Spectral features of polarized light absorption and anisotropy of a local field in the D ho discotic

Aver'yanov, E. M.; Gunyakov, V. A.; Korets, A. Ya.; Akopova, О. B.

doi:10.1134/1.626896

Cited by 2 publications

(5 citation statements)

References 14 publications

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“…The parameters s max and Dn max correspond to a perfectly ordered LC sample (S ¼ 1). Previously the parameter s max ¼ 0.18 AE 0.01 and the value s ¼ 0.16 AE 0.01 at DT ¼ 22.3 C for H7T were obtained by methods based on self-consistent measurements of the ordering and local field parameters [4]. To determine the unknown parameter Dn max we used the value Dn measured at the above temperature.…”

Section: Resultsmentioning

confidence: 99%

“…The preparation of the sample was same as in [4]. The spectra of the absorption bands of the H7T were obtained by Fourier transform infrared absorption (FTIR) spectrometer Vector-22 with multiscanning and subsequent averaging.…”

Section: Methodsmentioning

confidence: 99%

“…The study of dichroism of polarized IR bands corresponding to the normal molecular modes allows us to determine the order parameters of the molecular fragments [2], as well as the parameters of the anisotropic local field of a light wave acting on these fragments [3]. Besides, the local field effects cause the mixing of molecular excitations for adjacent absorption bands and have to modify spectral methods for experimental determination of these parameters in discotic LC's [4]. At the same time, it would be interesting to check validity of the modeling approaches for determination of the anisotropic local field in the discotic phases.…”

Section: Introductionmentioning

confidence: 99%

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Orientational Ordering and Polarizability of Molecules in the Columnar Phase of Discotic Liquid Crystal

Gunyakov

Shibli

2004

Molecular Crystals and Liquid Crystals

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The structural and molecular-optical properties of the columnar discotic liquid crystal 2,3,6,7,10,11-hexaheptyloxytriphenylene were studied by using of refractometric and infrared (IR) measurements. Temperature dependence of the orientational order parameter S with allowance for the anisotropy of the local field of a light wave and mixing of molecular excitations was evaluated for C-C aromatic stretching band. The local field parameters have been evaluated within approximation of the effective spheroidal Lorentz cavity model. The anisotropy c a and the mean value c of the molecular polarizability of triphenylene were investigated for several wavelengths. The experimentally observed changes of molecular-optical properties in columnar phase seem to be affected by the induction mechanism of the variety of the molecular polarizability with increasing of S, proposed previously for calamitic liquid crystals. Furthermore, these properties are not related to the effects of aliphatic tails disordering.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Orientational Ordering and Polarizability of Molecules in the Columnar Phase of Discotic Liquid Crystal

Gunyakov

Shibli

2004

Molecular Crystals and Liquid Crystals

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“…S 1 with l ¼ 358 nm and S o ! At the same time, the significant alteration of the electron absorption is possible due to local-field effects in the region of the dense spectrum [9]. S 3 and S o !…”

Section: Resultsmentioning

confidence: 99%

“…The electronic transitions of the disc-like molecules are polarized within the aromatic plane of the rigid molecular core [10], as is the C-C aromatic stretching vibration previously used in [9] for the measurement of the orientational order parameter S in the LC under consideration. The parameter L ?…”

Section: Resultsmentioning

confidence: 99%

Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

Gunyakov

Shibli

2003

Molecular Crystals and Liquid Crystals

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The changes of the electronic structure of molecules in the columnar discotic liquid crystal 2,3,6,7,10,11-hexaheptyloxytriphenylene were studied by using the polarized electronic absorption measurements. The detailed analysis of the spectral data showed that a mixing of electronic excitations is present in discotics and that it affects the measured values of the optical density and the oscillator strength of the electronic absorption bands. The changes in the oscillator strength of the long-wavelength electronic transition and the conformation of the aromatic molecular cores have been discovered experimentally upon the isotropic -columnar phase transition.

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Spectral features of polarized light absorption and anisotropy of a local field in the D ho discotic

Cited by 2 publications

References 14 publications

Orientational Ordering and Polarizability of Molecules in the Columnar Phase of Discotic Liquid Crystal

Orientational Ordering and Polarizability of Molecules in the Columnar Phase of Discotic Liquid Crystal

Conformation and Electronic Structure Studies of Molecules at the Col HO - I Phase Transition in Columnar Discotic Liquid Crystal

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