Electron paramagnetic resonance analysis of gamma irradiated 4-nitropyridine N-oxide single crystal

Abstract

A free radical produced by 60Co- γ irradiation in single crystals of 4-nitropyridine N-oxide, C5H4N2O3, has been observed and analyzed for different orientations of the crystal in the magnetic field at the temperature between 120 and 450 K, using an Electron Paramagnetic Resonance (EPR) technique. The spectra were found to be temperature independent and the resonance form of the radical was attributed to the 4-nitropyridinium cation radical. The isotropic average value of the g-factor and the hyperfine splitting constants are obtained as g av = 2.01077, , , and . The measurements indicate that 70% of the unpaired electrons are localized on the N(1).