ESR Linewidths in Solution. I. Experiments on Anisotropic and Spin—Rotational Effects

Abstract

The linewidths of the hyperfine components of the ESR spectra of vanadyl acetylacetonate in liquid toluene have been measured as a function of concentration, temperature, and applied field. The g-tensor and hyperfine-tensor components have been determined and used, along with the spectral data, to determine the Debye rotational correlation time τR. This analysis agrees very well with the experimental observations. A residual linewidth, not dependent upon the above mechanism, and independent of nuclear quantum number and applied field, has been studied and found to vary as T/η, where η is the viscosity. This residual linewidth is ascribed to a spin—rotational interaction.