Experimental ion mobility measurements in pure iC$_4$H$_{10}$10 and Ar-iC$_4$H$_{10}$ mixtures

In this paper we present the results of the ion mobility measurements made in pure isobutane (iC$_4$H$_{10}$) and in mixtures with argon (Ar-iC$_4$H$_{10}$) for a total pressure of 8 Torr (10.6 mbar) and for low reduced electric fields in the 10 Td to 45 Td range (2.4–10.8 kV$\cdot$cm$^{−1}\cdot$bar$^{−1}$), at room temperature. The reduced mobilities, obtained from the peak centroid of the time-of-arrival spectra, are presented for Ar concentrations in the 5%–95% range.