5 QUANTUM COHERENCE OF I=5 2 NUCLEI - AL-27 IN POLYCRYSTALLINE ALCL3/

Optimal conditions were calculated for the excitation and detection of the five quantum coherence of quadrupolar nuclei with 1 = 5/2 in powd er samples, observed by the two-pulse sequence (theta(1))(x) - tau(1) - (theta(2))(alpha) -tau(2), where alpha is the phase cycling angle. W e varied the pulse lengths and the relative values of the nutation fre quency omega(1) = gamma B-1 and the quadrupolar frequency omega(Q). Al so, the effect of the resonance offset was studied under optimal condi tions. Besides, the conditions for obtaining the maximal echo amplitud e after the two-pulse sequence with alpha=y were found. Theoretical re sults were compared with experiments on Al-27 nuclei in polycrystallin e AlCl3. (C) 1998 Elsevier Science B.V.