Photon Antibunching and Collective Effects in the Fluorescence of Single Bichromophoric Molecules

Hübner, Christian G.; Zumofen, G.; Renn, Alois; Herrmann, Andreas; Müllen, Kläus; Basché, Thomas

doi:10.1103/physrevlett.91.093903

Cited by 88 publications

(96 citation statements)

References 17 publications

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“…Additionally, longer-lived dark states with a duration ranging from milliseconds to seconds are observed. The short "off" times with a length on the 10-100 µs time scale, similar to that recently reported for a bichromophoric molecule where two PMI chromophores were linked by a benzil unit, 23 can be attributed to triplet excursions. The duration of the long-lived dark states is not exponentially distributed but instead follows a power law.…”

Section: Introductionsupporting

confidence: 86%

Exponential and Power-Law Kinetics in Single-Molecule Fluorescence Intermittency

et al. 2004

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Perylenemonoimide chromophores, attached to a small dendron arm embedded in the polymer hosts Zeonex, poly(vinylbutyral), and poly(methyl methacrylate), are studied by means of laser-induced confocal fluorescence detection. Transient fluorescence intensity exhibits dark periods on two different time scales: on a 100 µs time scale and on a considerably longer time scale, ranging from 100 ms to as much as tens of seconds under high-vacuum conditions. The exponentially distributed short "off" times are attributed to triplet excursions of the molecule. The long-lived dark states follow a power-law distribution and are discussed in terms of the formation of radical anions/cations via electron tunneling processes.

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Section: Introductionsupporting

confidence: 86%

Exponential and Power-Law Kinetics in Single-Molecule Fluorescence Intermittency

et al. 2004

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“…[21] However, triplet excitons may also act as efficient quenchers of singlet excitons. [24,25] As a triplet±singlet interaction can lead to the formation of a new triplet, it may be possible to keep the molecule in the excited (triplet) state for times exceeding the triplet lifetime, thereby producing prolonged intermittencies in the fluorescence. Strong fluorescence quenching due to a build-up of triplet excitons is most likely responsible for the fluorescence burst observed from the bulk material, keeping in mind the efficiency of intermolecular triplet migration in the bulk.…”

Section: Methodsmentioning

confidence: 99%

“…[8,23] Although singlet±triplet quenching will only be of relevance at high excitation densities as in our experiment, it may pose a severe loss channel in light-emitting diodes. Whereas triplet shelving in a single two-level system such as a simple dye molecule does not lead to a reduction of the overall fluorescence quantum yield as no photons are absorbed during the off time, quenching in multichromophoric molecules by either radicals [12,21] or triplets [24,25] poses a limit to the quantum efficiency. Single-molecule spectroscopy is a powerful technique to investigate fundamental photophysical properties of organic semiconductors.…”

Section: Methodsmentioning

confidence: 99%

Controlled Fluorescence Bursts from Conjugated Polymers Induced by Triplet Quenching

Schindler

Lupton²,

Feldmann

et al. 2004

Advanced Materials

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and lengths of up to several hundreds of micrometers. The intermediates in the formation of the nanoribbons were found to be series-wound beads, which gradually developed into a one-dimensional nanostructure confined by the highly anisotropic crystal structure of t-Se during their cooling period. The t-Se nanoribbons might find applications in the studies of structure±property relationships, and in the fabrication of nanoscale optoelectronic devices. ExperimentalThe vapor deposition was carried out in a horizontal tube furnace equipped with a temperature control system, a gas supply and control system. Before the experiment, copper plates (50 mm 50 mm 2 mm) were pre-treated with 5 % nitric acid to remove any adsorbates and placed downstream inside the quartz tube (deposition zone). Then a porcelain crucible with a diameter of 1 cm containing 0.1 g metallic selenium powder (purity greater than 99.99 %) was located at the center of the quartz tube (sublimation zone). A carrier gas of argon (Purity: 99.999 %) was kept flowing at a rate of 10 sccm for 0.5 h. Afterwards, the temperature of the evaporation zone and the deposition zone were set at 600 C and 300 C, respectively, and the thermal evaporation was conducted at this temperature gradient for 8 h, while the flow rate of the carrier gas was kept unchanged. Then, the products were naturally cooled to room temperature in an Ar atmosphere. The collected black and fiber-like products from the copper plates were used in the following characterizations.The X-ray diffraction patterns of the products were recorded on a Rigaku D/max-c rotation anode X-ray diffractometer (Cu Ka, k = 0.154178 nm). The measurement of Raman scattering was performed on a confocal laser micro-Raman spectrometer (JY Labram-HR), using 24 mW excitation at 514.5 nm. The samples for the study of XRD and Raman scattering were the collected powders. The scanning electron microscopy images were taken with a JEOL-JSM-6700F field emitting scanning electron microscope. The specimen was the powder, and was pre-coated with a thin layer of gold before the FES-EM observations. Transmission electron microscopy images and electron diffraction patterns were taken with a JEOL-2010 high-resolution electron microscope, operating at an accelerating voltage of 200 kV. The specimen was prepared by spreading a drop of ethanol suspension onto a copper grid, coated with a thin amorphous carbon film, and allowed to dry in air. EDAX analysis was performed using the JEOL-2010 high-resolution electron microscope equipped with EDAX-PV 9100 energy-dispersion X-ray fluorescence analyzer.

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“…After photon emission, a chromophore must be re-excited and wait, on average, a time interval equal to the fluorescence lifetime before another photon can be emitted. This property of the photon arrival-time statistics, termed photon antibunching, has been measured at room temperature under continuous-wave laser illumination as well as under pulsed-laser illumination for individual molecules by measuring the interphoton arrival times (25)(26)(27). These are histogrammed to get the interphoton arrival-times distribution.…”

Section: Visualization Of the Energy Hopping By Smsmentioning

confidence: 99%

Revealing competitive Förster-type resonance energy-transfer pathways in single bichromophoric molecules

Hofkens

Cotlet

Vosch

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

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T he current renaissance of the use of the fluorescence resonance energy-transfer (FRET) (1) process between two weakly coupled dipoles, one acting as donor and the other acting as acceptor, results from various elegant and successful studies of distance changes in individual biomolecules by using singlemolecule spectroscopy (SMS). This type of study is often referred to as single-pair Förster resonance ET (2-4). Recent advances in fluctuation microscopy allow the observation of changes in the ET efficiency in single-pair Förster resonance ET systems at the millisecond-to-nanosecond time scale (5, 6). It has been suggested that, in the latter time scale, thermally excited conformational dynamics of (bio)macromolecules will become accessible (5). Thus far, FRET measurements at these time scales have overlooked competitive Förster-type ET pathways, which might complicate data analysis and interpretation of the FRET data. The FRET process involves nonradiative transfer from a donor to an acceptor. For molecules within the weak coupling limit, Förster derived an expression for the rate constant of dipole-dipole-induced ET (7). This relation shows that the ET efficiency scales with the sixth power of the distance between the chromophores:Here, R 0 is the distance at which the efficiency equals 50%, i.e., the distance at which an equal probability exists for the excited chromophore to relax to the ground state via emission of a photon or to undergo ET. It includes the spectral properties and the relative orientation (in terms of the orientation factor 2 ) of donor and acceptor transition dipoles. If the distances and orientations of the chromophores are kept constant, the ET efficiency is determined by the spectral overlap of the corresponding transitions, i.e., the overlap of the emission spectrum of the donor and the absorption spectrum of the acceptor. Therefore, FRET can also occur between identical molecules if the Stokes shift is small enough to allow for a sufficient overlap of the emission and absorption spectrum of the chromophores. This so-called homo-transfer or energy hopping represents a key mechanism for energy transport in some light-harvesting complexes (8).However, Förster-type resonance ET is not restricted to the nonradiative transfer of energy from a donor in the excited state to a ground-state acceptor. Transfer processes that are allowed within the Förster formalism are those for which there are no changes in electron spin in the acceptor transition. Therefore, even ET processes between donor and acceptor molecules with different spin multiplicity likewise are possible. Hence, the transfer of excitation energy from a chromophore residing in the first excited singlet (S) state to another chromophore residing either in the triplet (T) or in an excited singlet state are possible and competitive ET pathways.In the present contribution, we demonstrate that, because of the specific excitation conditions that are applied in SMS, indeed several Förster-type ET pathways are prevalent in single bichromopho...

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Photon Antibunching and Collective Effects in the Fluorescence of Single Bichromophoric Molecules

Cited by 88 publications

References 17 publications

Exponential and Power-Law Kinetics in Single-Molecule Fluorescence Intermittency

Exponential and Power-Law Kinetics in Single-Molecule Fluorescence Intermittency

Controlled Fluorescence Bursts from Conjugated Polymers Induced by Triplet Quenching

Revealing competitive Förster-type resonance energy-transfer pathways in single bichromophoric molecules

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