ODESSA, A NEW 1D NMR EXCHANGE EXPERIMENT FOR CHEMICALLY EQUIVALENT NUCLEI IN ROTATING SOLIDS

A new 1D NMR exchange experiment in the slow-motion regime of spinning solids, with chemically equivalent nuclei exhibiting quadrupole coupl ing or chemical-shift anisotropy, is proposed. It consists of the usua l three-pulse sequence for 2D exchange spectroscopy, P1-t(1)-P2-tau(m) -P3-t-acquisition, but with the evolution time fixed at one-half a spi nning period, t(1) = T-R/2, and a mixing time equal to an integer mult iple thereof, tau(m) = GT(R). The magnetic polarizations associated wi th the various spinning sidebands are then polarized in alternate dire ctions at the beginning of the mixing time. Dynamic processes during t au(m) redistribute the polarizations, resulting in modified sideband p atterns during the detection time, t. Experimental results-are present ed for carbon-13 and deuterium in dimethyl sulfone, which undergoes mo lecular reorientation in the solid state. The results are compared wit h simulations which include the effect of reorientation and longitudin al relaxation. (C) 1996 Academic Press, Inc.