title: Vibrational Feshbach resonances in uracil and thymine.
abstract: Sharp peaks in the dissociative electron attachment (DEA) cross sections of uracil and thymine at energies below 3 eV are assigned to vibrational Feshbach resonances (VFRs) arising from coupling between the dipole bound state and the temporary anion state associated with occupation of the lowest sigma* orbital. Three distinct vibrational modes are identified, and their presence as VFRs is consistent with the amplitudes and bonding characteristics of the sigma* orbital wave function. A deconvolution method is also employed to yield higher effective energy resolution in the DEA spectra. The site dependence of DEA cross sections is evaluated using methyl substituted uracil and thymine to block H atom loss selectively. Implications for the broader issue of DNA damage are briefly discussed.
authors.affiliation: Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0111, USA. pburrow1@unl.edu
authors.forename: P D
authors.initials: PD
authors.lastname: Burrow
authors.forename: G A
authors.initials: GA
authors.lastname: Gallup
authors.forename: A M
authors.initials: AM
authors.lastname: Scheer
authors.forename: S
authors.initials: S
authors.lastname: Denifl
authors.forename: S
authors.initials: S
authors.lastname: Ptasinska
authors.forename: T
authors.initials: T
authors.lastname: Märk
authors.forename: P
authors.initials: P
authors.lastname: Scheier
mesh_terms: D001482:Base Composition; D002627:Chemistry, Physical / Q000379:methods*; D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D007477:Ions; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009690:Nucleic Acid Conformation; D011789:Quantum Theory; D013941:Thymine / Q000031:analogs & derivatives / Q000737:chemistry*; D014498:Uracil / Q000031:analogs & derivatives / Q000737:chemistry*; D014732:Vibration
chemical_list: D007477:Ions; C030630:1-methylthymine; D014498:Uracil; C055991:3-methyluracil; D006859:Hydrogen; D013941:Thymine