USE OF AN ALTERNATING-PHASE CPMG SEQUENCE TO AVOID SPIN-LOCKING EFFECTS IN T-2 MEASUREMENTS IN SOLIDS

Measurements of the decay of the spin-echo amplitude using a two-pulse Hahn echo (TPHE), a Carr-Purcell-Meiboom-Gill (CPMG) sequence, and an alternating phase-CPMG (AP-CPMG) sequence are presented and discussed for three solid samples. We show that the CPMG generates spin-locking effects which can be suppressed entirely using the AP-CPMG variant. T he comparison of the decay of the transverse magnetization in a TPHE a nd an AP-CPMG sequence allows one to separate the different T-2-type c ontributions of the spin-echo decay. (C) 1994 Academic Press, Inc.