Flow-drift technique for ion mobility and ion-molecule reaction rate constant measurements. I. Apparatus and mobility measurements

Abstract

The present paper describes the construction and operation of a new experimental device that combines the chemical versatility of a conventional flowing afterglow system with the energy variability of a drift tube. This allows the measurement of both positive and negative ion mobilities not previously measured. Ion mobility measurements offer a significant constraint upon the ion‐neutral intermolecular potential and are therefore of value in testing either empirical or quantum mechanical theory. The mobilities of He⁺, ${\mathrm{He}}_2^{+}$ , H⁺, D⁺, O⁺, N⁺, Ar⁺, ${\mathrm{H}}_2^{+}\mathrm{,\hspace{0.17em}}{\mathrm{H}}_3^{+}\mathrm{,\hspace{0.17em}}{\mathrm{H}}_2^{+}$ , H⁻, O⁻, and OH⁻ in helium and ${\mathrm{H}}_3^{+}$ in H₂ are presented in the present paper. The following papers describe positive ion‐neutral and negative ion‐neutral reaction rate constant measurements in the same device.