Single-pulse magic-angle spinning

The experiments described above were carried out on true solids, but solid-state techniques are also applicable to gels. Contrasting spectra of 10% amylose gels have been provided by single-pulse magic-angle spinning (SP/MAS) and CP/MAS experiments.280 At room temperature, the SP/MAS experiment... 

Fig. 3 Solid state 31P NMR spectra of fosinopril sodium acquired under single pulse, high-power proton decoupling and various conditions of magic-angle spinning (A) static, (B) 2.5 kHz, (C) 4.0 kHz, (D) 5.0 kHz, and (E) 6.0 kHz. The isotropic chemical shift is designated by an asterisk. (From Ref. 15.)...

Single Pulse Excitation Magic-Angle Spinning... 

Fig. 8 Schematic diagrams for the following pulse sequences (A) single pulse excitation/magic-angle spinning, (B) total suppression of sidebands, and (C) delayed decoupling, or dipolar dephasing.

FIGURE 3. 29Si-magic angle spinning NMR of silica and phenylsilsesquioxane products formed by the action of silicatein filaments on tetraethylorthosilicate (TEOS) or phenyltriethoxysilane, respectively. Single-pulse and cross-polarization spectra are shown. Results are discussed in the text. Redrawn from data in Reference 42... 

Fig. 14. The pulse sequence for recording the double-quantum 2H experiment.37 The entire experiment is conducted under magic-angle spinning. This two-dimensional experiment separates 2H spinning sideband patterns (or alternatively, static-like 2H quadrupole powder patterns) according to the 2H double-quantum chemical shift, so improving the resolution over a single-quantum experiment. In addition, the doublequantum transition frequency has no contribution from quadrupole coupling (to first order) so, the double-quantum spectrum is not complicated by spinning sidebands. Details of molecular motion are then extracted from the separated 2H spinning sideband patterns by simulation.37 All pulses in the sequence are 90° pulses with the phases shown (the first two pulses are phase cycled to select double-quantum coherence in q). The r delay is of the order 10 gs. The q period is usually rotor-synchronized.

Fig. 6.1.4. Room temperature NMR of H in (top) poly(methyl phenyl siloxane), (middle), a polystyrene, poly(methyl phenyl siloxane) (PS-b-PMPS) block copolymer, and (bottom) polystyrene, under single-pulse excitation and magic-angle spinning (MAS). The PMPS is sufficiently mobile that in the pure polymer, and in some samples of the block copolymer, anisotropic molecular motion, when combined with MAS at 4 kHz severely attenuates both dipolar broadening and shielding anisotropy [31].

Despite the obvious benefits of quantitative solid-state NMR via single pulse excitation methodology (SPE) (see Section 3), cross-polarisation combined with magic-angle spinning (CP/MAS) [1] has many intrinsic advantages which... 

---