AbstractThe Raman spectra of (NH4)2SO4single crystals have been recorded and measured using an Ar+laser as a scource of excitation. The polarization behaviour of the Raman lines in different crystal orientations has been studied. The observed shifts in the range 15–3400 cm−1have been attributed to the phonons of different symmetry species originating from the internal modes of NH 4+and SO 42−ions and the lattice modes calculated from group theoretical consi