Paramagnetic Resonance Spectrum of Manganese in Cubic MgO and CaF2

The paramagnetic resonance spectrum of manganese in cubic MgO and Ca${\mathrm{F}}_2$ has been analyzed at wavelengths of one and three cm. The cubic field splitting in MgO is given by $3a=(+55.9\pm 0.9)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. The twofold degenerate level lies lower than the fourfold degenerate level. The hyperfine structure constant is $A=(-81.0\mathrm{}\pm 0.2)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$; $g=2.0014\mathrm{}\pm 0.0005$. The large cubic field splitting and the reduced hyperfine structure point towards considerable covalent bonding. Anomalous intensity ratios of the fine structure lines were observed. In Ca${\mathrm{F}}_2$ the hyperfine structure constant has a value of $A=(95\mathrm{}\pm 1)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. The line width of 40 gauss even at very low concentration prevented any resolution of fine structure. The large line width is probably caused by the interaction of the magnetic electrons with the fluorine ions.