Characterization of the excimers of poly(N-vinylcarbazole) using TRANES

Ghosh, Dipak; Chattopadhyay, Nitin

doi:10.1016/j.jlumin.2011.05.043

Cited by 16 publications

(33 citation statements)

References 39 publications

(77 reference statements)

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“…Observed spectral changes indicate dense packaging of carbazole moieties and formation of excimers with different stacking motifs. According to the literature data, the high-energy emission centered at ∼370 nm is ascribed to a partially overlapped structure, whereas the low-energy signal centered at ∼410 nm corresponds to a sandwich-like stacking (see insets in Figure ), where two carbazole molecules attain an eclipsed or fully overlapped arrangement. − …”

Section: Resultsmentioning

confidence: 76%

Ultratrace Nitroaromatic Vapor Detection via Surface-Enhanced Fluorescence on Carbazole-Terminated Black Silicon

et al. 2019

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Detection of nitroaromatic compounds (NACs) is an important applied task for environmental monitoring, medical diagnostics, and forensic analysis. However, detection of NAC vapors is challenging owing to their low vapor pressure and relatively weak sensitivity of the existing detection techniques. Here, we propose a novel concept to design fluorescence (FL) detection platforms based on chemical functionalization of nanotextured dielectric surfaces exhibiting resonant light absorption, trapping, and localization effects. We demonstrate highly-efficient NAC vapor sensor with selective FL-quenching response from monolayers of carbazole moieties covalently bonded to a spiky silicon surface, “black” silicon, produced over the centimeter-scale area using simple reactive ion etching. The sensor is shown to provide unprecedented ppt (10–12) range limits of detection for several NAC vapors. Easy-to-implement scalable fabrication procedure combined with simple and versatile functionalization techniques applicable to all-dielectric surfaces make the suggested concept promising for realization of various gas sensing systems for social and environmental safety applications.

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Section: Resultsmentioning

confidence: 76%

Ultratrace Nitroaromatic Vapor Detection via Surface-Enhanced Fluorescence on Carbazole-Terminated Black Silicon

et al. 2019

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“…Looking at the reasonable disparity in the lifetime values for the lower and the higher energy emission bands, TRES spectra have been collected within the spectral range 300–550 nm at various selected time windows, as depicted in Figure A,C in EtOH and MCH, respectively. The spectral changes in TRES spectra at various time windows may occur because of the two or more emitting species or due to the different solvated cluster of single excited species. , To resolve this, we have opted for a model free extension of TRES, namely, TRANES by normalization of area under the time-resolved emission spectra. − Panels B and D of Figure represent the TRANES spectra of anthril in EtOH and MCH, respectively, at different time windows. Isoemissive points (at 400 nm in EtOH and 389 nm in MCH) are observed in the TRANES spectra, revealing the coexistence of two conformers in the excited state.…”

Section: Results and Discussionmentioning

confidence: 99%

Photophysics of Anthril in Fluids and Glassy Matrixes

Kundu

Chattopadhyay

2018

J. Phys. Chem. A

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Photophysics of 9,9'-anthril have been investigated at room temperature and cryogen phase (77 K) exploiting steady state and time-resolved emission techniques together with quantum chemical calculations. Absorption spectra, emission spectra, and emission lifetimes of anthril have been recorded and analyzed in polar ethanol and nonpolar methylcyclohexane media. Both room temperature and cryogenic experiments reveal a single emission band upon excitation at the nπ* absorption band whereas on exciting the system at the ππ* band, dual emission bands have been observed. Characterization of these two fluorescence bands to be originating from near-trans and relaxed skew conformers have been made by monitoring their differential effect on varying the polarity of solvents. Similarly, two phosphorescence bands have been assigned to trans and cis geometries by looking at the change in the emission spectra in the two rigid matrixes of different polarity. Observation of a single isoemissive point in the time-resolved area normalized emission spectroscopy (TRANES) for both fluorescence and phosphorescence emissions unambiguously validates the coexistence of the two conformers in the excited singlet and triplet states, respectively. Qualitative quantum chemical calculations indicate that the S and T states are responsible for the dual fluorescence and phosphorescence bands. Effortless transitions from the higher excited singlet states (S or S) to the lowest energy excited singlet (S) state because of their energy proximity discard any possibility of S emission, consistent with two other 1,2-dicarbonyl compounds like α-furil and 2,2'-pyridil, while going in contrast to the observation of S emissions from benzil and α-naphthil. On the basis of the vivid photophysical studies on five probes in fluid media and 77 K glassy matrixes, we conclude that exhibition of the S emission for aromatic 1,2-dicarbonyl compounds is truly system dependent and not a general phenomenon for all the molecular systems in the series.

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“…The emission at ∼380 nm (high energy excimer) is attributed to incompletely overlapped carbazole units while the emission at ∼405 nm (low energy excimer) is due to full overlapping. 44,45 The emission spectrum of PVK NPs shows that the intensity at 380 nm is lower than that at 405 nm. However when the PVK is dissolved in toluene (not nanoparticles), the trend is different; the emission intensity at 370 nm is higher than at 415 nm.…”

Section: Steady-state Studymentioning

confidence: 99%

“…However when the PVK is dissolved in toluene (not nanoparticles), the trend is different; the emission intensity at 370 nm is higher than at 415 nm. 45 Therefore, the excimer emission of the PVK NPs is coming mostly from the full overlapped excimers suggesting strong interactions between the carbazole units in the PVK NPs than in the toluene solution. Upon encapsulation of C153 (2.72 wt%) inside the PVK nanodomain, the emission of PVK is efficiently quenched (by 97% at the maximum of emission intensity), while the broad emission mainly comes from the trapped C153 (intensity maximum at 510 nm and no vibronic structure).…”

Section: Steady-state Studymentioning

confidence: 99%

“…The emission decay of undoped PVK NPs shows longer lifetimes (3.31 and 16.32 ns) as it has been reported (3.24 and 16.36 ns). 39,45,48 In these reports, the shortest component is assigned to high energy excimers while the longest one to the low energy ones. 45,46 The reduction in the lifetimes of the undoped and doped PVK NPs is due to a possible ET process between the two PVK excimers and C153 that acts as a quencher of PVK emission.…”

Section: Time-resolved Spectroscopic Studymentioning

confidence: 99%

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Single and multistep energy transfer processes within doped polymer nanoparticles

Martín

Bhattacharyya

Patra

et al. 2014

Photochem Photobiol Sci

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Herein, we demonstrate the design of multiple fluorophores Coumarin 153 (C153) and Nile Red (NR) encapsulated in semiconducting poly[N-vinylcarbazole] (PVK) polymer nanoparticles (50-70 nm in diameter) by a simple re-precipitation technique, and elucidate their photophysical properties by steady-state and picosecond (ps) time resolved emission spectroscopy. It is interesting to note that multistep cascaded energy transfer occurs from the excited host PVK molecules to NR dye molecules through C153. The energy transfer time constants are found to be 180 ps for PVK→C153, 360 ps for PVK→NR, and 140 ps for the overall energy transfer process from PVK to NR through C153 dye molecules. The multistep energy transfer allows tuning of the wide range emission from 350 nm to 700 nm by changing the relative concentrations of the encapsulated dye molecules. Bright, stable, and white light emission of the dye doped polymer nanoparticles with a quantum yield of 14% is achieved at a particular concentration ratio of the C153 : NR dye. The generation of "cool" white emission in suspension and in the solid state film opens up new possibilities to obtain white light OLEDs based on single nanoparticles.

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Characterization of the excimers of poly(N-vinylcarbazole) using TRANES

Cited by 16 publications

References 39 publications

Ultratrace Nitroaromatic Vapor Detection via Surface-Enhanced Fluorescence on Carbazole-Terminated Black Silicon

Ultratrace Nitroaromatic Vapor Detection via Surface-Enhanced Fluorescence on Carbazole-Terminated Black Silicon

Photophysics of Anthril in Fluids and Glassy Matrixes

Single and multistep energy transfer processes within doped polymer nanoparticles

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