Coherence-transfer processes by adiabatic pulses

The effect of adiabatic double-resonance excitation on the indirect spin-spin coupling spectra of a liquid-like spin system is discussed. It is shown in detail how adiabatic excitation affects the coherence-transfer process from one spin species to another (restricted to the case of two spin-1/2 nuclei), when the indirect Hamiltonian cannot be disregarded with respect to that of adiabatic excitation. The approach is based on the formalism of the ''single-transition Cartesian operators.'' The result shows that the in-phase and the antiphase coherences of the J spectra are modified and new spin-order terms can be generated. Furthermore, more widespread conditions of adiabaticity are given, together with the suggestion of new excitation pathways. (C) 1996 Academic Press, Inc.