COMBINED MULTIPLE PULSE NMR AND SAMPLE SPINNING - RECOVERY OF H-1 CHEMICAL-SHIFT TENSORS

Combined multiple pulse NMR and sample spinning techniques have been used to obtain the carboxylic acid 1H chemical shift tensor in 2,6-dimethylbenzoic acid. The values obtained were σ⊥=-18. 5 ppm and σ∥=-4.2 ppm relative to TMS. A discussion of the changes in line shape of chemical shift tensors under sample rotation is given. This leads to a quantitative expression for the sample rotation speed, ωr≫σzz-1/3 Trσ, to define rapid" sample rotation. © 1979 American Institute of Physics."