Magnetic susceptibility and low-lying crystal-field energies forCaF2:Ce3+

Magnetic-susceptibility measurements have been used to locate the first excited state in the energy-level diagram for ${\mathrm{CaF}}_2$:${\mathrm{Ce}}^{3+}$. All other levels in the tetragonally split system have been observed spectroscopically and from these experiments the first excited state was predicted to be at 110 ${\mathrm{cm}}^{\mathrm{-}1}$. Our results indicate this level to be at 100 ${\mathrm{cm}}^{\mathrm{-}1}$, in good agreement with the prediction.