Spin-1 double quantum spectroscopy in the isotropic phase: INADEQUATE spectra of H-2,H-2 and Li-6,Li-6 AX spin systems

A density matrix treatment is presented which describes the main features of INADEQUATE experiments for spin-1 AX spin systems. It is shown that apart from two-spin double quantum peaks, which carry correlation information, one-spin double quantum peaks are to be expected. In the latter, homoculear spin-spin coupling is amplified in the F-1 domain where the signal splitting amounts to 4J. The theoretical predictions are verified for the H-2,H-2 AX system of 3,3'-[D-2] norcamphor. In addition, experimental results for a Li-6,Li-6 A(2)X(2) or AA'XX' spin system are presented and the influence of spin-lattice relaxation on the relative intensity of the one-spin double quantum peaks for Li-6,Li-6 experiments is demonstrated.