Electron-spin relaxation phenomena in irradiated saccharides detected by pulsed electron paramagnetic resonance spectroscopy

We measured the relaxation times of radicals in saccharides upon γ-irradiation by means of X-band pulsed electron paramagnetic resonance (EPR) spectroscopy. We found that the field-swept signal of irradiated fructose by pulsed EPR showed three to four peaks depending on the dose. The relaxation times (T1 and T2) of the side peaks were longer than those of the main peak(s) from each irradiation, indicating that the radicals showing side peaks interact less with the surrounding environment. From relaxation time measurements of several irradiated saccharides, we conclude that T2 relaxation times decrease with the increasing irradiation dose. In contrast, T1 relaxation times show no correlation with the irradiation dose. - Highlights: ► Field-swept spectra of irradiated sugars were recorded by pulsed EPR spectroscopy. ► Relaxation times of unpaired electrons were directly determined at each peak. ► The relaxation times of side peaks were longer than those of main peaks. ► T1 values of irradiated sugars show no correlation with the irradiation dose. ► The T2 values become shorter relaxation times by the increasing doses.