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 coupling or chemical-shift anisotropy, is proposed. It consists of the usual three-pulse sequence for 2D exchange spectroscopy,P1—t₁—P2—τ_m—P3—t—acquisition, but with the evolution time fixed at one-half a spinning period,t₁= T_R/2, and a mixing time equal to an integer multiple thereof, τ_m= GT_R. The magnetic polarizations associated with the various spinning sidebands are then polarized in alternate directions at the beginning of the mixing time. Dynamic processes during τ_mredistribute the polarizations, resulting in modified sideband patterns during the detection time,t. Experimental results are presented for carbon-13 and deuterium in dimethyl sulfone, which undergoes molecular reorientation in the solid state. The results are compared with simulations which include the effect of reorientation and longitudinal relaxation.