ESR study of ascorbic acid irradiated with gamma-rays

Determination of dosimetric and kinetic features of gamma irradiated solid calcium ascorbate dihydrate using ESR spectroscopy

“…As it is seen, the spectrum area experiences fast decreases at the beginning of the storage period and after 2 weeks, more than 20% were decayed. In agreement with the results of the spectrum simulation and annealing at high temperature studies and with the literature findings on irradiated CaAs and AA (26,30), three radical species 70 H. Tuner having different decay characteristics were predicted to take part in the formation of the experimental ESR spectrum of gamma irradiated CaAs. The measured room temperature decay data of the spectrum area were fitted to the same function, which was used in the annealing study.…”

“…It is seen that theoretical and experimental spectra are in good agreement and that model based on the presence of three different radical species of different kinetic and spectroscopic features describes the experimental spectrum very well. According to the spectroscopic features derived from the spectrum simulations, these three radicals showed similar features to the radicals which were previously proposed for irradiated CaAs (26), AAs (26,(29)(30)(31) and NaAs (32). The radical proposed by Rexroad and Gordy (26), which was produced by loss of the hydroxyl H atom and did not show any hyperfine splitting, is the radical responsible for the main strong singlet line (I 1 ), and it is denoted as radical R1 in this study.…”

“…For this purpose, the best mathematical functions used to describe the dose-response curves should be determined. Linear, polynomial and exponential functions are frequently used for this purpose (27)(28)(29)(30)(31)(32). Samples irradiated at dose range 0.5-20.0 kGy were used to construct dose-response curves.…”

“…Despite these advantages, irradiation also causes damage in the molecular structure. Electron spin resonance (ESR) spectroscopy has been frequently used for identifying irradiation damage centers in many substances *Email: htuner@balikesir.edu.tr; htuner@hacettepe.edu.tr 62 H. Tuner (24)(25)(26)(27)(28)(29)(30)(31)(32). In this study, kinetic and structural features of the radicalic intermediates produced upon gamma irradiation and dosimetric features of CaAs were studied using ESR spectroscopy.…”

“…Effects of gamma radiation on AAs and its sodium salt (NaAs) have been reported by different researchers using ESR spectroscopy (26)(27)(28)(29)(30)(31)(32). Rexroad and Gordy (26) have already reported the gamma radiation effects on solid CaAs, and they observed a singlet ESR line.…”