Paramagnetic Centres in Oxidised Coal

L. Najder-Kozdrowskaa, R.I. Samoilovab, R. Kapplc, J. Hüttermannc and A.B. Więckowskia aInstitute of Physics, Faculty of Physics and Astronomy, University of Zielona Góra, Szafrana 4a, 65-516 Zielona Góra, Poland bInstitute of Chemical Kinetics and Combustion, Russian Academy of Sciences, Novosibirsk 630090, Russia cInstitute of Biophysics, Faculty of Medicine, University of Saarland, 66421 Homburg (Saar), Germany

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This paper comprises the results obtained by continuous wave (cw)/pulse electron paramagnetic resonance spectroscopy for oxidised coals. The values of EPR linewidths are different for samples of coal treated by different chemical agents. The asymmetric EPR line shape indicates to complex composition of paramagnetic centres in coal. In coal oxidised by HNO3 big changes of linewidth with temperature were observed. For all samples the spin-lattice relaxation time T1 was determined by pulse EPR method. The correlation between used chemical agents and the value of T1 was established.

DOI: 10.12693/APhysPolA.118.475 PACS numbers: 33.35.+r, 61.66.Hq, 76.30.Rn, 89.30.ag