Pairing of isolated nucleobases: Double resonance laser spectroscopy of adenine-thymine

Christian Plützer, Isabel Hünig, Karl Kleinermanns, Eyal Nir, Mattanjah S. De Vries

Research output: Contribution to journalArticlepeer-review

98 Scopus citations


The vibronic spectrum of the adenine-thymine (A-T) base pair was obtained by one-color resonant two-photon ionization (R2PI) spectroscopy in a free jet of thermally evaporated A and T under conditions favorable for formation of small clusters. The onset of the spectrum at 35 064 cm-1 exhibits a large red shift relative to the π-π* origin of 9H-adenine at 36 105 cm-1. The IR-UV spectrum was assigned to cluster structures with HNH ⋯ O=C/N ⋯ HN hydrogen bonding by comparison with the IR spectra of A and T monomers and with ab initio calculated vibrational spectra of the most stable A-T isomers. The Watson-Crick A-T base pair is not the most stable base-pair structure at different levels of ab initio theory, and its vibrational spectrum. Experiments with methylated A and T were performed to further support the structural assignment.

Original languageEnglish
Pages (from-to)838-842
Number of pages5
Issue number8
StatePublished - 18 Aug 2003
Externally publishedYes


  • Ab initio calculations
  • IR spectroscopy
  • Laser spectroscopy
  • Nucleobases
  • UV/Vis spectroscopy

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry


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