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A Raman spectroscopic study of bukovskýite Fe 2 (AsO 4 )(SO 4 )(OH)· 7H 2 O, a mineral phase with a significant role in arsenic migration
Author(s) -
Loun Jan,
Čejka Jiří,
Sejkora Jiří,
Plášil Jakub,
Novák Milan,
Frost Ray L.,
Palmer Sara J.,
Keeffe Eloise C.
Publication year - 2011
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.2900
Subject(s) - raman spectroscopy , amorphous solid , hydrogen bond , bending , chemistry , crystallography , spectral line , ion , molecule , hydrogen , molecular vibration , analytical chemistry (journal) , materials science , physics , optics , organic chemistry , astronomy , composite material
The Raman spectrum of bukovskýite [Fe 3+ 2 (OH)(SO 4 )(AsO 4 )· 7H 2 O] has been studied and compared with that of an amorphous gel containing specifically Fe, As and S, which is understood to be an intermediate product in the formation of bukovskýite. The observed bands are assigned to the stretching and bending vibrations of (SO 4 ) 2− and (AsO 4 ) 3− units, stretching and bending vibrations and vibrational modes of hydrogen‐bonded water molecules, stretching and bending vibrations of hydrogen‐bonded (OH) − ions and Fe 3+ (O,OH) units. The approximate range of OH···O hydrogen bond lengths was inferred from the Raman spectra. Raman spectra of crystalline bukovskýite and of the amorphous gel differ in that the bukovskýite spectrum is more complex, the observed bands are sharp and the degenerate bands of (SO 4 ) 2− and (AsO 4 ) 3− are split and more intense. Lower wavenumbers of δ H 2 O bending vibrations in the spectrum of the amorphous gel may indicate the presence of weaker hydrogen bonds compared to those in bukovskýite. Copyright © 2011 John Wiley & Sons, Ltd.