Berlin 2005 – scientific programme
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DY: Dynamik und Statistische Physik
DY 43: Einstein Symposium Brownian Motion, Diffusion and Beyond (SYBM) – Contributed Talks I
DY 43.11: Talk
Tuesday, March 8, 2005, 17:00–17:15, TU H2032
Diffusion of single fluorescent dyes in nanometersized channels and cage structures — •Johanna Kirstein1, Christian Hellriegel1, Christophe Jung1, Christoph Bräuchle1, Nikolay Petkov1, Barbara Fieres1, Thomas Bein1, and Ross Brown2 — 1LMU, Dept. Chemie und Biochemie, CeNS, Butenandtstr. 11, D-81377 München — 2U.P.P.A., umr 5624 du CNRS, IFR, rue Jules Ferry, F-64075 Pau Cedex
We investigate the diffusion of individual molecules incorporated into mesoporous hosts. Using wide-field imaging and single particle tracking we collect trajectories of single fluorescent dye molecules (TDI) with high temporal (70 frames/s) and spatial (< 20 nm) resolution. In the present study thin films of spincoated mesoporous silica are used as hosts. Two different pore architectures were obtained by liquid crystal templating: a hexagonal (pore diameter 6 nm) and a cubic phase (9 nm). Our method provides a direct microscopic view of the diffusion process of single molecules, revealing not only differences in the mean diffusivity, but structural heterogeneities on a nanometer scale. Two populations of mobile molecules could be distinguished in the hexagonal samples. In the cubic phase a broad distribution of diffusion coefficients was observed. Strong deviations from Brownian motion occured: in some cases the shape of the trajectories reflects pore structure and topology of the host system. Simulations of the diffusional behavior based on the structural data of the host-guest systems are done for comparison.