Paramagnetic Relaxation in Solutions of VO

The ESR spectrum of vanadyl ion in solutions has the interesting feature that the linewidths of the individual hyperfine components depend on the nuclear spin orientation, mI. We have determined that the origin of the effect is the mechanism proposed by H. M. McConnell, namely, the existence of a ``microcrystal'' about the VO++ ion which gives rise to anisotropies in the g tensor and hyperfine interaction. By comparing the results of linewidth measurements made at 9.25 kMc and at 24.3 kMc with the results of calculations made by D. Kivelson, we were able to conclude the validity of the microcrystallite model.