Impact of mutual and environmental dipole-dipole interactions on the relaxation of MQ NMR coherences in two-spin system in course of their excitation and reconversion

The relaxation of multiple-quantum (MQ) NMR coherences on the excitation and reconversion periods of MQ NMR experiment was investigated for the spin-pairs coupled by dipole-dipole interaction. The 1 H spin-pairs were obtained in the single crystal of hambergite at specific orientations in the external magnetic field. The planar zigzag arrangement of the protons in hambergite allows obtaining two situations with different strengths of interaction between spins in a pair and remote surrounding spins. The obtained experimental results show good agreement with the developed theory based on the Lindblad equation.