Raman spectroscopy of uranopilite of different origin - implications for molecular structure
(2007) Raman spectroscopy of uranopilite of different origin - implications for molecular structure. Journal of Raman Spectroscopy 38(4):pp. 398-409.
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Abstract
Uranopilite, [(UO2)6(SO4)O2(OH)6(H2O)6](H2O)8, the composition of which may vary, can be understood as a complex hydrated uranyl oxy hydroxy sulfate. The structure of uranopilite of different localities has been studied by Raman spectroscopy at 298 and 77 K. A single intense band at 1009 cm-1 assigned to the ￮1 (SO4)2- symmetric stretching mode shifts to higher wavenumbers at 77 K. Three low intensity bands are observed at 1143, 1117 and 1097 cm-1. These bands are attributed to the (SO4)2- ν3 antisymmetric stretching modes. Multiple bands provide evidence that the symmetry of the sulphate anion in the uranopilite structure is lowered. Three bands are observed at 843 to 816 cm-1 in both 298 and 77 K spectra and are attributed to the ν1 symmetric stretching modes of the (UO2)2+ units. Multiple bands prove the symmetry reduction of the UO2 ion. Multiple OH stretching modes prove a complex arrangement of OH groupings and hydrogen bonding in the crystal structure. A series of infrared bands not observed in the Raman spectra are found at 1559, 1540, 1526 and 1511 cm-1 attributed to ￤ UOH bending modes. U-O bond lengths in uranyl and O-H…O bond lengths are calculated and compared with X-ray single crystal structure analysis. Raman spectra of uranopilites of different origin show subtle differences in spectra proving the spectra are origin and sample dependent. Hydrogen-bonding network and its arrangement in the crystal structure play an important role in the origin and stability of uranopilite.
| Item Type: | Journal Article |
|---|---|
| Status: | Published |
| Keywords: | Keywords: uranopilite, johannite, zippeite, uranyl sulphate minerals, dehydroxylation, dehydration, infrared and Raman spectroscopy |
| Subjects: | 250000 Chemical Sciences > 250100 Physical Chemistry (incl. Structural) > 250105 Structural Chemistry 250000 Chemical Sciences > 250100 Physical Chemistry (incl. Structural) > 250104 Chemical Spectroscopy 250000 Chemical Sciences > 250100 Physical Chemistry (incl. Structural) > 250103 Colloid and Surface Chemistry |
| ID Code: | 7533 |
| Deposited By: | Frost, Ray |
| Deposited On: | 10 May 2007 |
| Alternative Locations: | http://dx.doi.org/10.1002/jrs.1660 |
| Copyright Owner: | Copyright 2007 John Wiley & Sons |
| Additional Information: | For more information, please refer to the journal's website (see hypertext link) or contact the author. |