Low-energy electron diffraction and induced damage in hydrated DNA
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)
Elastic scattering of 5-30 eV electrons within the B-DNA 5{sup '}-CCGGCGCCGG-3{sup '} and A-DNA 5{sup '}-CGCGAATTCGCG-3{sup '} DNA sequences is calculated using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to a featureless amplitude buildup of elastically scattered electrons on the sugar and phosphate groups for all energies between 5 and 30 eV. However, some constructive interference features arising from diffraction are revealed when examining the structural waters within the major groove. These appear at 5-10, 12-18, and 22-28 eV for the B-DNA target and at 7-11, 12-18, and 18-25 eV for the A-DNA target. Although the diffraction depends on the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8-10 A spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density buildup occurs in energy regimes associated with dissociative electron attachment resonances, direct electronic excitation, and dissociative ionization. Since diffraction intensity can be localized on structural water, compound H{sub 2}O:DNA states may contribute to energy dependent low-energy electron induced single and double strand breaks.
- OSTI ID:
- 21104054
- Journal Information:
- Journal of Chemical Physics, Vol. 128, Issue 19; Other Information: DOI: 10.1063/1.2907722; (c) 2008 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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