Dissociative electron attachment to DNA basic constituents: The phosphate group

Electron-stimulated desorption of H-, O- and OH- from thin films of sodium dihydrogenphosphate has been investigated in the range 0-19 eV. The yield functions exhibit a single broad peak with maxima at 8.8 +/- 0.3 eV, 8.0 +/- 0.3 eV, and 7.3 +/- 0.3 eV, respectively, and a continuous rise above 15 eV. The structure is attributed to dissociative electron attachment causing scission of the O-H, P=O and P-O bonds, which is accompanied by the corresponding formation of the stable anions H-, O- and OH-. From measurements of the time dependence of the anion signals, the effective cross-sections to damage the film near each peak energy are found to be 1.9, 1.7 and 0.9 X 10(-15) cm(2), respectively. The present results confirm previous conclusions on DNA damage induced by low energy electrons. (c) 2006 Elsevier B.V. All rights reserved.