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The hydrates and deuterates of ferrous sulfate (FeSO 4 ): a Raman spectroscopic study
Author(s) -
Chio Chi Hong,
Sharma Shiv K.,
Muenow David W.
Publication year - 2007
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1623
Subject(s) - raman spectroscopy , sulfate , chemistry , analytical chemistry (journal) , ferrous , hydrate , mineralogy , chromatography , physics , organic chemistry , optics
Abstract A comparative analysis has been carried out on the Raman spectra of FeSO 4 · n H 2 O ( n = 1, 4, 7) including the 2 D‐analogs. The effects of changing the degrees of hydration have been found from the lattice, SO 4 2− internal, and H 2 O internal modes. Increasing degrees of hydration shift the intense ν 1 (SO 4 ) peak to lower wavenumbers and reduce the amount of splitting on the ν 3 (SO 4 ) peaks. Some of the water librational bands cause the broadening of the ν 4 (SO 4 ) peaks in FeSO 4 ·7H 2 O and the ν 2 (SO 4 ) peaks in FeSO 4 ·7D 2 O. The ν 2 (H 2 O) band in FeSO 4 ·H 2 O is red‐shifted in excess of 100 cm −1 relative to the unperturbed H 2 O band. Between 240 and 190 K and between 140 and 90 K in the spectra of FeSO 4 .4H 2 O, two potential phase transitions have been identified from the changes in the lattice and water‐stretching regions. The resolution of the ν 1 (H 2 O) and ν 3 (H 2 O) bands in FeSO 4 ·4H 2 O and FeSO 4 ·H 2 O also improved sharply at low temperatures. The capability of distinguishing various forms of FeSO 4 hydrates unambiguously makes the Raman technique a potential analytical tool for the identification of sulfate minerals on planetary surfaces. Copyright © 2006 John Wiley & Sons, Ltd.