title: Getting to guanine: mechanism and dynamics of charge separation and charge recombination in DNA revisited.
abstract: The mechanism and dynamics of charge separation and charge recombination in synthetic DNA hairpins possessing a stilbenedicarboxamide linker and a single guanine-cytosine base pair have been reinvestigated. The combination of femtosecond broad-band pump probe spectroscopy, nanosecond transient absorption experiments, and picosecond fluorescence decay measurements permits analysis of the formation and decay of the stilbene anion radical. Reversible hole injection resulting in the formation of the stilbene-adenine contact radical ion pair is found to occur on the picosecond time scale. The mechanism for charge separation across two or more base pairs is revised from single step superexchange to a multi-step process: hole injection followed by hole transport and hole trapping. The mechanism of charge recombination remains assigned to a superexchange process.
authors.affiliation: Department of Chemistry, Northwestern University, Evanston, IL 60201, USA. lewis@chem.northwestern.edu
authors.forename: Frederick D
authors.initials: FD
authors.lastname: Lewis
authors.forename: Huihe
authors.initials: H
authors.lastname: Zhu
authors.forename: Pierre
authors.initials: P
authors.lastname: Daublain
authors.forename: Karsten
authors.initials: K
authors.lastname: Sigmund
authors.forename: Torsten
authors.initials: T
authors.lastname: Fiebig
authors.forename: Milen
authors.initials: M
authors.lastname: Raytchev
authors.forename: Qiang
authors.initials: Q
authors.lastname: Wang
authors.forename: Vladimir
authors.initials: V
authors.lastname: Shafirovich
mesh_terms: D000042:Absorption; D004247:DNA / Q000737:chemistry*; D004579:Electron Transport; D006147:Guanine / Q000737:chemistry*; D007700:Kinetics; D010777:Photochemistry; D013050:Spectrometry, Fluorescence; D055672:Static Electricity
chemical_list: D006147:Guanine; D004247:DNA