Excitons and photoluminescence in ZnO and [Zn.sub.0.99][Mn.sub.0.01] nanocrystals

The photoluminescence and photoluminescence excitation spectra for [Zn.sub.1-x][Mn.sub.x]O nanocrystals are presented. After annealing of powders in air, the intensity of the bands attributable to manganese decreases noticeably. This suggests that the oxygen vacancies affect the Zhang-Rice-like states appearing due to strong d-p-hybridization, which is confirmed by an increase in the band gap of [Zn.sub.1-x][Mn.sub.x]O for low x. The origin of the 2.9-eV peak and the shape of its excitation spectrum are discussed qualitatively. For [Zn.sub.1-x] [Mn.sub.x]O nanocrystals, the shape of the excitation spectrum is as unusual as the intense absorption in the range (2.2-3.0) eV.