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Experimental ESR spectra of the 2,2,6.6-tetramethyl-4-oxopiperidinoxyl (TEMPON) radical probe in the glycerol, polystyrene, and polyvinylbutyral matrices measured in the temperature range 77--373 K were quantitatively compared with the ESR spectra calculated using the known theoretical models of rotational mobility. It was shown that simulation of ESR spectra by the nonlinear least-squares method is an efficient procedure for discriminating ' between theoretical models. The temperature ranges were determined in which it is possible to achieve quantitative agreement between experimental and theoretical spectra as well as the ranges in which theoretical models are insufficient to quantitatively describe the experimental results. It was established that the widely used model of Brownian diffusion in isotropic medium is inadequate to describe the ESR spectra in the case of slow motions of small probe molecules. It was found that specific interactions (formation of weak complexes) between the probe molecules and the molecules of the medium results in strongly anisotropic molecular rotational motions.

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Using observations from the IMAGE magnetic observatories and the station for recording geomagnetically induced currents (GIC) in the electric transmission line in 2015, we examine relationships between geomagnetic field and GIC variations. The GIC intensity is highly correlated (R>0.7) with the field variability |dB/dt| and closely correlated with variations in the time derivatives of X and Y components. Daily variations in the mean geomagnetic field variability |dB/dt| and GIC intensity have a wide night maximum, associated with the electrojet, and a wide morning maximum, presumably caused by intense Pc5–Pi3 geomagnetic pulsations. We have constructed a regression linear model to estimate GIC from the time derivative of the geomagnetic field and AE index. Statistical distributions of the probability density of the AE index, geomagnetic field derivative, and GIC correspond to the log-normal law. The constructed distributions are used to evaluate the probabilities of extreme values of GIC and |dB/dt|.

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