Paramagnetic Absorption in Single Crystals of Copper Sulfate Pentahydrate

Abstract

We have studied paramagnetic resonance in CuS${\mathrm{O}}_4$ · 5${\mathrm{H}}_2$O, at 9375 mc/sec. Although two absorption peaks were expected, only one was found; Van Vleck has explained this in terms of exchange coupling between ${\mathrm{Cu}}^{++}$ ions. We have found electronic gyromagnetic ratios for a large number of orientations of the crystal (with respect to the external field). Theory agrees with experiment if the gyromagnetic ratios that correspond to the three principal susceptibilities are 2.39, 2.39, and 2.07. We also find a variation in absorption line width with orientation. The shapes of the absorption lines agree with a theory of exchange coupling advanced by Gorter and Van Vleck.