Ultralarge magic-angle spinning (MAS) systems (2.4-6.5 cm3) provide a sufficiently large increase in signal-to-noise ratio that 13C MAS experiments without cross-polarization (CP), as well as time-domain 13C CP/MAS studies, can be carried out expeditiously. The non-CP approach allows one to circumve
Structural characterization of non-reductively ethylated coal by 13C and 1H n.m.r.
β Scribed by Natsuko Cyr; Mieczyslawa Gawlak; Dennis W. Carson; Boleslaw S. Ignasiak
- Publisher
- Elsevier Science
- Year
- 1983
- Tongue
- English
- Weight
- 549 KB
- Volume
- 62
- Category
- Article
- ISSN
- 0016-2361
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High-resolution gated decoupling 13C spectra of soluble materials such as coal extracts have been analysed to evaluate the carbon aromaticity if,). A correlation was found between fa and the reciprocal of the square of the shorter component in spin-spin relaxation time (Tz), which was obtained by pu
## Magic-angle 13C n.m.r. spectra have been obtained for a series of vitrinite concentrates. Proper modification of the cross-polarization pulse sequence allows separation of protonated and nonprotonated carbon resonances. This technique is used to determine the relative fraction of nonprotonated