Cross-polarization techniques nuclear magnetic resonance

Discussions of old and new techniques used to study the surface of silica, including diffuse reflectance Fourier transform (DRIFT) infrared spectroscopy, 29Si cross polarization magic-angle nuclear magnetic resonance (CP MAS NMR) spectroscopy, as pioneered by Maciel and Sindorf... 

Solid state nuclear magnetic resonance spectroscopy (NMR), e.g. [107-109]. This technique is sensitive to the local environment of certain nuclei, their mobility and orientation [108]. It provides information about the heterogeneity of polymer blends to c. 5 nm or less (spin diffusion experiments) or c. 0.3 nm in cross-polarization experiments, from which the direct (averaged) distance between two types of nuclei in a sample can be determined [107,108]. Motions of moleuclar groups in a polymer chain can be analyzed and correlations with dispersion areas in the mechanical spectra may be possible [109]. Solid state NMR is not a standard technique at the present time but it is becoming increasingly important. 

To characterize the structure of silk, various techniques, namely X-ray diffraction (XRD), vibrational spectroscopy, and cross-polarization magic-angle spinning nuclear magnetic resonance, and so on, have been adopted. Hu et al. reported a study of self-assembled yS-pleated sheets in Bombyx mori silk fibroin films using... 

---