Magic-angle spinning theory

In this section, some NMR techniques which have been applied to the study of biomineralization are introduced. The NMR techniques discussed below are all under the condition of magic-angle spinning (MAS). The discussion is largely descriptive and qualitative. Readers who are interested in a more rigorous exposition of the NMR theories are referred to the original literature. The implications of the NMR results in biomineralization are discussed in other sections. 

The amplitudes of ring- and main-chain motions of a variety of polystyrenes have been established from the 13C NMR magic-angle spinning sideband patterns of dipolar and chemical shift tensors. The frequencies of the same motions have been determined by TiCC) and TjpCC) experiments. The most prevalent motion in these polymers is restricted phenyl rotation with an average total displacement of about 40°. Both the amplitude and frequency of this motion vary from one substituted polystyrene to another, and from site to site within the same polystyrene. A simple theory correlates the observed ring dipolar patterns with s. 

C. Filip, M. Bertmer, D.E. Demco, B. Bliimich, Application of the Floquet theory to multiple quantum NMR of dipolar-coupled multi-spin systems under magic angle spinning. Mol. Phys. 99 (2001) 1575. 

P.K. Madhu, A. Goldbourt, L. Frydman, S. Vega, Fast radio-frequency amplitude modulation in mrdtiple-quantum magic-angle-spinning nuclear magnetic resonance theory and experiments, J. Chem. Phys. 112 (2000) 2377—2391. 

---