Bond‐ and Site‐Selective Loss of H Atoms from Nucleobases by Very‐Low‐Energy Electrons (<3 eV)

When excess charge is deposited on thymine and uracil by resonant attachment of low-energy electrons (0–3 eV), H atoms are cleaved exclusively from the N positions. This bond selectivity can be made site selective (N1 vs. N3 position) by properly tuning the electron energy. This conclusion was drawn from experiments with methylated thymine and uracil (see picture) in crossed beam experiments.