2S12 state ions in inorganic luminescent materials

Selected examples of impurity ions with one unpaired electron in an unfilled shell are Pb³⁺ ions in II–IV compounds (ZnO, ZnSe, ZnTe), Pb³⁺ in CaWO₄,F centres in alkali halides and Ag⁰ and Au⁰ atoms in radiophotoluminescent (RPL) glasses. Comparative studies of EPR, luminescence, thermoluminescence and related phenomena were performed on systems with ²S_{$\text{1}\text{2}$} state ions as central ions and systematically varying ligand ions in the temperature range from 1.6°K to 450°K. Luminescence bands attributed to internal transitions ²P_{$\text{3}\text{2}$,$\text{1}\text{2}$}→²S_{$\text{1}\text{2}$} ground state are reported especially with respect to the corresponding EPR data. All data are summarized in a molecular orbital model for the luminescence complex.