The effect of thermal treatment of radiation-induced EPR signals of different polymorphic forms of trehalose

Electron paramagnetic resonance (EPR) studies of radiation-induced radicals in two anhydrous trehalose polymorphs, beta-crystalline (TRE c ) and glassy (TRE g ), were conducted with the aim to resolve whether different types of free radicals are induced in a differently disordered environment. The multifrequency approach (9.5 GHz, 94 GHz, and 244 GHz) was 2 applied to improve the g-tensor resolution of the complex EPR spectra. In addition, thermal stability of EPR spectra and respective decay kinetics were analyzed in a series of thermal annealing studies in the temperature interval from 333 K to 363 K. It was found that in the crystalline matrix a more complex transformation process of induced radicals is taking place than in the glassy host matrix. Qualitative decomposition of the experimental spectra reproduced essential EPR spectral features in both matrices when 4 contributing radical species were assumed. These were interpreted as carbon-centered radicals while the possibility of formation of alkoxy radicals due to the abstraction of a hydrogen atom was ruled out. Only in one case, tentative assignment of EPR spectral components revealed the formation of the same radical species in both TRE c and TRE g . Furthermore, thermal annealing of TRE g lost one of the radical species, whereas in TRE c all 4 radical species pertained irrespectively of the treatment. Therefore, the here presented results provide experimental evidence that the extent of disorder present in the material strongly affects the type and stability of radicals induced by ionizing radiation.

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Impact of disorder on formation of free radicals by gamma-irradiation: Multi-frequency EPR studies of trehalose polymorphs

Šarić

Jurec

Reijerse

et al. 2018

Journal of Physics and Chemistry of Solids

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The 2019–2020 EURADOS WG10 and RENEB Field Test of Retrospective Dosimetry Methods in a Small-Scale Incident Involving Ionizing Radiation

et al. 2020

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With the use of ionizing radiation comes the risk of accidents and malevolent misuse. When unplanned exposures occur, there are several methods which can be used to retrospectively reconstruct individual radiation exposures; biological methods include analysis of aberrations and damage of chromosomes and DNA, while physical methods rely on luminescence (TL/OSL) or EPR signals. To ensure the quality and dependability of these methods, they should be evaluated under realistic exposure conditions. In 2019, EURADOS Working Group 10 and RENEB organized a field test with the purpose of evaluating retrospective dosimetry methods as carried out in potential real-life exposure scenarios. A 1.36 TBq 192 Ir source was used to irradiate anthropomorphic phantoms in different geometries at doses of several Gy in an outdoor open-air geometry. Materials intended for accident dosimetry (including mobile phones and blood) were placed on the phantoms together with reference dosimeters (LiF, NaCl, glass). The objective was to estimate radiation exposures received by individuals as measured using blood and fortuitous materials, and to evaluate these methods by comparing the estimated doses to reference measurements and Monte Carlo simulations. Herein we describe the overall planning, goals, execution and preliminary outcomes of the 2019 field test. Such field tests are essential for the development of new and existing methods. The outputs from this field test include useful experience in terms of planning and execution of future exercises, with respect to time management, radiation protection, and reference dosimetry to be considered to obtain relevant data for analysis.

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The effect of thermal treatment of radiation-induced EPR signals of different polymorphic forms of trehalose

Cited by 2 publications

References 26 publications

Impact of disorder on formation of free radicals by gamma-irradiation: Multi-frequency EPR studies of trehalose polymorphs

Impact of disorder on formation of free radicals by gamma-irradiation: Multi-frequency EPR studies of trehalose polymorphs

The 2019–2020 EURADOS WG10 and RENEB Field Test of Retrospective Dosimetry Methods in a Small-Scale Incident Involving Ionizing Radiation

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