Large variations in the propensity of aqueous oxychlorine anions for the solution/vapor interface.
Core-level photoelectron spectroscopy measurements have been performed of aqueous solutions of NaCl codissolved with NaClO(n) (n=1-4). Each species has a distinct Cl 2p electron binding energy, which can be exploited for depth-profiling experiments to study the competition between Cl(-) and ClO(n)(-) anions for residing in the outermost layers of the solution/vapor interface. Strongest propensity for the surface is observed for n=4 (perchlorate), followed by n=3 (chlorate), n=2 (chlorite), n=0 (chloride), and n=1 (hypochlorite). Molecular dynamics simulations rationalize the greatest surface propensity of the most oxidized anions in terms of their larger size and polarizability. The anomalous behavior of hypochlorite, being less surface-active than chloride, although it is both larger and more polarizable, is suggested to arise from the charge asymmetry over the anion, increasing its efficiency for bulk solvation.
Ottosson
Niklas
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Department of Physics and Materials Science, Uppsala University, SE-751 21 Uppsala, Sweden. niklas.ottosson@fysik.uu.se
Vácha
Robert
R
Aziz
Emad F
EF
Pokapanich
Wandared
W
Eberhardt
Wolfgang
W
Svensson
Svante
S
Ohrwall
Gunnar
G
Jungwirth
Pavel
P
Björneholm
Olle
O
Winter
Bernd
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