Spectroscopy and Luminescence Properties of CdF2: Eu

Characteristics relevant to the application of Cd${\mathrm{F}}_2$: ${\mathrm{Eu}}^{+3\mathrm{}}$ to optical maser use were investigated. The line fluorescence was analyzed to obtain the positions of the lowest energy europium crystal states and these were found to be consistent with the europium ion being in a crystal field having essentially tetragonal symmetry. The strongest emission line, at 5893.1 A, contains $\frac{1}{10}$ of the total fluorescence and is due to a transition between states at 17278.6 ${\mathrm{cm}}^{-1\mathrm{}}$ and 309.7 ${\mathrm{cm}}^{-1\mathrm{}}$. At 15°K its width at half intensity is 0.32 ${\mathrm{cm}}^{-1\mathrm{}}$. It was found that the europium fluorescence could be sensitized by the addition of sulfide to the crystals and the total fluorescent quantum efficiency was determined to be 0.8±0.2. The threshold power for oscillations in a rod of 0.1 ${\mathrm{cm}}^2$ cross-sectional area was calculated to be 18 watts.