J. Phys. III France
Volume 1, Numéro 12, December 1991
Page(s) 1977 - 1984
DOI: 10.1051/jp3:1991244
J. Phys. III France 1 (1991) 1977-1984

20 °C, 9 GHz CW-EPR saturation measurements of five selected Alberta coals

J. Kudynska, H. A. Buckmaster and T. Duczmal

Department of Physics and Astronomy, the University of Calgary, Calgary, Alberta, Canada, T2N I N4

(Received 18 January 1991, revised 20 August 1991, accepted 20 August 1991)

This paper reports the first determination of the spin-lattice ( T1) and spin-spin ( T2) relaxation times at 20 °C for two subbituminous and three hv bituminous selected Alberta coals using 9 GHz CW-EPR saturation measurements. Argand diagrammatic techniques were used to verify that the lineshapes were Lorentzian since the deviation was less than 4%. Consequently, it was assumed that the CW-EPR spectral resonances could be approximated to homogeneously broadened lineshapes and saturation techniques could be used to determine these relaxation times. The T1 and T2 relaxation times are in good agreement with values reported in the literature using saturation measurements, but two orders of magnitude shorter than those obtained using ESE because coal EPR spectral resonances are the unresolved superposition of comparatively narrow homogeneous resonances.

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