Radiolysis of liquids with high static dielectric constant: An estimate of the total ionization yield, electron thermalization distance, and contribution of heterogeneous reactions

Abstract

In a previous study, we found an exponential dependence of the free-ion yield (Gfi) on the static dielectric constant (εs) for a number of irradiated liquids with εs>10. On the basis of this study, we develop here a simple model by which we quantitatively estimate the total ionization yield (Gtot), the most probable electron thermalization distance (b), and the yield of solvated electrons that are removed by diffusion-controlled reactions during spur expansion (Gdif). Using solvated electron yields available in the literature, we get Gtot≂6.6 mol/100 eV (value nearly independent of the nature of the liquid) and b≂29 Å at 298 K. b is found not to depend appreciably on εs which indicates that the Coulomb attractive force between the ion and secondary electron is practically inefficient before electron thermalization occurs. The evaluation of Gdif teaches us that spur reactions have a profound influence in the fate of ion pairs formed during radiolysis of liquids of high εs values.