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.
Department of Physics and Materials Science, Uppsala University, SE-751 21 Uppsala, Sweden. niklas.ottosson@fysik.uu.se
Niklas
N
Ottosson
Robert
R
Vácha
Emad F
EF
Aziz
Wandared
W
Pokapanich
Wolfgang
W
Eberhardt
Svante
S
Svensson
Gunnar
G
Ohrwall
Pavel
P
Jungwirth
Olle
O
Björneholm
Bernd
B
Winter