Dissociative electron attachment to DNA basic constituents : The phosphate group

Abstract 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 × 10 −15  cm 2 , respectively. The present results confirm previous conclusions on DNA damage induced by low energy electrons.

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