Contributions of di?erent parts of dipole-dipole interactions to relaxation of multiple quantum NMR coherences in a single crystal of calcium ?uorapatite

摘要

Dipolar relaxation of multiple quantum (MQ) nuclear magnetic resonance (NMR) coherences on the evolution period of the MQ NMR experiment is investigated experimentally and theoretically in a single crystal of calcium ?uorapatite. The theoretical approach is based on the zz model when the ?ip-?op part of the dipole-dipole interactions is not taken into account. The analytical results obtained in the zz model are compared with the numerical calculations for a chain consisting of 12 spins. The role of heteronuclear interactions of 19F and 31P nuclear spins in the dipolar relaxation of MQ NMR coherences is also investigated. A comparison of the experimental data and the theoretical predictions is discussed.