HIGH-RESOLUTION SOLUTION-STATE DOUBLE-QUANTUM SPECTROSCOPY OF 2-SPIN-1 AX SYSTEMS AND MIMICS

Double quantum spectroscopy (DQS) of the two-spin-1 AX system in the l iquid state is investigated theoretically. The two kinds of double qua ntum coherence (DQC) that arise are studied and expressions are given for their evolution under weak scalar coupling and chemical shifts. A one-dimensional double quantum J (DQJ) filter sequence for the separat ion of the two kinds of DQC is introduced. Analytical expressions are given for the spin response to the general two-dimensional DQS sequenc e, for an arbitrary reconversion pulse flip angle beta. A detailed inv estigation of the coherence transfer (CT) amplitudes has been carried out by computer simulation of CT amplitudes as a function of beta. The differences in the behaviour of CT amplitudes of one-spin DQC, 'outer ' and 'central' components of two-spin DQCs are discussed. Optimum fli p angles for maximizing sensitivity of N-type, P-type and pure phase d ouble quantum spectra of this system are deduced. The detailed predict ions are borne out by recently published experimental work on two-spin -1 AX systems, as well as our studies on a mimic arrangement, viz., a spin-1/2 A(2)X(2) system.