Photophysical properties of ZnS nanoclusters with spatially localized Mn²⁺

The synthesis and photophysical characterization of nanometer-size ZnS with and without Mn²⁺ are reported. Without Mn²⁺, the ZnS nanoclusters emit in the blue upon ultraviolet excitation. ZnS doped with 1-5% Mn²⁺ (presumably in Zn²⁺ sites) yields the orange emission observed for bulk Zn:Mn phosphors but with greatly reduced emissive lifetimes. ZnS with surface-bound Mn²⁺, in contrast, emits in the ultraviolet with even shorter lifetimes. Thus, the physical location of Mn²⁺ in the ZnS nanocluster determines its optical properties.