Berlin 2005 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 20: Dynamics II

CPP 20.3: Vortrag

Dienstag, 8. März 2005, 11:45–12:00, TU C230

NMR Investigations of Adsorbed Molecules in Zeolites — •Özlen Ferruh Erdem and Dieter Michel — Institut für Experimentelle Physik II, Universität Leipzig, Linnéstrasse 5, D-04103 Leipzig, Deutschland

High-resolution ¹ H MAS and ² H NMR spectroscopy are used to study the behaviour of ethylene glycol adsorbed in NaX zeolites. Typical changes in the proton chemical shift values for the CH ₂ and OH groups arise which are very sensitive to interactions between the molecules and the internal surfaces. This allows to clearly differentiate between molecules within the zeolite cages and those ones adsorbed at the outer surface of the zeolite grains as well as to study the dynamics of the different species. Selective measurements of the proton longitudinal relaxation times T ₁ were carried out for both type of the molecules which show large differences in the thermal mobility when the pore filling degree is varied. For molecules inside the supercages, a dynamic heterogeneity occurs. This may be related to the competing influences of molecule-molecule interactions within the network of intermolecular hydrogen bonds and molecule-surface interactions. ²H NMR measurements are performed for deuterated ethylene glycol adsorbed in NaX for the characterisation of the phase transition from liquid-like to glass-like behaviour.