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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 21: POSTER: Dynamics and Diffusion
CPP 21.7: Poster
Mittwoch, 28. März 2007, 16:00–18:30, Poster B
Diffusion and spin relaxation in thin excited slices — •Achim Gädke1 and Nikolaus Nestle1,2 — 1TU Darmstadt, Institut für Festkörperphysik — 2BASF AG Ludwigshafen
NMR experiments involving thin excited slices are of interest both for conventional NMR microimaging and for mechanically detected magnetic resonance. Especially in the latter case, the thickness of the excited slices may be well below 1 μm. In samples containing fast-diffusing liquid components such as water, the diffusive exchange of spin magnetization between such a thin excited slice and its surrounding on the time scale of the NMR experiments plays a major role [1]. Using static field gradients of 170 T/m we investigate the effects of periodic excitation inside thin slices. Vertical positioning of the sample cells at μm precision relative to the magnetic field gradient and flat coil design for optimal signal filling factor are prerequisites to systematic studies. A novel experimental cell adapted to such a coil design will be presented and experimental options for manipulating diffusion and relaxation properties of the walls and the liquid in the cell while retaining the exact positioning with respect to the magnet will be discussed. Both simulation and experimental results on the slice's NMR response under periodic excitation will be presented and consequences for further development in micro-MRI and mechanically detected NMR will be discussed.
[1]A. Gädke, N. Nestle, Diffusion Fundamentals 3 (2005) 38.1 - 38.12