Quadrupolar Nuclei in Solid‐State Nuclear Magnetic Resonance

Abstract

AbstractSolid‐state nuclear magnetic resonance (NMR) spectroscopy is mostly applied to1H or13C nuclei with the nuclear spin$\def\tovr#1#2{{\scriptstyle{#1\over #2}}} I = \tovr{1}{2}$, but about 100 of 130 NMR isotopes have$\def\tovr#1#2{{\scriptstyle{#1\over #2}}} I > \tovr{1}{2}$, and the electric quadrupole interaction strongly broadens the NMR signal in the solid‐state powder spectra. The perturbing effect of the electric quadrupole interaction is reduced at the higher magnetic fields which are available at present. In addition, approaches of the solid‐state NMR traditionally used in the study of spin‐$\def\tovr#1#2{{\scriptstyle{#1\over #2}}} \tovr{1}{2}$nuclei have been adapted for use with quadrupolar nuclei, and some techniques, e.g. double‐rotation (DOR) and multiple‐quantum transition in combination with fast spinning [multiple‐quantum magic‐angle spinning (MQMAS)], were recently developed for quadrupolar nuclei with half‐integer spins.This article describes the basic theory, the line shape for first‐ and second‐order quadrupole broadened spectra with and without magic‐angle spinning (MAS) of the powder, the most important experimental techniques for the study of quadrupolar nuclei with half‐integer spins such as DOR, dynamic‐angle spinning (DAS), MQMAS, echo and nutation techniques, and some recent developments in deuterium NMR. Electric field gradient and chemical shift data for the most commonly studied quadrupolar nuclei with half‐integer spins,27Al,23Na, and17O, and a few references to recent solid‐state NMR studies of some other quadrupolar nuclei are given.