Decomposition of the proton magnetic resonance line in paramagnetic crystals

Abstract

The fine structure of the proton magnetic resonance line in single-crystals of CuSO 4·5H 2O and CuCl 2·2H 2O has been observed. The position and number of the lines is strongly dependent on temperature and on the direction of the externally applied magnetic field. In CuSO 4·5H 2O always fewer lines than the theoretical number of 20 were observed. For CuCl 2·2H 2O the theoretical number of 8 lines is reached. The temperature dependence is measured for both crystals at different orientations at four temperatures in liquid helium and at two temperatures in liquid hydrogen. At the higher temperatures the deviation from the central position is in first approximation inversely proportional to T - Θ, as should be expected from the law of Curie-Weiss. At the lowest temperatures deviations from this law were found. At 1.5°K the position and width of the lines are measured as functions of the angle between the magnetic field and the crystal axis. This dependence is in good agreement with the theoretical expectation.