Magneto-optical properties ofF+centers in alkaline-earth oxides

The magneto-optical properties of $F^{+}$ centers in neutron-irradiated alkaline-earth oxide crystals were reexamined and further investigated. Magnetic circular dichroism, Faraday rotation, and optical absorption spectra were measured and analyzed, and the results are compared with those of previous studies. Values of -18 ± 3, -43 ± 4, -150 ± 30, and -380 ± 190 ${\mathrm{cm}}^{-1\mathrm{}}$ were, respectively, found for the spin-orbit splittings in the $F^{+}$ bands of MgO, CaO, SrO, and BaO. Orbital magnetic moments very close to zero were found for the CaO and SrO excited states. Higher moments of the spectra were found unreliable but imply large contributions to the bandwidths by noncubic lattice modes. Optically detected paramagnetic resonance confirms assignment of the BaO 2.0-eV band to the $F^{+}$ center and assigns the 2.6-eV band to an axial defect. A calculated spin-orbit splitting for CaO is found in good agreement with experimental values if contributions from several shells of neighboring ions are included and renormalization is largely neglected.