Studies on the Vibrational Spectrum of the SO4 = Ion in Crystalline M2′M″(SO4)2·6H2O (M′ = K or NH4 and M″ = Mg, Zn, Ni, or Co): Observations on the Symmetry of the Sulfate Ion in Crystals

Abstract

Polarization studies on the Raman spectra of suitably oriented single crystals of the isomorphous M2′M″ (SO4)2·6H2O (M′ = K or NH4 and M″ = Mg, Zn, Ni, and Co) have been carried out to assign the symmetry species of the sulfate group frequencies. The theoretical principles underlying these experiments are briefly explained. Infrared absorption spectra of these sulfates have been recorded by the pressed-disk and mull techniques. Infrared reflection data from the literature are also collected and analyzed along with the other data. The results relating to the multiplicity of the SO4= frequencies are discussed in terms of the symmetry of the sulfate ion in these crystals.