Spatially resolved homonuclear solid-state NMR. I. Slice selection by spin locking and localized spin temperature

Abstract

Slice selection by spin-locking pulses in the presence of field gradients is a technique particularly suitable for spatially resolved NMR experiments (imaging or localized spectroscopy) with solid-like samples. The theory of the excitation profiles in the limits of liquids and solids is presented. Under idealized conditions, the shapes are Lorentzian, but severe deviations are predicted if the preparation pulse is not a hard 90° pulse and/or if the spin-locking amplitude is comparable to the local field in the rotating frame. From the physical point of view, it is also of interest that slice-selection techniques produce localized spin temperatures in solids. Corresponding gradients thus can be prepared.