Hydrated electron-induced chemiluminescence of thallium(I) ion Original Research Article

Dissolution of X-ray irradiated sodium chloride or additively coloured potassium chloride induces generation of hydrated electrons which produce thallium(I)-specific chemiluminescence in the presence of thallium(I) ions. Such a luminescence is also called extrinsic lyoluminescence (ELL) of X-ray irradiation coloured sodium chloride, or additively coloured potassium chloride. The present ELL is considered chemiluminescence induced by dissolution-produced strong reducing and oxidising agents, i.e. hydrated electrons, surface-bound and only partially hydrated hole centres, and hydroxyl or sulphate radicals (in the case of additively coloured potassium chloride dissolved in solution containing peroxodisulphate ions). Dichlorothallate(I) (Tl(I)Cl−2) was the main emitter in the ELL processes at about 430 nm. The reduction-initiated excitation pathway of TlCl−2 involves a colloidal thallium atom surrounded by chloride anions (Tl(O):2Cl−) while in the less important oxidation-initiated excitation pathway the precursor of excited Tl(I)Cl−2 is transiently existing Tl(II)Cl−2 produced by dissolution-uncovered hole centres (or sulphate radicals). Both of the lyoluminescence procedures allow Tl(I) to be detected below nanomolar concentrations, yielding linear log–log calibration plots spanning several orders of magnitude of concentration.