The triplet state of 1,1′-diethyl-2,2′-cyanine iodide in neat and mixed crystals

Marchetti, Alfred P.; Scozzafava, M.

doi:10.1063/1.433353

Cited by 5 publications

(5 citation statements)

References 14 publications

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“…Additionally, the measured phosphorescence spectrum of larger PIC crystals is known to be peaked at 630 nm. 12 Finally, it is unclear why either impurities or phosphorescence would show the localization behavior observed here. Rather it is more likely that the crystals slowly form defects through the loss of solvent, and these defects appear in various concentrations throughout the sample.…”

Section: Resultsmentioning

confidence: 92%

“…Phosphorescence is also an unlikely explanation, since the 700 nm emission has a radiative rate that is inconsistent with phosphorescence. Additionally, the measured phosphorescence spectrum of larger PIC crystals is known to be peaked at 630 nm …”

Section: Resultsmentioning

confidence: 99%

“…PIC crystals have previously been studied by conventional means because the crystals of PIC have long stood as a benchmark on which to base models of aggregate structure. [11][12][13][14]25 Previous studies of PIC crystals were typically of large well-defined single crystals that were amenable to X-ray work and reflection studies. The crystals were found to crystallize in the monoclinic space group P 21/a with four molecules of dye per unit cell and no solvent included in the crystal structure.…”

Section: Introductionmentioning

confidence: 99%

“…With its propensity toward aggregation, PIC can be found in many molecular arrangements each with its own unique spectral properties. These differing spectral properties have sparked numerous studies of the varied forms that include the monomeric species, crystals, − dimers, solution-phase aggregates, , 2-D aggregates on silver halides, and in dye/polymer aggregates. ,,− Along with its interesting optical characteristics, the dye is also of great industrial importance and finds widespread application in imaging science as a photographic sensitizer.…”

Section: Introductionmentioning

confidence: 99%

“…Here, we present results of the near-field microscopy/spectroscopy studies of small PIC crystals. PIC crystals have previously been studied by conventional means because the crystals of PIC have long stood as a benchmark on which to base models of aggregate structure. − , Previous studies of PIC crystals were typically of large well-defined single crystals that were amenable to X-ray work and reflection studies. The crystals were found to crystallize in the monoclinic space group P 21/ a with four molecules of dye per unit cell and no solvent included in the crystal structure. , However, in one study “thin crystals” of a different crystalline structure were observed that were proposed to incorporate solvent. , Similarities in size, preparation, and spectral character indicate the crystals in the present NSOM study are most likely identical to the thin crystals in the previous study.…”

Section: Introductionmentioning

confidence: 99%

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Spatially Resolved Spectral Inhomogeneities in Small Molecular Crystals Studied by Near-Field Scanning Optical Microscopy

et al. 1996

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Near-field scanning optical microscopy (NSOM) has been employed to spatially resolve mesoscopic inhomogeneous spectral features in small crystals of the dye 1,1′-diethyl-2,2′-cyanine iodide (PIC). The small crystals show strong absorption perpendicular to their long direction of growth and no absorption in either of the two other orthogonal directions. This polarization is seen uniformly throughout the crystals. Topographic images reveal the crystals are composed of platelike single-crystalline domains separated by defect planes. The individual plates share a common orientation that gives the crystal its single polarization. Despite the uniformity of the polarization throughout the crystal, dramatic spatial variation is seen in the fluorescence spectrum. NSOM images and spectra reveal two distinct emission sources in the crystals. Strong self-absorption is seen in the PIC emission, and red-shifted fluorescence is also observed from lower energy emissive traps. These traps are seen to form in distinct regions within the crystal and become more abundant over long periods of time (months). In addition to the dual wavelength emission from the crystals, the fluorescence spectra taken in the near field are shown to be significantly narrower than those taken in the far field. The near-field spectra reveal that approximately 100 cm -1 of the broadening observed in the far-field fluorescence spectra can be attributed to inhomogeneous broadening due to crystal features which exist over distances as large as 100 nm. These results may be general to small molecular crystals but would have been nearly impossible to detect with any method other than NSOM.

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Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatially Resolved Spectral Inhomogeneities in Small Molecular Crystals Studied by Near-Field Scanning Optical Microscopy

et al. 1996

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Polymethine Dyes

Kachkovski¹

2000

Kirk-Othmer Encyclopedia of Chemical Technology

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Polymethine dyes (PMDs) encompass a large class of linear, conjugated, colored systems in the general form of \documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{(}{\rm{G^{\pm }_{1}}}{\relbar \kern-5pt{\relbar}\kern-7pt{\relbar}}{\hskip-7pt}{(}{\hskip0.167em}{\rm{CH}}{\raise1pt\hbox{$\Relbar \kern-4pt{\Relbar}$}}{\rm{CH}}{\relbar \kern-5pt{\relbar}\kern-7pt{\relbar}}{\hskip-9pt}{)}_{n}{\rm{CH}}{\raise1pt\hbox{$\Relbar \kern-4pt{\Relbar}$}}{\rm{G_{2}}}{)}{\rm{X^{\mp }}}}$\end{document} , where G 1 and G 2 are end groups. In the ground and first excited states, the carbon–carbon bonds within the polymethine chain are practically equalized and alternating positive and negative charges appear at the carbon atoms. The main topological factors affecting PMD color are chain length, nature of end groups, electron shell occupation, asymmetry, chain branching, and chromophore interaction. Polymethines are highly reactive compounds. Their photochemistry, protonation, and reactions with electrophiles, nucleophiles, reactants, and radicals are surveyed. The most important reason for the extremely wide technical uses of PMD is their low electron‐transition energies. Attention is paid to the application of polymethines as spectral sensitizers, laser dyes, and polymerization initiators. Synthetic methods for obtaining PMDs with various chain lengths, end groups, and chromophore modification are summarized, along with molecular designs and economic aspects.

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ChemInform Abstract: THE TRIPLET STATE OF 1,1′‐DIETHYL‐2,2′‐CYANINE IODIDE IN NEAT AND MIXED CRYSTALS

Marchetti¹,

Scozzafava²

1976

Chemischer Informationsdienst

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The triplet state of 1,1′-diethyl-2,2′-cyanine iodide in neat and mixed crystals

Cited by 5 publications

References 14 publications

Spatially Resolved Spectral Inhomogeneities in Small Molecular Crystals Studied by Near-Field Scanning Optical Microscopy

Spatially Resolved Spectral Inhomogeneities in Small Molecular Crystals Studied by Near-Field Scanning Optical Microscopy

Polymethine Dyes

ChemInform Abstract: THE TRIPLET STATE OF 1,1′‐DIETHYL‐2,2′‐CYANINE IODIDE IN NEAT AND MIXED CRYSTALS

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