We use dibutyl phosphate to simulate the behavior of the phosphate group in DNA towards the attack of low energy electrons. We find that the compound undergoes effective dissociative electron attachment within a low energy resonant feature at 1 eV and a further resonance peaking at 8 eV. The dissociative electron attachment (DEA) reactions are associated with the direct cleavage of the C-O and the P-O bond but also the excision of the ${\mathrm{PO}}^{-}$, $\mathrm{PO}_3{}^{-}$, ${\mathrm{H}}_2\mathrm{PO}_3{}^{-}$ units. For the phosphate group coupled in the DNA network these reactions represent single strand breaks. We hence propose that the most direct mechanism of single strand breaks occurring in DNA at subexcitation energies ($<4\mathrm{eV}$) is due to DEA directly to the phosphate group.

Reactions induced by the attachment of low energy electrons to an entire gas phase nucleotide (2′-deoxycytidine 5′-monophosphate) are reported for the first time. From the resonant attachment profiles information on the site of initial electron localization and from the observed ionic fragments information on final bond cleavage can be extracted.