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Wyświetlanie 1-15 z 21
Tytuł:
Global Maxima of the Acousto-Optic Effect in CaWO₄ Crystals
Autorzy:
Andrushchak, A.
Buryy, O.
Demyanyshyn, N.
Hotra, Z.
Mytsyk, B.
Powiązania:
https://bibliotekanauki.pl/articles/1030921.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Fm
78.20.Hp
Opis:
The global maxima of the acousto-optic interaction are theoretically determined for CaWO₄ crystals by extreme surfaces method. As it is shown, the highest value of the acousto-optic figure of merit M₂ is equal to 14.0×10¹⁵ s³/kg and achieved in the case of the diffraction of ordinary or extraordinary light beam on the slow quasi-transversal acoustic wave. At that the incident light wave propagates close to c-axis of the crystal and the corresponding acoustic wave propagates in the direction close to the perpendicular one.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 928-932
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electro-Optical Properties of Liquid Crystals Composite with Zinc Oxide Nanoparticles
Autorzy:
Eskalen, H.
Özğan, Ş.
Alver, Ü.
Kerlı, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398924.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Jq
77.84.Nh
78.20.Fm
Opis:
In this study, zinc oxide (ZnO) nanoparticles were synthesized by spray pyrolysis method. The properties of ZnO nanoparticles are determined by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and UV-vis spectroscopy. Nematic liquid crystal mixture E7 was doped with 1, 2, and 4% ZnO. We investigate electrical and optical parameters of pure and doped nematic liquid crystal mixture E7. The experiments related to voltage dependence and light transmittance of the pure and doped E7 were carried out. The values of threshold voltage, total phase retardation and birefringence are examined. The results show that doping zinc oxide nanoparticles into liquid crystal mixture E7 decreases threshold voltage significantly.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 756-760
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dielectric Permittivity and Viscoelastic Measurements οf Two Tricomponent Mixtures Consisting οf Laterally Fluorinated Terphenyl Derivatives
Autorzy:
Basak, S.
Dasgupta, P.
Das, B.
Das, M.
Dabrowski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1400143.pdf
Data publikacji:
2013-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.-v
78.20.Fm
87.19.rd
87.19.rf
83.60.Bc
Opis:
Two tricomponent room temperature nematic eutectic mixtures ABC and ABD with laterally fluorinated constituents A and B were prepared as base mixtures for vertically aligned mode LCD's. The physical properties of these mixtures viz. birefringence, dielectric anisotropy, bend elastic constant, relaxation time and rotational viscosities were determined in order to compare with the optimum values required to achieve the target specifications of VA mode materials. The dielectric anisotropy, Δ ε, and optical birefringence, Δ n, of these mixtures were found to be in the range of (-1.3 to -1.4) and (0.13 and 0.14), respectively, at around 20°C. The figure of merit for the ABD mixture has been found to be higher than that of ABC mixture throughout the entire temperature range. The pretilt angle effect in the physical parameters has also been studied. At T=20°C, the response time decreases to 25% and 35% for mixture ABC for 2° and 5° pretilt respectively in comparison to zero pretilt. On the other hand, at the same temperature for the ABD mixture these values are reduced by 16% and 35%, respectively.
Źródło:
Acta Physica Polonica A; 2013, 123, 4; 714-719
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Temperature on the Refractive Indices of Liquid Crystals and Validation of a Modified Four-Parameter Model
Autorzy:
Thingujam, K.
Sarkar, S.
Choudhury, B.
Bhattacharjee, A.
Powiązania:
https://bibliotekanauki.pl/articles/1418322.pdf
Data publikacji:
2012-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.15.+e
78.20.Fm
64.70.M-
Opis:
The variation of refractive indices with temperature of three pure nematogenic compounds 5OCB, CPHB and 6CHBT were studied experimentally using thin prism technique. The refractive indices $n_{o}$ and $n_{e}$ were measured using 633 nm lines from a He-Ne laser. A modified four-parameter model was taken which is based on the Vuks equation describing the effect of temperature on the refractive indices of liquid crystals. In this paper we report the variation of refractive indices of these three liquid crystals with temperature, using the thin prism method. The variation in birefringence was determined experimentally. The variation in refractive indices and birefringence were also fitted theoretically using the modified Vuks equation. On comparison, the theoretically fitted values show close agreement with the experimental values.
Źródło:
Acta Physica Polonica A; 2012, 122, 4; 754-757
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Linear Dichroism Spectra of Doped Calcium Gallogermanate Crystals
Autorzy:
Shopa, Y.
Ftomyn, N.
Powiązania:
https://bibliotekanauki.pl/articles/1550185.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Ci
78.20.Fm
Opis:
Polarized absorption and linear dichroism spectra of chromium and manganese doped gallogermanate $(Ca_{3}Ga_{2}Ge_{4}O_{14})$ crystals were measured and analyzed. Electronic transitions were identified and crystal field parameters have been determined. The value of linear dichroism obtained at the wavelength of 633 nm was compared with polarimetric measuring data for chromium doped $Ca_{3}Ga_{2}Ge_{4}O_{14}$ crystals.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 114-116
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phase Transitions in $[N(CH_3)_4]_2ZnCl_4$ and $[N(CH_3)_4]_2CuCl_4$ Crystals Related with the Incommensurate Modulation Existence
Autorzy:
Sveleba, S.
Semotyuk, O.
Katerynchuk, I.
Kunyo, I.
Karpa, I.
Pankivskyi, Yu.
Powiązania:
https://bibliotekanauki.pl/articles/1812043.pdf
Data publikacji:
2008-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.44.Fw
64.70.Rh
78.20.Fm
65.40.Ba
Opis:
The continuous phase transitions are observed in the crystals with incommensurate phase. They are transitions of parent-incommensurate phases $(T_i)$; transitions between metastable states; incommensurate-commensurate phases $(T_c)$. It was set that phase transition between parent and incommensurate phase is a continuous second-order phase transition with a critical index β = 0.5. The transition between metastable states is a continuous phase transition through the intermediate temperature region - incommensurate phase. The wave vector changes with the temperature here and wave vectorwe q* = q₁ - q₂ appears, where q₁, q₂ denote commensurate values of incommensurability wave vector of neighboring metastable states. It was shown that the phase transition between incommensurate and commensurate phases is a continuous phase transition.
Źródło:
Acta Physica Polonica A; 2008, 114, 4; 791-806
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculation of Optical Parameters of Liquid Crystals
Autorzy:
Kumar, A.
Powiązania:
https://bibliotekanauki.pl/articles/1814025.pdf
Data publikacji:
2007-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.-e
78.20.Ci
78.20.Fm
77.84.Nh
Opis:
Validation of a modified four-parameter model describing temperature effect on liquid crystal refractive indices is being reported in the present article. This model is based upon the Vuks equation. Experimental data of ordinary and extraordinary refractive indices for two liquid crystal samples MLC-9200-000 and MLC-6608 are used to validate the above-mentioned theoretical model. Using these experimental data, birefringence, order parameter, normalized polarizabilities, and the temperature gradient of refractive indices are determined. Two methods: directly using birefringence measurements and using Haller's extrapolation procedure are adopted for the determination of order parameter. Both approches of order parameter calculation are compared. The temperature dependences of all these parameters are discussed. A close agreement between theory and experiment is obtained.
Źródło:
Acta Physica Polonica A; 2007, 112, 6; 1213-1221
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Stochastic Mode of the Modulated Structure in [N(CH$\text{}_{3}$)$\text{}_{4}$]$\text{}_{2}$MeCl$\text{}_{4}$ Dielectric Crystals
Autorzy:
Sveleba, S.
Semotyuk, O.
Katerynchuk, I.
Furgala, Yu.
Pankivskyi, Yu.
Powiązania:
https://bibliotekanauki.pl/articles/2046819.pdf
Data publikacji:
2006-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.25.Lc
61.44.Fw
64.70.Rh
78.20.Fm
Opis:
Temperature behavior of the optical birefringence in the transitional regions of the incommensurate phase of [N(CH$\text{}_{3}$)]CuCl$\text{}_{4}$ was studied. Temperature dependencies of the modulated structure wave vector and of the specific heat in these regions were analyzed. The stochastic mode of the incommensurate modulated structure in [N(CH$\text{}_{3}$)]MeCl$\text{}_{4}$ (Me = Cu, Fe) dielectric crystals was discovered.
Źródło:
Acta Physica Polonica A; 2006, 109, 6; 695-700
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Role of Intermolecular Interactions in the Electro-Optical Kerr Effect in Liquid Alkanes
Autorzy:
Prezhdo, O. V.
Switek, L.
Zubkova, V. V.
Prezhdo, V. V.
Powiązania:
https://bibliotekanauki.pl/articles/2043659.pdf
Data publikacji:
2005-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.70.Dk
78.20.Fm
Opis:
The electro-optical Kerr effect of n-alkanes from C$\text{}_{5}$ to C$\text{}_{16}$ was investigated in gas phase, liquid phase, and solution. The values of the Kerr constants in gas phase are noticeably distinguishable from those in liquids, where the molecules interact by the London dispersion forces. Both the energy of the dispersion interaction and the difference in the Kerr constants in liquid and gas phase grow with molecular size, indicating the key influence of the interaction on the magnitude of the Kerr effect. Several orientation and molecular-statistical theories of electro-optical Kerr effect were applied to model the change in electro-optical Kerr effect due to the dispersion force. Most theories show significant divergence compared to the experimental data. It is argued that the decisive contribution to electro-optical Kerr effect in liquids and the deviations between the experiment and theory arise due to local liquid structures that collectively orient in the external electric field.
Źródło:
Acta Physica Polonica A; 2005, 108, 3; 429-447
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of the Electro-Optical Kerr Effect in Physical-Chemical Analysis of Binary Systems
Autorzy:
Prezhdo, O. V.
Tyurin, S. A.
Pisarczyk, M.
Odziemek, A.
Prezhdo, V. V.
Powiązania:
https://bibliotekanauki.pl/articles/2030490.pdf
Data publikacji:
2002-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.70.Dk
78.20.Fm
72.80.Jc
Opis:
Applications of the electro-optical Kerr effect in physical-chemical analysis of binary mixtures are reviewed. Improvements in the experimental techniques, in particular, development of the pulsed and alternating electric field based approaches, have led to significant advances in this area. However, problems associated with the description of the internal field of liquids remain and hamper broader applications of the techniques. It is shown that a further progress in the electro-optical Kerr effect characterization of chemical systems relies on the development of a more general theory of optical properties of condensed phase chemical mixtures that can account for nonlinear effects, such as hyperpolarizability, dispersion and specific conditions of the Kerr constant measurements.
Źródło:
Acta Physica Polonica A; 2002, 101, 4; 477-494
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Breakdown of Rotational Symmetry at Semiconductor Interfaces: a Microscopic Description of Valence Subband Mixing
Autorzy:
Cortez, S.
Krebs, O.
Voisin, P.
Powiązania:
https://bibliotekanauki.pl/articles/2014160.pdf
Data publikacji:
2000-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Fm
78.20.Jq
Opis:
The recently discovered in-plane optical anisotropy of [001]-grown quantum wells offers a new theoretical and experimental insight into the electronic properties of semiconductor interfaces. We first discuss the coupling of X and Y valence bands due to the breakdown of rotation inversion symmetry at a semiconductor hetero-interface, with special attention to its dependence on effective parameters such as the valence band offset. The intracell localization of Bloch functions is explained from simple theoretical arguments and evaluated numerically from a pseudo-potential microscopic model. The role of envelope functions is then considered, and we discuss the specific case of non-common atom interfaces. Experimental results and applications to interface characterization are presented. These calculations give a microscopic justification, and establish the limits of the heuristic "H$\text{}_{BF}$" model.
Źródło:
Acta Physica Polonica A; 2000, 98, 3; 303-323
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On Linear Birefringence Anomalies in Crystals of Triglycine Family
Autorzy:
Przesławski, J.
Powiązania:
https://bibliotekanauki.pl/articles/2010959.pdf
Data publikacji:
1999-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.80.Bh
78.20.Fm
Opis:
Temperature dependence of the linear birefringence in TGS crystal family has been studied with a high temperature resolution. Temperature derivatives of the linear birefringence are compared with the specific heat transients measured for triglycine sulphate, triglycine selenate, and triglycine fluoberyllate crystals. Detailed studies revealed an anomaly of the linear birefringence at about 310 K for two cuts (a*- and c-cut) of the TGS crystal.
Źródło:
Acta Physica Polonica A; 1999, 95, 6; 997-1004
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Dilatometric Properties of (CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O Crystals in Paraelectric and Ferroelectric Phases
Autorzy:
Podsiadła, D.
Czapla, Z.
Andriyevsky, B.
Myshchyshyn, O.
Powiązania:
https://bibliotekanauki.pl/articles/2011078.pdf
Data publikacji:
1999-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
64.70.Kb
78.20.Fm
Opis:
Experimental investigation of the thermal linear expansion l(T) and temperature dependencies of the interference optical path difference D(T) were carried out for (CH$\text{}_{3}$)$\text{}_{2}$ NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O crystal, in the range of 120-310 K for three crystal physical directions. Decrease in electrostriction coefficients g of crystal was observed on approaching the phase transition point T$\text{}_{c}$ ≈ 150 K in ferroelectric phase. Relative temperature changes of the lengthening δl/l and refractive index δn/(n-1) are of the same order of magnitude. Peculiarities of temperature dependence of dilatometric and optical parameters of (CH$\text{}_{3}$)$\text{}_{2}$NH$\text{}_{2}$Al(SO$\text{}_{4}$)$\text{}_{2}$·6H$\text{}_{2}$O testify for qualitative reconstruction of chemical bonds in the crystal when temperature changes in the same phase.
Źródło:
Acta Physica Polonica A; 1999, 96, 3-4; 409-416
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optical and Dilatometric Manifestations of Phase Transitions in K$\text{}_{2}$SeO$\text{}_{4}$ Crystal
Autorzy:
Andriyevsky, B.
Myshchyshyn, O.
Powiązania:
https://bibliotekanauki.pl/articles/1967887.pdf
Data publikacji:
1997-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.20.Fm
64.70.Kb
Opis:
Temperature dependencies of the characteristic optical paths difference D(Τ) of K2SeO4 crystal in the range of 80-295 K were measured using the Jamen type interferometer. Significant anomalies of D(Τ) dependencies in the vicinity of incommensurate-paraelectric phase transition (T$\text{}_{i}$ = 130 K) are observed. On the basis of D(Τ) temperature dependencies measured experimentally and linear expansion l(Τ) known, the temperature derivative of the refractive indices dn/dT are found to be negative in the ranges above and below the temperature T$\text{}_{i}$=130 K.
Źródło:
Acta Physica Polonica A; 1997, 92, 3; 557-562
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electric Polarization of Onsager Fluids. II. Birefringence. 3. Role of Universal Pairwise Interactions
Autorzy:
Prezhdo, V. V.
Tarasova, G. V.
Prezhdo, O. V.
Tyurin, S. A.
Akulova, O. N.
Ivanov, N. I.
Powiązania:
https://bibliotekanauki.pl/articles/1943971.pdf
Data publikacji:
1996-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.70.Dk
78.20.Fm
72.80.Jc
Opis:
A comparative analysis of several methods of interpretation of solvent influence on molar Kerr constants of solutes was done. The analysis was based on experimentally determined electro-optical and dielectric properties of binary solutions of organic substances with various polarities, polarizabilities and optical anisotropies. It was found that the role of universal van-der-Waals interactions treated via London-Debye-Keesom potentials was best accounted for by a modified orientational theory of Kerr effect that developed the ansatz of reactive field and local dielectric permittivity. An extrapolation method of determination of gas phase molar Kerr constants of solutes was deduced from the theory.
Źródło:
Acta Physica Polonica A; 1996, 89, 1; 47-59
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 21

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