Radical Formation in Lithium and Magnesium Oxalate

Abstract

Lithium oxalate (Li-oxalate: Li2C2O4) and magnesium oxalate (Mg-oxalate: MgC2O4·2H2O) were investigated by electron spin resonance (ESR) spectroscopy as new ESR dosimeter materials. The ESR spectra of Li- and Mg-oxalates irradiated by γ-rays have a singlet with a spectroscopic splitting factor (g-factor) of g=2.0043±0.0004 and are ascribed to a self-trapped hole, the oxalate radical C2O4 -. A broad signal formed by high dose irradiation is considered to be due to the zero field fine structure splitting, D S 2 (D/gβ\cong0.65 mT) for the triplet state (S=1) of a dimer of C2O4 - or a pair of electron and hole centers. The response to the γ-ray dose and thermal stability as well as the effect of illumination have been studied with respect to using these materials as ESR dosimeter elements. The radical formation efficiencies (G-value) for Li- and Mg-oxalates were 0.4±0.1 and 0.21±0.06 and the activation energies (E) from the Arrhenius plot were 1.16±0.24 eV and 1.28±0.26 eV, respectively. These lead to the respective lifetimes of 2.6±0.9 and 3.2±1.1 years at 25°C, which are sufficient for practical dosimetry.

Creation and Recombination of Free Radicals in Fluorocarbon Plasma Polymers: An Electron Spin Resonance Study

“…Many studies concern the investigation of γ ‐radiation‐induced free radicals in organic and also inorganic materials and their time dependant decay kinetics. ESR spectrometry of irradiation‐induced free radicals is, therefore, widely used as a dating method for materials9–11 and in radiation dosimetry 12. The spin concentrations are investigated as a function of the absorbed radiation dose.…”

Identification and dose assessment of irradiated cardamom and cloves by EPR spectrometry

“…The radical formation efficiency was determined by double integration of the first derivative spectra of DPPH (α-α-diphenyl-β-picrylhydrazyl) and compared with those of irradiated materials. The absolute spin concentration was estimated by using the following equation (Hassan et al, 2000;Ikeya, 1985):…”

ESR Dosimetric Properties of Sodium Glutamate

“…The radical formation efficiency was determined by double integration of the first derivative spectra of DPPH and compared with those of irradiated materials. The absolute spin concentration was estimated according to Hassan et al (2000) and Ikeya (1985) by using the following equation:-n= = 6.25x10 13 . G (Gy -1 g -1 ) where, A sample, A strong pitch π strong pich and m are the areas of integrated signals of sample and strong pich, number of spin in strong pitch, number of spin in strong pitch and the mass of sample, respectively.…”