Thermally excited multiplet states in macerals separated from bituminous coal

Electron paramagnetic resonance searches of thermally excited multiplet sta tes in macerals, exinite, vitrinite, and inertinite of Polish medium-rank c oal (85.6 wt% C), were performed. Numerical analysis of lineshape indicates a multicomponent structure of the EPR spectra of macerals heated at 300 de grees and 650 degrees C. EPR spectra of exinite and vitrinite are a superpo sition of broad Gauss, broad Lorentz (Lorentz 1), and narrow Lorentz (Loren tz 3) lines. Two narrow Lorentz (Lorentz 2 and Lorentz 3) lines were observ ed in the resonance absorption curves of inertinite. The influence of the m easuring temperature (100-300 K) on the EPR lines of the macerals was also studied. The experimentally obtained temperature dependence of the EPR line intensities were fitted by the theoretical functions characteristic for pa ramagnetic centers with ground doublet state (S = 1/2) and paramagnetic cen ters with thermally excited triplet (S = 1) and quadruplet (S = 3/2) states . Thermally excited multiplet states were found in exinite and vitrinite, B oth paramagnetic centers with doublet ground state (S = 1/2) and paramagnet ic centers with thermally excited states, probably quadruplet states (S = 3 /2), exist in the group of paramagnetic centers of exinite and vitrinite wi th the broad Lorentz 1 lines, Intensities (I) of the broad Gauss and the na rrow Lorentz 3 lines of exinite and vitrinite changes with temperature acco rding to the Curie law (I = C/T), The existence of thermally excited multip let states was not stated for inertinite, The two groups of paramagnetic ce nters of inertinite with Lorentz 2 and Lorentz 3 lines obey the Curie law. (C) 2000 Academic Press.