Paramagnetic Centres in Oxidised Coal

Abstract

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 HNO 3 big changes of linewidth with temperature were observed. For all samples the spin-lattice relaxation time T 1 was determined by pulse EPR method. The correlation between used chemical agents and the value of T 1 was established.