The structure of water in the hydration shell of cations from x-ray Raman and small angle x-ray scattering measurements
2011 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 134, no 6, 064513- p.Article in journal (Refereed) Published
X-ray Raman scattering (XRS) spectroscopy and small angle x-ray scattering (SAXS) are used to study water in aqueous solutions of NaCl, MgCl2, and AlCl3 with the particular aim to provide information about the structure of the hydration shells of the cations. XRS spectra show that Na+ weakens the hydrogen bonds of water molecules in its vicinity, similar to the effect of increased temperature and pressure. Mg2+ and Al3+, on the other hand, cause formation of short and strong hydrogen bonds between the surrounding water molecules. SAXS data show that Mg2+ and Al3+ form tightly bound hydration shells that give a large density contrast in the scattering data. From the form factor extracted from the SAXS data, we found that Mg2+ and Al3+ have, respectively, an equivalent of one and one and a half stable hydration shells that appear as a density contrast. In addition, we estimated that the density of water in the hydration shells of Mg2+ and Al3+ is, respectively, ~61% and ~71% higher than in bulk water.
Place, publisher, year, edition, pages
2011. Vol. 134, no 6, 064513- p.
IdentifiersURN: urn:nbn:se:su:diva-47125DOI: 10.1063/1.3533958ISI: 000287327400058OAI: oai:DiVA.org:su-47125DiVA: diva2:373050