ANALYTICAL SOLUTION TO SOLOMON EQUATIONS FOR 3-SPIN GROUPINGS

Analytical solutions are provided for a set of three simultaneous firs t-order differential equations which describe either cross relaxation among three groupings of spin-1/2 nuclei (regardless of the number of spins within each grouping) or the complete longitudinal relaxation of a system of two spins-1/2, including CSA-dipolar interference terms ( which couple the longitudinal spin order to conventional longitudinal magnetizations). In spite of their complexity, the expressions so obta ined afford a time savings by a factor of 50 when used in a computer p rogram. The efficiency of the method is illustrated by the fit of expe rimental data, exhibiting an unusual evolution due to both intra- and intermolecular dipolar couplings. (C) 1996 Academic Press, Inc.