Magic angle with quadrupolar nuclei

Fig. 4. Quadrupolar powder patterns (a) Spin NMR powder pattern showing that the central -)<- ) transition is broadened only by dipolar coupling, chemical shift anisotropy, and the second-order quadrupolar interactions, (b) Spin 1 NMR powder pattern for a nucleus in an axially symmetric electric field gradient (see text). The central doublet corresponds to 6 = 90° in Eq. (10). The other features of low intensity correspond to 6 = 0° and 6 = 180°. (c) Theoretical line shape of the ) - -) transition of a quadrupolar nuclear spin in a powder with fast magic-angle spinning for different values of the asymmetry parameter t (IS) ...

Fig. 5 The effect of magic-angle spinning on the central transition lineshape for a half-integer spin quadrupolar nucleus. Left central transition lineshape under static, i.e., non-spinning conditions. Right the same transition under magic-angle spinning. The asymmetry parameter r is given with each spectrum. Reproduced with permission from [61])...

Figure 9 (A) Typical line shape of an observed quadrupolar nucleus S, showing the second-order quadrupole shift AcTqs, and the relative position of the centre-of-gravity with respect to the isotropic chemical shift ajso- (B) Al solid-state MAS NMR spectrum of Sr8(AI02)i2-Se2 at 78.15 MHz (7.05 T). Asterisks denote sidebands. Reproduced with permission of Elsevier Science Publishers from Weller MT, Brenchley ME, Apperley DC and Davies NA (1994) Correlations between aI magic-angle spinning nuclear magnetic resonance spectra and the coordination geometry of framework alumlnates. Solid State Nuclear Magnetic Resonance Z 103-106.

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