Electronic spectrum of NiII in MgWO4, ZnWO4 and CdWO4 at 4.2 K

Abstract

The ligand-field spectrum of Ni^II has been measured in crystals of MWO₄(M = Mg, Zn, Cd) from 5000 to 30 000 cm^–1. Spectra were measured with light incident on the (100) and (010) faces with the electric vector parallel to all three crystallographic axes at temperatures from 300 to 4.2 K. The splittings and intensities of the bands in different polarizations are interpreted in terms of a major C_2v and a minor C₂ perturbation of the octahedral site. Most of the observed intensity is derived from the static low-symmetry distortion but the effect of vibronic interactions is also discussed.