Amplified spontaneous emission of proton transfer dyes in polymers

Fellows, C. E.; Täuber, U.; Carvalho, C. A. A. de; Carvalhaes, Claudio G.

doi:10.1590/s0103-97332005000600004

Cited by 11 publications

(5 citation statements)

References 10 publications

(16 reference statements)

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“…One possible explanation for DO11/PMMA's greater resistance to irreversible degradation is based on our recent hypothesis that the reversibly damaged species is related to a photo-induced reversible change in the dye molecule, while the the irreversibly damaged species is due to the formation of a damaged dye-polymer complex [25,28]. Since neat PMMA is transparent in the visible, photodamage to the polymer must be mediated by energy transfer between the dye molecules and the polymer [8,32,[36][37][38][39][40]. This implies an indirect damage mechanism for the irreversibly damaged species, which is less efficient than a direct damage mechanism.…”

Section: Resultsmentioning

confidence: 99%

Wavelength dependence of reversible photodegradation of disperse orange 11 dye-doped PMMA thin films

2015

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Using transmittance imaging microscopy we measure the wavelength dependence of reversible photodegradation in disperse orange 11 (DO11) dye-doped (poly)methyl-methacrylate (PMMA). The reversible and irreversible inverse quantum efficiencies (IQEs) are found to be constant over the spectral region investigated, with the average reversible IQE being Bα = 8.70(±0.38) × 10 5 and the average irreversible IQE being Bǫ = 1.396(±0.031) × 10 8 . The large difference between the IQEs is hypothesized to be due to the reversible decay channel being a direct decay mechanism of the dye, while the irreversible decay channel is an indirect mechanism, with the dye first absorbing light, then heating the surrounding environment causing polymer chain scission and cross linking. Additionally, the DO11/PMMA's irreversible IQE is found to be among the largest of those reported for organic dyes, implying that the system is highly photostable. We also find that the recovery rate is independent of wavelength, with a value of β = 3.88(±0.47) × 10 −3 min −1 . These results are consistent with the correlated chromophore domain model of reversible photodegradation.

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Section: Resultsmentioning

confidence: 99%

Wavelength dependence of reversible photodegradation of disperse orange 11 dye-doped PMMA thin films

2015

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“…We also conclude that during conditioning leftover monomer undergoes polymerization due to photothermal heating leading to increases in the peaks associated with polyurethane [65]. As the neat polymer is transparent at the pump wavelength, the most likely degradation pathway is via energy transfer be- tween the dye and polymer [56,[69][70][71] with thermalization [72,73] being the largest effect.…”

Section: Ftir Measurementsmentioning

confidence: 85%

“…Given the irreversible changes in the RL linewidth and peak location, as well as the irreversible changes in the IR-VIS absorbance, we can conclude that the irreversibly damaged species is primarily related to Norrish type I photocleavage and photooxidation of the polymer host, with additional changes due to the photoinduced formation of R6G dimers and trimers. Since the polymer host is transparent at the pump wavelength, its damage is most likely mediated by energy transfer between the dye and polymer [56,[69][70][71][72][73][74]. To further refine the identification of the irreversible damaged species we plan on performing dose-dependent studies using imaging [75], absorbance [42,76,77], interferometry [78,79] and FTIR.…”

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confidence: 99%

Photodegradation and self-healing in a Rhodamine 6G dye and $$\hbox {Y}_{2}\hbox {O}_{3}$$ nanoparticle-doped polyurethane random laser

2015

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One of the fundamental difficulties in implementing organic dyes in random lasers is irreversible photodegradation of the dye molecules, leading to loss of performance and the need to replace the dye. We report the observation of self-healing after photodegradation in a Rhodamine 6G dye and nanoparticle doped polyurethane random laser. During irradiation we observe two distinct temporal regions in which the random lasing (RL) emission first increases in intensity and redshifts, followed by further redshifting, spectral broadening, and decay in the emission intensity. After irradiation the emission intensity is found to recover back to its peak value, while still being broadened and redshifted, which leads to the result of an enhancement of the spectrally integrated intensity. We also perform IR-VIS absorbance measurements and find that the results suggest that during irradiation some of the dye molecules form dimers and trimers and that the polymer host is irreversibly damaged by photooxidation and Norrish type I photocleavage.

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“…2-(2′-Hydroxyphenyl)-benzimidazole (H 2 hbi) and its derivatives are long known ligands with various uses (Scheme ). They have been studied as laser dyes, while the coordination chemistry of H 2 hbi has been previously studied in conjunction with the electro- and photoluminescence properties of its complexes. In our area of interest, the ligand offers the simultaneous presence of one imidazole nitrogen donor, as well as one phenol oxygen donor.…”

Section: Introductionmentioning

confidence: 99%