title: Spectroscopy and photophysics of self-organized zinc porphyrin nanolayers. 2. Transport properties of singlet excitation.
abstract: Exciton diffusion has been studied in 5-25-nm-thick films of zinc tetra-(p-octylphenyl)-porphyrin (ZnTOPP) spin-coated onto quartz slides by intentional doping with quenchers using steady-state as well as time-resolved fluorescence spectroscopy. The fluorescence spectra of the films are very similar to those of solutions, indicating emission from localized exciton states. From the dependence of the fluorescence quenching on the quencher concentration and fluorescence lifetime measurements, the exciton diffusion can be concluded to be quasi-one-dimensional with an exciton diffusion length of 9 +/- 3 nm and an intrastack energy-transfer rate constant of 10(11)-10(12) s(-1). From fluorescence anisotropy decay measurements, we conclude that neighboring stacks aggregate in a herringbone structure, forming ordered domains that are randomly oriented in the substrate plane. These measurements indicate an interstack energy-transfer rate constant of (7 +/- 2) x 10(10) s(-1).
authors.affiliation: Laboratory for Biophysics, Department of Agrotechnology and Food Sciences, Wageningen University, Dreijenlaan 3, 6703 HA Wageningen, The Netherlands.
authors.forename: Harry
authors.initials: H
authors.lastname: Donker
authors.forename: Arie
authors.initials: A
authors.lastname: van Hoek
authors.forename: Willem
authors.initials: W
authors.lastname: van Schaik
authors.forename: Rob B M
authors.initials: RB
authors.lastname: Koehorst
authors.forename: Mikalai M
authors.initials: MM
authors.lastname: Yatskou
authors.forename: Tjeerd J
authors.initials: TJ
authors.lastname: Schaafsma
mesh_terms: D008665:Metalloporphyrins / Q000737:chemistry*; D055585:Physical Phenomena; D010825:Physics; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D008665:Metalloporphyrins; C017802:zinc hematoporphyrin