title: Fluorescence of natural DNA: from the femtosecond to the nanosecond time scales.
abstract: The fluorescence of calf thymus DNA is studied by steady-state and time-resolved spectroscopy combining fluorescence upconversion and time-correlated single photon counting. The fluorescence spectrum is very similar to that of a stoichiometric mixture of monomeric chromophores, arising from bright pi pi* states, and contrasts with the existing picture of exciplex emission in natural DNA. Yet, the DNA fluorescence decays span over five decades of time, with 98% of the photons being emitted at times longer than 10 ps. These findings, in association with recent studies on model duplexes, are explained by the involvement of dark states, possibly related to charge separation, serving as a reservoir for the repopulation of the bright pi pi* states.
authors.affiliation: Laboratoire Francis Perrin, CEA/DSM/IRAMIS/SPAM-CNRS URA 2453, CEA/Saclay, 91191 Gif-sur-Yvette, France.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Vayá
authors.forename: Thomas
authors.initials: T
authors.lastname: Gustavsson
authors.forename: François-Alexandre
authors.initials: FA
authors.lastname: Miannay
authors.forename: Thierry
authors.initials: T
authors.lastname: Douki
authors.forename: Dimitra
authors.initials: D
authors.lastname: Markovitsi
mesh_terms: D000818:Animals; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D005453:Fluorescence; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D004247:DNA; C427203:calf thymus DNA