Calculated optical absorption spectra of Ni²⁺-bearing compounds

Abstract

The transition energies responsible for optical absorption spectra can be obtained by crystal-field analysis, but the transition intensities are notoriously difficult to calculate. This paper examines the basic ingredients of the calculation of optical spectrum intensities. Magnetic dipole and electric quadrupole transitions intensities are evaluated, as well as the direct d(Ni²⁺) to p(O²⁻) electric dipole transitions. All these contributions are shown to be small in the optical range, so that spectral intensities are due to the mixing of odd orbitals with the Ni²⁺ 3d ⁿ states.