J. Kusakovskij, F. Callens and H. Vrielinck Electron Magnetic Resonance group, Ghent University, Department of Solid State Sciences, Krijgslaan 281-S1, 9000 Gent, Belgium Study of transient radicals created immediately after room temperature X-ray irradiation in single crystal sucrose Why study carbohydrates? X-, - etc. Why study carbohydrates? X-, - etc. dominated by G + /T - Why study carbohydrates? X-, - etc. h + scavenging e - scavenging dominated by G + /T - Why study carbohydrates? X-, - etc. dominated by G + /T - h + scavenging e - scavenging neutral radicals Why is sucrose interesting? Its EPR spectrum is stable, detectable at RT and has a linear dose response up to 10 kGy. Why is sucrose interesting? Its EPR spectrum is stable, detectable at RT and has a linear dose response up to 10 kGy. Characterization of irradiated foodstuffs Why is sucrose interesting? Its EPR spectrum is stable, detectable at RT and has a linear dose response up to 10 kGy. Characterization of irradiated foodstuffs (Emergency) EPR dosimetry Dose (arb. u.) Intensity (arb. u.) It is also cheap and readily available But I will talk about the structure of the sucrose molecule and crystals, how we prepared the samples, characterization of contributing radicals, and their DFT-assisted identification. Sucrose molecule consists of a glucose unit and a fructose unit linked by a glycosidic bond. Sucrose molecule consists of a glucose unit and a fructose unit linked by a glycosidic bond. Sucrose molecule consists of a glucose unit and a fructose unit linked by a glycosidic bond. Sucrose molecule consists of a glucose unit and a fructose unit linked by a glycosidic bond. H. De Coomans PhD thesis, 2008 Sucrose single crystals are monoclinic systems (P2 1 ) with 2 molecules/unit cell. Sucrose molecule consists of a glucose unit and a fructose unit linked by a glycosidic bond. Sample preparation Sucrose was purchased from Sigma-Aldrich and used without further purification. Sample preparation Sucrose was purchased from Sigma-Aldrich and used without further purification. Crystals were oriented visually and polished to fit sample tubes. Sample preparation Sucrose was purchased from Sigma-Aldrich and used without further purification. Crystals were oriented visually and polished to fit sample tubes. Irradiated with a W-anode X ray tube for 30 min at 0 C. H. De Coomans PhD thesis, 2008 Radicals were characterized using EPR, ENDOR and EIE B * H. De Coomans PhD thesis, 2008 Radicals were characterized using EPR, ENDOR and EIE B * B ENDOR S = , I = H. De Coomans PhD thesis, 2008 Radicals were characterized using EPR, ENDOR and EIE B * B ENDOR U2 HF2 U2 HF1 U1 HF2 U1 HF1 S = , I = H. De Coomans PhD thesis, 2008 Radicals were characterized using EPR, ENDOR and EIE B * B ENDOR U2 HF2 U2 HF1 U1 HF2 U1 HF1 RF EIE H. De Coomans PhD thesis, 2008 Radicals were characterized using EPR, ENDOR and EIE B * B ENDOR U2 HF2 U2 HF1 U1 HF2 U1 HF1 RF EIE Determined parameters IsoAnisoEigenvectors Radical(MHz) a*bc U U Determined parameters IsoAnisoEigenvectors Radical(MHz) a*bc U U RadicalOrientationg U U 16 MHz 10 MHz U2 is a radical formed by a 1 H abstraction from C4 IsoAnisoEigenvectors Radical(MHz) a*bc U U2 is a radical formed by a 1 H abstraction from C4 Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. U2 is a radical formed by a 1 H abstraction from C4 Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. 1 H abstraction from C4 H1H1 H2H2 H OH Iso CouplingIsoAniso U2 HF 4 5 7.0 33 U2 HF 6 7 6.9 33 First of all U2 is a radical formed by a 1 H abstraction from C4 Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. 1 H abstraction from C4 H1H1 H2H2 H OH Iso CouplingIsoAniso U2 HF 4 5 7.0 33 U2 HF 6 7 6.9 33 First of allSecondly, A(H OH )|| is 10.9 MHz. U2 is a radical formed by a 1 H abstraction from C4 Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. 1 H abstraction from C4 H1H1 H2H2 H OH Iso CouplingIsoAniso U2 HF 4 5 7.0 33 U2 HF 6 7 6.9 33 RadicalOrientationExpSim U First of allSecondly, A(H OH )|| is 10.9 MHz. And finally U1 is a C6 centered radical IsoAnisoEigenvectors Radical(MHz) a*bc U U1 is a C6 centered radical Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. U1 is a C6 centered radical Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. 1 H abstraction from C6 HH HH H OH Iso CouplingIsoAniso U1 HF U1 HF First of all U1 is a C6 centered radical 1 H abstraction from C6 HH HH H OH Iso CouplingIsoAniso U1 HF U1 HF First of all Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. Secondly, A(H OH )|| is 16 MHz, assuming a iso 11 MHz. U1 is a C6 centered radical 1 H abstraction from C6 HH HH H OH Iso CouplingIsoAniso U1 HF U1 HF RadicalOrientationExpSim U First of all Periodic calculation with CP2K ( ): Geometries GTH pseudopotentials, 300 Ry; HF tensors all-electron Gaussians, 350 Ry. And finally Secondly, A(H OH )|| is 16 MHz, assuming a iso 11 MHz. Conclusions Transient radicals in X-irradiated sucrose are rather well characterized. U2 has been identified as a 1 H abstraction from C4. Conclusions Transient radicals in X-irradiated sucrose are rather well characterized. U2 has been identified as a 1 H abstraction from C4. Most likely, U1 is a C6 centered radical. Acknowledgements My group Freddy Callens Irena Nevjestic (P21) Henk Vrielinck for the support; Acknowledgements My group Freddy Callens Irena Nevjestic (P21) Henk Vrielinck for the support; UGent for the funding Acknowledgements My group Freddy Callens Irena Nevjestic (P21) Henk Vrielinck for the support; UGent for the funding and you for your kind attention.