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

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