On the mechanism of the Hofmeister effect

Marc C. Gurau, Soon Mi Lim, Edward T. Castellana, Fernando Albertorio, Sho Kataoka, Paul S. Cremer

Research output: Contribution to journalArticlepeer-review

237 Scopus citations

Abstract

Vibrational sum frequency spectroscopy was used to probe fatty amine monolayers spread on various electrolyte solutions. The spectra revealed ion specific changes in both monolayer ordering and water structure with the former following the Hofmeister series. Separate measurements of the surface potential as a function of ion tracked closely to changes in alkyl chain structure, but less closely to changes in water structure. The disruption of the monolayer ordering could be ascribed to the relative ability of the ions to penetrate past the hydrophilic surface of the monolayer's headgroups and into the more hydrophobic portion of the thin film. The corresponding trends observed in the surface water structure showed significant deviations from the Hofmeister series, leading to the conclusion that the changes in surface water structure, often credited with being the origin of Hofmeister effects, are probably not of primary importance. On the other hand, dispersion forces almost certainly play a large role in the order of the Hofmeister series.

Original languageEnglish (US)
Pages (from-to)10522-10523
Number of pages2
JournalJournal of the American Chemical Society
Volume126
Issue number34
DOIs
StatePublished - Sep 1 2004

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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