This is for a high initial concentration of ions of about 3.5 × ${10}^6$ ions per ${\mathrm{cm}}^3$. With an initial concentration of 1.55 × ${10}^6$ ions per ${\mathrm{cm}}^3$, $\alpha$ drops only to 1.15 × ${10}^{-6\mathrm{}}$ after a time of one second. In pure oxygen the values of $\alpha$ are in general higher than the corresponding ones for air, although they become equal at low initial concentrations.