title: Single molecule fluorescence microscopy investigations on heterogeneity of translational diffusion in thin polymer films.
abstract: Translational diffusion of single perylene diimide molecules in 25 nm thin polymer films was investigated by single molecule widefield fluorescence microscopy. Spatial heterogeneities in single molecule motion were detected and analyzed by a new, quantitative method which draws a comparison of log-Gaussian fits of experimentally determined diffusion coefficient-distributions and diffusion coefficient-distributions from Monte Carlo random walk simulations. Heterogeneities could be observed close to the glass transition temperature, but disappear at ca. 1.1 × T(g). At higher temperatures, heterogeneities do not exist or they average out on the time and length scales of observation. The observed heterogeneities also explain why the dependency of diffusion coefficients on temperature does not follow Vogel-Fulcher-Tammann behavior.
authors.affiliation: Fachbereich Chemie, Universität Konstanz, Universitätsstrasse 10, 78464 Konstanz, Germany.
authors.forename: Bente M I
authors.initials: BM
authors.lastname: Flier
authors.forename: Moritz
authors.initials: M
authors.lastname: Baier
authors.forename: Johannes
authors.initials: J
authors.lastname: Huber
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
authors.forename: Stefan
authors.initials: S
authors.lastname: Mecking
authors.forename: Andreas
authors.initials: A
authors.lastname: Zumbusch
authors.forename: Dominik
authors.initials: D
authors.lastname: Wöll