EFFECT OF SAMPLE SPINNING ON DETECTION OF C-13 NMR IN COALS

The effects of sample spinning and of Hartmann-Hahn mismatch on detection of 13C for a Pittsburgh No. 8 coal and coronene (as a model compound) by CP/MAS NMR have been studied. The results on the coal were compared with the “true” 13C intensities under a Bloch decay, indicating that reasonable 13C intensities may be obtained by using cross-polarization and variable contact time. It is suggested that when CP/MAS is used to obtain NMR of 13C in coals, the most reliable results are obtained at low enough static fields such that at moderate spinning speeds production of sidebands and the interference of spinning with the cross-polarization process are avoided. © 1990, American Chemical Society. All rights reserved.