Ion-pairing in aqueous CaCl2 and RbBr solutions : Simultaneous structural refinement of XAFS and XRD data
(2013) In Journal of Chemical Physics 138(4).- Abstract
We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (x-ray absorption/diffraction structural refinement, XADSR) to study the hydration and ion pair structure of CaCl2 and RbBr salts in concentrated aqueous solutions. The XADSR method combines the x-ray absorption fine structure (XAFS) spectral analysis of both the cation and anion as a probe of their short-range structure with an x-ray diffraction (XRD) spectral analysis as a probe of the global structural. Together they deliver a comprehensive picture of the cation and anion hydration, the contact ion pair (CIP) structure, and the solvent-separated ion pair (SSIP) structure. XADSR analysis of 6.0 m aqueous... (More)
We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (x-ray absorption/diffraction structural refinement, XADSR) to study the hydration and ion pair structure of CaCl2 and RbBr salts in concentrated aqueous solutions. The XADSR method combines the x-ray absorption fine structure (XAFS) spectral analysis of both the cation and anion as a probe of their short-range structure with an x-ray diffraction (XRD) spectral analysis as a probe of the global structural. Together they deliver a comprehensive picture of the cation and anion hydration, the contact ion pair (CIP) structure, and the solvent-separated ion pair (SSIP) structure. XADSR analysis of 6.0 m aqueous CaCl2 reveals that there are ∼0.26 Ca2+-Cl- CIP's separated by about 2.71 Å, while there are 3.4 SSIP's separated by about 4.98 Å. In contrast XADSR analysis of 6 m aqueous RbBr yields about 0.7 pair CIP at a bond length of 3.51 Å. The present work demonstrates a new approach for a direct co-refinement of XRD and XAFS spectra in a simple and reliable fashion, opening new opportunities for analysis in various disordered and crystalline systems.
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- author
- Pham, Van-Thai and Fulton, John L.
- publishing date
- 2013-01-28
- type
- Contribution to journal
- publication status
- published
- in
- Journal of Chemical Physics
- volume
- 138
- issue
- 4
- article number
- 044201
- publisher
- American Institute of Physics (AIP)
- external identifiers
-
- scopus:84873594509
- ISSN
- 0021-9606
- DOI
- 10.1063/1.4775588
- language
- English
- LU publication?
- no
- id
- 094bcba5-94af-4ec7-8081-3bcc6f17a63c
- date added to LUP
- 2019-06-30 09:45:00
- date last changed
- 2022-01-31 22:55:42
@article{094bcba5-94af-4ec7-8081-3bcc6f17a63c, abstract = {{<p>We present a new methodology involving the simultaneous refinement of both x-ray absorption and x-ray diffraction spectra (x-ray absorption/diffraction structural refinement, XADSR) to study the hydration and ion pair structure of CaCl<sub>2</sub> and RbBr salts in concentrated aqueous solutions. The XADSR method combines the x-ray absorption fine structure (XAFS) spectral analysis of both the cation and anion as a probe of their short-range structure with an x-ray diffraction (XRD) spectral analysis as a probe of the global structural. Together they deliver a comprehensive picture of the cation and anion hydration, the contact ion pair (CIP) structure, and the solvent-separated ion pair (SSIP) structure. XADSR analysis of 6.0 m aqueous CaCl<sub>2</sub> reveals that there are ∼0.26 Ca<sup>2+</sup>-Cl<sup>-</sup> CIP's separated by about 2.71 Å, while there are 3.4 SSIP's separated by about 4.98 Å. In contrast XADSR analysis of 6 m aqueous RbBr yields about 0.7 pair CIP at a bond length of 3.51 Å. The present work demonstrates a new approach for a direct co-refinement of XRD and XAFS spectra in a simple and reliable fashion, opening new opportunities for analysis in various disordered and crystalline systems.</p>}}, author = {{Pham, Van-Thai and Fulton, John L.}}, issn = {{0021-9606}}, language = {{eng}}, month = {{01}}, number = {{4}}, publisher = {{American Institute of Physics (AIP)}}, series = {{Journal of Chemical Physics}}, title = {{Ion-pairing in aqueous CaCl<sub>2</sub> and RbBr solutions : Simultaneous structural refinement of XAFS and XRD data}}, url = {{http://dx.doi.org/10.1063/1.4775588}}, doi = {{10.1063/1.4775588}}, volume = {{138}}, year = {{2013}}, }