title: Energy transfer within Zn-porphyrin dendrimers: study of the singlet-singlet annihilation kinetics.
abstract: In this article, we explore energy transfer processes within a series of Zn-porphyrin-appended dendrimers by means of excitation intensity dependent transient absorption measurements. We report singlet-singlet annihilation on two distinct time scales of 18 +/- 5 ps and 130 +/- 10 ps in the dimer and the dendrimers. The two distinct processes reflect the presence of two structural conformer distributions. Analysis of the singlet-singlet annihilation transient kinetics shows that sequential annihilation occurs within subunits up to four Zn-porphyrins in the dendrimers. The onset of the singlet-singlet annihilation process depending on the size of the molecule reveals a difference in the number of communicating Zn-porphyrins. We further report a full characterization of the transient absorption kinetics of the monomer over a spectral range from 450 to 730 nm.
authors.affiliation: Department of Chemical Physics, Lund University, Box 124, SE-221 00 Lund, Sweden. Jane.Larsen@chemphys.lu.se
authors.forename: Jane
authors.initials: J
authors.lastname: Larsen
authors.forename: Ben
authors.initials: B
authors.lastname: Brüggemann
authors.forename: Tomás
authors.initials: T
authors.lastname: Polívka
authors.forename: Villy
authors.initials: V
authors.lastname: Sundström
authors.forename: Eva
authors.initials: E
authors.lastname: Akesson
authors.forename: Joseph
authors.initials: J
authors.lastname: Sly
authors.forename: Maxwell J
authors.initials: MJ
authors.lastname: Crossley