OBSERVATION OF CROSS CORRELATIONS IN A WEAKLY COUPLED F-19-H-1 4-SPIN SYSTEM

Cross correlation, an interference term between different relaxation pathways, manifests itself as a multiplet effect in coupled spin systems, which can be described in terms of longitudinal multispin orders. Experimental observation of these multispin orders is proof and a measure of the cross correlations. The cross correlations between the chemical-shift anisotropy (CSA) relaxation of fluorine and its dipolar relaxation with protons have been measured here in 1-fluoro-2,4-dinitrobenzene. It is found that this cross correlation is significant between the fluorine CSA and its dipolar relaxation to the proton ortho to it and is small but measurable to the other protons. (C) 1995 Academic Press, Inc.