Determination of orientational order parameters of uniaxial films with a commercial 90°-angle fluorescence spectrometer

Damerau, T.; Hennecke, Manfred

doi:10.1063/1.470450

Cited by 17 publications

(14 citation statements)

References 23 publications

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“…11 Hence, polarized fluorescence spectroscopy has been extensively used to study orientational characteristics of anisotropic samples such as liquid crystalline materials [12][13][14][15][16][17][18][19] and stretched polymers. [20][21][22][23][24][25][26] We note also that polarized EL is governed by the same matrices and hence the development of polarized backlights and other devices can benefit directly from the information obtained via polarized fluorescence studies.…”

Section: Introductionmentioning

confidence: 92%

“…The method used for the evaluation of the polarized fluorescence data is described in detail elsewhere. 26 The Absorption spectra were measured with a UV/VIS spectrophotometer ͑Zeiss DMR10͒. The ellipsometric experiments were performed using a Sopra ES4G spectroscopic ellipsometer.…”

Section: Materials and Experimental Techniquesmentioning

confidence: 99%

“…Concerning the later Regardless of an entire description, we mainly need two correction factors G 1 and G 2 for our objective. 26 The difficulty in interpreting the measured polarized fluorescence intensities arises mainly from the fact that the direction of propagation of light in the spectrometer is different from the direction within the sample. This complicates the usual method to determine G 1 and G 2 .…”

Section: Background To Polarized Fluorescence Measurementsmentioning

confidence: 99%

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Polarized fluorescence and orientational order parameters of a liquid-crystalline conjugated polymer

et al. 1999

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We report a study of the orientational order of aligned thin films of the liquid crystalline conjugated polymer poly͑9,9-dioctylfluorene͒. Steady state polarized fluorescence measurements were used to determine the orientational order parameter ͗P 2 ͘ and ͗P 4 ͘. The influence of intermolecular and intramolecular excitation energy transfer on the degree of polarization is discussed. The role of film morphology is also examined by comparison of the results for glassy and crystalline films. ͓S0163-1829͑99͒05525-3͔

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Section: Introductionmentioning

confidence: 92%

Section: Materials and Experimental Techniquesmentioning

confidence: 99%

Section: Background To Polarized Fluorescence Measurementsmentioning

confidence: 99%

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Polarized fluorescence and orientational order parameters of a liquid-crystalline conjugated polymer

et al. 1999

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“…This is in accordance with stretch orientation studies of different OPV derivatives dissolved in polyethylene or polystyrene foils. [24] For a quantitative evaluation of the experiments it is necessary to take the individual sample cross-sections S i (S = thickness width) of the foil for each point of the measurement into account by calculating the applied mean tensile stresses using Equation (1):…”

Section: Fluorescence Anisotropymentioning

confidence: 99%

Fluorophores as Optical Sensors for Local Forces

et al. 2009

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The main aim of this study is to investigate correlations between the impact of an external mechanical force on the molecular framework of fluorophores and the resultant changes in their fluorescence properties. Taking into account previous theoretical studies, we designed a suitable custom-tailored oligoparaphenylenevinylene derivative (OPV5) with a twisted molecular backbone. Thin foils made of PVC doped with 100 nM OPV were prepared. By applying uniaxial force, the foils were stretched and three major optical effects were observed simultaneously. First, the fluorescence anisotropy increased, which indicates a reorientation of the fluorophores within the matrix. Second, the fluorescence lifetime decreased by approximately 2.5% (25 ps). Finally, we observed an increase in the emission energy of about 0.2% (corresponding to a blue-shift of 1.2 nm). In addition, analogous measurements with Rhodamine 123 as an inert reference dye showed only minor effects, which can be attributed to matrix effects due to refractive index changes. To relate the observed spectroscopic changes to the underlying changes in molecular properties, quantum-chemical calculations were also performed. Semiempirical methods had to be used because of the size of the OPV5 chromophore. Two conformers of OPV5 (C(2) and C(i) symmetry) were considered and both gave very similar results. Both the observed blue-shift of fluorescence and the reduced lifetime of OPV5 under tensile stress are consistent with the results of the semiempirical calculations. Our study proves the feasibility of fluorescence-based local force probes for polymers under tension. Improved optical sensors of this type should in principle be able to monitor local mechanical stress in transparent samples down to the single-molecule level, which harbors promising applications in polymer science and nanotechnology.

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“…[19] This is somewhat surprising since an analysis of the fluorescence anisotropy evolution can yield the second and, although not always, the fourth rank order parameter and these are of particular importance for the structural characterization of the material in a more reliable way than that offered by the often used time independent, steady state technique. [3,17,[20][21][22][23][24][25] Moreover the time resolved approach can offer important information on the rotational mobility or microfluidity of the probe.…”

Section: Introductionmentioning

confidence: 99%

Order and Mobility of the Fluorescent Probe 1,6-Diphenylhexatriene in a Polyester Liquid Crystal Polymer

Arcioni

Bacchiocchi

D’Elia³

et al. 2001

Molecular Crystals and Liquid Crystals Science and Technology.

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We have employed time dependent fluorescence polarization to investigate a main chain semiflexible polyester type liquid crystal polymer using the fluorescent probe 1,6-diphenylhexatriene. We have obtained the second rank order parameter and the tumbling reorientational time of the probe as a function of temperature. We have found the polymer disordering to occur in a temperature range very close to the nematic-isotropic transition.

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Determination of orientational order parameters of uniaxial films with a commercial 90°-angle fluorescence spectrometer

Abstract: The orientational order parameters of a dendritic liquid crystal organo-siloxane tetrapode oligomer, determined using polarized infrared spectroscopy

Cited by 17 publications

References 23 publications

Polarized fluorescence and orientational order parameters of a liquid-crystalline conjugated polymer

Polarized fluorescence and orientational order parameters of a liquid-crystalline conjugated polymer

Fluorophores as Optical Sensors for Local Forces

Order and Mobility of the Fluorescent Probe 1,6-Diphenylhexatriene in a Polyester Liquid Crystal Polymer

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