Optical absorption of Co²⁺ in zinc acetate dihydrate single crystal

Abstract

The optical absorption spectrum of Co²⁺ doped in a single crystal of zinc acetate dihydrate has been studied under polarization. Some of the bands obtained have been found to show up in σ polarization only, while others show up in both σ and π polarizations. An analysis of the results obtained shows that the site symmetry of Co²⁺ in the crystal is trigonal (C₃, C_3v, or D₃) and that the ground state of Co²⁺ is ⁴E. The cubic levels of Co²⁺ corresponding to octahedral coordination have been observed to be split in the expected manner under the lower site symmetry. The transitions of Co²⁺ in zinc acetate dihydrate have been found to be in general on the low-energy side compared to those in cobalt acetate tetrahydrate.