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Volume 85, Number 1, January 2009
Article Number 18005
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 13 January 2009
EPL, 85 (2009) 18005
DOI: 10.1209/0295-5075/85/18005

Radiation damage in biological material: Electronic properties and electron impact ionization in urea

C. Caleman1, C. Ortiz2, E. Marklund3, F. Bultmark2, M. Gabrysch4, F. G. Parak1, J. Hajdu3, M. Klintenberg2 and N. Tîmneanu3

1   Physik Department E17, Technische Universität München - James-Franck-Strasse, D-85748 Garching, Germany, EU
2   Department of Physics and Material Science, Uppsala University - Ångströmlaboratoriet, Box 530, SE-751 21 Uppsala, Sweden, EU
3   Department of Cell and Molecular Biology, Uppsala University - Biomedical Centre, Box 596, SE-751 24 Uppsala, Sweden, EU
4   Department of Engineering Sciences, Uppsala University - Ångströmlaboratoriet, Box 534, SE-751 21 Uppsala, Sweden, EU

received 8 August 2008; accepted in final form 25 November 2008; published January 2009
published online 13 January 2009

Radiation damage is an unavoidable process when performing structural investigations of biological macromolecules with X-rays. In crystallography this process can be limited through damage distribution in a crystal, while for single molecular imaging it can be outrun by employing short intense pulses. Secondary electron generation is crucial during damage formation and we present a study of urea, as model for biomaterial. From first principles we calculate the band structure and energy loss function, and subsequently the inelastic electron cross-section in urea. Using Molecular Dynamics simulations, we quantify the damage and study the magnitude and spatial extent of the electron cloud coming from an incident electron, as well as the dependence with initial energy.

87.15.A- - Biomolecules: structure and physical properties: Theory, modeling, and computer simulation.
71.20.Rv - Electron density of states and band structure of crystalline solids: Polymers and organic compounds.
79.20.Hx - Electron and ion emission by liquids and solids; impact phenomena: Electron impact: secondary emission.

© EPLA 2009