title: Exciton diffusion and relaxation in methyl-substituted polyparaphenylene polymer films.
abstract: Exciton diffusion in ladder-type methyl-substituted polyparaphenylene film and solution was investigated by means of femtosecond pump-probe spectroscopy using a combined approach, analyzing exciton-exciton annihilation, and transient absorption depolarization properties. We show that the different views on the exciton dynamics offered by anisotropy decay and annihilation are required in order to obtain a correct picture of the energy transfer dynamics. Comparison of the exciton diffusion coefficient and exciton diffusion radius obtained for polymer film with the two techniques reveals that there is substantial short-range order in the film. Also in isolated chains there is considerable amount of order, as revealed from only partial anisotropy decay, which shows that only a small fraction of the excitons move to differently oriented polymer segments. It is further concluded that interchain energy transfer is faster than intrachain transfer, mainly as a result of shorter interchain distances between chromophoric units.
authors.affiliation: Institute of Physics, Savanoriu, 231 Vilnius, Lithuania. vidgulb@ktl.mii.lt
authors.forename: V
authors.initials: V
authors.lastname: Gulbinas
authors.forename: I
authors.initials: I
authors.lastname: Mineviciūte
authors.forename: D
authors.initials: D
authors.lastname: Hertel
authors.forename: R
authors.initials: R
authors.lastname: Wellander
authors.forename: A
authors.initials: A
authors.lastname: Yartsev
authors.forename: V
authors.initials: V
authors.lastname: Sundström
mesh_terms: D000042:Absorption; D004058:Diffusion; D004735:Energy Transfer; D007700:Kinetics; D008697:Methane / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
chemical_list: D011108:Polymers; D008697:Methane