| Issue |
J. Phys. III France
Volume 1, Number 12, December 1991
|
|
|---|---|---|
| Page(s) | 1977 - 1984 | |
| DOI | https://doi.org/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. DuczmalDepartment 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)
Abstract
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.
© Les Editions de Physique 1991