An investigation of radicals produced in the photolysis of thiosulfate solutions by electron spin resonance

The photochemistry of alkaline, aqueous thiosulfate solutions has been studied in a flow system. The primary radicals produced were trapped with nitromethane and the resulting adducts were detected by esr. Three different intermediates were identified as a result of two different photolytic processes. The radicals Ṡ^- and ṠO₃^- are produced as a result of excitation of the n-π* band involving the electrons on the sulfur atom: S₂O₃^2- →^hv Ṡ^- + ṠO₃^- (λ_max 240 nm) and the solvated electron is produced by excitation of the charge transfer to solvent band: S₂O₃^2- →^hv Ṡ₂O₃^- + e^eq- (λ_max 215 nm).