Raman and infrared spectra of ammonium selenate and lithium ammonium selenate

Abstract

The Raman and infrared absorption spectra of (NH₄)₂ SeO₄, (NH₄)₂ SeO₄ and Li (NH₄) SeO₄ have been recorded at 300°K; while the spectra of the non-deuterated compounds have been recorded at 110° K also. (NH₄)₂ Se0₄ crystal exhibits 33 Raman lines, while LiNH₄SaO₄ shows 30 Raman lines at 300° K. Proper assignments have been given to the observed vibration frequencies. The SeO₄ ^-- ions and the (NH₄)⁺ ions are found to be highly distorted in these selenates. There is lowering of the N-H vibration frequencies due to hydrogen bonding. The present spectroscopic investigations do not reveal the existence of any phase transition in these selenates in the temperature region investigated.