The stop-and-go spinning technique in MAS experiments

Abstract

High-resolution solid-state NMR experiments are described in which detection occurs under magic-angle spinning conditions, but other portions of the experimental sequence are carried out with the sample static. This is achieved by starting and stopping the spinner during the sequence. In a 2D FT experiment designed to provide a chemical-shift tensor pattern for each isotropic chemical-shift tensor average, the sample is static during the evolution period and the magnetization evolves according to the complete chemical-shift tensor during that period. In another experiment, I to S cross polarization is carried out under static-sample conditions, avoiding the well-known modulation patterns in the Hartmann-Hahn match condition for systems with weakly coupled I spins. Examples of the application of these techniques are presented and prospects for such techniques are discussed.