Raman spectra of crystalline double sulphates Part II. Ammonium double sulphates

Abstract

Raman spectra of single crystals of (NH₄)₂M(SO₄)₂·6 H₂O whereM=Mg, Zn Ni or Co have been recorded using λ 2537 excitation. Interesting results concerning the substitution of the divalent atoms in the double sulphate lattice on the sulphate and ammonium frequencies are observed. The spectra of these double sulphates are discussed in the light of the known crystal structure details and in relation, to the spectra of the corresponding potassium double sulphates, reported recently by the author. The Raman spectrum of NaNH₄SO₄·2 H₂O has also been recorded for the first time and the results obtained are also included.