Наукові публікації кафедри загальної та прикладної фізики

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Structure and Intermolecular Interactions in Ionic Liquid Crystals Doped with Electrochromic Viologen
(Russian Journal of Physical Chemistry, Vol. 79, Suppl. 1, 2005, pp. S66–S70, 2005) Bordyuh, Hanna; Polishchuk, Arkadiy
The results of an investigation of structural and electrooptical properties of potassium caprylate lyotropic liquid crystals (LCs) doped with electrochromic viologen are presented. The samples are colored when an electric field is applied. The color deepens with the voltage applied, and relevant features appear in electronic absorption spectra. Two stages may be recognized in the processes that occur in a sample in the field. The first stage (at 2–2.5 V) involves the formation of radical cations (RCs) from viologen molecules, which makes the samples blue (two absorption bands appear at wavelengths of 395 and 610 nm in optical spectra). At the second stage (at 3.5–4 V), the radical cations are dimerized, and the sample becomes red (the spectra show bands in the region of 365 and 520 nm). Absorption in a lyotropic LC increases with the viologen concentration increasing from 1 to 2 to 4%. Small-angle X-ray scattering was measured on unoriented samples of pure potassium caprylate with thicknesses ranging from 30 μm to 1 mm. In all samples, a smectic order was observed in lyotropic ionic LC (LILC). From the X-ray scattering data, the bilayer thickness and the smectic correlation length were computed. It was inferred that viologen molecules, when present in low concentrations (1–4%), are organically incorporated into the matrix without spoiling the layer order intrinsic to the matrix.
Cubic Susceptibility and Hyper-polarizability of the Lyotropic Liquid Crystal−Viologen System
(Ukr. J. Phys. 2008, Vol. 53, N 12, p.1167-1173, 2008) Bordyuh, Hanna; Polishchuk, Arkadiy
Nonlinear optical properties of the “lyotropic liquid crystal–viologen” system are investigated. The system shows electrochromism under the action of an external electric field. For the colored samples, the recording of dynamic holographic gratings is obtained, by using the pulse laser method. The main characteristics of a recording on such samples are studied. On their base in view of the electrooptical properties of the system, the mechanism of the recording of gratings is proposed. The recording is realized due to a change in the polarizability of the π-electron system of viologen derivatives under the action of an intense laser radiation. The main nonlinear optical parameters (n2, χ(3), γ) of the system under study are determined.
Dynamic grating recording in lyotropic ionic smectics of metal alkanoates doped with electrochromic impurities
(Elsevier, Optical Materials 31 (2009) 1109–1114, 2009) Bordyuh, Hanna; Polishchuk, Arkadiy
In this work, we investigated nonlinear-optical properties in lyotropic ionic liquid crystals (LILC) of potassium caprilate doped with electrochromic impurities (viologens). It is known that after applying a direct electric field to the LILC-viologen cells colouration of samples is observed [1]. Dynamic grating recording under the action of nanosecond pulse laser radiation was obtained for the coloured samples. We analyzed the origin of the optical nonlinearity in the investigated materials taking into account their electrochemical and electrooptical properties. To explain grating recording in LILC doped with viologens, we proposed the mechanism of photoconversion in viologen molecules.
Novel Nanocomposite Materials Based on Mesomorphic Glasses of Metal Alkanoates: Structure and Nonlinear Optical Properties
(High Energy Chemistry, 2009, Vol. 43, No. 7, pp. 532–535, 2009) Gridyakina, Alexandra; Polishchuk, Arkadiy
Novel nanocomposite materials based on an ordered mesomorphic glass of metal alkanoates have been proposed for fast transfer and processing of optical information. Metal alkanoate salts when heated form a smectic mesophase which can be easily supercooled forming an ordered mesomorphic glass at room temperature. The glass has the structure of the smectic-A phase: electrostatic cation–anion layers alternate with bilayers of alkane chains. The mesomorphic glass is a universal matrix for organic and inorganic nanoinclusions and nanosized crystals. In this paper, the structure of the cells of the mesomorphic glasses with various inclusions and their nonlinear optical properties, which become evident upon the impact of pulsed laser radiation with an intensity of up to 5.5 MW/cm2, have been investigated.
Fast Nolinear Optical Mechanisms in Bi-Layered Cells Composed by Lyotropic Ionic Liquid Crystals with Dye and Viologen Films
(Taylor & Francis Group, LLC, Mol. Cryst. Liq. Cryst., Vol. 508, pp. 296[658]–308[670], 2009, 2009) Bordyuh, Hanna
Mechanisms of the fast optical nonlinearity are studied in two types of cells based on lyotropic ionic liquid crystals (LILC) of metal alkanoates. They are (I) bi-layer cell, which consists of a thin dye film covered by LILC, and (II) LILC with electrochromic impurity (viologen). Applying dc electric voltage to the cell II leads to adsorption of viologen redox products with formation of a thin nanosized layer on the cathode. The dynamic holographic technique with pulsed laser radiation of the nanosecond duration was used to investigate nonlinear optical properties in both types of cells. The mechanism of photoconversion of viologen redox products under strong laser radiation is proposed to explain grating recording in the cell II.
Nonlinear optical response of smectic structure glasses based on cobalt alkanoates
(IEEE, 2010, 2010) Gridyakina, Alexandra
Nonlinear-optical response of metal-alkanoates anisotropic glasses based on cobalt-alkanoate was studied using method of the dynamic holography. Fundamental optical (refractive index and absorption coefficient) and nonlinear-optical (nonlinear susceptibilities and polarizabilities) parameters of the mesomorphic glasses based on cobalt-alkanoates can be tuned via varying chain length anion (interlayer distance of homologous lines) and\or by changing of the cation composition (exploiting binary or ternary systems).
Tunable optical and nonlinear optical response of smectic glasses based on cobalt alkanoates
(Liquid Crystals, Vol. 37, No. 11, November 2010, 1411–1418, 2010) Gridyakina, Alexandra
The nonlinear optical response of anisotropic smectic glasses based on cobalt alkanoates has been studied using dynamic holography. Laser-dynamic gratings induced by the action of nanosecond laser pulses were observed and analysed for such materials. It was found that the cubic optical nonlinearity of all the anisotropic glasses studied had an electronic origin in the nanosecond range, caused by nonlinear polarisation of the cobalt alkanoate complexes. Fundamental optical (refractive index and absorption coefficient) and nonlinear optical (nonlinear susceptibility and polarisability) parameters of mesomorphic glasses based on cobalt alkanoates could be tuned by varying the length of the alkanoate anion chain, thereby determining the interlayer smectic distance.
Структурні та електрооптичні властивості електрохромних рідкокристалічних композитів
(Національний Авіаційний Університет, 2012) Бордюг, Ганна Борисівна; Поліщук, Аркадій Петрович
Наведено результати структурних та електрооптичних досліджень новостворених композитів на основі ліотропних рідких кристалів каприлату калію та віологенів. Визначено наявність у дослі-джуваних зразках смектичного впорядкування. Описано його основні параметри. Показано, що електрохромні властивості віологенів зберігаються і при розчиненні в рідкокристалічній матриці, що проявляється в забарвленні зразків під дією зовнішнього електричного поля і підтверджується оптичними спектрами поглинання. Проаналізовано процеси, які проходять у композитах ліотропні рідкі кристали – віологен у разі прикладання електричного поля.
Electrooptical and Nonlinear Optical Properties of Lyotropic Liquid Crystals Doped with Electrochromic Viologen
(Український фізичний журнал, 2012) Bordyuh, Hanna; Polishchuk, Arkadiy
This work presents the results of experimental studies of the electrooptical and nonlinear optical properties of lyotropic ionic liquid crystals (LILC) with soluted electrochromic admixtures of viologens. It is established that the Smectic A ordering of the LILC of potassium caprylate is not disrupted by the introduction of viologens. Moreover, LILC-viologen composites obtain electrochromic properties inherent to viologens, which produce colored radical cations and dimers, while reducing. The presence of radical cations and dimmers is fixed by the optical absorption spectra. It is found that, under the action of an electric field, the LILC-viologen samples form a bilayer structure consisting of a liquid crystal layer and an absorptive layer of viologen redox products (radical cations and dimers). A dynamic grating recording is realized and studied in bilayer LILC-viologen cells. It is determined that the recording takes place in the colored layer of viologen redox products. A possible mechanism of grating recording in LILC-viologen cells is proposed.
Nonlinear Optical Response of Smectic Glasses Based on Cobalt Alkanoates
(Український фізичний журнал, 2012) Gridyakina, Alexandra; Polishchuk, Arkadiy
The nonlinear-optical response of anisotropic smectic glasses based on cobalt-alkanoates is studied using the method of dynamic holography. Laser-induced dynamic gratings under the action of nanosecond laser pulses are observed and analyzed for such materials. It is found that a cubic optical nonlinearity of all studied anisotropic glasses is of electronic origin in the nanosecond diapason and caused by a nonlinear polarization of cobalt-alkanoates complexes.
Holographic grating recording in “lyotropic liquid crystal – viologen” system
(Національний Авіаційний Університет, 2013) Bordyuh, Hanna; Polishchuk, Arkadiy
This work presents the results of nonlinear optical experiment run on the samples of lyotropic liquid crystal (LLC) with viologen admixtures. During the experiment we obtained dynamic grating recording on bilayered LLC-viologen samples and determined main characteristics of recoded gratings. It was found out that the recording takes place in a thin near-cathode coloured viologen layer. The analysis of kinetics of thermal gratings erasing showed that contribution of a thermal nonlinearity into general diffraction efficiency is negligible small. The last fact is connected with a separation of LLC-viologen samples under the action of an electric field and heat sink into the liquid crystal layer.
Optical properties of mesophases and mesomorphic glasses of Co2+ alkanoates homologous series
(Proceedings of the National Aviation University. 2013. N 4 (57): 48–52, 2013) Gridyakina, Alexandra; Polishchuk, Arkadiy
The results of spectral studies of thermotropic ionic liquid crystals (TILC) of homologous series of cobalt alkanoates and their mesomorphic glasses are presented. It is shown that the dominant coordination of the cobalt ions in the investigated media is an octahedron. A significant decrease the absorption coefficient with increasing of the aliphatic chain length in the homologous series of cobalt alkanoates is caused by the decrease of the volume concentration of the cobalt cation complexes and the dipole moments of d-d-transitions.
Liquid crystal materials with regulated optical properties
(Національний Авіаційний Університет, 2013) Bordyuh, Hanna
In this work we present the results of structural and electrooptical investigations of the new-created composites based on lyotropic liquid crystals (LLC) of potassium caprylate and viologens. Provided structural analysis showed the presence of a Smectic ordering in the investigated samples and allowed to determine its main parameters. It was shown that the electrochromic properties of viologens are preserved after their solution in the liquid-crystalline matrix. They reveal themselves as a coloration of the samples under applying of an electric field and are proved by the optical absorption spectra. Also we analyzed the processes taking place in LLC-viologen composites in the case of an electric field applying.
Structural characteristics of mesophases and mesomorphic glasses of metalalkanoates
(Proceedings of the National Aviation University. 2014. N 2 (59): 82–87, 2014) Gridyakina, Alexandra; Polishchuk, Arkadiy
The structure of the mesophases and mesomorphic glasses of cobalt alkanoates homologous series was obtained. It is shown, that typical for ITLC smectic A packing of molecules (cation-anion layer between layers alkanoate chains) preserves also in a glass phase (at room temperature).
Mechanism of optical nonlinearity in “Lyotropic Liquid Crystal-Viologen” system
(2014) Bordyuh, Hanna; Polishchuk, Arkadiy
In the present work we analyze the characteristics of holographic grating recording and consider a mechanism of optical nonlinearity in the lyotropic liquid crystal (LLC) —viologen samples. Taking into account structural and electrooptical properties of the admixture molecules it is possible to suggest that the recording is realized due to the change of polarizability of -electron system of coloured viologen derivatives under the action of laser radiation. The main nonlinear optical parameters such as nonlinear refraction coefficient, cubic nonlinear susceptibility, and hyperpolarizability were calculated.
ЦИФРОВИЙ АЛЬФА-ІНДИКАТОР КОНТРОЛЮ ПОВІТРЯНО-ПАЛИВНОЇ СУМІШІ НА БАЗІ ЦИРКОНІЄВОГО КИСНЕВОГО ЗОНДА
(Институт технической теплофизики НАН Украины, 2014-02) Запорожець, Артур Олександрович; Бабак, Віталій Павлович; Назаренко, Олег Олексійович
Розглянуто розроблену експериментальну модель зондового альфа-індикатора для контролю стехіометричного співвідношення повітняно-паливної суміші в котлоагрегатах. Показані можливості застосування зондового альфа-індикатора для зворотного зв’язку в системі частотного регулювання вентилятора подачі повітря на газовий пальник при оптимізації процесу горіння в котлах малої потужності (до 3,5 МВт).
Isostructural magnetic phase transitions and the magnetocaloric effect in Ising ferromagnets
(Low Temperature Physics 40, 823 (2014), 2014-04) Лаванов, Геннадій Юрійович
It is shown that the first-order isostructural magnetic phase transition between antiferromagnetic phases with different magnitudes of the antiferromagnetism vector induced by an external magnetic field in Ising antiferromagnets can be related to entropy. It is found that, depending on the temperature, the entropy jump and the corresponding heat release can change their signs at the phase transition point. In the low-temperature region of the metamagnetic first-order phase transition the entropy jump is positive, while the entropy jump is negative near the triple point for isostructural magnetic phase transitions.
Исследование стехиометрической смеси «воздух-топливо» горючих и взрывоопасных углеводородов
(Научные известия на НТСМ, 2014-06) Запорожец, Артур Александрович; Бабак, Виталий Павлович
Analyzed the feasibility of incorporation air’s shortage/excess in the control of combustion process of inflammable and explosive hydrocarbones. The mass stoichiometric of air-fuel mixture of organic compounds are calculated. The importance of incorporation obtained data for industrial and municipal power are shown.
Влияние метеорологических параметров на оптимизацию процесса горения
(Научные известия на НТСМ, 2015) Запорожец, Артур Александрович; Бабак, Виталий Павлович; Редько, Александр Александрович
Considered the influence of meteorological parameters (temperature, pressure, humidity) on oxygen quantitative content in the air. Showed the bias that introduced with not accounting the parameter of the oxygen current concentration in the air during the energy calculations in the power system. On the basis of experimental data established the dependence of oxygen volume concentration in the air from meteorological parameters (temperature, pressure, humidity). Analyzed the seasonal changes of oxygen concentration in the air in 12 European capitals (based on 2014 year): Brussels (Belgium), Paris (France), Berlin (Germany), Vienna (Austria), London (United Kingdom), Helsinki (Finland), Warsaw (Poland), Bucharest (Romania), Prague (Czech Republic), Sofia (Bulgaria), Riga (Latvia), Rome (Italy). Proposed the method for eliminating the methodical error of the excess air ratio measurement based on current oxygen volume concentration in the environment.
ПІДВИЩЕННЯ ЕФЕКТИВНОСТІ СПАЛЮВАННЯ ПАЛИВА В КОТЛАХ ПОТУЖНІСТЮ ДО 3,5 МВТ З ВИКОРИСТАННЯМ α-ЗОНДУ
(Інститут електрозварювання ім. Є.О. Патона, 2015) Запорожець, Артур Олександрович; Бабак, Віталій Павлович; Назаренко, Олег Олексійович
Проведено комплексний аналіз теплофізичних та гідродинамічних процесів в робочому просторі котла НІІСТУ-5 з використанням пальника типу ГБГМ. Розроблені алгоритм та принципова схема процесу регулювання співвідношення повітряно-паливної суміші для пальника ГБГМ зі зворотним зв’язком по сигналам α-зонду на базі частотно-регульованих електроприводів. Запропонована математична модель повітряно-паливного тракту для котлів малої та середньої потужності та проведено комп’ютерне моделювання розробленої системи для оптимізації процесу спалювання палива. Представлено рішення для підвищення точності визначення коефіцієнта надлишку повітря на базі поточної об’ємної концентрації кисню в повітрі. Наведено результати аналізу сезонної зміни об’ємної концентрації кисню в повітрі на території України. Розроблена та впроваджена комплексна система оптимізації процесу горіння в котлах потужністю до 3,5 МВт з використанням α-зонду.

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