Comparison of energy levels of Mn2+ in nanosized- and bulk-ZnS crystals

The 3d(5) multiplet level structure of the manganese ion is determined for two ZnS : Mn2+ nanoparticle samples, whose average crystallite sizes are different, by measuring the photoluminescence excitation spectra in the ultraviolet- and visible-regions. The peak positions of the spectra of both samples are found to he almost the same as those observed for the bulk crystal, showing that the multiplet energies of Mn2+ are almost independent of the ZnS host crystal size. This result suggests that the degree of the mixing between the s-p state of ZnS and the 3d orbitals of Mn2+ does not change significantly with the reduction in the host crystallite diameter down to a few nanometers. (C) 2000 Elsevier Science B.V. All rights reserved.