Berlin 2008 – scientific programme
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DF: Fachverband Dielektrische Festkörper
DF 6: Glasses I (joint session DF/DY)
DF 6.2: Talk
Tuesday, February 26, 2008, 10:00–10:15, EB 407
Confined glass formers in nanoporous materials studied by 31P NMR — •Sabine Gradmann1, Gilberte Dosseh2, Christiane Alba Simionesco2, and Ernst Rössler1 — 1Experimentalphysik II, Universität Bayreuth, 95440 Bayreuth, Germany — 2Laboratoire de Chimie Physique, CNRS-UMR 8000, Bâtiment 349, Université de Paris-Sud, 91405 Orsay, France
We investigate the dynamics of the glass former m-tricresylphosphate (mTCP) confined in the nanoporous matrices CPG, SBA15, MCM41 with different pore sizes, varying in diameter from 4nm up to 300nm, within a temperature range above the glass transition temperature (from 210 K up to 370 K). The performed 31P NMR experiments demonstrate a great change in the relaxation times (T1 and T2) reflecting a significant slowing down of the dynamics for small pore systems in comparison with the bulk. Additionally, a detailed analysis of 1D spectra reveals pronounced dynamic heterogeneities, which we describe by a distribution of correlation times. The width of the latter decreases gradually while approaching the bulk limit. Furthermore, exploiting the large dynamic window of 31P NMR, 2D exchange NMR is applied in order to establish whether the dynamic heterogeneities are of static or transient nature.