title: Electronically excited states of DNA oligonucleotides with disordered base sequences studied by fluorescence spectroscopy.
abstract: DNA double-stranded oligomers are studied by steady-state and time-resolved fluorescence spectroscopy from the femtosecond to the nanosecond time-scale, following excitation at 267 nm. It is shown that emission arises from three types of excited states. (i) Bright ππ* states emitting around 330 nm and decaying on the sub-picosecond time-scale with an average lifetime of ca. 0.4 ps and a quantum yield lower than 4 × 10(-6). (ii) Excimers/exciplexes emitting around 430 nm and decaying on the sub-nanosecond time-scale. (iii) Excited states emitting mainly at short wavelengths (λ < 330 nm) and decaying on the nanosecond time-scale, possibly correlated to GC pairs. The properties of the examined duplexes, exhibiting significant disorder with respect to the nearest neighbour base sequence, are radically different than those of the much longer and disordered calf thymus DNA. Such behaviour suggests that long range and/or sequence effects play a key role in the fate of excitation energy.
authors.affiliation: CNRS, IRAMIS, SPAM, Laboratoire Francis Perrin, URA 2453, F-91191 Gif-sur-Yvette, France.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Vayá
authors.forename: Johanna
authors.initials: J
authors.lastname: Brazard
authors.forename: Thomas
authors.initials: T
authors.lastname: Gustavsson
authors.forename: Dimitra
authors.initials: D
authors.lastname: Markovitsi
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D004583:Electrons; D009841:Oligonucleotides / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence
chemical_list: D009841:Oligonucleotides; D004247:DNA; C427203:calf thymus DNA