Analysis of multiple pulse NMR in solids. III

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Abstract
A 52-pulse cycle recently introduced in a communication, which has a substantially increased resolving power compared to previously available techniques, is analyzed in detail. Also, a new 24-pulse cycle which is essentially equivalent to the 52-pulse cycle in resolving power is introduced. These pulse cycles achieve their enhanced resolution compared to the REV-8 cycle by removing the effects of the homonuclear dipolar interaction in solids to higher orders of magnitude without reintroducing any dipolar terms eliminated by REV-8. Principles of pulse cycle decoupling are introduced which greatly simplify the systematic development of compound multiple pulse cycles. Beginning with the 2-pulse solid echo sequence, we show how these principles could have been used in designing the WAHUHA and REV-8 cycles and the 14-pulse cycle recently introduced by Haeberlen. We further demonstrate the application of this method by developing several new pulse cycles such as a 12-pulse cycle equivalent to the 14-pulse cycle, the 24-pulse cycle, and the 52-pulse cycle. Finally, proton chemical shift tensor components for several organic solids which were measured using the 52-pulse cycle are reported without detailed discussion.