Lindblad Relaxation of Multiple Quantum NMR Coherence in Two-Spin Systems

The Lindblad equation for dissipative open systems is applied for an investigation of relaxation of multiple-quantum (MQ) NMR coherences in two-spin systems. We choose two examples of two-spin systems. One of them is the zigzag proton chain in a single crystal of hambergite in such an orientation that one of the two intra-chain dipolar coupling constants becomes zero. Then, the chain consists of well-isolated pairs of spins, with the spins of each pair coupled by the dipole–dipole interaction. The second example of a two-spin system is a single crystal of gypsum in which protons belong to water molecules. The MQ NMR dynamics with relaxation was investigated for different preparation times of the MQ NMR experiment.