title: Photoabsorption and photofragmentation of isolated cationic silver cluster-tryptophan hybrid systems.
abstract: We present a theoretical study of the size and structure selective absorption properties of cationic silver cluster-tryptophan Trp-Ag(n)(+) (n = 2-5,9) hybrid systems supported by photofragmentation experiments. Our time-dependent density functional theory calculations provide insight into the nature of excitations in interacting nanoparticle-biomolecule subunits and allow to determine characteristic spectral features as fingerprints of two different classes of structures: charge solvated and zwitterionic. Moreover, different types of charge transfer transitions have been identified. Charge transfer from pi system of tryptophan to silver cluster occurs for charge solvated structures while charge transfer from silver to the NH(3) (+) group takes place for zwitterionic structures. This has been confirmed by experimentally measured photofragmentation channels and molecular dynamics simulations. Our findings provide fundamental insight into the structure- and size-dependent mechanism responsible for the enhanced absorption and emission in nanoparticle-biomolecular hybrid systems.
authors.affiliation: Institut für Chemie, Humboldt-Universität zu Berlin, Brook-Taylor-Strasse 2, D-12489 Berlin, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Mitrić
authors.forename: Jens
authors.initials: J
authors.lastname: Petersen
authors.forename: Alexander
authors.initials: A
authors.lastname: Kulesza
authors.forename: Vlasta
authors.initials: V
authors.lastname: Bonacić-Koutecký
authors.forename: Thibault
authors.initials: T
authors.lastname: Tabarin
authors.forename: Isabelle
authors.initials: I
authors.lastname: Compagnon
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Antoine
authors.forename: Michel
authors.initials: M
authors.lastname: Broyer
authors.forename: Philippe
authors.initials: P
authors.lastname: Dugourd
mesh_terms: D000042:Absorption; D002412:Cations / Q000737:chemistry / Q000528:radiation effects; D003198:Computer Simulation; D008027:Light; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation / Q000528:radiation effects; D012834:Silver / Q000737:chemistry* / Q000528:radiation effects; D014364:Tryptophan / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D002412:Cations; D012834:Silver; D014364:Tryptophan