Dominant Stable Radicals in Irradiated Sucrose: g Tensors and Contribution to the Powder Electron Paramagnetic Resonance Spectrum

Abstract

Ionizing radiation induces a composite, multiline electron paramagnetic resonance (EPR) spectrum in sucrose, that is stable at room temperature and whose intensity is indicative of the radiation dose. Recently, the three radicals which dominate this spectrum were identified and their proton hyperfine tensors were accurately determined. Understanding the powder EPR spectrum of irradiated sucrose, however, also requires an accurate knowledge of the g tensors of these radicals. We extracted these tensors from angular dependent electron nuclear double resonance-induced EPR measurements at 110 K and 34 GHz. Powder spectrum simulations using this completed set of spin Hamiltonian parameters are in good agreement with experimentally recorded spectra in a wide temperature and frequency range. However, as-yet nonidentified radicals also contribute to the EPR spectra of irradiated sucrose in a non-negligible way.