Journal of Inorganic and Nuclear Chemistry
The 13C-NMR spectra of gem quality and industrial diamonds show two resonances with the more intense resonance at high field. Two resonances are also shown in 13C-NMR spectra of various graphites; however, the low field resonance is of greater intensity than the high field resonance in the graphites. The resonances are very broad and they are assigned to graphite type (sp2) carbon and diamond type (sp3) carbon.
Wilkie, Charles A.; Ehlert, Thomas C.; and Haworth, Daniel T., "A Solid State 13C-NMR Study of Diamonds and Graphites" (1978). Chemistry Faculty Research and Publications. 934.
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