Spur recombination and diffusion processes in pulse irradiated inorganic glasses

Pulse radiolysis Studies are carried out in pure and doped metaphosphate, borate, and silicate glasses in the range between 80 and 315°. The observed decay patterns are shown to be due to the recombination of ions, holes, and electron centers, within spurs. The time dependence of the fraction of surviving radicals is in good agreement with the empirical expression F(t) = exp(k_s/α) erfc(k_st/α)^1/2 (where α is a constant and k_s is the diffusion-controlled recombination rate constant) predicted by Rzad, et al., for systems undergoing spur recombination processes. Differences of several orders of magnitude among the diffusion coefficients of the various ions and centers explain the large variations in the rates of the corresponding diffusion-controlled electron-transfer reactions in glasses. The possibility of calculating relative diffusion coefficients in glasses from the annihilation data is discussed. Our results indicate that the diffusion coefficient of Mn³⁺ is (3 ± 1) × 10³ higher than that of Cd⁺ in the temperature range 80-240°.