Peculiarities of Separation of Spin–Phonon Coupling Mechanisms for ²³Na in a NaF Crystal Depending on Temperature and the Number of Paramagnetic Centers

The possibility of changing the efficiency of nuclear spin–phonon coupling by NMR methods using the example of a NaF crystal in a wide temperature range is investigated. To suppress nuclear spin-lattice relaxation involving paramagnetic centers, continuous magnetic saturation at a single Larmor frequency is used instead of acoustic saturation of the ²³Na NMR signal at a double frequency. The influence of the (i) color centers induced by gamma irradiation and (ii) temperature on the separation of spin–phonon coupling mechanisms is studied. No suppression of impurity relaxation is observed for ¹⁹F dipole nuclei. It is shown that the suggested magnetic saturation technique for complete or partial shutdown of impurity relaxation of quadrupole nuclei can be implemented on commercial pulse NMR spectrometers.