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Title: Electron accommodation dynamics in the DNA base thymine

The dynamics of electron attachment to the DNA base thymine are investigated using femtosecond time-resolved photoelectron imaging of the gas phase iodide-thymine (I{sup −}T) complex. An ultraviolet pump pulse ejects an electron from the iodide and prepares an iodine-thymine temporary negative ion that is photodetached with a near-IR probe pulse. The resulting photoelectrons are analyzed with velocity-map imaging. At excitation energies ranging from −120 meV to +90 meV with respect to the vertical detachment energy (VDE) of 4.05 eV for I{sup −}T, both the dipole-bound and valence-bound negative ions of thymine are observed. A slightly longer rise time for the valence-bound state than the dipole-bound state suggests that some of the dipole-bound anions convert to valence-bound species. No evidence is seen for a dipole-bound anion of thymine at higher excitation energies, in the range of 0.6 eV above the I{sup −}T VDE, which suggests that if the dipole-bound anion acts as a “doorway” to the valence-bound anion, it only does so at excitation energies near the VDE of the complex.
Authors:
; ;  [1] ;  [2] ; ;  [3] ;  [1] ;  [4]
  1. Department of Chemistry, University of California, Berkeley, California 94720 (United States)
  2. Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 København Ø (Denmark)
  3. Department of Chemistry, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama City, Saitama 338-8570 (Japan)
  4. (United States)
Publication Date:
OSTI Identifier:
22490901
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 143; Journal Issue: 2; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ANIONS; BOUND STATE; DIPOLES; DNA; ELECTRON ATTACHMENT; ELECTRONS; EV RANGE; EXCITATION; IODIDES; IODINE; MEV RANGE; PULSES; THYMINE; TIME RESOLUTION