Narrowing Effect in Nuclear Magnetic Double Resonance in Solids

Abstract

Experiments on nuclear magnetic double resonance were performed in several ionic crystals of type AB where the resonance behavior of the A-spin was investigated under the irradiation of strong rf field resonating to the B-spin. At the strongest rf field experimented, narrowing of the line width was observed and this fact showed evidently that the local field at the position of A-spin originating from B-spin was averaged out to zero. By using this principle the origin of the anomalously broad line width in TlBr crystal was pursued. The experimental results supported our suggestion that the broad line width would be attributable to the indirect nuclear spin-spin coupling. The second moment of the line width in double resonance calculated by the use of rotating coordinate system was in agreement with the experimental value.