Abstract
Seventeen kinds of vitrains in different ranks were immersed in ethylene diamine at room temperature and variation of ESR absorption spectra was examined. Absorption intensity increases in the cases of brown coals and anthracite while it decreases in the cases of bituminous coals. Degree of the variation seemed to be in close connection with the rank of coals. It was also observed that in ethylene diamine the line width at half height and the peak-to-peak line width were smaller and that saturation took place more easily than in air or in vacuum. The variations of ESR spectra caused by ethylene diamine were reversible by wash with methanol. In ethylene diamine some kinds of bituminous coals showed a composite ESR signal and the variation of line shape was also reversible. Considering with the effects of the other solvents and reagents on ESR spectra, it is considered that the increase in intensity observed in the cases of brown coals originates from formation of semiquinone type anion radicals and that the variations for bituminos coals is explained with the assumptions that a part of localized spin centres forms a complex with ethylene diamine which has a radical masking effect and that the process is reversible.
