On the application of Onsager theory to `warm liquids´ irradiated by γ-rays

Data on the free ion yield produced by γ-radiolysis of neopentane (NP), 2,2,4,4-tetramethylpentane (TMP), tetramethylsilane (TMS), tetramethylgermanium (TMG), and tetramethyltin (TMSn) are analyzed using Onsager theory. Four distributed functions describing the separation distance between electron-ion pairs at thermalization were considered: a delta function (DELTA), an exponential function (EXP), an exponential modified by a first power of r (R1EXP), and an exponential modified by a quadratic power of r (R2EXP). With a suitable choice of adjustable parameters, G(∞) and ρ, where G(∞) is the number of electron-ion pairs initially produced per every 100 eV released in the sample and ρ is the mean thermalization distance, all four distributions approximately describe the data. For NP, TMP, and TMG, the data are best described by R1EXP; for TMSn, R2EXP is best