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

Cross correlation, an interference term between different relaxation p athways, manifests itself as a multiplet effect in coupled spin system s, which can be described in terms of longitudinal multispin orders. E xperimental observation of these multispin orders is proof and a measu re of the cross correlations. The cross correlations between the chemi cal-shift anisotropy (CSA) relaxation of fluorine and its dipolar rela xation with protons have been measured here in 1-fluoro-2,4-dinitroben zene. It is found that this cross correlation is significant between t he fluorine CSA and its dipolar relaxation to the proton ortho to it a nd is small but measurable to the other protons. (C) 1995 Academic Pre ss, Inc.