Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: Polymer Physics II
CPP 21.6: Vortrag
Mittwoch, 25. März 2009, 11:00–11:15, ZEU 114
Dielectric and electric relaxations at nanometric length scales — •Friedrich Kremer1, Anatoli Serghei1,2, Martin Treß1, Joshua Rume Sangoro1, and Ciprian Iacob1 — 1Institute for Experimental Physics I, University of Leipzig, Germany — 2Department of Polymer Science and Engineering, University of Massachusetts Amherst, Amherst, MA 01003, USA
Dielectric spectroscopy benefits from the extraordinary advantage that its sensitivity increases with decreasing thickness of a sample capacitor. This enables one for instance to carry out broadband spectroscopic measurements on quasi isolated polymer coils in nano structured capacitor arrangements, having thicknesses as small as 100 nm. It is demonstrated that for polymers like polyvinyl pyridin (P2VP) or polyvinylacetate (PVAC) the dynamic glass transition can be measured for (averaged) sample thickness as small as ∼ 2 nm in a wide spectral range (10−2 Hz – 106 Hz) and at temperatures between 150 K to 350 K. No shift of the mean relaxation rate and no broadening of the relaxation time distribution function are found compared to the bulk liquid.
Electrode polarization is an ubiquitous phenomenon taking place at the interface between a metal and an ionic conductor. A quantitative theory will be presented, which enables one to deduce from its characteristic frequency, temperature and concentration dependencies – by use of a novel formula – the bulk conductivity of the ionic liquid under study. It is shown that the electrical relaxation processes take place within a nanometric layer at the (ionic conductor/metal) interface which can be analysed in detail.