Optical Absorption of Mn 2+ ‐Doped Alkali Halides

The absorption spectra of Mn 2+ ‐doped KCl and NaCl are discussed over 0.1 to 15 mol% cange of dopant concentration. The spectra observed for concentrations > 5 mol% are characteristic of divalent manganese and the bands are assigned to various excited quartet levels of the ion in a cubic crystalline field. The band positions are fitted by adjusting B , C , Dq , and α parameters. Fine structure of the bands observed at 77 °K is interpreted in terms of the vibrational–electronic and spin–orbit splitting of the cubic field levels. The different types of Mn 2+ centres in the alkali halides at different concentrations are discussed in the light of the observed spectra. The formation of K 4 MnCl 6 and NaMnCl 3 complexes is thought to be probable at high concentrations.