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 C˙H3,P˙O42-, C˙O2−, organic (probably, humic or fluvic acid), S˙O2− and S˙O3− 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.