Fitting of EPR spectra: the importance of a flexible bandwidth

Utilizing a standard spin Hamiltonian for an S=32 spin system, we fit complete X-band powder EPR spectra of the Cr(oxalate)(3)(3-) anion diluted into K(3)[Co(oxalate)(3)]·3H(2)O. By using models for the bandshape and bandwidths of varying degree of flexibility, we show that the successful outcome of such a fitting endeavour very much depends on the used bandshape-bandwidth model. The best results are obtained when the bandwidth model incorporates anisotropic intrinsic bandwidths in addition to being able to account for inhomogeneous line broadening caused by distributions of the spin Hamiltonian parameters.