Photoluminescence of additively coloured magnesium oxide. II. Transient features in circular polarisation and optically detected magnetic resonance

Transient magnetic circular polarisation and optically detected magnetic resonance are reported for the 520 nm luminescence in additively coloured MgO. The results are shown not to be consistent with the F + +F - centre recombination model for this luminescence of P. Edel et al. (1979, 1980). An alternative model is proposed in which a metastable state F Dagger is populated during relaxation from the excited state reached optically in the 250 nm band. In this state one of the electrons may tunnel from F Dagger to a neighbouring F + , being captured there in the F* state and de-exciting with the emission of a 520 nm photon. As a consequence of spin selection rules during the electron tunnelling, polarisation of both the F + centre ground state and the F Dagger excited state is transferred to the F* state. Thus both magnetic circular polarisation and optically detected magnetic resonance are detected on the long-lived components of the 520 nm band.