Probing Photophysical Processes in Individual Multichromophoric Dendrimers by Single-Molecule Spectroscopy

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• 作者：Johan Hofkens ; Michael Maus ; Thomas Gensch ; Tom Vosch ; Mircea Cotlet ; Fabian Kö ; hn ; Andreas Herrmann ; Klaus Mü ; llen ; and Frans De Schryver
• 刊名：Journal of the American Chemical Society
• 出版年：2000
• 出版时间：September 27, 2000
• 年：2000
• 卷：122
• 期：38
• 页码：9278 - 9288
• 全文大小：618K
• 年卷期：v.122,no.38(September 27, 2000)
• ISSN：1520-5126

文摘

Individual multichromophoric dendrimer molecules, bearing eight perylenecarboximide chromophoresat the rim, immobilized in a thin polyvinylbutyral (PVB) film were studied by far-field fluorescence microscopy.Fluorescence intensity trajectories as a function of time (transients), spectra, and decay traces were recordedseparately or simultaneously. For comparison, similar measurements have been performed on a model compoundcontaining one perylenecarboximide chromophore. Collective on/off jumps of the fluorescence intensity wereobserved for single dendrimer molecules, resembling previously reported collective jumps for the emission ofsingle light-harvesting antenna systems. Spectra and decays of both non-interacting and dimer-like interactingchromophoric sites could be distinguished within an individual dendrimer. Transitions between the differentspectral forms and decay times, observed for a single molecule, underline the dynamic character of theinteractions among the chromophores. Evidence for a stepwise bleaching process of the multichromophoricsystem was found. Furthermore, the single-molecule data incontestably prove the assumptions stated in theensemble model.