title: Ultrafast exciton dynamics after Soret- or Q-band excitation of a directly β,β'-linked bisporphyrin.
abstract: We report on a comprehensive transient absorption study with β,β'-linked bis[tetraphenylporphyrinato-zinc(II)] and its corresponding monomer, covering the ultrafast dynamics from femtoseconds up to several microseconds. By exciting these porphyrins either to their first (S(1)) or second (S(2)) electronically excited states and by probing the subsequent dynamics, a multitude of reaction pathways have been identified. In the spectral region associated with the ground-state recovery of the bisporphyrin, transient absorption changes occur within the first few picoseconds, which are ascribable to excitonic interaction both in the S(2) (fs time-domain) and in the S(1) (ps time-domain) state. This is substantiated by complementary experiments with the monomeric porphyrin, in which the S(2) state exhibits a longer lifetime. In contrast to the picosecond dynamics the bisporphyrin and the monomer behave similarly on the nanosecond time-scale, that is nearly all excited molecules eventually reach a long-lived triplet excited state.
authors.affiliation: Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Kullmann
authors.forename: Arthur
authors.initials: A
authors.lastname: Hipke
authors.forename: Patrick
authors.initials: P
authors.lastname: Nuernberger
authors.forename: Torsten
authors.initials: T
authors.lastname: Bruhn
authors.forename: Daniel C G
authors.initials: DC
authors.lastname: Götz
authors.forename: Michael
authors.initials: M
authors.lastname: Sekita
authors.forename: Dirk Michael
authors.initials: DM
authors.lastname: Guldi
authors.forename: Gerhard
authors.initials: G
authors.lastname: Bringmann
authors.forename: Tobias
authors.initials: T
authors.lastname: Brixner
mesh_terms: D019281:Dimerization; D004583:Electrons; D007700:Kinetics; D008665:Metalloporphyrins / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D013057:Spectrum Analysis; D013237:Stereoisomerism
chemical_list: D008665:Metalloporphyrins; C076448:zinc tetraphenylporphine