title: On the analyses of fluorescence depolarisation data in the presence of electronic energy migration. Part II: Applying and evaluating two-photon excited fluorescence.
abstract: Electronic energy migration within a bifluorophoric molecule has been studied by time-resolved two-photon excited (TPE) fluorescence depolarisation experiments. Data were analysed by using a recently developed quantitative approach [O. Opanasyuk and L. B.-Å. Johansson, On the Analyses of Fluorescence Depolarisation Data in the Presence of Electronic Energy Migration. Part I: Theory and General Description, Phys. Chem. Chem. Phys., submitted]. The energy migration occurs between the 9-anthrylmethyl groups of the bifluorophoric molecule, bis-(9-anthrylmethylphosphonate) bisteroid. These groups undergo local reorientations, while overall tumbling of the bisteroid is strongly hampered in the used viscous solvent, 1,2-propanediol. To solely obtain information about local reorientations of the 9-anthrylmethyl group, also the mono-(9-anthrylmethylphosphonate) bisteroid was studied, which enabled modelling of the ordering potential shape. The analysis of data is partly performed in the Fourier domain and the best-fit parameters are determined by using an approach based on a Genetic Algorithm. The energy migration process was described by an extended Förster theory (EFT). A reasonable value of the distance between the 9-anthrylmethyl groups, as well as for the mutual orientation of the ordering potentials, is found. Furthermore, values of the two-photon tensor components were obtained.
authors.affiliation: Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
authors.forename: Oleg
authors.initials: O
authors.lastname: Opanasyuk
authors.forename: Therese
authors.initials: T
authors.lastname: Mikaelsson
authors.forename: Linus
authors.initials: L
authors.lastname: Ryderfors
authors.forename: Emad
authors.initials: E
authors.lastname: Mukhtar
authors.forename: Lennart B-Å
authors.initials: LB
authors.lastname: Johansson
mesh_terms: D000465:Algorithms; D000873:Anthracenes / Q000737:chemistry*; D004735:Energy Transfer; D005454:Fluorescence Polarization; D017785:Photons; D019946:Propylene Glycol / Q000737:chemistry
chemical_list: D000873:Anthracenes; D019946:Propylene Glycol