QUADRUPOLE EFFECTS OF SPIN-3 2 NUCLEI ON THE SOLID-STATE MAGIC-ANGLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE SPECTRA OF SPIN-1/2 NUCLEI - DEVIATIONS FROM 1ST-ORDER THEORY AND IMPLICATIONS CONCERNING THE SIGN OF THE INDIRECT COUPLING-CONSTANT/

The effect of the interaction between spin-3/2 and spin-1/2 nuclei on solid-state magic-angle spinning nuclear magnetic resonance (MAS NMR) spectra of the latter is studied in cases where deviations from first- order theory are expected. A comparison is made between the exact and first-order perturbation approaches. Both dipolar and indirect (iso- a nd anisotropic) coupling interactions are considered. Implications reg arding C-13, Cl-35, Cl-37, P-31, Cu-63, Cu-65, and Sn-119, Cl-35, Cl-3 7 cases are discussed. It is shown that in the latter two cases the si gn of the indirect coupling constant J can be derived.