Theory of Radiation Chemistry. VIII. Ionization of Nonpolar Liquids by Radiation in the Absence of External Electric Field

Abstract

A theory of separated ion pairs in the x and γ irradiation of nonpolar liquids is presented. In this theory consideration is made of the mechanisms involved in the thermalization of electrons, and it is shown that a very significant portion of the prethermalization electron range occurs while the electron is in the subvibrational energy region (∼0.4 eV to thermal energy). The temperature dependence of the yield of separated charges arises in a perfectly natural manner. ``Thermalization lengths'' turn out to be 80–90 Å. Good agreement with experimental observations is obtained with reasonable values of the three adjustable parameters. The theory is also applied to the special case of ³⁷Ar, where most of the effect is due to 2.4‐keV conversion electrons. Calculated results are in reasonable agreement with experiment in this case. A small temperature effect is predicted.