Measurement of longitudinal and rotating frame relaxation times through fully J-decoupled homonuclear spectra

It is shown that fully J-decoupled homonuclear spectra involving Lorentzian Lines can be readily obtained by straightforward processing of the 2D data arising from a conventional spin echo sequence (pi/2-t(1)/2-pi-t(1)/2-Acq( t(2))) used in the so-called J-resolved experiment. The method simply rests on power spectra with the drawback of lines having meaningless relative in tensities. In principle, the experiment should also yield transverse relaxa tion times. Several tests demonstrate that this is not so, due to pulse imp erfections and nonresolved long-range J couplings. Conversely, longitudinal and rotating frame relaxation times can be easily determined by means of a n appropriate preparation period (for instance, a saturation-recovery perio d in the case of longitudinal relaxation) inserted before the 2D spin echo sequence. Since one is dealing with a single line per nucleus, relaxation m easurements become reliable and accurate. (C) 1999 Academic Press.