Laser dye stability. Part 5

Fletcher, A. N.; Bliss, D. E.

doi:10.1007/bf00885124

Cited by 130 publications

(80 citation statements)

References 11 publications

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“…Because of this large difference in the dipole moments, these coumarin dyes show very large solvent-polarity-dependent Stokes shifts. Most of the coumarin molecules also have relatively high fluorescence quantum yields [22][23][24][25][26]. Because of these properties, the 7-aminocoumarin dyes have been used extensively as fluorescence probes to study different processes in the condensed phase, namely solvatochromic studies [27,28], to determine the microenvironment of different types of microheterogeneous medium [29][30][31], solvent relaxation studies [29][30][31], etc.…”

Section: Introductionmentioning

confidence: 99%

Effect of H‐Bonding on the Photophysical Behaviour of Coumarin Dyes

Nath

Kumbhakar

Pal

2010

Hydrogen Bonding and Transfer in the Excited State

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The Lippert-Mataga [1, 2] expression is the most generalized equation used to describe the solvent-dependent spectral shifts of many chromophoric molecules. The Lippert-Mataga equation considers mainly two characteristic factors of the solvents, namely the refractive index (n) and the static dielectric constant («). According to the Lippert-Mataga representation, a chromophore should show bathochromic shifts in the absorption and emission spectra and a linear increase in the Stokes shift with increasing solvent polarity parameter, Df (Df ¼ [(« À 1)/(2« þ 1) À (n 2 À 1)/(2n 2 þ 1)]). This general solvent effect predicted by the Lippert-Mataga equation is expected to be independent of the chemical properties of the chromophore and the solvent used.Besides its extensive use, the Lippert-Mataga equation fails to predict the spectral properties of several chromophores in different solvent environments [3][4][5][6][7][8]. This failure is mainly due to the presence of specific interactions of the chromophores with their surrounding solvent molecules. These specific interactions can arise owing to different mechanisms such as preferential solvation [9-11], charge transfer interaction [12], hydrogen bonding interaction [13][14][15], etc. The changes in spectral characteristics experienced by a chromophore owing to its specific interaction with the surrounding solvent can sometimes be much more prominent than those expected from the general solvent effect as predicted by the Lippert-Mataga equation. For example, N-phenyl-2-aminonaphthalene shows a structured emission spectrum in a non-polar solvent such as cyclohexane. However, the structures in the emission spectrum disappear, and the emission maxima undergo a large shift on the addition of just $0.2% of ethanol in the cyclohexane solution of the dye [16]. Further, it is seen that the spectrum of N-phenyl-2-aminonaphthalene in 3% ethanolic solution is only marginally different from that observed in the neat ethanol solution. Such a small amount of ethanol in

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Section: Introductionmentioning

confidence: 99%

Effect of H‐Bonding on the Photophysical Behaviour of Coumarin Dyes

Nath

Kumbhakar

Pal

2010

Hydrogen Bonding and Transfer in the Excited State

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“…Natural and synthetic coumarins continue to engage interest for their wide ranging applications e.g., in the areas of biological activities [1][2][3][4], laser dyes [5][6][7][8][9][10], fluorescence brighteners [11][12][13][14] and fluorochromophores [15][16][17][18]. Among a class of 3-(heteroaryl) coumarins, a variety of 3-(thiazolyl) coumarins containing a biologically significant heterocycle, thiazole has been synthesized and evaluated as pharmaceutically active agents, fluorescence probes and laser dyes [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

π‐Aryl/heteroaryl conjugated coumarin‐thiazoles: Synthesis, optical spectral and nonlinear optic properties

Mashraqui

Mistry

Sundaram

2006

Journal of Heterocyclic Chem

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A series of -aryl/heteroaryl conjugated coumarin-thiazole systems 8a-f has been synthesized by using Hantzsch thiazole protocol and Wittig olefination as the keys. In the UV-Visible spectra of 8a-f, a main absorption band associated with a dominant -* transition is observed in the region of 338 to 390 nm. Qualitatively, the values of max have been found to correlate satisfactory with the donor/acceptor characteristics of the -attached chromophores. Marked changes observed in the absorption maxima of 8a under acidic conditions are rationalized on the basis of mono-or bis-protonation and modification of the donor/acceptor properties of chromophores undergoing protonation. The emission spectra of 8a-f, obtained by exciting the molecules at their main absorption bands showed emission maxima in the region of 429 nm to 537 nm, with relatively high Stokes shifts of 145 and 171 nm being observed for 8a and 8e, carrying a -donor, dimethylaminophenyl and a -acceptor, p-nitrophenyl chromophore, respectively. Although, the first hyperpolarisability , measured by the hyper-Reileigh scattering (HRS) technique are modest (12 to 23 10 -30 esu), all the compounds exhibited complete transparency in the frequency doubling region at 532 nm and showed high thermal stability (T d from 330 to 365 °C).

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“…Recent publications show that the photostability of laser dyes drastically depends on the pump wavelength [1,2]. A related dependence of the fluorescence quantum yield could be expected, since photochemical and fluorescence quantum yield together with the nonradiative desactivation result unite in most dyes.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Quantum Yields of Laser Dyes Determined by On-Line Computer Evaluation

Gauglitz

Lorch

Oelkrug

1982

Zeitschrift Für Naturforschung A

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The determination of relative fluorescence quantum yields has been improved to better than 3% precision by use of a multichannel analyzer and an on-line desk-top computer. The new combined device for data acquisition and handling as well as a new correction procedure are described. Drifts of excitation source and dark current can be omitted. The yields for laser dyes, emitting at short wavelengths, are presented in dependence on excitation wavelength. These results simplify the optimal choice of the pump conditions of laser dyes, which usually are not photostable.

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Laser dye stability. Part 5

Cited by 130 publications

References 11 publications

Effect of H‐Bonding on the Photophysical Behaviour of Coumarin Dyes

Effect of H‐Bonding on the Photophysical Behaviour of Coumarin Dyes

π‐Aryl/heteroaryl conjugated coumarin‐thiazoles: Synthesis, optical spectral and nonlinear optic properties

Fluorescence Quantum Yields of Laser Dyes Determined by On-Line Computer Evaluation

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