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An anomalous x-ray diffraction study of the hydration structures of Cs+ and I- in concentrated solutions.

Ramos, Silvia, Neilson, G.W., Barnes, A.C., Buchanan, P. (2005) An anomalous x-ray diffraction study of the hydration structures of Cs+ and I- in concentrated solutions. The Journal of chemical physics, 123 (21). ISSN 0021-9606. E-ISSN 1089-7690. (doi:10.1063/1.2128706) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided. (Contact us about this Publication)
Official URL
https://doi.org/10.1063/1.2128706

Abstract

Anomalous x-ray diffraction experiments were carried out on concentrated aqueous solutions of sodium iodide (6 molal) and cesium iodide (3 molal). Data were gathered at two energies below the absorption edges of the Cs+ and I- ions in order to avoid contributions from fluorescence. The statistics and quality of the raw data were improved by the use of a focusing analyzer crystal. Differences were taken between the data sets and used to calculate the hydration structures of Cs+ and I-. The structures found are more complex than anticipated for such large ions with relatively low charge densities and show evidence of ion-pair formation in both solutions. A two-Gaussian fit to the Cs+ data gives information about the Cs+-O and Cs+-I- correlations. The central position of the Gaussian representing the Cs+-O was fixed at 3.00 A, that is, the maximum of this contribution. The other parameters were allowed to vary freely, giving a Cs+-I- distance of 3.84+/-0.05 A and coordination numbers of 7.9 and 2.7, respectively, for the Cs+-O and Cs+-I- correlations. The results on the structure of I- in the 6 molal NaI aqueous solution were also fitted to a model based on Gaussians; this gives correlations for I- -O and I- -Na+ at 3.17+/-0.06 and 3.76+/-0.06 A with respective coordination numbers of 8.8 and 1.6. The structure of I- in the 3 molal CsI solution shows overlapping contributions due to I- -H, I- -O, and I- -Cs+. The best Gaussian fit gives two peaks centered at 3.00+/-0.08 and 3.82+/-0.04 A and shows that the latter two correlations are unresolved. The hydration structures are compared with those of other alkali and halide ions. The results are also found to be in good agreement with those obtained from standard x-ray diffraction and computer simulation.

Item Type: Article
DOI/Identification number: 10.1063/1.2128706
Uncontrolled keywords: Physics of Quantum Materials, cesium, iodine, ion, water, article, chemical structure, chemistry, solution and solubility, X ray diffraction, Cesium, Iodine, Ions, Molecular Structure, Solutions, Water, X-Ray Diffraction
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences
Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Silvia Ramos
Date Deposited: 05 Dec 2017 22:51 UTC
Last Modified: 17 Jul 2019 09:52 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/46998 (The current URI for this page, for reference purposes)
Ramos, Silvia: https://orcid.org/0000-0003-2725-7706
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