The Velocity Spectrum of Normal Gaseous Ions in Air and the Problem of Ionic Structure

Publisher Website
Google Scholar
Abstract
A consideration of the evidence as to the existence of the so called spectra of ion mobilities recently reported by various observers combined with experimental results of the writers indicate that while ions at ages of from 0.5 to 2.0 seconds show marked ranges of mobilities this is not necessarily the case for the normal ions studied over shorter time intervals. It is shown from the recent work of Loeb and the more recent results of Luhr that ions probably consist of one or two molecular addition products of an active type of molecule which pick up the original charged carrier as a result of electrochemical forces depending on the molecular constitution and the sign of the charge. Such products may be present in traces as impurities or may be produced in air by the ionizing agent. The rate of formation of the velocity spectrum therefore will depend on the relative stability of the various ion addition products and the relative and absolute concentrations of the active molecules. Hence the appearance of such a spectrum will vary with the age of the ions and the experimental conditions. It is believed that the greater portion of the lowering of the mobility of the ions below the theoretical value deduced by the assumption that the neutral molecules are not attracted by the ions is due to the usually assumed force of dielectric polarization as utilized in the complete Langevin equation. While the law utilized is not accurate for close approach of ion and molecule (i.e. to one or two atomic radii) it suffices at greater distances. The effect of the electrochemical combinations mentioned above are superposed on this general attraction and lead to an explanation of the differences of positive and negative mobilities and to the three fold lowering of the recombination coefficient on long aging without a very significant (10 percent) change in the ionic mobility recently observed by Luhr and Bradbury.

This publication has 35 references indexed in Scilit: