Single-molecule observations of surfactant diffusion at the solution-solid interface.
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.
Honciuc
Andrei
A
Department of Chemical and Biological Engineering, University of Colorado, Boulder, CO 80309, USA.
Harant
Adam W
AW
Schwartz
Daniel K
DK
D004058:Diffusion; D015394:Molecular Structure; D012996:Solutions; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry*
D012996:Solutions; D013501:Surface-Active Agents