The mobility of alkali ions in gases. IV. Measurements in gaseous mixtures

The mobilities of some of the alkali ions have been measured in binary mixtures of the inert gases. Blanc’s relation that the reciprocal of the mobility is a linear function of the concentration of one of the constituents is accurately obeyed in all cases except for Li+ in He-Xe mixtures, where the maximum deviation is 4%. With clustered Li+ ions in mixtures of water vapour and an inert gas deviations from this simple relation are observed and increase in magnitude progressively with the density of the gas. These deviations, due to the polar nature of the water molecule, can be explained by assuming a gradual increase in the size of the clustered ion with increase in the percentage of water vapour.