Luminescence from oxygen vacancies in MgO crystals thermochemically reduced at high temperatures

Experimental measurements and theoretical calculations are reported which may resolve some of the remaining difficulties associated with photoemission from anion vacancies in thermochemically reduced MgO crystals. The intensities of the 2.3- and 3.2-eV luminescence bands are found to be strongly influenced by both the concentrations of H/sup -/ ions and anion vacancies present, and also by the intensity of the approx.5.0-eV exciting light. Theoretical calculations predict that for a /sup 1/A/sub 1g/ relaxation of the surrounding ions the /sup 1/T/sub 1u/ and /sup 3/T/sub 1u/ electronic states of the F center are almost degenerate and approx.0.05 eV above the /sup 3/A/sub 1g/ state. The /sup 1/T/sub 1u/..-->.. /sup 1/A/sub 1g/ and the /sup 3/T/sub 1u/..-->.. /sup 1/A/sub 1g/ transition energies are predicted to be 2.2 and 2.9 eV, respectively.