ODMR in the photo-excited3B1ustate of F22+centres in MgO. I. Zero-field spectra and spin coherence phenomena

Abstract
Optically detected magnetic resonance (ODMR) experiments at 1.2K in zero and low magnetic fields show that the 440 nm luminescence band in additively coloured MgO is due to emission from a photo-excited triplet state of a centre with orthorhombic I symmetry. The triplet state is associated with a (1s2p) configuration of a pair of F+ centres occupying nearest-neighbour anion sites along a (110) direction (i.e. an F22+ centre). A preliminary study is reported of spin coherence phenomena observed using the technique of optical detection of spin echoes. The characteristic phase memory time was measured as TM=250 mu s.