title: Fluorescence correlation spectroscopy in thin films at reflecting substrates as a means to study nanoscale structure and dynamics at soft-matter interfaces.
abstract: Structure and dynamics at soft-matter interfaces play an important role in nature and technical applications. Optical single-molecule investigations are noninvasive and capable to reveal heterogeneities at the nanoscale. In this work we develop an autocorrelation function (ACF) approach to retrieve tracer diffusion parameters obtained from fluorescence correlation spectroscopy (FCS) experiments in thin liquid films at reflecting substrates. This approach then is used to investigate structure and dynamics in 100-nm-thick 8CB liquid crystal films on silicon wafers with five different oxide thicknesses. We find a different extension of the structural reorientation of 8CB at the solid-liquid interface for thin and for thick oxide. For the thin oxides, the perylenediimide tracer diffusion dynamics in general agrees with the hydrodynamic modeling using no-slip boundary conditions with only a small deviation close to the substrate, while a considerably stronger decrease of the interfacial tracer diffusion is found for the thick oxides.
authors: Institute of Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors: Daniela
authors: D
authors: Täuber
authors: Institute of Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors: Kathrin
authors: K
authors: Radscheit
authors: Institute of Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors: Christian
authors: C
authors: von Borczyskowski
authors: Institute of Physics, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors: Michael
authors: M
authors: Schulz
authors: Department of Chemical Physics, Lund University, S-22362 Lund, Sweden.
authors: Vladimir Al
authors: VA
authors: Osipov