Optical Spectrum of Divalent Vanadium in Octahedral Coordination

Sharp-line fluorescence of the ${\mathrm{V}}^{2+}$ ion in magnesium oxide and corundum has been studied at low temperatures, with and without a magnetic field. The excitation spectrum is used to determine the energy level scheme. The results are analyzed in terms of crystal field theory, and the vibrational structure is briefly discussed. The variation of the crystal field parameters through the $d^3$ sequence ${\mathrm{V}}^{2+}$, ${\mathrm{Cr}}^{3+}$, ${\mathrm{Mn}}^{4+}$ is considered in terms of a point-charge model.