title: Single molecule studies of a ladder type conjugated polymer: vibronic spectra, line widths, and energy transfer.
abstract: Confocal fluorescence microscopy and spectroscopy are employed to investigate single poly(ladder-type pentaphenylene) (LPPentP) molecules dispersed in thin poly(methyl methacrylate) (PMMA) films at 1.2 K. Emission spectra of single chains show single as well as multi-chromophore emission indicating variegated communication along the chains. The vibronic structure in the emission spectra resembles the one found for other ladder-type polymers. Purely electronic zero-phonon lines in emission are substantially broadened, most probably due to fast spectral diffusion. By surmounting the limitations of emission spectroscopy, nonemitting donor chromophores, which transfer their excitation energy in a radiationless manner to emitting chromophores, are accessed by excitation spectroscopy. Remarkably, by comparing the data of emitting and nonemitting chromophores a contribution to the zero-phonon excitation line width has to be considered which places a lower limit on the estimated energy transfer time of several picoseconds between adjacent chromophores. Finally, the data indicate qualitatively a restricted flexibility of LPPentP compared to poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV).
authors.affiliation: Institut für Physikalische Chemie, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany.
authors.forename: Martin F
authors.initials: MF
authors.lastname: Zickler
authors.affiliation: Institut für Physikalische Chemie, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany.
authors.forename: Florian A
authors.initials: FA
authors.lastname: Feist
authors.affiliation: Max Planck-Institut für Polymerforschung, 55128, Mainz, Germany.
authors.forename: Josemon
authors.initials: J
authors.lastname: Jacob
authors.affiliation: Max Planck-Institut für Polymerforschung, 55128, Mainz, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
authors.affiliation: Institut für Physikalische Chemie, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Basché
mesh_terms: D004735:Energy Transfer; D018613:Microscopy, Confocal; D060739:Phonons; D011108:Polymers / Q000737:chemistry*; D019904:Polymethyl Methacrylate / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D011108:Polymers; D014753:Vinyl Compounds; C520682:poly(2-methoxy-5-(2'-ethylhexyloxy)-p-phenylenevinylene); D019904:Polymethyl Methacrylate
keywords: conjugated polymers; energy transfer; fluorescence; low temperature; single molecule spectroscopy