Deuteration at the nitrogen sites of uracil produces a striking change in the dissociative attachment cross-section at electron energies below 3 eV. In particular, sharp structures observed in uracil are absent or too small to observe. This result, as well as theoretical modeling, supports the earlier assignment of the sharp structure to vibrational Feshbach resonances that decay by tunneling of the N-1 hydrogen atom through the barrier created by the avoided crossing of the dipole bound anion potential surface by that of the lowest (2)Sigma valence anion state. (c) 2005 Elsevier B.V. All rights reserved.