The change in inter- and intra-molecular interaction in coal with electron acceptor has been investigated by means of EPR and ^1H-NMR spectroscopy. The EPR spectra of high rank coal were simulated in terms of two component signals, one broad and one narrow. The intensity of broad signal enhanced with increase in the amount of iodine doped in coal. The intensity of narrow signal, however, did not change with increase in the amount of iodine. The spin-lattice relaxation time T_1 decreased with increase in the amount of iodine. These facts indicate that the iodine doped in high rank coal modified the inter- and intra-molecular interaction system in coal.
