Berlin 2001 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 2: Single Molecule Spectroscopy

CPP 2.3: Talk

Tuesday, April 3, 2001, 16:25–16:45, 110

Single Molecule Diffuision at Liquid-Solid Interfaces — •J. Schuster, F. Cichos, and C. von Borczyskowski — Institut für Physik 122501, TU Chemnitz, 09107 Chemnitz

The presence of a solid surface alters the structural and dynamical properties of a liquid. As one result structural order appears in a thin liquid layer close to the solid surface known as molecular layering. In similar way the wetting of solid surfaces by liquids is often dominated by these layers which precede the droplet spreading as a precursor layer. Thus the diffusion properties of molecules in such layers have to differ from the bulk.

We present video microscopy studies on single dye molecules in wetting structures and in thin liquid films. By imaging single molecule motion onto a CCD camera we are able to reconstruct single molecule diffusion trajectories. Their analysis shows that most single molecule trajectories exhibit two diffusion components which form a broad distribution of diffusion coefficients for the ensemble. We assign this distribution to different spatial regions. In addition attachments of molecules on the surface are found. The attachment duration shows a exponential duration statistic.

The experimental results are compared to simulation results of two different random walk models.