FREE ION YIELDS, ELECTRON THERMALIZATION DISTANCES, AND ION MOBILITIES IN LIQUID CYCLIC HYDROCARBONS - CYCLOHEXANE AND TRANS-DECALIN AND CIS-DECALIN

Free ion yields G(fi)E were measured as a function of electric field strength E in liquids of the cycLic hydrocarbons cyclohexane, trans-decalin, and cis-decalin at temperatures up to 514, 386, and 372 K, respectively. By comparing the measured G(fi)E to values calculated using the extended Onsager model, zero-field free ion yields G(fi)0 and thermalization distances b(GP) were obtained. The values of G(fi)0 in trans-decalin were used to correct previously reported values of the electron mobility obtained using estimates of G(fi)0. Values of the density-normalized thermalization distances b(GP)d were approximately 9% higher than in the linear n-alkanes, that is, at a given reduced density d/d(c), energy transfer from the thermalizing electron is less efficient than to the n-alkanes. Measured molecular cation mobilities mu+ were correlated with liquid viscosity and compared with neutral molecule diffusion coefficients. The mobility of the molecular cations was three to four times smaller than that of the corresponding neutral molecules. A free volume model was used to describe the temperature dependence of mu+. Ion transport in a liquid is made easier by increasing the free volume of the liquid, which occurs when it is heated under its vapor pressure. The amount of thermal energy required to activate the actual transport of the ions is considerably smaller than suggested by the Arrhenius model.