EFFECT OF RF INHOMOGENEITY UPON QUANTITATIVE SOLID-STATE NMR MEASUREMENTS

Spin counting in solid-state NMR spectroscopy requires the use of a reference standard to calibrate the magnetization detected from the unknown material. Quantitation is performed by a direct comparison of standard and unknown peak integrals that are simultaneously acquired under conditions which account for any differing relaxation behavior. Such a straightforward analysis is complicated by RF inhomogeneity effects inherent in the designs of all commercial MAS NMR probes currently available. The implications of RF inhomogeneity effects for quantitation in both Bloch-decay and cross-polarization experiments are discussed, and experimental strategies for optimization of quantitative measurements in solid-state NMR spectroscopy are given. (C) 1995 Academic Press, Inc.