Magic-angle spinning molecular dynamics

In general, multiple pulse techniques sufficiently average the dipolar interactions, compress the chemical shift scale, but they do not affect heteronuclear dipolar interactions and the chemical shift anisotropy. A combination of both multiple pulse techniques and magic angle spinning, so-called CRAMPS (Combined Rotational And Multiple Pulse Spectroscopy) is found to yield satisfactory results in the solid state H NMR of solids 186). The limitations of all these techniques, from the analytical point of view, arises from the relatively small chemical shift range (about 10 ppm) as compared with some other frequently studied nuclei. However, high resolution H NMR of solids is useful in studies of molecular dynamics. 

Solid-state NMR with magic angle spinning has been used to good effect in studying organic crystals and their dynamics [41]. The powdered samples used in such studies can stabilize reaction intermediates or products and provide them with a uniform molecular environment. In order to simplify the spectra, this technique intentionally discards the information contained in... 

It has been demonstrated that cross-polarization/magic-angle spinning (CP/MAS) NMR spectroscopy is the most powerful means available to characterize the structure and dynamics of inorganic polymers in the solid state [1], The most recent development of a variable-temperature (VT) spinner provided an indispensable means to study slow chemical exchange, molecular motion and phase transitions of inorganic polymers. 

Cellulose, which Is one of the most abundant organic substances found In nature, has been extensively studied by various techniques such as x-ray scattering, electron microscopy, IR and Raman spectroscopy, NMR spectroscopy etc. However, the crystal structure and noncrystalline state are not yet solved for cotton, ramie, bacterial and valonla celluloses which can be easily obtained in pure form. Cross-polarization/magic angle spinning(CP/MAS) C NMR spectroscopy is a promising new method to study these unsolved problems of cellulose, because this method is very sensitive to local molecular conformations and dynamics. 

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