EFFECTS OF HIGHER-RANK MULTIPOLES ON SPECTRAL LINESHAPES OF HIGHER QUADRUPOLAR NUCLEI NEAR THE NULL POINT IN INVERSION-RECOVERY EXPERIMENTS

The effects of higher-rank multipoles on the spectral lineshape of I = 5/2 and 7/2 quadrupolar nuclei have been examined near the null point in the inversion-recovery measurements. Al-27 (I = 5/2) and Cs-133 (I = 7/2) NMR inversion-recovery experiments were performed in D2O/glyce rol-d(8) solutions. The longitudinal and transverse relaxational matri x elements using state multipole formalism for spin-5/2, -7/2, and -9/ 2 have been derived. It is found that the null-point spectra of spin-5 /2, -7/2, and -9/2 are similar to those of the spin-3/2 system. This i ndicates that the direct coupling between rank-one and rank-three elem ents plays the key role in the generation of fine structure in null-po int spectra. (C) 1994 Academic Press, Inc.