I-STMAS, a new high-resolution solid-state NMR method for half-integer quadrupolar nuclei

In complement to the previously proposed multiple-quantum magic-angle-spinning (MQMAS) and satellite transition MAS (STMAS) sequences, we describe a new two-dimensional high-resolution method, inverse-STMAS (I-STMAS) that allows second-order quadrupolar averaging. Like STMAS, I-STMAS correlates second-order quadrupole dephasing occurring on coherences related to the central transition (CT) and satellite transitions (STs), but does it in a reverse manner: CT evolves during the t(1) period while STs are detected during t(2). Although STMAS and I-STMAS are symmetric, there are some interesting and useful differences between the two methods. For example, we show that during the acquisition time t(2), it is possible to over-sample the data and then to process them to suppress the CT-CT correlation resonance. (C) 2003 Elsevier Science (USA). All rights reserved.