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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Mean polarizability of molecules and anisotropy of the Lorentz tensor upon a nematic-smectic a phase transition: Their behavior in a homologous series
Место публикации : Russ. J. Phys. Chem. A: MAIK Nauka-Interperiodica / Springer, 2012. - Vol. 86, Is. 5. - P.720-728. - ISSN 0036-0244, DOI 10.1134/S0036024412050044
Примечания : Cited References: 37
Предметные рубрики: CHOLESTERIC LIQUID-CRYSTALS
REFRACTIVE-INDEX DATA
A PHASE
MESOMORPHIC PROPERTIES
ORIENTATIONAL ORDER
OPTICAL ANISOTROPY
LOCAL-FIELD
POLYMORPHISM
TEMPERATURE
A-monotone
Alkyl chain
Experimental values
Homologous series
Homologues
Limiting values
Lorentz
Mesophases
Molecular core
Molecular polarizabilities
Nematic
Orientational order parameters
Polarizabilities
Polarizability density
Quadratic dependence
A-monotone
Smectic
Smectic phase
Smectic phasis
Smectic-A phasis
Ключевые слова (''Своб.индексиров.''): molecular polarizability--anisotropy--phase transition--nematic--smectic--homologues
Аннотация: Experimental values of the mean polarizability of molecules, (gamma) over bar, and components of the Lorentz tensor, L-j, in the nematic and smectic A phases are obtained for a homologous series of n-alkyl-p-(4-ethoxybenzylideneamino)-alpha-methylcinnamates. Dependences of the (gamma) over bar and L-j values on the mesophase temperature, the orientational order parameter S of molecules, and the number n in the homologous series are revealed. The quadratic dependence of (gamma) over bar (S) in the nematic and smectic phases is established that is invariant with respect to the nematic-smectic A transition. Polarizability densities of the molecular core and the alkyl chain are found from the monotone decreasing dependence (gamma) over bar (n)/v (where v is volume per one molecule) in the smectic phase. The presence (or absence) of the odd-even alternation of L-j(n) in the nematic (smectic) phase is shown. A monotone decrease in the Lorentz tensor anisotropy L with an increase in n is revealed in the smectic phase, and limiting values L-j(n - infinity) are determined.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Аверьянов, Евгений Михайлович
Заглавие : Влияние нематического и смектического порядка на поляризуемость молекул жидкого кристалла этил-p-(4-этоксибензилиденамино-)α-метилциннамата
Место публикации : Физ. тверд. тела. - 2013. - Т. 55, вып. 11. - С. 2271-2275. - ISSN 0367-3294
Аннотация: Получены экспериментальные значения компонент тензора поляризуемости gamma молекул жидкого кристалла этил-p-(4-этоксибензилиденамино-)α-метилциннамата в нематической и смектической A фазах. Установлены квадратичные зависимости продольнойϒl и поперечной ϒt компонент, среднего значения Ῡ и анизотропии Δϒ поляризуемости в обеих фазах от параметра ориентационного порядка молекул S при максимально широком интервале изменения S. Фазовый переход нематик-смектик A с непрерывным изменением S проявляется в виде изломов на линейных зависимостях величин Ῡ, Δϒ, ϒl от S[[p]]2[[/p]] и не влияет на зависимость ϒt(S[[p]]2[[/p]]). Дан вывод наблюдаемых зависимостей в рамках теории перехода нематик-смектик A. Выяснены причины различного влияния ориентационного и позиционного упорядочения молекул на параметры поляризуемости.
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3.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Аверьянов, Евгений Михайлович
Заглавие : Изменение поляризуемости молекул МВВА при переходе нематик-изотропная жидкость и физические следствия
Место публикации : Физ. тверд. тела. - 2013. - Т. 55, вып. 10. - С. 2020-2025. - ISSN 0367-3294
Аннотация: Получены экспериментальные значения компонент Lj и ϒj тензоров Лорентца и поляризуемости молекул жидкого кристалла 4-метоксибензилиден-4'-бутиланилина (МВВА) в нематической и изотропной фазах. Установлены квадратичные зависимости среднего значения Ῡ(S) и анизотропии Δϒ(S) поляризуемости в нематической фазе от параметра ориентационного порядка молекул S. В рамках феноменологического подхода дан вывод зависимостей Ῡ(S), Δϒ(S) и объяснены их особенности для МВВА и других известных объектов. Выяснена связь зависимостей Ῡ(S), Δϒ(S) с особенностями фазового перехода нематик-изотропная жидкость.
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Change in the polarizability of MBBA molecules upon the nematic-isotropic liquid transition and physical consequences
Место публикации : Phys. Solid State. - 2013. - Vol. 55, Is. 10. - P.2136-2141. - ISSN 1063-7834, DOI 10.1134/S106378341310003X
Аннотация: The Lorentz tensor components Lj and the polarizability tensor components ?j of 4-methoxyben-zylidene-4?-butylaniline (MBBA) liquid crystal molecules in nematic and isotropic phases have been determined experimentally. The quadratic dependences of the mean value ?(S) and anisotropy ??(S) of the polarizability in the nematic phase on the orientational order parameter S of molecules have been established. Within the phenomenological approach, the dependences ?(S) and ??(S) have been derived, and their features for MBBA and other known objects have been interpreted. The relation of the dependences ?(S) and ??(S) to the features of the nematic-isotropic liquid phase transition has been found. В© 2013 Pleiades Publishing, Ltd.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mironov V. L., Bobrov P. P., Fomin S. V.
Заглавие : Multirelaxation generalized refractive mixing dielectric model of moist soils
Место публикации : IEEE Geosc. Remote Sens. Letters. - 2013. - Vol. 10, Is. 3. - Ст.6332477. - P.603-606. - ISSN 1545-598X, DOI 10.1109/LGRS.2012.2215574
Ключевые слова (''Своб.индексиров.''): bound soil water--dielectric model--dielectric relaxations--dielectric spectra--free soil water--moist soil--bound waters--complex dielectric constant--debye relaxation--dielectric models--dielectric spectra--dipole relaxation--frequency ranges--gigahertz frequencies--gigahertz range--moist soil--soil water--spectroscopic parameters--water molecule--dielectric relaxation--mixing--molecules--soil moisture--geologic models
Аннотация: In this letter, a multirelaxation generalized refractive mixing dielectric model (GRMDM) for moist soil is proposed and substantiated in the frequency range from 0.04 to 26.5 GHz. This model is based on the methodology of a single-relaxation GRMDM which accounts only for the dipole relaxation of water molecules in the gigahertz frequency range. The proposed multirelaxation GRMDM takes into account both the dipole (Debye) and ionic (Maxwell-Wagner) relaxations of soil water molecules. For this purpose, it uses a two-frequency Debye relaxation equation for the dielectric spectra of bound water. The spectroscopic parameters of the multirelaxation GRMDM were derived by fitting the spectra calculated by this model to the respective measured ones. The main advantage of this model is that it predicts the complex dielectric constant of moist soils throughout the megahertz and gigahertz frequency ranges with the same error as the single-relaxation GRMDM does only in the gigahertz range.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Influence of nematic and smectic orders on polarizability of molecules of ethyl-p-(4-ethoxybenzylideneamino-)alpha-methyl cinnamate liquid crystals
Место публикации : Phys. Solid State: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2013. - Vol. 55, Is. 11. - P.2391-2396. - ISSN 1063-7834, DOI 10.1134/S1063783413110048
Примечания : Cited References: 16
Предметные рубрики: TRANSITION
MBBA
Аннотация: Experimental values of the polarizability tensor gamma components of molecules of ethyl-p-(4-ethoxybenzylideneamino-)alpha-methyl cinnamate liquid crystals in the nematic and smectic A phases have been obtained. Quadratic dependences of the longitudinal, gamma (l) , and transverse, gamma (t) , components, the mean value , and anisotropy Delta gamma in both phases have been established as functions of the orientational order parameter S of molecules in a maximally wide range of S. The nematic-smectic A phase transition with a continuous variation of S manifests itself as kinks in the linear dependences of , Delta gamma, and gamma (l) on S (2) and does not influence the dependence gamma (t) (S (2)). The observed dependences have been derived in the framework of the theory of the nematic-smectic A phase transition. The factors responsible for different influences of the orientational and positional orderings of molecules on the polarizability parameters have been determined.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gerasimova J. V., Vtyurin A. N.
Заглавие : Evans hole in internal modes IR spectrum of WO3F33-ions in (NH4)(3)WO3F3 crystal
Место публикации : Chem. Phys. Lett.: ELSEVIER SCIENCE BV, 2012. - Vol. 523. - P.144-147. - ISSN 0009-2614, DOI 10.1016/j.cplett.2011.12.041
Примечания : Cited References: 11. - We would like to thank Prof. E. M. Aver'yanov for discussion, and V. A. Ouskin for the technical assistance. This work has been supported by the Russian Foundation for Basic Researches, Grant No. 11-02-98002-r_sibir_a.
Предметные рубрики: INFRARED-SPECTRA
PHASE-TRANSITIONS
OXYFLUORIDE
MOLECULES
Аннотация: Infrared absorption of (NH4)(3)WO3F3 compound has been studied. Profile of asymmetric band in 600-1000 cm (1) range associated with polar W-O vibrations of WO3F33- ions is explicable on the basis of multi-oscillatory dynamics with account of damping. Complex profile with Evans holes proves that internal modes of WO3F33- anions in the fluorine-oxygen octahedron interact due to the effects of the local field. (C) 2011 Elsevier B. V. All rights reserved.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Slyusareva E. A., Sizykh A. G., Gerasimova M. A., Slabko V. V., Myslivets S. A.
Заглавие : Laser photolysis of fluorone dyes in a chitosan matrix
Место публикации : Quantum Electron.: Turpion LTD, 2012. - Vol. 42, Is. 8. - P.687-692. - ISSN 1063-7818, DOI 10.1070/QE2012v042n08ABEH014860
Примечания : Cited References: 32
Предметные рубрики: POLY(VINYL ALCOHOL) MATRIX
XANTHENE DYES
ROSE-BENGAL
FLUORESCENCE PROPERTIES
DELAYED FLUORESCENCE
ORGANIC-MOLECULES
TRIPLET-STATE
EXCITATION
ABSORPTION
PHOSPHORESCENCE
Ключевые слова (''Своб.индексиров.''): laser photolysis--fluorescein--dibromofluorescein--eosin y--erythrosin b--rose bengal--chitosan--photobleaching kinetics--two-step absorption
Аннотация: Kinetics of laser-induced photobleaching of fluorone dyes (fluorescein, dibromofluorescein, eosin Y, erythrosin B, Rose Bengal) is studied in a chitosan matrix. For all dyes the bleaching kinetics at the intensities of laser radiation 0.7 — 11.9 W cm-2 demonstrates quasi-monomolecular behaviour. The results are analysed using a kinetic model, based on the four-level (S0, S1, T1, Tn) scheme of the dye with chemically active triplet states taken into account. It is shown that the rate constants of the chemical reaction involving higher triplet states in the dyes studied amount to (3.9 — 18.6) × 106 s-1 and exceed the analogous values for the reaction involving the first lower triplet states by nine orders of magnitude. The rate of reaction involving the first triplet states appeared to be higher by one — two orders of magnitude than that in the case of higher triplet states involved because of low population of the latter. The possible mechanism of dye bleaching with participation of chitosan that consists in reduction of the dye to the leuco form by transfer of hydrogen from the chitosan matrix is discussed.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : New features of a smectic-A-crystal-B phase transition in a homologous series of liquid crystals
Место публикации : JETP Letters. - 2014. - Vol. 99, Is. 3. - P.158-163. - ISSN 0021-3640, DOI 10.1134/S0021364014030047. - ISSN 1090-6487
Примечания : Cited References: 21
Предметные рубрики: POLARIZABILITY
POLYMORPHISM
ANISOTROPY
MOLECULES
BEHAVIOR
Аннотация: The components L j of the Lorentz tensor and the polarizability density of molecules G in the smectic-A and crystalline-B phases have been determined for homologues of the series of alkyl-p-(4-alkoxybenzylideneamino-)cinnamates. The quantity L j (G) in both phases is a linear (quadratic) function of the orientational order parameter of molecules S, which is invariant (noninvariant) with respect to the A-B transition, which is manifested in the form of jumps δL j and δG and enhancement of the G(S) dependence. An increase in the length of terminal molecular chains and weakening of interlayer correlation of molecules are accompanied by strengthening of the A-B transition of the first order and G(S) dependences in both phases together with an increase in δL j and δG. Change δG and dependence G(S) in the B phase are related to change in the conformation (flattening) of aromatic molecular cores.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Orientational order and polarizability of molecules in a nematic liquid crystal
Место публикации : Phys. Solid State. - 2014. - Vol. 56, Is. 5. - P.1058-1063. - ISSN 1063-7834, DOI 10.1134/S1063783414050035
Примечания : Cited References: 17
Предметные рубрики: NORMAL-BUTYLANILINE MBBA
INTERNAL-ROTATION
TRANSITION
PHASE
Аннотация: The influence of the orientational order of molecules in a nematic liquid crystal on the mean value ?? and anisotropy ?? of the molecular polarizability has been studied in the framework of the molecular statistical approach with allowance for the perturbation of the electronic structure of molecules due to the change in the conformation of their aromatic core and intermolecular interactions. Experimental dependences of ?? and ?? on the molecular orientational order parameter S have been derived, and their specific features for the known objects have been explained. The possibility of separating the contributions of opposite signs to the dependence ??(S) due to the change in the conformation of molecules and intermolecular interactions has been shown using nematic MBBA as an example. © 2014 Pleiades Publishing, Ltd.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Structural and thermodynamic consequencies of the interaction of conformational degrees of freedom of azomethines in the nematic phase
Место публикации : J. Struct. Chem.: Springer, 2014. - Vol. 55, Is. 4. - P.605-611. - ISSN 0022-4766, DOI 10.1134/S0022476614040039. - ISSN 1573-8779
Примечания : Cited References: 21
Предметные рубрики: CONJUGATED POLY(AZOMETHINE)S
TERMINAL SUBSTITUENTS
ELECTRONIC-STRUCTURES
FLUORINATED ANALOGS
INTERNAL-ROTATION
MOLECULES
COMPOUND
ANGLES
STATE
NMR
Ключевые слова (''Своб.индексиров.''): azomethines--benzylideneaniline--conformation--steric effects of substituents--nematic-isotropic liquid transition--conformational polymorphism
Аннотация: The interaction of the conformational degrees of freedom of azomethines in the nematic phase, which is induced by electronic donor-acceptor properties of the terminal substituents of the benzylideneaniline core is studied. These degrees of freedom related to the rotation angles phi (k) around the bonds between the substituent and the aniline ring (phi(1)) and also between the CH=N bridge and the aniline ring (omega(2)) are characterized by the parameters Q (k) = aOE (c) cos(2)phi (k) . It is found that the interaction of these degrees of freedom is manifested in the linear dependence Q (2)(Q (1)). Within the phenomenological theory the effect of this interaction on changes delta (k) in the Q (k) values during the nematic liquid crystal-isotropic liquid phase transition is revealed along with the temperature T (NI) and character of this transition. The derivation of previously established empirical dependences T (NI)(Q (k) ) is presented in the presence of direct and indirect steric effects of side substituents affecting the Q (k) values. A diverse combination of delta (k) signs in the nematic phase, which is a prerequisite for the conformational polymorphism of the nematic phases of azomethines, is shown.
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Chernov A. I., Fedotov P. V., Krylov A. S., Vtyurin A. N., Obraztsova E. D.
Заглавие : Heat-induced transformations in coronene - Single-walled carbon nanotube systems
Коллективы : International Workshop on Nanocarbon Photonics and Optoelectronics (4th; 28 July - 1 August, 2014; Polvijärvi, North Karelia, Finland)
Место публикации : J. Nanophoton.: SPIE-Int. Soc. Optical Engineering, 2016. - Vol. 10, Is. 1: Special Section on Nanocarbon Photonics and Optoelectronics. - Ст.012504. - ISSN 19342608 (ISSN), DOI 10.1117/1.JNP.10.012504
Примечания : Cited References: 14
Предметные рубрики: Graphene nanoribbons
Encapsulation
Reactor
Ключевые слова (''Своб.индексиров.''): graphene nanoribbons--coronene molecules--coronene stacks--columns--single-walled carbon nanotubes--nanoreactor
Аннотация: Coronene molecules are used as filler for single-walled carbon nanotubes. Variation of the synthesis temperature regimes leads to formation of different types of carbon nanostructures inside the nanotubes. Accurate determination of the structures by optical spectroscopy methods remains an important issue in composite materials. Clear distinction between adsorbed organic molecules on the surface of the tubes and filled structures may be accessed by Raman and photoluminescence spectroscopies. We perform additional heat treatment after the initial synthesis procedure and show the evolution of the optical spectral features corresponding to the filled structures and adsorbed materials on the surface of single-walled carbon nanotubes. © 2015 Society of Photo-Optical Instrumentation Engineers (SPIE).
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Artyushenko P. V., Tomilin F. N., Kuzubov A. A., Ovchinnikov S. G., Tsikalova P. E., Ovchinnikova T. M., Soukhovolsky V. G.
Заглавие : Action of the atomic and electronic structure of pheromone molecules on the effectiveness of communication in xylophagous insects
Коллективы : RFBR [13-04-00375, 16-04-00132]
Место публикации : J. Struct. Chem.: MAIK Nauka-Interperiodica / Springer, 2016. - Vol. 57, Is. 2. - P.287-293. - ISSN 0022-4766, DOI 10.1134/S0022476616020074. - ISSN 1573-8779(eISSN)
Примечания : Cited References:27. - This work was supported by RFBR projects Nos. 13-04-00375 and16-04-00132.
Предметные рубрики: Monochamus-galloprovincialis coleoptera
Density-functional theories
Beetle Ips-typographus
Pine sawyer beetle
Aggregation pheromone
Cerambycidae
Attraction
Components
Attack
Set
Ключевые слова (''Своб.индексиров.''): atomic and electronic structure--functional density methods--absorption--spectra--excited states--xylophages--pheromones
Аннотация: The B3LYD /6-31(p,d) density functional method is applied to pheromones of the forest xylophagous insects Ips typographus L., Monochamus urussovi Fisch., and Monochamus galloprovincialis Oliv. to calculate the absorption spectra and find excited states. The calculated results are used to assess the possible activity of the molecules when they are affected by solar radiation.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Local-Field Anisotropy of a Light Wave in Quasi-Two-Dimensional Soft-Matter Objects
Коллективы :
Разночтения заглавия :авие SCOPUS: Local-field anisotropy of a light wave in quasi-two-dimensional soft-matter objects
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2010. - Vol. 110, Is. 4. - P622-636. - ISSN 1063-7761, DOI 10.1134/S1063776110040102
Примечания : Cited References: 73. - This study was supported by the Presidium of the Russian Academy of Sciences within the Program of Basic Research (project no. 27.1) and the Siberian Branch of the Russian Academy of Sciences within the Program of Interdisciplinary Basic Research (project no. 5).
Предметные рубрики: INTEGRATED OPTICAL TECHNIQUES
LANGMUIR-BLODGETT-FILMS
SMECTIC LIQUID-CRYSTALS
UNIAXIAL POLYMER-FILMS
MOLECULAR-ORIENTATION
INTERNAL FIELD
DIELECTRIC-CONSTANT
SPECTRAL FEATURES
REFRACTIVE-INDEX
THIN-FILMS
Ключевые слова (''Своб.индексиров.''): anisotropic films--bilayer lipid membrane--chemical structure--comblike polymers--conductive polymer--discotics--dispersion of refractive index--experimental data--experimental values--hexatic-b phase--isotropization--langmuir films--light wave--lorentz--macromolecular polymers--model approach--molecular polarizabilities--optical axis--order parameter--orientational order parameters--orientational orderings--orientational orders--smectic layers--smectic-a--smectics--soft matter--structural unit--sub-micron films--substrate types--tensor components--visible range--anisotropy--cell membranes--conductive plastics--conjugated polymers--electronic structure--light measurement--liquid crystal polymers--molecules--multilayer films--organic polymers--phase transitions--polarization--polymers--refractive index--substrates--tensors--two dimensional--conductive films
Аннотация: Experimental values of the Lorentz tensor components L-j for uniaxial quasi-two dimensional "soft matter" objects on substrates (bilayer lipid membranes, multilayer Langmuir films, smectics A, hexatic smectics B, submicron films of discotics Col(hd), micron anisotropic films of liquid-crystal comblike polymers and macromolecular polymers, submicron films of conjugated conductive polymers), freely suspended sub-micron films of smectics A, and uniaxially stretched micron films of conjugated conductive polymers have been determined using dispersion of refractive indices in the visible range. The dependences of the components L-j on the type of orientation (axial, planar) of uniaxial molecules (structural units of the film) with respect to the optical axis of the film, the film thickness, the substrate type, the chemical structure of molecules, and their long-range orientational order are established. It is revealed that the smectic A-hexatic B phase transition and two-dimensional crystallization of the smectic layer lead to changes in the components L-j due to the change in the orientational ordering of molecules as a result of the relation between the orientational and hexatic order parameters. All the above objects are characterized by isotropization of the Lorentz tensor L and the local-field tensor f with a simultaneous decrease in the birefringence of the sample and in the anisotropy of the molecular polarizability due to the change in the electronic structure of molecules. The correction for the anisotropy of the local-field tensor f to the orientational order parameter or the anisotropy of the molecular polarizability increases. The existing model approaches to calculating the components L-j for the objects under consideration are compared with the experimental data.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Nonlinear coupling between the mean polarizability (gamma)over-bar of molecules and the local-field anisotropy in a liquid crystal and change of the "(gamma)over-bar = const" paradigm
Разночтения заглавия :авие SCOPUS: Nonlinear coupling between the mean polarizability gamma ̄ of molecules and the local-field anisotropy in a liquid crystal and change of the "gammā = const" paradigm; авие SCOPUS: Nonlinear coupling between the mean polarizability gamma ? of molecules and the local-field anisotropy in a liquid crystal and change of the "gamma = const" paradigm
Место публикации : JETP Letters. - 2008. - Vol. 87, Is. 5. - P.258-261. - ISSN 0021-3640, DOI 10.1134/S002136400805007X; \b JETP Letters. - 2008. - Vol. 87, Is. 5. - P.258-261. - Вариант Sopus
Примечания : Cited References: 14
Предметные рубрики: REFRACTIVE-INDEXES
ORDER
Аннотация: The nonlinear relation between the mean effective polarizability (gamma) over bar of molecules and the local-field anisotropy in uniaxial liquid crystals is demonstrated. Stringent constraints on (gamma) over bar from below, indicative of the dependence of on the liquid-crystal state and the change of the "(gamma) over bar = const" paradigm, are established. The theoretical results are confirmed by experiments with nematic liquid crystals having high and low birefringences.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Dimension of mesogenic molecules as atomic clusters
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2005. - Vol. 47, Is. 2. - P378-389. - ISSN 1063-7834, DOI 10.1134/1.1866424
Примечания : Cited References: 19
Предметные рубрики: LIQUID-CRYSTAL CHEMISTRY
ORIENTATIONAL ORDER
TRANSITION
Аннотация: The problem regarding the mass dimension D of mesogenic molecules as atomic clusters is formulated and solved using computer simulation and analytical calculations. For a large number of compounds belonging to different chemical classes, it is shown that the cores of discotic lacunar (rodlike, lathlike) molecules forming nematic or columnar discotic (calamitic) phases have a fractional dimension 1 D-c 2 (D-c approximate to 1). The dependences of the dimension D-c on the symmetry, the conformation, and the structural-chemical features of the molecular core are determined. It is demonstrated that, in the region of side flexible chains in molecules of both types, the dimension D-ch can be either smaller or larger than unity, depending on the chain conformation. An analytical expression accounting for the results of numerical experiments is obtained for the dimension D-ch. (C) 2005 Pleiades Publishing, Inc.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sadreev A. F., Sukhunin Y. V., Petoral R. M., Uvdal K.
Заглавие : Ground state and phase transitions in a system of arg-cysteamines self-assembled on a Au(111) crystal surface
Место публикации : J. Chem. Phys.: AMER INST PHYSICS, 2004. - Vol. 120, Is. 2. - P954-960. - ISSN 0021-9606, DOI 10.1063/1.1631920
Примечания : Cited References: 38
Предметные рубрики: MOLECULAR-DYNAMICS SIMULATION
HYDROGEN-BOND
MONOLAYERS
MODEL
GOLD
PEPTIDES
ALKANETHIOLS
ACTIVATION
FILMS
CYS
Ключевые слова (''Своб.индексиров.''): gold--ground state--hydrogen bonds--molecules--phase transitions--self assembly--surfaces--temperature--arg-cysteamines--crystal surface--dipole moments--dipole-dipole interactions--molecular dynamics
Аннотация: The translational and orientation order of arg-cysteamine molecules chemiabsorbed on the Au(111) crystal surface is considered. Couplings between carbon, nitrogen, and hydrogen atoms of the n-alkanethiols are approximated by the Lennard-Jones potential. Moreover, hydrogen bonds between oxygen and nitrogen and dipole-dipole interactions of the dipole moments of different atomic groups are taken into account. It is found that molecules are arranged in a 2x2 lattice and have the total symmetry C(6)xZ(2). The critical temperature of the phase transition to the tilted state T-c1, which breaks the symmetry C-6, is estimated to be extremely high. The spontaneous breakdown of the remaining symmetry Z(2) leads to the twisted state of the molecules and has the critical temperature T-c2=340 K. (C) 2004 American Institute of Physics.
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18.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M., Rumyantsev V. G.
Заглавие : Manifestations of the higher moments of the orientation distribution function of molecules in the spectral properties of an impurity nematic
Место публикации : J. Exp. Theor. Phys.: AMER INST PHYSICS, 2004. - Vol. 98, Is. 6. - P1146-1151. - ISSN 1063-7761, DOI 10.1134/1.1777627
Примечания : Cited References: 15
Предметные рубрики: LIQUID-CRYSTAL
SCATTERING
PHASES
MATRIX
ORDER
DYES
Ключевые слова (''Своб.индексиров.''): absorption--band structure--impurities--molecular dynamics--polarization--spectrum analysis--distribution function--local field parameters--splitting--temperature dependence--nematic liquid crystals
Аннотация: The polarized electronic absorption spectra, orientation ordering, and the special local field features were studied for push-pull linear dye molecules with strong donor-acceptor electronic conjugation of terminal fragments in the matrix of a nematic liquid crystal. The temperature-induced inversion of the sign of the splitting of polarized impurity absorption bands was observed. This effect was shown to be caused by the statistical character of orientation ordering of impurity molecules and manifestation of the higher moments of the orientation distribution function. The dependence of local field parameters (Lorentz tensor components) of impurity molecules on their orientation ordering was established. This dependence was used to reproduce the temperature dependence of the orientation order parameter of the matrix. (C) 2004 MAIK "Nauka / Interperiodica".
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aver'yanov E. M.
Заглавие : Fluctuations of orientational order in a uniaxial nematic liquid crystal with biaxial molecules and its response to an external field
Место публикации : Phys. Solid State: AMER INST PHYSICS, 2003. - Vol. 45, Is. 5. - P990-1001. - ISSN 1063-7834, DOI 10.1134/1.1575350
Примечания : Cited References: 30
Предметные рубрики: PHASE-TRANSITION
SMECTIC-A
PARTICLES
SYSTEM
LANDAU
MODEL
Аннотация: Homogeneous thermal fluctuations of the orientational order parameters S and G of biaxial molecules in a uniaxial nematic liquid crystal are investigated in the framework of the molecular-statistical theory. It is demonstrated that the molecular biaxiality significantly affects the order parameters S and G, their temperature dependences in the nematic phase, the amplitude and the temperature dependence of the order parameter fluctuations in the nematic and isotropic phases, and the character of the transition from the nematic phase to the isotropic liquid phase. It is established that the fluctuations of the parameters S and G in the nematic phase are related to the temperature dependences of S and G and the susceptibilities chi(S) and chi(G) of the nematic liquid crystal to external fields, which leads to a change in the parameters S and G at a fixed director orientation. Explanations are offered for the known experimental data on the orientational ordering of biaxial molecules under the action of external fields in the isotropic phase of nematic liquid crystals. (C) 2003 MAIK "Nauka/Interperiodica".
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Shabanov V. F., Korshunov M. A.
Заглавие : Migration of molecules in p-bromochlorobenzene with vacancies in its structure
Место публикации : Phys. Solid State: AMER INST PHYSICS, 1998. - Vol. 40, Is. 10. - P1664-1666. - ISSN 1063-7834, DOI 10.1134/1.1130630
Примечания : Cited References: 8
Аннотация: Based on polarization measurements of the low-frequency Raman spectra of p-bromochlorobenzene and calculations of the frequency spectra of lattice vibrations by the Dean method it is shown that the structure may contain vacancies. Their presence affects the appearance of additional lines in the low-frequency spectrum, particularly in the vicinity of 70 cm(-1), and their positions depend weakly on the orientational disorder of the molecules with respect to the para substituents. The activation energies for diffusion in a randomly disordered p-bromochlorobenzene crystal with vacancies in the structure is calculated from atom-atom potentials. It is shown that the value of the activation energy varies along a selected direction and depends on the arrangement of the p-bromochlorobenzene molecules with respect to the para substituents, in contrast to the results for ordered p-dibromobenzene and p-dichlorobenzene. (C) 1998 American Institute of Physics. [S1063-7834(98)01410-5].
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