Five-quantum coherence of I = 5/2 nuclei:: 27Al in an Al2O3 single crystal

Optimal conditions were calculated for excitation and detection of the five-quantum coherence of quadrupolar nuclei with I = 5/2 in single crystals, observed by the two-pulse sequence (theta(1))(x) - tau(1) - (theta(2))(alpha) - tau(2), where alpha is the phase cycling angle. Variations in the pulse lengths, the relative values of the nutation frequency omega(1) = gamma B-1, and the quadrupolar frequency omega(Q) as well as in the resonance offset were taken into account. In addition, the effect of the pulse length on the intensity of spectral lines was considered. Theoretical results were compared with experiments on Al-27 nuclei in an Al2O3 single crystal. (C) 1998 Academic Press.