Optical absorption spectra of tripositive erbium ion in certain nitrate complexes

Optical absorption of Er³⁺ ion in Er(NO₃)₃·5H₂O, NH₄NO₃, Mg(NO₃)₂·6H₂O, KNO₃ and NaNO₃ complexes has been studied. The second derivative spectra of these Er³⁺ complexes exhibited splittings in the⁴ I _9/2,⁴ F _9/2,⁴ F _7/2,⁴ F _5/2 and² H _9/2 levels. These splittings have been tentatively explained as due to a cubic crystalline field. The partial derivatives for Er³⁺ ion have been calculated in terms of Racah (E ^k ) parameters. The results of a least squares fit of the energy levels and oscillator strengths of the bands are reported in terms of interaction parameters and Judd-Ofelt parameters. Radiative transition probabilities for various fluorescence levels are theoretically estimated. The lifetime of the⁴ G _11/2 level is found to be lowest in all nitrate complexes.