Application of the {sup 13}C NMR magic angle turning experiment to coal studies
Journal Article
·
· Preprints of Papers, American Chemical Society, Division of Fuel Chemistry
OSTI ID:422062
- Univ. of Utah, Salt Lake City, UT (United States)
One of the important contributions of high resolution {sup 13}C CP/MAS to coal science is the measurement of the structural parameters of coal. It has been demonstrated that the structural parameters directly derived from {sup 13}C CP/MAS experiments can be utilized to predict the details of coal devolatilization and char formation processes. One of the advantages of spinning a solid sample at the magic angle is the reduction of the line broadening contributions due to the chemical shift anisotropy (CSA). The chemical shift anisotropy is proportional to the strength of the external magnetic field and the CSA of aromatic carbons (200-240 ppm) is greater than that of the aliphatic carbons (20-100 ppm). When the sample is spun at the magic angle the CSA induced powder patterns break up into spinning sidebands and, in order to obtain a {sup 13}C CP/MAS spectrum in which the aromatic carbon sidebands do not overlap the aliphatic carbon signals, it is necessary to spin the sample at approximately 4 KHz at a magnetic field of 2.35 Tesla. At a higher magnetic field strength a greater spinning rate is required. High speed magic angle spinning not only reduces the contributions of the spinning side bands but it also destroys very useful information on the local electronic environment that is embedded in the principal values of the CSA tensors.
- OSTI ID:
- 422062
- Report Number(s):
- CONF-950801--
- Journal Information:
- Preprints of Papers, American Chemical Society, Division of Fuel Chemistry, Journal Name: Preprints of Papers, American Chemical Society, Division of Fuel Chemistry Journal Issue: 3 Vol. 40; ISSN 0569-3772; ISSN ACFPAI
- Country of Publication:
- United States
- Language:
- English
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