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The influence of concentration on the molecular surface structure of simple and mixed aqueous electrolytes

Ottosson, Niklas; Heyda, Jan; Wernersson, Erik; Pokapanich, Wandared; Svensson, Svante; Winter, Bernd; Öhrwall, Gunnar LU ; Jungwirth, Pavel and Bjorneholm, Olle (2010) In Physical Chemistry Chemical Physics 12(36). p.10693-10700
Abstract
We investigate various mechanisms contributing to the surface ion distributions in simple and mixed aqueous alkali-halide solutions depending on the total salt concentration, using a combination of photoelectron spectroscopy and molecular dynamics simulations. In simple solutions, the surface enhancement of large polarizable anions is reduced with increasing concentration. In the case of a NaBr/NaCl mixed aqueous solution, with bromide as the minority component, the situation is more complex. While the total anion/cation charge separation is similarly reduced with increasing salt content, this alone does not uniquely determine the ion distribution due to the co-existence of two different anions, Br- and Cl-. We show that bromide is... (More)
We investigate various mechanisms contributing to the surface ion distributions in simple and mixed aqueous alkali-halide solutions depending on the total salt concentration, using a combination of photoelectron spectroscopy and molecular dynamics simulations. In simple solutions, the surface enhancement of large polarizable anions is reduced with increasing concentration. In the case of a NaBr/NaCl mixed aqueous solution, with bromide as the minority component, the situation is more complex. While the total anion/cation charge separation is similarly reduced with increasing salt content, this alone does not uniquely determine the ion distribution due to the co-existence of two different anions, Br- and Cl-. We show that bromide is selectively surface enhanced at higher concentrations, despite the fact that the total anion surface enhancement is reduced. This phenomenon, which can be viewed as "salting out'' of bromide by NaCl might have consequences for our understanding of the surface structure of mixed aqueous solutions subjected to concentration increase due to dehydration, such as seawater-born aerosols. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Physical Chemistry Chemical Physics
volume
12
issue
36
pages
10693 - 10700
publisher
Royal Society of Chemistry
external identifiers
  • wos:000281613300005
  • scopus:77956329851
ISSN
1463-9084
DOI
10.1039/c0cp00365d
language
English
LU publication?
yes
id
1c7883c1-71a8-4a12-875e-f346f8dfe94e (old id 1697317)
date added to LUP
2010-10-25 11:00:05
date last changed
2018-05-29 11:43:22
@article{1c7883c1-71a8-4a12-875e-f346f8dfe94e,
  abstract     = {We investigate various mechanisms contributing to the surface ion distributions in simple and mixed aqueous alkali-halide solutions depending on the total salt concentration, using a combination of photoelectron spectroscopy and molecular dynamics simulations. In simple solutions, the surface enhancement of large polarizable anions is reduced with increasing concentration. In the case of a NaBr/NaCl mixed aqueous solution, with bromide as the minority component, the situation is more complex. While the total anion/cation charge separation is similarly reduced with increasing salt content, this alone does not uniquely determine the ion distribution due to the co-existence of two different anions, Br- and Cl-. We show that bromide is selectively surface enhanced at higher concentrations, despite the fact that the total anion surface enhancement is reduced. This phenomenon, which can be viewed as "salting out'' of bromide by NaCl might have consequences for our understanding of the surface structure of mixed aqueous solutions subjected to concentration increase due to dehydration, such as seawater-born aerosols.},
  author       = {Ottosson, Niklas and Heyda, Jan and Wernersson, Erik and Pokapanich, Wandared and Svensson, Svante and Winter, Bernd and Öhrwall, Gunnar and Jungwirth, Pavel and Bjorneholm, Olle},
  issn         = {1463-9084},
  language     = {eng},
  number       = {36},
  pages        = {10693--10700},
  publisher    = {Royal Society of Chemistry},
  series       = {Physical Chemistry Chemical Physics},
  title        = {The influence of concentration on the molecular surface structure of simple and mixed aqueous electrolytes},
  url          = {http://dx.doi.org/10.1039/c0cp00365d},
  volume       = {12},
  year         = {2010},
}