Dissipative dynamics of multiple-quantum NMR coherences in two-spin systems.

Multiple-quantum (MQ) NMR experiments were performed at a special orientation of a hambergite (BeBOOH) single crystal, which consists of alternating zigzag proton chains. At the chosen orientation, one of the dipolar coupling constants in the chain becomes zero and the system becomes a set of well-isolated dipolar coupled spin pairs. The relaxation of the spin pairs in the MQ NMR experiment was studied on the basis of the Lindblad equation.