title: Ultrafast energy transfer and structural dynamics in DNA.
abstract: Ultrafast structural dynamics concomitant to excitation energy transfer in DNA has been studied using a pair of pyrene-labeled DNA bases. The temporal evolution of the femtosecond pump-probe spectra reveals the existence of two electronic coupling pathways, through-base stack and through-space, which lead to excitation energy transfer and excimer formation even when the labeled DNA bases are separated by one AT base pair. The electronic coupling which mediates through-base stack energy transfer is so strong that a new absorption band arises in the excited-state absorption spectrum within 300 fs. From the analysis of time-dependent spectral shifts due to through-space excimer formation, the local structural dynamics and flexibility of DNA are characterized on the picosecond and nanosecond time scale.
authors.affiliation: Eugene F. Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA.
authors.forename: A
authors.initials: A
authors.lastname: Trifonov
authors.forename: M
authors.initials: M
authors.lastname: Raytchev
authors.forename: I
authors.initials: I
authors.lastname: Buchvarov
authors.forename: M
authors.initials: M
authors.lastname: Rist
authors.forename: J
authors.initials: J
authors.lastname: Barbaric
authors.forename: H-A
authors.initials: HA
authors.lastname: Wagenknecht
authors.forename: T
authors.initials: T
authors.lastname: Fiebig
mesh_terms: D000097:Acetonitriles; D002138:Calibration; D004247:DNA / Q000737:chemistry*; D004735:Energy Transfer; D007202:Indicators and Reagents; D007700:Kinetics; D000432:Methanol; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D019265:Spectroscopy, Near-Infrared
chemical_list: D000097:Acetonitriles; D007202:Indicators and Reagents; D009841:Oligonucleotides; D012997:Solvents; D004247:DNA; D000432:Methanol; C032159:acetonitrile