Carbon-13 cross-polarization/magic

Figure 4. Carbon-13 cross-polarization, magic-angle spinning NMR spectra from an acrylic-melamine (A) and acrylic-urethane (B) coating. (Reproduced with permission from ref. 28. Copyright 1986 Elsevier Sequoia.)...

Szeverenyi, N. M., Sullivan, M. J. and Maciel, G. E. (1982). Observation of spin exchange by two-dimensional Fourier transform carbon-13 cross- polarization— magic angle spinning. / Magn. Reson., 47,462-75. [141]... 

Ikan P., Rubinsztain Y., losehs P., Aizenshtat Z., Pugmire R., Anderson L. L., and Ishiwatari R. (1986) Carbon-13 cross polarized magic-angle spinning nuclear magnetic resonance of melanoidins. Org. Geochem. 9(3), 199-212. 

Preston C.M., Sayer B.G. What s in a nutshell an investigation of structure by carbon-13 cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy. Journal of Agricultural and Food Chemistry, 40 206-210 (1992). 

Table 1. Structural carbon distribution (%) of the humic acids extracted from soil horizons, adopted from Xing (2001). The distribution was calculated from solid state 13C Cross-Polarization Magic-Angle-Spinning (CP/MAS) NMR spectra. Chemical shift assignment for carbon functional groups alkyl 0-50 ppm O-alkyl 50-117 ppm aromatic 107-165 ppm.

The 13C NMR study utilized cross polarization-magic angle spinning (CP-MAS) with spin counting. The elemental and functional group analyses provided input for a series of analytical constraints calculations that yield an absolute upper limit for the amount of aromatic carbon and most probable estimates of both aromatic and non-carboxyl aliphatic carbon in each sample. Spin counting experiments demonstrate that less than 50% of the... 

Ripmeester, J.A. Ratcliffe, C.I. (1988). Low-temperature cross-polarization/magic angle spinning carbon-13 NMR of number solid methane hydrates structure, cage occupancy, and hydration. J. Phys. Chem., 92, 337-339. 

Fig. 13.9 Carbon-13 solid-state NMR spectra of poly(ethylene) (a) cross-polarization magic angle spinning (CP/MAS), (b) progressive saturation, and (c) Torchia T, experiment.

Zumbulyadis N. 1983. Selective carbon excitation and the detection of spatial heterogeneity in cross-polarization magic-angle-spinning NMR. J. Magn. Reson. 59 486-494. 

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... 

C NMR spin-lattice relaxations in solid PMMAs of different tacticity were studied by CP/MAS NMR spectroscopy.324-328 The relaxation proceeds more slowly in isotactic PMMA than in syndiotactic PMMA even in the solid state this is because of the faster reorientation of the a-CH3 group in the isotactic chain.135 The nC-T times of the a-methyl carbons of PMMAs with different tacticities were measured over a wide range of temperatures by cross polarization, magic-angle spinning, dipole dephasing (CP/DD)... 

---