Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
4700265 | Chemical Geology | 2009 | 7 Pages |
Abstract
The local and geometrical structure around gold (III) e.g., Au3+ ions in aqueous solution with different OHâ/Clâ molar ratios, has been investigated by X-ray absorption spectroscopy (XAS). X-ray absorption near-edge structure (XANES) spectra of [AuCln(OH)4ân]â solutions have been calculated and the multiple-scattering spectral features have been attributed to Cl d-states, axial water molecules and the replacement of Clâ ligands by OHâ ligands. A square-planar geometry for [AuCln(OH)4ân]â with two axial water molecules has been identified. Moreover, a spectral correlation between XANES features and the type of planar atoms has been identified. By extended X-ray absorption fine structure spectra (EXAFS), the planar Au bond distances in the solutions have also been determined, e.g., 2.28Â Ã
for Au-Cl and 1.98Â Ã
for Au-O, respectively. The same EXAFS analysis provides evidence that the peak at about 4.0Â Ã
in solutions with the lowest OHâ/Clâ molar ratio arises from collinear Cl-Au-Cl multiple-scattering contributions. For the first time, a complete detailed reconstruction of the hydration structure of an Au ion at different pH values has been achieved.
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Authors
Xing Chen, Wangsheng Chu, Dongliang Chen, Zhonghua Wu, A. Marcelli, Ziyu Wu,