Cross-polarization techniques magic angle spinning

The basic spectrometer we have employed for the study of solid polymers by cross-polarization/magic-angle spinning techniques is a Nicolet TT-14 pulse-FT system operating at 1.4T with resonance frequencies of 15.087 MHz, 60.0 MHz and 56.4 MHz for 1r and... 

The cross polarization-magic angle spinning technique used for C n.m.r. of solid methyl and -D-xylo yranosides has been shown to be sensitive to the crystal packings. 

Solid-state NMR (using cross-polarization magic-angle spinning techniques), isotopic substitution, and faster methods such as infrared, Raman, and, especially. X-ray photoelectron spectroscopy (ESCA) are particularly useful in investigating these systems. Some typical examples are depicted in Fig. 3. 

In recent years new NMR techniques offering broad applications in stereochemical analysis have come into use. A prominent example is 2D-NMR (both 2D-resolved and 2D-correlated spectroscopy), which has been extensively applied to biopolymers (149-151). Its use with synthetic polymers has, until now, been limited to but a few cases (152, 153). A further technique, cross-polarization magic-angle spinning spectroscopy (CP-MAS NMR) will be discussed in the section on conformational analysis of solid polymers. 

During the last 15 years, the cross-polarization magic-angle spinning (CPMAS) technique (2) has been used with increasing frequency to provide detailed structural information about solid polymers and biopolymers... 

Cook, R., and Langford, C. (1999). Ramped amphtude cross polarization magic angle spinning NMR (Ramp-CP-MAS-NMR) A technique for quantitative study of the composition of solid state polymers. Polymer News 24, 6-15. 

Cross-Polarization/Magic-Angle Spinning (CPMAS) Techniques. 212... 

By combining all of the above techniques into the so-called cross-polarization magic-angle spinning experiment (CP/MAS), relatively high-resolu-tion solid-state NMR spectra can be obtained. It should be pointed out, however, that the best solid-state spectra are still of substantially lower resolution than routine liquid-state spectra, and therefore additional information not present in the solid-state spectra can be obtained from liquid spectra. 

The dehydrohalogenation products of poly(ethylene-a/z-chlorotrifluor-oethylene) were also studied using solid-state NMR spectroscopy and the cross-polarization magic angle spinning (CP MAS) technique [18]. The elimination reaction induced by potassium ZerZ-butoxide (z-BuOK) in tetrahydrofuran (THF) was found to proceed slowly only 50% of hydrogen... 

The ability of NMR spectrometers to operate in the cross-polarization/ magic angle spinning mode is a powerful tool for structural elucidation of insoluble materials (556). Natural abundance solid-phase C-NMR spectra could be obtained for synthetic L-dopa eumelanin. The inordinate number of resonance signals, however, prevented definitive assignments of the peaks to specific carbons. Subsequently Chedekel et al. (357) used this technique to study the conversion of specifically labeled L-dopa and... 

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