Spin side-effects

If the CSA is large (10-20 kHz, as for carbons in aromatic and in other conjugated bond systems), spinning at 3 kHz will not be sufficient and spinning side bands (SSB) will be obtained around the isotropic resonance line. By application of special pulse techniques these side bands (time dependent effects, (4)) can be removed or at least minimised in most of the cases. 

Figure 4.1. MAS NMR spectra of two natural muscovite micas illustrating the effect of the Fc203 content on the broadness of the central transition and the size of the spinning side bands (indicated by asterisks). A. Muscovite from Stewart Island, New Zealand, B. Muscovite from North Carolina, U.S.A. Adapted from MacKenzie et al. (1987).

Figure 5.38. Effect of hot-pressing on the MAS NMR spectra of yttrium-a-sialon synthesised by carbothermal and silicothermal synthesis using Si02 as the silica source (top) and Si as the silica source (bottom). Asterisks denote spinning side bands. From Ekstrdm et al. (1998).

In NMR, extensive studies have shown that solid-state CPMAS NMR spectra of most soils can be analyzed quantitatively(5,25,26) if one considers the relaxation and cross polarization lanetics of the compounds observed in the spectra. We can extend these results to imply that solid-state N CPMAS NMR spectra are also quantitative. Comparable to C CPMAS NMR, in a N CPMAS NMR experiment, quantification problems may arise from 1) incomplete relaxation of the spins during the experiment, 2) incomplete polarization transfer because of the isolation of protons from nitrogen atoms and 3) spinning side bands. The effects of these parameters on a C CPMAS NMR spectrum are extensively discussed by Wilson.(5)... 

Nevertheless, the availability of g and k parameters for Co + permits a reasonable estimate to be made of Bcompiex for CoFe of 787 cm. i (/Ss6 = 0.72). The experimental Dg- value of 1310 cm.-i is subject to some imcertainty by virtue of the dynamic Jahn-Teller effect associated with the upper E state, and is somewhat lower than the value of 1710 cm. i predicted from 10 T>q=f-g, but the experimental and theoretical Dg values lead respectively to Dg/B equal to 1.66 and 2.17, i.e. on either side of the crossover point, and on balance are in accordance with the expectation that Dg/B should lie slightly on the high-spin side of the crossover. It is also noteworthy that the calculated p value agrees extremely closely with that deduced from the tentative assignment of the spin-forbidden transition, (c.f. Section 2 (vi)). 

Those treatments, like the leuprolide acetate depot, will also likely spin premenopausal women right into pseudomenopause. But are the side effects similar ... 

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