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Abstract:
Vacuum experiments with monoenergetic low-energy electrons (LEEs) impacting on biomolecules have revealed basic mechanisms of radiobiological damage. To move closer to cellular conditions, we explore the possibility of damaging DNA at standard atmospheric pressure with electrons of 01.5 eV. These electrons are produced by UV light incident on a tantalum or n-Si substrate, onto which a five-monolayer film of DNA is deposited. Total conformational damage, cross-links, and double- and single-strand breaks (SSBs) are measured as a function of LEE fluence. The photoelectron energy distribution can be modified by changing the work function of the substrate or the photon energy. In a N-2 atmosphere with a tantalum substrate, the yields of SSBs (5 +/- 2 x 10(-14) electron(-1) molecule(-1)) and their number per energy deposited (46 +/- 36 x 10(-4)/eV) are in good agreement with those obtained, under similar conditions, by monoenergetic 0.51.0 eV electron impact in vacuo and 1.5 KeV X-ray photoelectrons at atmospheric pressure, respectively. SSB is the only conformational change detected; it results from electron capture on a DNA base followed by dissociative electron attachment at the phosphate unit.
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JOURNAL OF PHYSICAL CHEMISTRY C
ISSN: 1932-7447
Year: 2016
Issue: 1
Volume: 120
Page: 487-495
4 . 5 3 6
JCR@2016
3 . 3 0 0
JCR@2023
ESI Discipline: CHEMISTRY;
ESI HC Threshold:235
JCR Journal Grade:1
CAS Journal Grade:2
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