INEPT EXPERIMENTS INVOLVING QUADRUPOLAR NUCLEI IN SOLIDS

Coherence transfer from quadrupolar Al-27 (I = 5/2) nuclei to P-31 (I = 1/2) via INEPT experiments is investigated. Al-27 --> P-31 INEPT exp eriments on a (CH3)(3)P-AICl(3) complex in zeolite NaX are performed, and the results demonstrate that the P-31 INEPT signals strongly depen d on whether or not the Al-27 pulses are applied synchronously with th e rotor period, and on the length of the Al-27 pulses. A density-matri x calculation involving the use of the spin operators for spin 3/2 and 1/2 nuclei has been performed to help understand the evolution behavi or of the density matrix under the influence of the quadrupolar intera ction, the dipolar and J-couplings, and the pulse lengths applied to t he quadrupolar nuclei. The theoretical predictions obtained from these calculations are consistent with the INEPT experimental observations, (C) 1998 Academic Press.