Adsorption of thiocyanate ions to the dodecanol/water interface characterized by UV second harmonic generation
Date
2009
Authors
Onorato, R.M.
Otten, D.E.
Saykally, R.J.
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Journal article
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Proceedings of the National Academy of Sciences of the United States of America, 2009; 106(36):15176-15180
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Abstract
Recent experimental and theoretical results have firmly established the existence of enhanced concentrations of selected ions at the air/water interface. Ion adsorption to aqueous interfaces involving complex organic molecules is relevant to biology in connection with the familiar but incompletely understood Hofmeister effects. Here, we describe resonant UV second harmonic generation (SHG) studies of the strongly chaotropic thiocyanate ion adsorbed to the interface formed by water and a monolayer of dodecanol, wherein the Gibbs free energy of adsorption was determined to be -6.7 ± 1.1 and -6.3 ± 1.8 kJ/mol for sodium and potassium thiocyanate, respectively, coincident with the value determined for thiocyanate at the air/water interface. Interestingly, near 4 M and higher concentrations, the resonant SHG signal increases discontinuously, indicating a structural change in the interfacial region.
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Link to a related website: http://europepmc.org/articles/pmc2741224?pdf=render, Open Access via Unpaywall
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Copyright 2009 PNAS