Chemical shift anisotropies spinning sidebands systems

RF pulse and spinning speed effects/ (iv) When the second-order quadrupolar interaction is much smaller than the chemical shift anisotropy, the quadrupolar parameters can be estimated by monitoring the frequency shift of the centre band as a function of the Bo field and the chemical shift anisotropy can be determined by Herzfeld—Berger sideband analysis/ We shall discuss the applicabihty of these methods to Co systems in turn. 

We have referred to the various interactions which can cause line broadening in the solid state. One of these, which is normally not a problem in liquid state NMR, is due to the fact that the chemical shift itself is a tensor, i.e. in a coordinate system with orthogonal axes x, y and z its values along these axes can be very different. This anisotropy of the chemical shift is proportional to the magnetic field of the spectrometer (one reason why ultra-high field spectrometers are not so useful), and can lead in solid state spectra to the presence of a series of spinning sidebands, as shown in the spectra of solid polycrystalline powdered triphenylphosphine which follows (Fig. 49). In the absence of spinning, the linewidth of this sample would be around 75 ppm ... 

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