Energy Spectrum of Mn⁺⁺ Ion in Calcium Fluorophosphate II

The absorption spectrum of the manganese impurity ion in calcium fluorophosphate is calculated by using crystalline field approximation, taking into account the effect of polarization of oxygen ions near the manganese ion, and taking the ionicity in the bond between oxygen and phosphorus in phosphate ions as a parameter. Among the coefficients in the expression of crystalline field potential at the position of Mn ++ ion, c 2 0 can be compared with the coefficient D in the spin Hamiltonian, which appears in the theory of Watanabe. From a comparison of the calculated c 2 0 with that deduced from ESR experiment, it is concluded that the ionicity is about 40%. Although the energies of the absorption band of Mn ++ ion in calcium fluorophosphate phosphor are not observed, they can be estimated from the consideration of the mechanism of luminescence in this crystal. Comparison of these estimated energies with the calculated energies shows that the ionicity in phosphate ion is about 35% which is consistent with that obtained from the comparison of calculated c 2 0 with that deduced from ESR experiment.