Berlin 2001 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 17: Poster: Spectroscopy and Single Particle Spectroscopy of Molecular Systems, Photoprocesses, Biological Systems

CPP 17.8: Poster

Dienstag, 3. April 2001, 12:30–15:00, AT1

Single Molecule Diffusion in Liquids near Interfaces −o Experiments and Computer Simulations — •Jörg Schuster, Frank Cichos, and Christian von Borczyskowski — Institut für Physik 122501, TU Chemnitz, 09107 Chemnitz

We present experimental results and random walk simulations of the diffusion of single molecules in liquids close to interfaces. The diffusion of molecules close to a solid interface is strongly influenced by surface potentials. From video microscopy of single diffusing molecules in liquids near a solid interface we extract that the diffusion is characterized by a broad distribution of diffusion constants. We also observe attachments of molecules to the surface, where the attachment times show an exponential distribution and are independent of the charge state of the diffusing molecule.

The experimental results are compared to computer simulations where the influence of the surface is modeled either by attachments to the surface or by a thin sheet of liquid with a reduced diffusion constant. While both models lead to similar results, i.e. a broad distribution of diffusion constants, we can extract a correlation of the thickness ratio of the bulk liquid and the “surface sheet” with the distribution function of the observed diffusion constants.