title: High-field/ high-frequency EPR study on stable free radicals formed in sucrose by gamma-irradiation.
abstract: The EPR spectrum of sucrose irradiated by high-energy radiation is complex due to the presence of more than one radical species. In order to decompose the spectrum and elucidate the radical magnetic parameters a high-field (HF(-)EPR) study on stable free radicals in gamma-irradiated polycrystalline sucrose (table sugar) was performed at three different high frequencies--94, 190 and 285 GHz as well as at the conventional X-band. We suggest a presence of three stable radicals R1, R2 and R3 as the main radical species. Due to the increase of g-factor resolution at high fields the g-tensors of these radicals could be extracted by accurate simulations. The moderate g-anisotropy suggests that all three radicals are carbon-centred. Results from an earlier ENDOR study on X-irradiated sucrose single crystals (Vanhaelewyn et al., Appl Radiat Isot, 52, 1221 (2000)) were used for analyzing of the spectra in more details. It was confirmed that the strongest hyperfine interaction has a relatively small anisotropy, which indicates either the absence of alpha-protons or a strongly distorted geometry of the radicals.
authors.affiliation: Institute of Catalysis, Bulgarian Academy of Sciences, Sofia, Bulgaria. elka@ic.bas.bg
authors.forename: Elka R
authors.initials: ER
authors.lastname: Georgieva
authors.forename: Luca
authors.initials: L
authors.lastname: Pardi
authors.forename: Gunnar
authors.initials: G
authors.lastname: Jeschke
authors.forename: Dante
authors.initials: D
authors.lastname: Gatteschi
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Sorace
authors.forename: Nicola D
authors.initials: ND
authors.lastname: Yordanov
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry* / Q000528:radiation effects*; D005720:Gamma Rays; D015394:Molecular Structure; D013395:Sucrose / Q000737:chemistry* / Q000528:radiation effects*
chemical_list: D005609:Free Radicals; D013395:Sucrose