Knowledge Bank

“The absorption spectrum of $CoF2$ has been studied in oriented single crystals of both pure $CoF2$ and 3% $CoF2$ in $ZnF2$. Absolute absorption intensities have been measured over the range 4000 to 20,000 \AA at liquid hydrogen, liquid nitrogen, and room temperatures for light polarized both parallel and perpendicular to the crystallographic c axis. Oscillator strengths have been calculated, and are found to vary with polarization, temperature, and $Co++$ ion concentration. The positions of the broad transitions are consistent with those expected from splitting of the $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}F$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}P$ levels of the free ion by the ligand field of the crystal. In addition, sharp transitions are observed at the low temperatures, which are tentatively identified as excitations to doublet levels Having the same octahedral field dependence as the ground state.”