EXTRACTION OF HOMOGENEOUS NA-23 NMR LINEWIDTHS FROM 2-DIMENSIONAL JEENER-BROEKAERT SPECTRA

The Jeener-Broekaert experiment has recently been applied to heterogen eous biological systems for selective observation of spin I = 3/2 nucl ei which exhibit residual quadrupolar splittings, This paper describes the use of a two-dimensional version of this experiment to extract th e homogeneous linewidths of such nuclei. The powder-like spectra produ ced by the one-dimensional Jeener-Broekaert experiment have lineshapes which depend on both homogeneous and inhomogeneous quadrupolar broade ning, In two-dimensional Jeener-Broekaert spectra, the inhomogeneous b roadening appears along the omega(1) = omega(2) and w(1) = - omega(2) diagonal axes, with the result that the two broadenings are separated, The homogeneous linewidth can then be extracted by fitting cross sect ions through analytically generated lineshapes to the experimental spe ctra, The reliability of this technique is evaluated by computer simul ation, and Na-23 NMR linewidths are measured experimentally in disorde red liquid crystalline and heterogeneous biological samples, The possi bility of measuring frequency-dependent variations in the homogeneous linewidth is also discussed. (C) 1995 Academic Press, Inc.