Electron paramagnetic resonance of rhyolite and ?-irradiated Trona minerals

Abstract

Rhyolite from the "Yellow Stone of Nevşehir" and ?-irradiated trona from the Ankara Mine have been investigated by electron paramagnetic resonance at ambient temperature and at 113 K. Rhyolite was examined by X-ray powder diffraction and found to consist mainly of SO2. Before ?-irradiation, the existing paramagnetic species in rhyolite were identified as ?O42-, ?H2OH, ?O3-, ?O2-, ?O33-, and ?O2- free radicals and Fe3+ at ambient temperature. At 113 K ?O2-, ?O33-, and ?O2- radicals and Fe3+ were observed. The ?-irradiation produced neither new species nor detectable effects on these free radicals. The disappearance of some of the radicals at 113 K is attributed to the freezing of their motions. Before ?-irradiation, the trona mineral shows only Mn2+ lines, but after ?-irradiation it indicated the inducement of ?O33- and ?O2- radicals at ambient temperature, 113 K, in addition to the Mn2+ lines. The g and a values of the species were determined.