LUMINESCENCE STUDIES OF LOCALIZED GAP STATES IN COLLOIDAL ZNS NANOCRYSTALS

ZnS nanoparticles were prepared by chemical precipitation of Zn2+ with sulfur ions in aqueous solution. The ultraviolet-excited samples reve al detailed structure in the luminescence spectra. A doublet pattern o bserved in the long wavelength region is attributed to the coexistence of the two crystalline forms in ZnS particles. The visible luminescen t radiation at 590.1 nm is due to Mn impurities. The dominant emission band at short wavelengths exhibits a quadruple fine structure with pe aks located at 416.1, 423.9, 430.1, and 437.8 nm which are identified with optical transitions arising from vacancy and interstitial sites f or both Zn and S atoms. (C) 1998 American Institute of Physics. [S0021 -8979(98)07717-2].