ESR identification of γ-irradiated redoxon and determination of ESR parameters of radicals produced in irradiated ascorbic acid

In the present work, electron spin resonance (ESR) identification of irradiated redoxon and its potential use as a normal and/or accidental dosimetric material were investigated in details. The ground redoxon samples exhibited a single weak resonance line of peak-to-peak width ΔHpp = 0.9 mT appearing at g = 2.0057. γ-Radiation produced many resonance lines beside four different intense lines (denoted as I1, I2, I3 and I4) of different spectral features in the studied dose range of 2.5-25 kGy. Experimental dose-response curves associated with I1, I2, I3 and I4 resonance lines were found to follow an exponential function. From stability and kinetic studies at room and above room temperatures it was concluded that radicals contributing to I3 and I4 resonance lines were more stable than the radical species contributing to I1 and I2 resonance lines. Simulation calculations based on the room temperature ESR intensity data of an ascorbic acid (active ingredient of redoxon) sample irradiated at 10 kGy was performed to determine the structure and spectral parameters of the radiation-induced radical species involved in the formation of experimental ESR spectrum of ascorbic acid. The contributions of these species to the ESR spectrum of irradiated redoxon were discussed.