Spinning sideband suppression

Fig. 14. Pulse sequence of the 5-ir-pulse experiment used in the pseudo-twodimensional spinning-sideband-suppression experiment. All pulses in the observe channel are ir pulses. The constant delay T must be a multiple of the rotor period T, but not 3t,. (Reproduced from Gan " with permission.)...

Figure 8 VT C CP MAS NMR spectrum with spinning sideband suppression of PBLA in the solid state at various temperatures dashed line, ap helix form, light solid line, col helix form and bold solid line, p sheet form. Reproduced with permission of American Chemical Society from Akieda T, Mimura H, Kuroki S, Kurosu H and Ando I (1992) Macromolecules 25 5794.

The CP step is an essential building block for pulse sequences in solid-state NMR. The easiest ID experiments that are routinely used for characterization of organic, organometallic and hybrid solids are total suppression of spinning sidebands (TOSS), nonquatemary suppression, and so on. 

Fig. 1 SSNMR spectra of ibuprofen, 75.6 MHz. (A) Bloch decay experiment (single pulse), no decoupling, static, 240-sec pulse delay, 100 scans, 400-min experiment time. (B) Same as (A) but with decoupling ( 60 kHz). (C) Same as (B) but with 5-kHz MAS. (D) Cross-polarization experiment, with H decoupling ( 60 kHz), 5-kHz MAS, 1.5-msec contact time, 3-sec pulse delay, 100 scans, 5-min experiment time. (E) Same as (D) with the TOSS pulse sequence applied to suppress spinning sidebands. Note Asterisk ( ) denotes spinning sidebands sharp ( ) denotes spectrometer background artifact.

Fig. 6 CPMAS NMR spectra of (A) bupivacaine-fb (5% wt/wt) in lipospheres (95% wt/wt) (B) lipospheres (C) difference spectrum of (A) minus (B) (D) bupivacaine-fb. Asterisks ( ) denote spinning sidebands incompletely suppressed by the TOSS sequence. (From Ref. l)...

Z. Song, O. N. Antzutkin, X. Feng and M. H. Levitt, Sideband suppression in magic-angle spinning NMR by a sequence of 5 it pulses. Sol. Stat. Nucl. Magn. Reson., 1993, 2, 143-146. 

The pulse sequence used most often for this purpose is the TOSS sequence (total suppression of spinning sidebands. Fig. 3.3.9) [Dixl, Gril]. Before the start of data acquisition at r = ts the spin system is prepared by four 180° pulses at well-defined times... 

Fig. 3.3.9 TOSS preparation in MAS NMR for suppression of spinning sidebands. The 180 TOSS pulses are not equally spaced in practice.

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