Improvement of analytical accuracy of EPR spectrometry by taking into account variations in the shapes of samples

Summary

A method is proposed for the elimination of the systematic errors of quantitative electron paramagnetic resonance (EPR) spectrometric analysis resulting from the nonuniformity of microwave and modulation fields in the resonator. The errors are especially significant by a non-destructive analysis of solids when the samples are large and the sample to be analyzed differs from the reference one in shape and size. The method involves preliminary experimental characterization of the real configuration of the fields in a specific resonator on the basis of the set of signals recorded by approximately 500 different positions of a tiny sample in the resonator. The dependence of intensity of the ‘point’ sample signal on the sample coordinates can be expressed by an analytical function, and the correction factor can be obtained by means of integration of this function over the shapes of the two samples. In most cases the method enables an analyst to reduce the values of the systematic errors mentioned down to the level typical for random errors. The analytical description of the configuration of intraresonator fields is also beneficial for the solution of various methodological problems.