Differential Förster resonance energy transfer from the excimers of poly(N-vinylcarbazole) to coumarin-153 (original) (raw)

Energy Transfer from Poly(Vinyl Carbazole) to a Fluorene-Vinylene Copolymer in Solution and in the Solid State†

Photochemistry and Photobiology, 2012

This article reports a comparative study of the energy transfer processes in solution and the solid state from poly(vinyl carbazole; the donor) to dimethylphenyl-terminated poly[(9,9dioctylfluorenyl-2,7-divinylene-fluorene)-co-alt-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (the acceptor). The results in solutions suggest that a decrease of the donor emission intensity with an increasing acceptor concentration is more closely related to the trivial energy transfer process, indicating that the donor and acceptor chains are not in close contact during the lifetime of the donor excited state. This conclusion was reached using the amplitude-averaged lifetime of the donor, which is practically independent of the acceptor concentration. In the solid state, the polymer blends showed a decrease in the donor emission with an increasing acceptor concentration, and a decrease in the donor lifetime was also observed. Thus, in the solid state, changes in morphology interfere with the nonradiative resonant energy transfer process, but influence on the trivial process cannot be completely neglected. The lifetime does not follow a continuous decrease with the PFO-MEHPV concentration like the emission intensity does. The changes in the lifetime values occur over the same concentration range as do the changes of morphology, as shown by the scanning electron micrographs.

Fluorescence and molecular dynamics to study the intramolecular energy transfer in N-vinyl carbazole/styrene copolymers of different molar compositions

Polymer, 2006

Emission spectra, fluorescence polarization, quenching and lifetime measurements were performed on dilute solutions of poly(N-vinyl carbazole) and N-vinyl carbazole/styrene copolymers to study the intramolecular energy transfer between carbazole groups along the polymer chain. Fluorescence anisotropy values for the samples dissolved in a PMMA solid matrix and quenching measurements in toluene by CCl 4 were used to estimate the efficiency of energy transfer as a function of the monomer molar composition. Analysis of the experiments suggests that the copolymer with the highest carbazole content, which corresponds to the highest amount of carbazole excimers, does not show the highest energy transfer efficiency. Intramolecular excimers which strongly increase with the carbazole content and that are mainly due to carbazolee carbazole monomer sequence interactions undoubtedly act as energy transfer traps. Molecular dynamics simulations on isotactic and syndiotactic copolymer fragments were used for obtaining different parameters related to the energy transfer process as a function of the number of styrene monomer units between vinyl carbazole ones.

Excitation energy transfer efficiency of dipole–dipole interaction in a dye pair in polymer medium

Research on Chemical Intermediates, 2005

Excitation energy transfer efficiency (η) of dipole–dipole interaction has been studied in the dye pair 3,3′-dimethyloxacarbocyanine iodide (DMOCI) (donor) to o-(6-diethylamino-3diethylimino-3H-xanthen-9-yl) benzoic acid (Rhodamine B, RB) (acceptor) in polyvinyl alcohol (PVA) thin films by steady-state and ps time-resolved fluorescence spectroscopy. In the presence of the acceptor the fluorescence intensity of the donor decreases, while that of the acceptor increases as a function of the added acceptor concentration. Time-resolved study of the donor at various acceptor concentrations suggest that the non-radiative energy transfer mechanism as proposed by Förster is responsible for the observed behaviour along with some modifications at very low acceptor concentrations. Modified η values have been simulated and compared with those obtained experimentally. It is found that the value of η increases with acceptor concentration.

Subpicosecond time-resolved intramolecular electronic energy transfer in flexible bichromophoric coumarin molecules

The Journal of Physical Chemistry, 1990

By excite-and-probe spectroscopy with subpicosecond time resolution, we have measured the intramolecular electronic energy transfer in bichromophoric coumarins linked by a flexible polymethylene chain. The transfer proceeds on a time scale between 1 and 20 ps depending on the polymethylene chain length. The results can be well described by a dipole-dipole interaction model that takes into account the statistical distribution of intramolecular distances between the two chromophores.

Non-radiative resonance energy transfer in bi-polymer nanoparticles of fluorescent conjugated polymers

Optics Express, 2010

This work demonstrates the comparative studies of non-radiative resonance energy transfer in bi-polymer nanoparticles based on fluorescent conjugated polymers. For this purpose, poly[(9,9-dihexylfluorene) (PF) as a donor (D) and poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) as an acceptor (A) have been utilized, from which four different bi-polymer nanoparticle systems are designed and synthesized. Both, steady-state fluorescence spectra and time-resolved fluorescence measurements indicate varying energy transfer efficiencies from the host polymer PF to the acceptor polymer MEH-PPV depending on the D-A distances and structural properties of the nanoparticles. The first approach involves the preparation of PF and MEH-PPV nanoparticles separately and mixing them at a certain ratio. In the second approach, first PF and MEH-PPV solutions are mixed prior to nanoparticle formation and then nanoparticles are prepared from the mixture. Third and fourth approaches involve the sequential nanoparticle preparation. In the former, nanoparticles are prepared to have PF as a core and MEH-PPV as a shell. The latter is the reverse of the third in which the core is MEH-PPV and the shell is PF. The highest energy transfer efficiency recorded to be 35% is obtained from the last system, in which a PF layer is sequentially formed on MEH-PPV NPs.

Optical Transition, Excitation, and Emission Properties of Poly(N-Vinlycarbazole) Blended with Poly(Vinylidene Fluoride-co-Hexafluoropropene) and Polyvinylpyrrolidone

Acta Physica Polonica A, 2015

We present the results concerning the excitation and emissions spectra of Poly (N-carbazole) (PVK) blended with poly(vinylidene uoride-co-hexauoropropene), (PVDF-HfP) and polyvinylpyrrolidone (PVP). Thin lms of PVK blended with PVDF-HfP (PVK:PVDF-HfP) and PVP (PVK:PVP) were prepared using doctor blade technique on spectrosil substrate. The inuences of polymer blends on the excitation and emission spectra were observed under UV excitation source of a xenon lamp. The result shows a discrepancy in the maximum excitation and emission for each sample. The possible energy transfer and recombination mechanisms have been related with singlet-singlet semi-empirical INDO electronic calculation and FTIR measurements.

Energy-Transfer Processes in Donor–Acceptor Poly(fluorenevinylene- alt -4,7-dithienyl-2,1,3-benzothiadiazole)

The Journal of Physical Chemistry C, 2013

The emission ellipsometry technique was applied to the donor−acceptor structure, poly[9,9′-dioctyl-2,7-fluorenevinylene-alt-4,7-(di-2,5-thienyl)-2,1,3-benzothiadiazole], to quantify the energy transferred from the donor (fluorene) to the acceptor (thiophene−benzothiadiazole−thiophene). The relative contributions to the total emission from both donor and acceptor were determined and also the amount of the emitting species that lost coherence with the polarization of the excitation light. The results were discussed in terms of energy transfer via multiphonon processes.

Energy migration and excimer formation in a vinyl carbazole-fumaronitrile copolymer

Polymer Photochemistry, 1982

Steady-state and time-resolved fluorescence measurements have been used to examine intramolecular energy migration and excimer formation in dilute solutions of poly(N-vinyl carbazole) and a vinyl carbazole-fumaronitrile alternating copolymer. Fluorescence polarisation studies indicate that energy migration is a very efficient process in these polymers. In the copolymer a small amount of excimer emission is present and solvent dependence studies confirm that these excimers form via long-range interactions between chromophores. In the homopolymer the majority of emission arises from excimers formed between nearest-neighbour carbazole groups.