Electron Paramagnetic Resonance of Organic and Inorganic Centers in γ-Irradiated Natural Sepiolite Minerals

Natural sepiolite minerals and their γ -irradiated forms were investigated by electron paramagnetic resonance (EPR) at room temperature and at 113 K. The EPR signals in powders of natural sepiolite were observed due to clusters of Fe3+ ions. The paramagnetic centers produced by γ - irradiation of natural sepiolite minerals were attributed to the ĊH3 at room temperature and ṠO− 2 and ṠO− 3 radicals at 113 K. These centers were found to be perfectly observable above 20 mW microwave power. The g values of all paramagnetic centers have been measured and the A values of some of them have been reported. The results were consistent with the literature data for similar paramagnetic centers.