Dissociative electron attachment to uracil deuterated at the N1 and N3 positions

Interaction of low-energy electrons with the pyrimidine bases and nucleosides of DNA

“…Moreover, the strong peak at 1.0 eV, which does not appear to correlate with any shape resonance, is puzzling. This peak is entirely suppressed in DA to N 1 -methyl thymine, 26,27 consistent with the hypothesis 15,23,27 that it is due to a vibrational Feshbach resonance built on the dipolebound anion of T. Attachment of a sugar rather than a methyl at N 1 should be even more effective at preventing the formation and subsequent dissociation of a dipole-bound state. Accordingly, Burrow et al 27 have suggested that the ͑T-H͒ − anions observed by Abdoul-Carime et al 32 arise not from DA to dT itself but from DA to T produced by inadvertent thermolysis of dT.…”

“…Characterizing the low-energy resonances of nucleic-acid subunits is thus crucial to a full understanding of the mechanism or mechanisms by which slow electrons damage DNA. The considerable experimental attention that has been focused on DA to the nucleobases has not only demonstrated that resonant DA does indeed occur in them but has also led to important mechanistic insights, notably that such resonant DA can be bond selective 16,[23][24][25][26][27] and that gas-phase DA may be driven by vibrational Feshbach resonances built on dipole-bound temporary anions, 15,23,27 rather than on "conventional" elastic shape resonances involving trapping of the electron in an empty valence orbital. Some information is also available concerning DA to the nucleosides deoxythymidine 32 ͑dT͒ and 5-bromouridine.…”

Elastic and inelastic low-energy electron collisions with pyrazine

“…32) is given as a subscript to the number of each state. The first two lines in each of these panels present results of our SA-CASSCF calculations using the active space (10,8) and basis sets cc-pVDZ and 6-311+G** respectively. The CASSCF calculations of Weber and Reimers used the state-specific optimization, cc-pVDZ basis set and the active space (10,8).…”

“…[2][3][4] Three π * electron resonances have been found experimentally in the four DNA bases and in uracil. 5,6 It has been proposed [6][7][8][9][10][11] on the basis of experimental evidence, that the lowest-energy features (below 3 eV) in the dissociative electron attachment (DEA) spectra of the bases do not correspond directly to any of these π * resonances but are rather caused by the formation of vibrational Feshbach resonances 11,12 and by an interaction, mediated by nuclear motion, between the π * resonances and a possible σ * resonance occurring in this energy region.…”

Interaction of low-energy electrons with the purine bases, nucleosides, and nucleotides of DNA

“…13, 16, and 23-27͒ and the important role that vibrational Feshbach resonances associated with dipole-bound anion states appear to play in driving such dissociation. 15,23,27 No gas-phase total or elastic scattering cross section measurements for the nucleobases have, to our knowledge, been reported, except for the relative 90°differential cross sections for uracil and halouracils obtained by Abouaf and Dunet. 21 However, Scheer et al 15 and Aflatooni et al 39 have conducted valuable studies of the electron-transmission spectra for the nucleobases that reveal the energies of resonances in the lowenergy total scattering cross section, and they have assigned the features they see to * shape resonances.…”