A new colour centre in calcium oxide: possible identification of the FA+centre
- 5 September 1972
- journal article
- Published by IOP Publishing in Journal of Physics C: Solid State Physics
- Vol. 5 (17), 2543-2552
- https://doi.org/10.1088/0022-3719/5/17/028
Abstract
A new colour centre has been observed in neutron-irradiated crystals of calcium oxide doped with magnesium. It has an absorption band peaking at 374 nm and a complementary emission band at 398 nm. A zero-phonon line appears at 384.5 nm in absorption and emission. The value of the Huang-Rhys factor for both bands is S approximately=4. The defect cannot be detected in absorption in irradiated pure crystals, but the zero-phonon line has been detected weakly in emission. The line is shifted to the blue and broadened in the doped crystals compared with the pure crystals. A similar shift and broadening occurs for the F+ centre zero-phonon line. These effects can be understood in terms of internal strains caused by the magnesium impurities. Uniaxial stress experiments show that the new centre has tetragonal symmetry, the absorption and emission bands having electric dipole transition moments parallel to the fourfold axis. It is proposed that this defect is an FA+ centre, an interpretation supported by a comparison of its properties with those of the F+ centre.Keywords
This publication has 18 references indexed in Scilit:
- Jahn-Teller coupling in the excited level of the F+centre in CaO: uniaxial stress effectJournal of Physics C: Solid State Physics, 1972
- Optical Detection of Paramagnetic Resonance in the Excited State ofCenters in CaOPhysical Review Letters, 1972
- Symmetry assignments of one-phonon sidebands in the emission spectrum of the F+centre in calcium oxideJournal of Physics C: Solid State Physics, 1972
- Vibronic properties of the F+absorption band in calcium oxideJournal of Physics C: Solid State Physics, 1971
- Luminescence fromCenters in Calcium OxidePhysical Review B, 1969
- Stress and Zeeman spectra in bismuth-doped and undoped calcium oxideJournal of Physics C: Solid State Physics, 1969
- Defects in the alkaline earth oxidesAdvances in Physics, 1968
- Faraday rotation studies of F centres in alkaline earth oxidesJournal of Physics and Chemistry of Solids, 1968
- Shift and broadening of the KBr:Li resonant mode by internal strainsSolid State Communications, 1968
- Dynamical Jahn-Teller Effect in Paramagnetic Resonance Spectra: Orbital Reduction Factors and Partial Quenching of Spin-Orbit InteractionPhysical Review B, 1965