Optical absorption spectra of Pr3+ in maleato complexes

Abstract

It is shown that the absorption spectra of Pr³⁺(4f²) can be conveniently analysed in terms of Racah parameters (E¹, E², E³), spin-orbit coupling constant(ζ) and configuration-interaction parameters (α, β, γ) by incorporating relationships based on the matrix elements corresponding to the ³P₁, ³P₀, ³F₃ and ³H₅ terms and experimental transition energies. The proposed method leads to more reliable results than those from the usual Taylor series method. The absorption spectra of Pr(Hmale)₃·7H₂O (H₂male = maleic acid) and Pr³⁺-doped maleato complexes of Zn²⁺, Mg²⁺ and Cd²⁺ have been analysed for the energy parameters. The parameters E¹, E³ and ζ were invariably found to be significantly less than the free-ion values, while E² remains practically unchanged. These variations are accounted for in terms of weak covalency and the nephelauxetic effect. The spectral intensities have been analysed in terms of the Judd–Ofelt parameters and predicted lifetimes have been calculated for the transitions ³P₂â†�³H₄, ³P₁â†�³H₄, ³P₀â†�³H₄ and ¹D₂â†�³H₄.