INTRINSIC ASYMMETRY IN MULTIDIMENSIONAL SOLID-STATE NMR CORRELATION SPECTRA

Solid-state MAS correlation spectra involving cross polarization will generally provide spectra which are asymmetric about the main diagonal . A quantitative treatment of this effect is provided and is demonstra ted experimentally with examples of two-dimensional spin-diffusion spe ctra, The effect, which is due to the nonuniform nonequilibrium initia l coherent state induced by cross polarization, is usually pronounced, and cannot be eliminated simply. It must be taken into account when q uantifying solid-state CPMAS correlation spectra. (C) 1998 Academic Pr ess.