Fluoreszenzuntersuchungen einzelner Dendrimermoleküle mit mehreren Chromophoren

Gensch, Thomas; Hofkens, Johan; Herrmann, Andreas; Tsuda, Kenji; Verheijen, Wendy; Vosch, Tom; Christ, Thomas; Basché, Th.; Müllen, Kläus; Schryver, F. C. De

doi:10.1002/(sici)1521-3757(19991216)111:24<3970::aid-ange3970>3.0.co;2-i

Cited by 37 publications

(18 citation statements)

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“…However, since the observed process is always connected with slightly higher maximum count rates we assume that we had two molecules simultaneously under laser illumination. As shown recently for multiple labeled dendrimer molecules (33), jumps in fluorescence intensity may display cooperative effects if the fluorophores are located well within a wavelength of light (34). On the suposition that we have two molecules simultaneously in the laser spot, a spontaneous spectral jump of one of the two molecules can result in a more or less efficient fluorescence resonance energy transfer (FRET) process (35,36).…”

Section: Resultssupporting

confidence: 64%

Confocal Fluorescence Lifetime Imaging Microscopy (FLIM) at the Single Molecule Level

et al. 2000

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We report on confocal fluorescence lifetime imaging microscopy (CFLIM) of single dye molecules adsorbed on glass surface. Applying a short-pulse diode laser emitting at 635 nm with a repetition rate of 64 MHz we studied the time-resolved identification of individual carbocyanine and oxazine dyes via their characteristic fluorescence lifetimes of 2.06± 0.37 ns (Cy5) and 3.89± 0.91 ns (JA242). Fluctuations in fluorescence intensity and lifetime of individual adsorbed molecules were investigated with millisecond time resolution. These jumps exhibit short offstates t off of 0.5 ms which can be ascribed to the triplet state lifetime under dry conditions with an intersystem crossing yield Y ISC of ~0.2 %. Besides triplet states, other quantum jumps into longer lived states (several milliseconds) with lower transition probability were observed. The correlation of rotational and spectral jumps of single and coupled fluorophores with changes in the observed fluorescence lifetime are discussed.

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Section: Resultssupporting

confidence: 64%

Confocal Fluorescence Lifetime Imaging Microscopy (FLIM) at the Single Molecule Level

et al. 2000

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“…[22,24,26] Figure 3b shows the green PL of a single 1 % copolymer molecule as a function of time. The emission exhibits discrete switching to both higher and lower intensities, before it disappears completely after 65 s. Such stepwise random switching and blinking events due to reversible photoquenching processes [22,24,26] …”

Section: Single-molecule Emission From On-chain Fluorenone Defectsmentioning

confidence: 99%

“…[22][23][24][25][26][27][28][29][30][31] In this article, we demonstrate green band emission from single fluorenone-polyfluorene statistical copolymers in dependence on the intramolecular defect concentration. Keto defect emission is clearly observed on the single-molecule level in coexistence with polymer-backbone emission.…”

Section: Introductionmentioning

confidence: 99%

On‐Chain Fluorenone Defect Emission from Single Polyfluorene Molecules in the Absence of Intermolecular Interactions

Becker

Lupton

Feldmann

et al. 2006

Adv Funct Materials

152

128

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The emission of semiconducting polyfluorenes is often accompanied by an undesired feature in the green spectral region. Whereas a number of previous investigations have argued in favor of a monomolecular origin of the emission species based on ketonic defects, recent experimental results suggested the necessity of excimer formation between individual fluorenone units. We provide a range of new evidence supporting the monomolecular origin of green band emission in polyfluorenes. Most importantly, we succeed in performing single‐molecule spectroscopy on fluorenone‐containing polyfluorene model compounds. Whereas most fluorenone‐containing molecules exhibit both blue backbone and green fluorenone emission independent of fluorenone concentration, it is the relative intensities of the two species which correlate strongly with the fluorenone concentration on the single‐molecule level. Furthermore, we consider a novel model compound with a bifacial arrangement of two fluorenone units. This compound does not provide any signatures of enhanced intramolecular excimer formation but does strongly indicate that concentration quenching effects occur once fluorenone units can interact electronically. The ability to detect on‐chain defect emission in a single polymer molecule demonstrates that photochemical reactions in conjugated polymers can be monitored by fluorescence spectroscopy down to the level of a few atoms, constituting an unprecedented degree of materials characterization.

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“…In its simplest version such a set-up can be used for wide-field (not shown here) or laser scanning confocal microscopy in the temperature range between 2 and 250 K. Actually, it has been possible to reproducibly image the same set of single molecules over this temperature range [28]. An interesting application for the combination of confocal microscopy and frequency selective single molecule spectroscopy will be the study of multichromophoric units like dendrimers decorated with a variable number of chromophores [29]. In such an experiment confocal microscopy will serve to isolate a single multichromophoric unit spatially.…”

Section: Frequency Selective Single Molecule Spectroscopy At Low Tempmentioning

confidence: 99%

Single Molecule Spectroscopy: Methodological Developments and Experiments at Low Temperature

Basché

2001

Single Mol.

Self Cite

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In this contribution I briefly will summarise the main issues which were discussed in my lectures at the spring school "Optical Spectroscopy and Microscopy of Single Objects" in Les Houches. After a short survey of methodological developments during the last two decades I will focus on the technique of single molecule spectroscopy at low temperatures and present some results obtained in this regime. Finally, I will briefly discuss a set-up, which allows single molecule spectroscopy over a wide temperature range and combines laser scanning confocal microscopy and frequency selective single molecule spectroscopy.

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Fluoreszenzuntersuchungen einzelner Dendrimermoleküle mit mehreren Chromophoren

Abstract: Diese Arbeit wurde von der FWO, dem flämischen Ministerium für Bildung (GOA/1/96), der Europäischen Union (TMR-Projekte ¹Sisitomasª und ¹Marie Curieª), der Volkswagen-Stiftung und der DWTC (Belgien; IUAP-IV-11) gefördert. J.H. dankt der FWO für ein Graduiertenstipendium.

Cited by 37 publications

References 50 publications

Confocal Fluorescence Lifetime Imaging Microscopy (FLIM) at the Single Molecule Level

Confocal Fluorescence Lifetime Imaging Microscopy (FLIM) at the Single Molecule Level

On‐Chain Fluorenone Defect Emission from Single Polyfluorene Molecules in the Absence of Intermolecular Interactions

Single Molecule Spectroscopy: Methodological Developments and Experiments at Low Temperature

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