Magic-Angle Spinning NMR and Molecular Mobility in Heterogeneous Systems
Autor: | Dieter Michel |
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Rok vydání: | 2018 |
Předmět: |
Materials science
Solid-state physics Resonance 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Atomic and Molecular Physics and Optics Spectral line 0104 chemical sciences Magnetic field Membrane Chemical physics Magic angle spinning Molecule lipids (amino acids peptides and proteins) 0210 nano-technology Order of magnitude |
Zdroj: | Applied Magnetic Resonance. 49:537-552 |
ISSN: | 1613-7507 0937-9347 |
Popis: | Magic-angle sample spinning (MAS) nuclear magnetic resonance (NMR) measurements are treated for heterogeneous systems with nanometer dimensions. An appreciable line narrowing in the MAS NMR spectra of the embedded molecules may be achieved also in the cases when the molecules still possess an appreciable local mobility. It appears that the MAS frequencies are of comparable order of magnitude as the frequencies which characterize the random molecular motional processes and which compete with MAS. It will be shown that this behavior may occur if inhomogeneous local magnetic fields due to susceptibility effects have a dominating influence on the widths and shapes of the resonance NMR lines. Properties of these local fields are described. Spectra simulations are carried for molecules embedded in these heterogeneous systems when the coherent averaging by MAS is superimposed by random local motions. This situation may occur for molecules contained in nanoporous solids and also for heterogeneous systems like membranes and biological tissues with flexible components like water, lipids, and small peptides. Several examples are treated which reveal advantages and limitations of these experiments and their theoretical interpretation. |
Databáze: | OpenAIRE |
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