title: Single-molecule observations of surfactant diffusion at the solution-solid interface.
abstract: Individual fatty acid molecules adsorbed at the interface between hexadecane and fused silica have been tracked using total internal reflection fluorescence microscopy. Two cooperative diffusive mechanisms are observed: continuous small-scale Brownian motion and occasional large "jumps." The continuous diffusion exhibits evidence of confinement. The effective interfacial diffusion coefficients for each mechanism increase systematically with temperature; an Arrhenius analysis gives an activation barrier of approximately 50 kJ/mol for "jumping" and an upper limit of approximately 10 kJ/mol for confined diffusion.
authors.affiliation: Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA.
authors.forename: Andrei
authors.initials: A
authors.lastname: Honciuc
authors.forename: Adam W
authors.initials: AW
authors.lastname: Harant
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Schwartz
mesh_terms: D004058:Diffusion; D015394:Molecular Structure; D012996:Solutions; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D012996:Solutions; D013501:Surface-Active Agents