Effect of concentration on the absorption peaks in the lowest 4f to 5d band of Ce³⁺ in CaF₂ crystals

The effect of the concentration of Ce3+ on the absorption peaks in the lowest 4f to 5d band of Ce3+ in CaF2 crystals has been measured at Ce3+ concentrations between 0.005 and 5% by both wavelength modulation spectroscopy and conventional ultraviolet absorption spectroscopy. The data show that absorption of the C4v sites known to contribute to the spectrum at low Ce3+ concentrations is overtaken by absorption attributable to other centres at Ce3+ concentrations higher than about 0.1%.