Identification of paramagnetic radicals in γ-irradiated natural diatomite minerals by electron paramagnetic resonance

In this study, gamma-irradiated natural diatomite minerals were investigated by electron paramagnetic resonance (EPR) spectroscopy at ambient temperature. The paramagnetic radicals produced by γ-irradiation in natural diatomite minerals at ambient temperature were attributed to ĊH3, ṖO42-, ĊO2-, organic (probably, humic or fluvic acid), ṠO2- and ṠO3- free radicals. These centers were found to be perfectly observable at below 20 mW microwave power. The g values of all the paramagnetic centers were obtained, and some of their a values were reported. The results were found to be consistent with the existing literature data and theoretical predictions for similar paramagnetic centers.