Electric-dipole increase in NMR intensity in mixed-valence complexes

The possibility of a considerable increase in NMR intensity has been shown for absorption on mixed-valence $3d$ ions in magnetically ordered crystals. This effect is determined by the high intensity of electric dipole transitions between the ground and low excited levels of a mixed-valence complex, as well as by the existence of the unfrozen orbital angular momentum in such complexes, which mixes nuclear and electron states.