Electronic Structure of DNA Nucleobases and Their Dinucleotides Explored by Soft X-ray Spectroscopy

Authors:
  • TTTomoyuki Takeuchi
    Tomoyuki Takeuchi
  • HKHiori Kino
    Hiori Kino
  • AFAkiko Fukushima
    Akiko Fukushima
  • KTKaoru Takakura
    Kaoru Takakura
  • KHKotaro Hieda
    Kotaro Hieda
  • ANAiko Nakao
    Aiko Nakao
  • SSShik Shin
    Shik Shin
  • HFHidetoshi Fukuyama
    Hidetoshi Fukuyama
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Abstract
The electronic structures of a series of DNA nucleobases and their dinucleotides were investigated by N 1s X-ray absorption, X-ray photoemission, and resonant X-ray emission spectroscopy. Resonant X-ray emission spectra of the guanine base and its dinucleotide indicate that it has a weak structure at the lowest binding energy; at this energy, it isolates from the main valence band and forms the HOMO state. This indicates that the HOMO state is localized in the guanine base, as claimed by valence and core photoemissions and expected from theoretical predictions. In addition, the XAS and XES profiles of the guanine dinucleotide indicate that disruption of the aromatic character of the six-membered ring results in the localization of the π state at the imine (−N) site of the guanine base; this may favor charge transfer among stacked guanine bases and further influence the conductivity of DNA.

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