Berlin 2005 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 36: Glasses II (joint session DF/DY)
DY 36.9: Vortrag
Montag, 7. März 2005, 16:45–17:00, TU A060
Type A and type B glass formers: a 2H NMR approach — •Sorin A. Lusceac, M. Vogel, C. Koplin, P. Medick, and E. A. Rössler — Lehrstuhl Experimentalphysik II, Uni. Bayreuth, Universitatsstrasse 30, 95440 Bayreuth
Concerning the manifestation of the secondary relaxation process in molecular glasses, the classification of glass formers in two groups was introduced based on dielectric spectroscopy investigations; type B glass formers present a secondary relaxation process (β-process) while type A do not. Since then 2H NMR studies became a complementary approach. New NMR results, including mean spin-lattice relaxation time measurements (<T1>) and solid-echo line shape analysis will be presented for the type B glass former m-fluoroaniline, which has a β-process with a significantly smaller dielectric strength than the previous studied systems. The findings will be compared with those in glycerol, toluene, polybutadiene. We will estimate the relaxation strength of the β-process from NMR data and try to rationalize the different temperature dependence of <T1> for the various systems.