Triplet state of rhodamine dyes and its role in production of intermediates

Korobov, V. E.; Shubin, Vladimir; Чибисов, А. К.

doi:10.1016/0009-2614(77)80074-2

Cited by 58 publications

(44 citation statements)

References 4 publications

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“…One is to examine the alternative de-excitation processes: intersystem crossing (ISC) to a triplet state and internal conversion back to the ground electronic state. The former is low in solution, estimated at less than 0.01 yield [88]. Kappes and coworkers have recently reported that gaseous rhodamine 6G cations have a long-lived triplet state, however they did not suggest an ISC yield higher than the solution-phase value.…”

Section: Discussionmentioning

confidence: 95%

Fluorescence lifetimes of rhodamine dyes in vacuo

Nagy

Talbot

Czar

et al. 2012

Journal of Photochemistry and Photobiology A: Chemistry

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Section: Discussionmentioning

confidence: 95%

Fluorescence lifetimes of rhodamine dyes in vacuo

Nagy

Talbot

Czar

et al. 2012

Journal of Photochemistry and Photobiology A: Chemistry

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“…If there is any triplet-state absorption of the excitation laser light, the thermal energy coming out by the relaxation from the higher excited triplet state should also contribute to the thermal lens signal. The triplet states of Rhodamine B have been studied in aqueous and alcohol solutions by means of flash photolysis by Korobov et al 13 Their studies showed negligible, or no, T-T absorption for the wavelengths 514 nm and 532 nm, whereas the T-T absorption spectra overlaps the singlet fluorescence. Thus the influence of T-T absorption at the pump wavelengths used in our studies could be safely neglected.…”

Section: Resultsmentioning

confidence: 99%

“…It is noteworthy that under the conditions of our experiments with cw excitation of dye solutions the lifetime of the triplet state is much less than the duration of the modulated cw laser excitation. In this case, the concentration of triplet molecules is associated with the concentration of singlet excited molecules (S*) by the expression 13 of the triplet and singlet excited states, respectively, and φT is the quantum yield of the intersystem crossing. Hence, a slowly rising pump light pulse would transfer most of the molecules to the triplet state.…”

Section: Resultsmentioning

confidence: 99%

Effect of the Excitation Source on the Quantum-Yield Measurements of Rhodamine B Laser Dye Studied Using Thermal-Lens Technique

Bindhu

Harilal

2001

ANAL. SCI.

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Photothermal spectroscopy is a group of highly sensitive methods used to measure the optical absorption and thermal characteristics of a sample. [1][2][3] The basis of photothermal spectroscopy is a photo-induced change in the thermal state of the sample. The advantage of the photothermal technique is that it can be used to investigate the optical properties of materials that are unsuitable with traditional spectrophotometry. In fact, both thermal and fluorescence spectroscopy are complementary: thermal spectroscopy measures the photon energy, which has been converted to heat, while fluorescence spectroscopy observes re-emitted photons. When a medium is illuminated with laser radiation, some of the incident energy is absorbed by the molecules in the ground state, and becoming excited to higher energy states in the process. Following the absorption of a photon, any excess energy of a molecule can be dissipated in many ways.When the decay involves a radiationless process, localized temperature increases are produced, leading to heating of the sample. The thermal fluctuations produced by nonradiative relaxations may be probed optically, since the resulting density change also produces a change in the refractive index. Specifically, the transient refractive index forms an effective lens, which diverges the light as it passes through a sample. This phenomenon is called thermal lensing, and provides a nice example of laser spectroscopy.The fluorescence quantum yield (Qf), one of the key photophysical quantities, is a measure of the rate of nonradiative transitions that compete with the emission of light. The absolute values of Qf of organic laser dyes are practically important, because they are necessary to calculate thresholds for laser action. 4 Measurements based on photothermal effects are capable of giving absolute fluorescence yields of highly fluorescent solutions with high accuracy and reproducibility. In order to evaluate the absolute fluorescence efficiency, we must consider both radiative and nonradiative processes taking place in the medium. Because the contribution from nonradiative processes is not directly measurable using the traditional optical detection methods, thermo-optic techniques, such as photoacoustic (PA) and thermal lens (TL) spectroscopic methods, have been adopted for this purpose. 5,6 In this present study, the sensitivity and viability of photothermal lensing technique were exploited to determine the absolute fluorescence quantum yield of Rhodamine B (RhB) laser dye. The Qf values were found to be strongly influenced by different parameters, like environmental effects, concentration of the dye solution and type of excitation (cw or pulsed) source used for the thermal lens measurements. ExperimentalDetails of the experimental set up used for the cw thermal lens 7 and pulsed thermal lens 8 are given elsewhere. For a transient thermal lens, 532 nm radiation from a frequency-doubled Qswitched Nd:YAG laser (FWHM 9 ns) was used as the pump source to generate a thermal lens in the medium. A 632...

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“…The formation of Cu(I) was assisted more efficiently by EY where the best yield for 3a was observed. The absence of 3a was noticed when R6G was used (Table 1, entry 9), attributed to two possible reasons: (i) inability to form Cu(I) from Cu(II) due to the negligible intersystem crossing quantum yield (F ISC ¼ 0.002), 26 or (ii) absence of free carboxyl groups which could act as ligands of the catalytically active cations. 27 Then, other Cu(II) sources such as Cu(NO 3 ) 2 , Cu(OAc) 2 , and CuCl 2 were used (Table 1, entries 11-13 respectively).…”

Section: Resultsmentioning

confidence: 99%

A straightforward and sustainable synthesis of 1,4-disubstituted 1,2,3-triazoles via visible-light-promoted copper-catalyzed azide–alkyne cycloaddition (CuAAC)

et al. 2017

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A simple and green synthesis of 1,4-disubstituted 1,2,3-triazoles through the effective reduction of copper(II) assisted by organic dyes and promoted by visible light was developed. This reaction was performed under very mild conditions, using water as solvent, under a non-inert atmosphere, with low catalyst precursor loading, and in the absence of any additive. Copper and solvent recycling was successfully achieved at least three times without loss of efficiency. In addition, a safer one-step one-pot procedure was designed with very good yield.

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Triplet state of rhodamine dyes and its role in production of intermediates

Cited by 58 publications

References 4 publications

Fluorescence lifetimes of rhodamine dyes in vacuo

Fluorescence lifetimes of rhodamine dyes in vacuo

Effect of the Excitation Source on the Quantum-Yield Measurements of Rhodamine B Laser Dye Studied Using Thermal-Lens Technique

A straightforward and sustainable synthesis of 1,4-disubstituted 1,2,3-triazoles via visible-light-promoted copper-catalyzed azide–alkyne cycloaddition (CuAAC)

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