Effect of dielectric constants, sample container dimensions and frequency of magnetic field modulation on the quantitative EPR response Original Research Article

The dependence of the direct and relative (to reference standard situated outside the sample) EPR response estimations on the sample’s dielectric constant, the sample container’s internal diameter and the frequency of the magnetic field modulation in quantitative EPR estimations is studied. It is shown that it is possible to compare with good accuracy and reproducibility quantitative results obtained with samples of different dielectric constants and inserted in sample containers of different internal and outer dimensions if: (a) reference standard and unknown sample are simultaneously recorded making all calculations with the ratio Iuk/Ist; (b) the reference standard is situated outside the sample; (c) EPR spectrometer settings do not affect both the unknown sample and the standard spectra; (d) low frequency (12.5 kHz or less) modulation of the magnetic field is used all the time.