LINESHAPES OF A SPIN-1 2 NUCLEUS WITH SCALAR COUPLING TO A QUADRUPOLAR NUCLEUS SUBJECT TO RANDOM-FIELD RELAXATION/

The lineshapes in solution of a spin-1/2 nucleus with scalar coupling to one quadrupolar nucleus which is subject to random-field relaxation have been calculated using a relaxation matrix treatment. For the cas e of the quadrupolar nucleus having I = 1, a lineshape expression has been derived. For I > 1, lineshapes have been calculated numerically. As an example of the use of these calculations, the C-13 NMR spectra o f the hexacyanocobaltate(III) anion in aqueous solution were recorded at various temperatures and these spectra were simulated invoking cont ributions from both quadrupolar relaxation and spin-rotation relaxatio n to the total spin-lattice relaxation rate of the Co-59 nucleus. At 3 60 K, spin-rotation relaxation constitutes 28% of the total Co-59 nucl ear relaxation rate. (C) 1996 Academic Press, Inc.