title: Electronic structure of adenine and thymine base pairs studied by femtosecond electron-ion coincidence spectroscopy.
abstract: Femtosecond pump-probe spectroscopy was combined with photoelectron-photoion coincidence detection to investigate the electronic structure and dynamics of isolated adenine (A) and thymine (T) dimers and the adenine-thymine (AT) base pair. The photoelectron spectra show that pipi* and npi* states are only weakly perturbed in the hydrogen-bound dimers as compared to the monomers. For cationic base pairs with internal energies greater than 1 eV, we observed considerable cluster fragmentation into protonated monomers. This process selectively removed signals from the npi* --> n-1 ionization channel in all dimers. The photoelectron spectra are compared to time-resolved mass spectra and confirm the assignment of short-lived pipi* and npi* populations in the adenine, thymine, and mixed AT dimers.
authors.affiliation: Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, K1A 0R6 Canada.
authors.forename: Niklas
authors.initials: N
authors.lastname: Gador
authors.forename: Elena
authors.initials: E
authors.lastname: Samoylova
authors.forename: Valoris Reid
authors.initials: VR
authors.lastname: Smith
authors.forename: Albert
authors.initials: A
authors.lastname: Stolow
authors.forename: David M
authors.initials: DM
authors.lastname: Rayner
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Radloff
authors.forename: Ingolf Volker
authors.initials: IV
authors.lastname: Hertel
authors.forename: Thomas
authors.initials: T
authors.lastname: Schultz
mesh_terms: D000225:Adenine / Q000737:chemistry*; D020029:Base Pairing; D019281:Dimerization; D004583:Electrons; D006860:Hydrogen Bonding; D008027:Light; D013058:Mass Spectrometry / Q000379:methods*; D015394:Molecular Structure; D013941:Thymine / Q000737:chemistry*
chemical_list: D000225:Adenine; D013941:Thymine