A FAST METHOD FOR FITTING THE G-TENSOR OF EPR POWDER SPECTRA USING THE LEVENBERG-MARQUARDT ALGORITHM

A finite difference Levenberg-Marquardt algorithm is used for optimizing the principal g tensor values of paramagnetic radicals observed in EPR spectra of polycrystalline materials. A special method is presented to select a small number of data points which are assumed to be representative for the entire EPR powder spectrum. Thus, the spectrum has only to be calculated in a small number of points resulting in a drastic reduction of the computer time. The method is demonstrated on two simulated EPR powder spectra and one experimentally recorded spectrum of X-irradiated powdered human tooth enamel.