Influence of the Fractional Composition of Unoxidized Coal on Its Radical Structure

By electron paramagnetic resonance (EPR) spectroscopy, the influence of the particle size of unoxidized KS coal on the EPR spectra is investigated. For all the size fractions considered, the EPR spectrum is a singlet. It consists of a broad line described by a Gaussian function; and a narrow line described by a Lorentzian function. The particle size significantly affects the shape of the spectral lines. The 0.1–0.2 mm size fraction is optimal for studying Russian coal by EPR spectroscopy. For this fraction, the difference in width of the EPR lines described by the Gaussian and Lorentzian functions is greatest.