Carbon-13 Magnetic Resonance in Diamonds, Coals, and Graphite.
J Phys Chem 1973 Jan; 77:68-71
Carbon-13 magnetic resonance (13c nmr) spectra of gem-quality diamonds, powdered natural graphite, and four coals were obtained as part of a comprehensive spectral investigation of the structure of coal and other carbonaceous materials. The chemical shift in diamond was found to agree well with empirical predictions based on prior studies of pure aliphatic and alicyclic hydrocarbons. The spectrum of graphite reflects both a chemical shift anisotropy and the semiconductivity of the material. The results for the coals were compared with those for diamond and graphite and found to be best rationalized in terms of increasing carbon aromaticity with increasing coal rank leading finally to the formation of graphite- like structures.
J. Phys. Chem., V. 77, January 1973, PP. 68-71