Fluorescence study of nano-scale cyanine dye association generated in polymer ma

2019-06-02 02:45:58

temperature dependent fluorescence aggregate DODCI

责任者: Moriya, T.;Hiraga, T. 单位: 来源出处: Denshi Gijutsu Sogo Kenkyusho Iho/Bulletin of the Electrotechnical Laboratory,1998,62(1-2):21-34 摘要: Nano-scale association of 3,3-diethyloxadicarbocyanine iodide (DODCI) is experimentally realized by several preparation procedures such as thin film formation with a hot-press process after coprecipitation of DODCI and a polymer. The size-dependent phenomena of the associated molecular aggregate having dimensions less than 100 nm have been found by performing optical measurements under controlled conditions over a wide range of the dye concentration and the temperature down to 8 K. We have proposed a model for the excited-state energy transfer kinetics between the monomolecule and the aggregate of DODCI, which can consistently explain the concentration and temperature dependence of fluorescence spectra and lifetimes we have investigated. The appearance of the nano-scale aggregate is predictable by using the model based on the analysis of the fluorescence intensity decay profile after a pulsed light excitation; the activation energy of 6.0-8.2 kJ mol-1 for the excited-state deactivation processes of DODCI in poly(2-hydroxypropyl methacrylate) matrix have been obtained from the temperature dependence of the long and short fluorescence lifetime components and quantum yield. As the size of the aggregate or crystalline decreases, the fluorescence peak position has shifted toward shorter wavelengths, reflecting the confinement of the electronic state into an extremely small volume; the fluorescence peak wavelength varied from approximately equals 730 nm for the crystalline powder to approximately equals 640 nm for the small DODCI aggregate. 关键词: Nanostructured materials;Nanotechnology;Fluorescence;Dyes;Organic polymers;Electron energy levels;Size dependent phenomena;Temperature dependence