Resonant electron capture by 5-Br-2'-deoxyuridine

The results of the study of resonant electron capture by molecules of 5-Br-2'-deoxyuridine (BrdUrd) over the range of electron energies from near zero to 14 eV are described. In the thermal energy range, long-lived molecular negative ions, unstable with respect to autoneutralization and dehalogenation, have been registered. Examination of the kinetics of these decay processes led us to the conclusion that the most probable structure for molecular negative ions is that with an extended C-Br bond, which was predicted earlier using quantum-chemical calculations. Estimates have shown that the BrdUrd molecule owns a significant electronic affinity of 0.93-1.38 eV. The most intense fragmentation channel leads to the abundant formation of Br^- ions. The dissociative electron attachment cross section for Br^- ions formation was estimated to amount to no less than 1.65 × 10^-15 cm², indirectly implying a fairly intense formation of complementary highly reactive deoxyuridine-5-yl particles. These particles are known to be responsible for the radiosensitizing properties of BrdUrd.