Oriental behaviour of some homologues of 4-n-pentyl-phenylthio-4′-n-alkoxybenzoate doped with dichroic dye

2008 ◽  
Vol 16 (3) ◽  
Author(s):  
D. Bauman ◽  
A. Zięba ◽  
E. Mykowska
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Polarized Light ◽  
Emission Spectra ◽  
Smectic C ◽  
Fluorescence Measurements ◽  
Dichroic Dye ◽  
Linearly Polarized

AbstractThe long-range orientational order of three members of 4-n-pentylphenylthio-4′-n-alkoxybenzoate $$ (\bar nS5) $$ series doped with a dichroic dye was studied by means of electronic absorption and fluorescence measurements. The order parameters <P2> and <P4> as well as the orientational distribution function were determined on the basis of absorption and emission spectra of linearly polarized light recorded as a function of temperature in the nematic, smectic A, and smectic C phases. An influence of the dye molecular structure on the orientational order of the dye/liquid crystal mixture was observed. Moreover, the dependence of the order parameter values on the length of the alkoxy chain in liquid crystal molecules was found. It was shown that the order parameter <P4>, obtained from fluorescence measurements, can be helpful in recognizing the second-order or weakly first-order transitions between various liquid crystalline phases.

Orientational Behaviour of some Novel Fluoro-Substituted Liquid Crystals as Studied by Optical Spectroscopy Methods

2011 ◽  
Vol 66 (3-4) ◽  
pp. 251-258 ◽  
Author(s):  
Anna Modlínska ◽  
Danuta Bauman ◽  
Jan Jadżyn ◽  
Roman Dąbrowski
Keyword(s):  
Liquid Crystals ◽  
Optical Spectroscopy ◽  
Orientational Order ◽  
Polarized Light ◽  
Emission Spectra ◽  
Dielectric Anisotropy ◽  
Dichroic Dye ◽  
Linearly Polarized ◽  
Orientational Distribution ◽  
Orientational Distribution Function

The long-range orientational order of eight newly synthesized fluoro-substituted liquid crystals, two with a positive dielectric anisotropy and six with a negative dielectric anisotropy, was studied by means of the optical spectroscopy methods: electronic absorption and fluorescence. The liquid crystals were doped with small amount of the fluorescent dichroic dye. The absorption and emission spectra of linearly polarized light were recorded as a function of temperature in the whole range of the mesophase. The results obtained allow to determine the order parameters〈P2 and〈P4〉as well as the orientational distribution function. An importance of the molecular structure of the liquid crystal on the orientational order was ascertained and discussed.

Bragg Reflection of Linearly Polarized Light in a Chiral Smectic C Liquid Crystal for Oblique Incidence

1984 ◽  
Vol 102 (6-7) ◽  
pp. 187-192 ◽  
Author(s):  
S. N. Aronishidze ◽  
G. S. Chilaya ◽  
M. N. Kushnirenko ◽  
S. M. Osadchii
Keyword(s):  
Liquid Crystal ◽  
Oblique Incidence ◽  
Bragg Reflection ◽  
Polarized Light ◽  
Smectic C ◽  
Linearly Polarized

scholarly journals DNA Origami Nano-Sheets and Nano-Rods Alter the Orientational Order in a Lyotropic Chromonic Liquid Crystal

Nanomaterials ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1695
Author(s):  
Bingru Zhang ◽  
Kevin Martens ◽  
Luisa Kneer ◽  
Timon Funck ◽  
Linh Nguyen ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Orientational Order ◽  
Dna Origami ◽  
Nano Particles ◽  
Width Ratio ◽  
Disodium Cromoglycate ◽  
Orientational Order Parameter ◽  
Nano Rods

Rod-like and sheet-like nano-particles made of desoxyribonucleic acid (DNA) fabricated by the DNA origami method (base sequence-controlled self-organized folding of DNA) are dispersed in a lyotropic chromonic liquid crystal made of an aqueous solution of disodium cromoglycate. The respective liquid crystalline nanodispersions are doped with a dichroic fluorescent dye and their orientational order parameter is studied by means of polarized fluorescence spectroscopy. The presence of the nano-particles is found to slightly reduce the orientational order parameter of the nematic mesophase. Nano-rods with a large length/width ratio tend to preserve the orientational order, while more compact stiff nano-rods and especially nano-sheets reduce the order parameter to a larger extent. In spite of the difference between the sizes of the DNA nano-particles and the rod-like columnar aggregates forming the liquid crystal, a similarity between the shapes of the former and the latter seems to be better compatible with the orientational order of the liquid crystal.

Polarized Fluorescence from Vitrified Liquid Crystalline Films

1996 ◽  
Vol 425 ◽  
Author(s):  
Brooke M. Conger ◽  
H. Shi ◽  
S. H. Chen ◽  
T. Tsutsui
Keyword(s):  
Liquid Crystal ◽  
Linear Polarization ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Emission Spectra ◽  
Polarized Fluorescence ◽  
Circularly Polarized ◽  
Chiral Nematic ◽  
Polarization Factor ◽  
Crystalline Films

AbstractLinearly and circularly polarized photoluminescence (PL) were observed from neat vitrified liquid crystal (LC) films. Electronic properties of the compounds were investigated through measurement of absorption and emission spectra in solution and in film. The nematic film exhibited a polarization factor (linear polarization) of 2.8 at an order parameter of 0.70, whereas the chiral nematic film gave rise to an absolute dissymmetry factor (circular polarization) of 0.27 at an order parameter of 0.54.

scholarly journals Liquid Crystal Ordering in the Hexagonal Phase of Rod-Coil Diblock Copolymers

Polymers ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1262
Author(s):  
Mikhail A. Osipov ◽  
Maxim V. Gorkunov ◽  
Alexander A. Antonov
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Density Functional ◽  
Diblock Copolymers ◽  
Microphase Separation ◽  
Hexagonal Phase ◽  
Orientational Order ◽  
Order Parameters ◽  
Copolymer Composition ◽  
Rigid Rod

Density functional theory of rod-coil diblock copolymers, developed recently by the authors, has been generalised and used to study the liquid crystal ordering and microphase separation effects in the hexagonal, lamellar and nematic phases. The translational order parameters of rod and coil monomers and the orientational order parameters of rod-like fragments of the copolymer chains have been determined numerically by direct minimization of the free energy. The phase diagram has been derived containing the isotropic, the lamellar and the hexagonal phases which is consistent with typical experimental data. The order parameter profiles as functions of temperature and the copolymer composition have also been determined in different anisotropic phases. Finally, the spatial distributions of the density of rigid rod fragments and of the corresponding orientational order parameter in the hexagonal phase have been calculated.

Study of orientational order of some nematogenic compounds by spectroscopy methods using linearly polarized light

2005 ◽  
Vol 744-747 ◽  
pp. 307-313 ◽  
Author(s):  
D. Bauman ◽  
E. Chrzumnicka ◽  
E. Mykowska ◽  
M. Szybowicz ◽  
N. Grzelczak
Keyword(s):  
Orientational Order ◽  
Polarized Light ◽  
Linearly Polarized

Thermoassisted Photorecording in Chiral Smectic Azodye Copolymers

2001 ◽  
Vol 709 ◽  
Author(s):  
Mikhail V. Kozlovsky ◽  
Wolfgang Haase ◽  
Matthias Rehahn
Keyword(s):  
Order Parameter ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Holographic Gratings ◽  
Copolymer Films ◽  
Shock Heating ◽  
Mesophase Formation ◽  
Photoinduced Birefringence ◽  
High Diffraction Efficiency ◽  
High Diffraction

ABSTRACTIllumination of photochromic liquid-crystalline (PCLC) copolymer films with polarized light during the mesophase formation has been studied. Both thick pressed and thin spin-coated, the films show prominent increase in photoinduced orientation, as compared with conventional isothermal photorecording. Two methods of the thermoassisted recording have been suggested, one of those with simultaneous cooling of the film and another one after a shock heating and quenching. The photoinduced birefringence, Δnind, and the order parameter of photochromic groups, Sazo, have been measured. The thermally assisted recording produces holographic gratings with high diffraction efficiency, η, up to 20-30%.

Studies Of Orientational Order Of Some Nematogens By Means Of Raman Scattering Spectroscopy

2004 ◽  
Vol 59 (7-8) ◽  
pp. 510-516 ◽  
Author(s):  
Ewa Chrzumnicka ◽  
Mirosław Szybowicz ◽  
Danuta Bauman
Keyword(s):  
Liquid Crystals ◽  
Raman Scattering ◽  
Orientational Order ◽  
Polarized Light ◽  
Molecular Structures ◽  
Raman Scattering Spectroscopy ◽  
Linearly Polarized ◽  
Scattering Spectra ◽  
Raman Scattering Spectra ◽  
Molecular Distribution Function

The orientational behaviour of some liquid crystals with various molecular structures was studied by means of the Raman scattering depolarization method. The Raman scattering spectra of linearly polarized light were recorded as a function of temperature in the nematic phase. On the basis of these spectra the order parameters 〈P2〉 and 〈P4〉 as well as the molecular distribution function were determined. The obtained data were compared with those estimated on the basis of polarized light absorption and emission measurements. The influence of the molecular structure on the orientational order of liquid crystals was discussed.

Deuteron NMR investigation on orientational order parameter in polymer dispersed liquid crystal elastomers

2020 ◽  
Vol 22 (40) ◽  
pp. 23064-23072
Author(s):  
Andraž Rešetič ◽  
Jerneja Milavec ◽  
Valentina Domenici ◽  
Blaž Zupančič ◽  
Alexej Bubnov ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Order Parameter ◽  
Orientational Order ◽  
Orientational Order Parameter ◽  
Liquid Crystal Elastomer ◽  
H Nmr ◽  
Polymer Dispersed Liquid Crystal ◽  
Polymer Dispersed ◽  
Liquid Crystal Elastomers ◽  
Magnetically Aligned

Orientational order parameter of magnetically aligned liquid crystal elastomer particles suspended in a cured silicone matrix is assessed using 2H-NMR spectroscopy. Obtained results correspond well with the composite's thermomechanical response.

scholarly journals Mesomorphism behaviour and photoluminescent properties of new asymmetrical 1,2-di(4-alkoxybenzylidene)hydrazines

2019 ◽  
Vol 43 (1-2) ◽  
pp. 67-77 ◽  
Author(s):  
Adil A Awad ◽  
Al-Ameen Bariz OmarAli ◽  
Ahmed Jasim M Al-Karawi ◽  
Zyad Hussein J Al-Qaisi ◽  
Samer Ghanim Majeed
Keyword(s):  
Differential Scanning Calorimetry ◽  
Liquid Crystal ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Luminescent Properties ◽  
Scanning Calorimetry ◽  
Crystalline Materials ◽  
X Ray ◽  
Step Procedure ◽  
Liquid Crystalline Materials

{1-[4-( n-Alkoxy)]-2-(4’-decyloxy)benzylidene}hydrazines ( n-alkoxy = O(CH2) nH, n = 1–9, 12, 16 or 18), an asymmetrical series of 1,2-disubstituted hydrazines, were prepared in a simple two-step procedure as a part of our continuing work in evaluating hydrophobic azine compounds as photoluminescent liquid crystalline materials. The compounds were characterized spectroscopically and their liquid crystalline behaviour and luminescent properties were evaluated using polarized light optical microscopy, differential scanning calorimetry and X-ray powder diffraction techniques. The studies revealed that all of these compounds are liquid crystalline materials exhibiting photoluminescent properties in the crystalline and liquid crystal states.

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