The variation of the mobility of gaseous ions with temperature I–Positive ions in their own gas

Recent work in this laboratory on the mobility of gaseous ions has shown that the results of early investigators were all influenced by the effect of polar impurities in the gas, which led to the formation of clustered ions. When precautions are taken to exclude them, the higher values of mobility which are obtained indicate that, as at low pressures, the positive ions are normally singly charged atoms or molecules. The negative carriers are electrons in all the purified gases in which these experiments have been carried out, namely helium, neon, argon, krypton, xenon, nitrogen and hydrogen. In view of its possible theoretical interest, it seemed desirable to repeat another early investigation,y that of the variation of mobility with temperature. The following account records experiments on the positive ions of helium in helium and of nitrogen in nitrogen, and discusses the results obtained.