Hydrogen loss from nucleobase nitrogens upon electron attachment to isolated DNA and RNA nucleotide anions.

Electron transfer to isolated nucleotide monoanions in collisions with Na vapor induces hydrogen loss from nitrogen of the transient nucleobase anion. The cross section for this process is linearly correlated with the number of N-H hydrogens and is highest for guanine. The process is much faster than microseconds since only dehydrogenated dianions survived for mass spectrometric detection. The lifetime of the adenosine 5(')-monophospate dianions was measured to be 0.2 ms in an electrostatic ion storage ring but also a longer-lived component with a lifetime of at least 10 ms was identified. Implications of dissociation along the N-H coordinate for a nucleotide in DNA are briefly discussed in terms of Watson-Crick base pairs. (c) 2004 American Institute of Physics