Direct and indirect effects in pulse irradiated concentrated aqueous solutions of chloride and sulfate ions

Yields of Cl2- have been measured in concentrated aqueous solutions of NaCl which contained ethanol to suppress ClOH- and HCO3- to neutralize the acid spur. Yields of SO4- and Cl2- have been measured in solutions of (NH4)2SO4, some containing 50 mM NaCl to convert SO4- to Cl2-. Yields of SO4- are considerably larger for solutions of (ND4)2SO4 in D2O. Optical spectra, extinction coefficients, and rate constants have been measured as needed for confirmation. Yields of oxidized species are attributed principally to electron transfer from the reagent R to ionized solvent S, with some contribution from direct effect. The effective electron fraction of R is phi = f/sub R/ ) 7R{/(f/sub R/7R{ + f/sub S/7S{) in terms of oscillator strengths f, with f/sub R//f/sub S/ adjustable. For direct and indirect primary yields G/sub d/0 and G/sub i/0 the yield is described by G = G/sub d/0phi + G/sub i/0(1 - phi)7ν1(R)/7ν1(R) + ν2(S){{ where ν17R{ is the frequency of electron transfer and ν27S{ is the frequency of dry hole localization, e.g., by formation of H3O+. For 1 - phi approximately 1, the direct and indirect yields are algebraically indistinguishable. Large yields of SO4- in D2O cannot be explained by phi. They are attributed to the vibration-limited frequency ν2 which increases the lifetime of D2O+. )]