Adsorption of thiocyanate ions to the dodecanol/water interface characterized by UV second harmonic generation.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 19706409.
- Also identified by DOI 10.1073/pnas.0904800106 and PMC identifier 2741224.
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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.
Medical subject headings
- Dodecanol
- Models, Chemical
- Thiocyanates
- Water