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Tytuł:
Structure and Magnetic Properties of Iron/Iron-Oxide Nanoparticles Prepared by Precipitation from Solid State Solution
Autorzy:
Milkovič, O.
Gamcová, J.
Sopko, M.
Škorvánek, I.
Powiązania:
https://bibliotekanauki.pl/articles/1030258.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
Opis:
The influence of precipitation temperature on structural and magnetic properties of iron/iron-oxide nanoparticles is investigated. Nanoparticles were prepared by precipitation of γ-Fe precipitates in Cu-Fe solid solution and subsequently isolated by matrix dissolution. Precipitation annealing temperatures were 773, 873, and 973 K. Nanoparticles core-shell structure and morphology were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction. These measurements showed that average diameter of nanoparticles increases with precipitation temperature from 8.5 nm to 20.5 nm. The measurements of magnetization as a function of temperature and applied field have been performed by SQUID magnetometer in temperature range from 5 K to 200 K.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 747-749
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure characterization of noble metal-silica nanocomposites
Autorzy:
Zienkiewicz-Strzałka, M.
Pikus, S.
Powiązania:
https://bibliotekanauki.pl/articles/1075855.pdf
Data publikacji:
2016-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
Opis:
The presence of highly dispersed metal particles on solid supports with well-defined microstructure is important in the field of functional materials, active catalysts as well as bionanomaterials for medical applications. Noble metal nanostructures, in particular silver, palladium, and platinum nanoparticles were formed from ammine complexes ([Pt(NH₃)₄]Cl₂, [Ag(NH₃)₂]OH, and [Pd(NH₃)₄]Cl₂) and supported on high ordered mesoporous silica (SBA-15) and aluminosilica matrix. In this work, the distribution, composition and crystal structure of supported noble metal nanoparticles were determined and characterized. Finally the stability of incorporated nanostructures was confirmed. The microstructures of the obtained samples were analyzed by high resolution transmission electron microscopy. Obtained results indicated that developed procedures of synthesis and modification of mesoporous ordered silica or their derivate by proposed nanostructures are effective and allow to obtain new nanocomposites and nanocatalysts in repeatable and controlled way.
Źródło:
Acta Physica Polonica A; 2016, 130, 4; 972-974
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Porous Silicon Based Sensor for Organic Vapors
Autorzy:
Kayahan, E.
Bahsi, Z.
Oral, A.
Sezer, M.
Powiązania:
https://bibliotekanauki.pl/articles/1193711.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.07.Df
Opis:
Porous silicon (PS) has been an attractive material for enhancing optical properties of silicon. Its large surface area for sensor applications and compatibility with silicon-based technologies has been a driving force for further technology development. In this study, ability of PS to sense at room temperature organic vapors such as acetone, trichloroethylene and hexane, which are harmful to human health, has been investigated. Electrical (DC) and photo-luminescence (PL) measurements in a controlled atmosphere (nitrogen gas and an organic vapor mix) were performed to test the sensor response towards the organic vapors. It was found that PS surface is very sensitive against these vapors. The experimental results also suggested that PS can be used as a new electro-optical material to sense harmful vapors.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1400-1402
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Porous Silicon Based Humidity Sensor
Autorzy:
Kayahan, E.
Powiązania:
https://bibliotekanauki.pl/articles/1401435.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.07.Df
Opis:
Porous silicon (PS) is well known as a photovoltaic material. However, in the last couple of years, research has focused on the use of porous silicon as chemical-biological sensors. This paper discusses the use of PS as an optical humidity sensor. Photo-luminescence (PL) quenching measurements in a controlled humidity atmosphere (mixed Nitrogen gas and water vapor) were performed to test the sensor response towards the water vapor. Surface morphologies of the PS samples were characterized by a scanning electron microscopy (SEM) and structural properties were investigated via Fourier Transform Infrared (FTIR) spectroscopy. It was found that PS surface is very sensitive to the water vapor. The experimental results suggested that PS surface is a promising candidate material to be used as a humidity sensor.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1397-1399
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Methanol Vapor Sensing by Porous Silicon
Autorzy:
Yılmaz, O.
Kayahan, E.
Gören, F.
Dumludağ, F.
Powiązania:
https://bibliotekanauki.pl/articles/1195231.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.07.Df
Opis:
In this study, methanol vapor sensing of porous silicon was investigated. The porous silicon samples were anodized in HF based solution and rinsed with ethanol or deionized water after the anodisation. Porous silicon surface is very sensitive for methanol vapor sensing and the sensitivity affect from the rinsing procedure of porous silicon. The experimental results show that porous silicon is a promising candidate material for sensing methanol vapor.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 288-289
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Water-Sorption Effects near Grain Boundaries in Modified MgO-Al₂O₃ Ceramics Tested with Positron-Positronium Trapping Algorithm
Autorzy:
Klym, H.
Ingram, A.
Shpotyuk, O.
Hadzaman, I.
Chalyy, D.
Powiązania:
https://bibliotekanauki.pl/articles/1030933.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
07.07.Df
Opis:
Water-sorption processes near grain boundaries in the MgO-Al₂O₃ ceramics prepared at different temperatures were studied using positron annihilation lifetime spectroscopy. Numerical values of three- and four-component treatment of spectra were used for study of physical- and chemical-sorption processes in the MgO-Al₂O₃ ceramics. To apply mathematical approach in the form of positron-positronium trapping algorithm into three-component treatment of positron annihilation lifetime spectra it was shown that physical-adsorbed water did not modify positron trapping sites near grain boundaries in water-immersed MgO-Al₂O₃ ceramics and localized mainly in nanopores. The chemically-adsorbed water modifies structural extended defects located near grain boundaries that accompanied them by void fragmentation at water desorption.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 864-868
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermoelectric properties of Ca₂Sn/Ca₃SnO
Autorzy:
Kalinowski, L.
Fijałkowski, M.
Goraus, J.
Powiązania:
https://bibliotekanauki.pl/articles/1047668.pdf
Data publikacji:
2018-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Jf
66.70.Df
Opis:
We measured thermopower, thermal conductivity and electrical resitivity for Ca₂Sn sample across 4-350 K temperature range. Contrary to expectations from recent DFT based calculations the thermopower is not particularly large, reaching 7 μV at 350 K. The thermoelectric figure of merit renders this material in unmodified form practically unusable for thermoelectric aplications.
Źródło:
Acta Physica Polonica A; 2018, 133, 3; 384-386
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature Sensitive Spinel-Type Ceramics in Thick-Film Multilayer Performance for Environment Sensors
Autorzy:
Hadzaman, I.
Klym, H.
Shpotuyk, O.
Brunner, M.
Powiązania:
https://bibliotekanauki.pl/articles/1550632.pdf
Data publikacji:
2010-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
07.07.Df
Opis:
Temperature sensitive thick films based on spinel-type semiconducting ceramics of different chemical composition $Cu_{0.1}Ni_{0.1}Co_{1.6}Mn_{1.2}O_{4}$ (with $p^{+}$-types of electrical conductivity), $Cu_{0.1}Ni_{0.8}Co_{0.2}Mn_{1.9}O_{4}$ (with p-types of electrical conductivity) and their multilayer $p^{+}$-p structures were fabricated and studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170°C. It is shown that degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p- and $p^{+}$-conductive thick films. The $p^{+}$-p structures were of high stability, the relative electrical drift was not greater than 1%.
Źródło:
Acta Physica Polonica A; 2010, 117, 1; 234-237
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inverted Rib Waveguides - Theoretical Analysis of Sensing Properties
Autorzy:
Tyszkiewicz, C.
Powiązania:
https://bibliotekanauki.pl/articles/1399407.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Gn
07.07.Df
Opis:
Optical waveguides are fundamental components of chemical and biochemical evanescent wave sensors. Presented work is devoted to theoretical investigations of homogeneous and surface sensitivity characteristics of the inverted rib waveguide structure. The inverted rib waveguide discussed in this paper is composed of an ion-exchange based channel waveguide formed in a glassy substrate and a uniform, high refractive index, sol-gel derived $SiO_2-TiO_2$ film. Characteristics of a homogeneous sensitivity, a surface sensitivity and fundamental modes sensitivity differences in function of a uniform film thickness and a maximal refractive index contrast of the gradient index channel waveguide are given. The influence of the $SiO_2-TiO_2$ film thickness on sensitivity characteristics is discussed. The analysis is carried out on a bases off the effective index method used with the transfer matrix method.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 582-585
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Free Space Optical Detection Module Operating at the Wavelength Range of 8-12 μm
Autorzy:
Gutowska, M.
Nowakowski, M.
Bielecki, Z.
Mikolajczyk, J.
Szabra, D.
Paliwoda, R.
Pedzinska, M.
Pawluczyk, J.
Gawron, W.
Powiązania:
https://bibliotekanauki.pl/articles/1506789.pdf
Data publikacji:
2010-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.07.Df
85.60.Bt
Opis:
The paper presents the construction and test results of a long-term radiation detector module for free space optical communication operated at the wavelength range of 8-12 μm. In the module a Polish detector manufactured in the company Vigo System S.A. was applied. High sensitivity of the detection module was achieved through a multi-layered heterostructure HgCdTe with immersion lens, which is optimized for the radiation detection at the wavelength of 10 μm. Detector noises were reduced as a result of detector cooling by means of four-stage thermoelectric cooler. The developed detection module is dedicated to design a next-generation optical data link. The link will be characterized by a greater range in difficult weather conditions in relation to the currently offered links operating at the shorter wavelengths.
Źródło:
Acta Physica Polonica A; 2010, 118, 6; 1143-1147
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optopneumatic Detector with Platinum Flow Sensor
Autorzy:
Jasek, K.
Budzyński, T.
Stryszak, E.
Powiązania:
https://bibliotekanauki.pl/articles/1796139.pdf
Data publikacji:
2009-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.Iv
07.07.Df
Opis:
In optopneumatic detectors, operating on principle of the gaseous infrared detectors, the radiation absorbed in the gas is changed into pressure fluctuation, followed by periodic flow of the gas between detector chambers. This flow is usually measured by means of hot-wire or hot-film anemometers. Their parameters in a great measure determine the quality of the whole detector. The flow sensor used in optopneumatic detectors should have short time constant, high sensitivity, possibility to distinguish the flow direction, and high chemical resistance to the gas which the detector is filled with. To meet these requirements, micro-electro-mechanical system flowmeter consisting of two platinum hot films placed in series in the flow direction was made. Platinum film of 0.3 μm thickness was deposited by magnetron spattering on thin membrane, which was composed of polysilicon substrate (0.5 μm) and two $Si_{3}N_{4}$ layers with thickness of 0.1 μm. The obtained platinum elements have resistance of 32 Ω and temperature coefficient of resistance of 2.31× $10^{-3}$/°C. Hot film does not change its parameters up to 350°C, whereas typical working temperature of such films ranged from 150 to 200°C. Anemometer characteristics and voltage-current dependences were determined in this work. The linear range of operation from 0 to 10 ml/min and sensitivity suitable for optopneumatic detectors were found. The time constant of the flowmeter is equal to 11 ms (95% of final signal), that enables the detector to operate with frequency up to 100 Hz. The flowmeters were applied in detectors filled with sulphur dioxide and were tested for six months at temperature of hot-film about 150°C. During that time no changes of their parameters were observed.
Źródło:
Acta Physica Polonica A; 2009, 116, 3; 321-324
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Hyper-Solitons in Nematic Liquid Crystals
Autorzy:
Strinic, A.
Petrović, M.
Belić, M.
Powiązania:
https://bibliotekanauki.pl/articles/1791208.pdf
Data publikacji:
2009-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.65.Tg
Opis:
We study laser light propagation in a cell containing a liquid crystal in the nematic phase. We launch hyper-Gaussian beams and follow their behavior within the cell, in time and in three spatial dimensions, utilizing an appropriately developed theoretical model and a numerical procedure based on the fast Fourier transform. We demonstrate the formation of stable "hyper-soliton" breathers in a narrow region of beam intensities, for fixed other parameters. Hyper-solitons are similar in appearance and behavior to the usual solitons, formed by launching the usual Gaussian beams; however noticeable differences persist.
Źródło:
Acta Physica Polonica A; 2009, 116, 4; 510-512
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
In Situ Monitoring of Electroepitaxial Growth of Thick AlGaAs Layers
Autorzy:
Żytkiewicz, Z. R.
Powiązania:
https://bibliotekanauki.pl/articles/1929752.pdf
Data publikacji:
1993-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Df
81.10.Dn
Opis:
In situ growth monitoring technique has been used to analyse growth disturbances during the liquid phase electroepitaxial growth of thick AlGaAs layers. It allowed us to explain the nature of growth instability occurring at the end of the growth and affecting the maximum thickness of AlGaAs layers obtainable by liquid phase electroepitaxy.
Źródło:
Acta Physica Polonica A; 1993, 84, 4; 777-780
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Raman Scattering from Acoustic Phonons Confined in Spherical Nanoparticles
Autorzy:
Kostić, R.
Powiązania:
https://bibliotekanauki.pl/articles/1807815.pdf
Data publikacji:
2009-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.46.Df
63.22.-m
Opis:
Low-frequency Raman scattering from small spherical particles is analyzed. Frequencies of vibrational modes are calculated in elastic continuum approximation, which considers one nanoparticle as homogeneous elastic sphere. Parameters of this model are transverse $(v_T)$ and longitudinal $(v_L)$ sound velocities of material, i.e. elastic properties of bulk material. Frequencies of vibrational modes are scaled as function of mentioned bulk parameters for symmetric l=0 and quadrupolar l=2 spheroidal modes, in the case of stress-free boundary conditions. Calculated values are compared with the low-frequency Raman experimental results from literature (Ge, Si, CdS, CdSe, $CeO_2$, ...). These calculated relations can be practically used to examine nanoparticles of any bulk material. We presented also a procedure how to establish $v_L$ and $v_T$ of material from low-frequency Raman spectra and dimension d of particles.
Źródło:
Acta Physica Polonica A; 2009, 116, 1; 62-64
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nonlinear Optical Measurements of Elastic Constants in Nematic Liquid Crystal
Autorzy:
Bajdecki, W. K.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2008272.pdf
Data publikacji:
1999-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
A new method of measurements of elastic constants of nematic liquid crystals by applying the nonlinear optical effect is presented. This method bases on measurements of a value of the reorientation threshold in a liquid crystal layer while the reorientation is induced by the light beam passing through the layer. The obtained results are in a qualitative compatibility with the results obtained by classical methods.
Źródło:
Acta Physica Polonica A; 1999, 95, 5; 793-800
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reorientational Nonlinear Phenomena in Thin Nematic Liquid Crystals Layer
Autorzy:
Brzdąkiewicz, K.
Bajdecki, W. K.
Kozanecka, A.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2023855.pdf
Data publikacji:
2001-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
In this paper the detailed study of the self-diffraction phenomena due to reorientational optical nonlinearity in nematic liquid crystalline cell is presented. The optical nonlinear effect is additionally modified by external low-frequency electric field. The dependence of nonlinear response on light polarization is also analyzed. The theoretical investigations are compared with experimental results and the theoretical predictions are in excellent agreement with experimental data.
Źródło:
Acta Physica Polonica A; 2001, 99, 1; 183-192
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electroepitaxial Growth of GaSb and AlGaSb Thick Epitaxial Layers
Autorzy:
Zytkiewicz, Z. R.
Dobosz, D.
Powiązania:
https://bibliotekanauki.pl/articles/1934052.pdf
Data publikacji:
1995-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Df
81.10.Dn
Opis:
Semi-bulk epitaxial layers of GaSb and AlGaSb up to 3 and 1 mm thick, respectively, were successfully grown by the liquid phase electroepitaxy on GaSb substrates. The growth procedure allowed us to achieve high crystallographic perfection as well as compositional uniformity of ternary layers.
Źródło:
Acta Physica Polonica A; 1995, 88, 5; 965-968
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spatial Optical Solitons in Bulk Nematic Liquid Crystals
Autorzy:
Assanto, G.
Peccianti, M.
Conti, C.
Powiązania:
https://bibliotekanauki.pl/articles/2035665.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.65.Tg
Opis:
We present an overview of our recent experimental results on two-dimensional optical spatial solitons in voltage biased planar cells with nematic liquid crystals. Excitation, induced waveguiding, and interactions are illustrated and interpreted in terms of the inherent re-orientational, non-resonant and nonlocal nonlinear response.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 161-167
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modeling of Spatial Solitons in Twisted Nematics Waveguides
Autorzy:
Karpierz, M. A.
Brzdąkiewicz, K. A.
Nguyen, Q. V.
Powiązania:
https://bibliotekanauki.pl/articles/2035666.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.Wi
42.70.Df
Opis:
Theoretical analysis of light beam propagation in twisted nematic liquid crystalline waveguides is presented. Due to the optical reorientation nonlinearity, the light beam changes the direction of propagation and optical spatial soliton is formed. Modeling of such behavior is presented by using (2+1)-dimensional vector beam propagation method as well as simplified (1+1)-dimensional method. Although both approaches give similar results, the differences are discussed in detail.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 169-175
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamical Electro-Optical Characterization of Policryps Gratings
Autorzy:
Abbate, G.
Marino, A.
Vita, F.
Powiązania:
https://bibliotekanauki.pl/articles/2035667.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.70.Df
42.79.Kr
Opis:
We have studied the dynamical response at 633 and 1550 nm of a new polymer-liquid crystal composite, realized in a form of a thick grating. This composite is known as Policryps, an acronym that stands for "Polymer Liquid Crystals Polymer Slides", because it shows a sequence of polymeric sheets alternated by layers containing only liquid crystal. Policryps gratings can be electrically switched between diffracting and non-diffracting states with a good diffraction efficiency in the visible region. After optimization of their performances, including response time, in the near infrared region, they can be conveniently proposed as a key component in photonic devices for telecom applications. Our results show very interesting response times ranging from 1 to 3 ms (switching on) and from 0.1 to 0.4 ms (switching off). Furthermore, switching ON times appear to be ruled by two different physical mechanisms with characteristic times differing by one order of magnitude. A deeper insight of these mechanisms might lead to response times, all in the submillisecond range.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 177-186
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Light Polarization on Reorientation Nonlinearity in Nematic Liquid Crystals
Autorzy:
Brzdąkiewicz, K. A.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2035686.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
Nematic liquid crystals are characterized by a giant optical nonlinearity which has its origin in the molecular reorientational phenomenon. Uniqueness of this nonlinear mechanism causes that response of the medium is dependent on many conditions. Among various circumstances, both an initial alignment of liquid crystal cell and geometry of the system are very important, but in this paper a significant role of light polarization in nonlinear effects observed in nematics is emphasized. Additionally, it is underlined that dependence on light polarization does not have only trivial aspect of initial conditions. More complex seems to be the fact that due to the high optical anisotropy of the medium the state of light polarization is changing on the way of beam propagation. As a consequence, the modifications of molecular orientation in the liquid crystal cell are strongly dependent upon light polarization.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 195-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Discrete Space-Time by Means of the Weyl-Dirac Theory
Autorzy:
Agop, M.
Chicos, L.
Gîrţu, M.
Powiązania:
https://bibliotekanauki.pl/articles/2047353.pdf
Data publikacji:
2007-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
04.20.Cv
05.45.Df
Opis:
A connection between the Weyl-Dirac theory and scale relativity theory through the hydrodynamic models (relativistic and non-relativistic approaches) is established. In such conjecture, considering that the motions of the microparticles take place on continuous but non-differentiable curves i.e. on fractals, a Weyl-Dirac type equation was found. Some correspondences with known hydrodynamic models, particularly Białynicki-Birula's approach, are analyzed. All these results reflect the fractal structure of the space-time (a concept in agreement with the new ideas on the space-time)
Źródło:
Acta Physica Polonica A; 2007, 112, 1; 3-12
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nodal Domains in Chaotic Microwave Rough Billiards with and without Ray-Splitting Properties
Autorzy:
Hul, O.
Savytskyy, N.
Tymoshchuk, O.
Bauch, S.
Sirko, L.
Powiązania:
https://bibliotekanauki.pl/articles/2044609.pdf
Data publikacji:
2006-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.45.Mt
05.45.Df
Opis:
We study experimentally nodal domains of wave functions (electric field distributions) lying in the regime of Breit-Wigner ergodicity in the chaotic microwave half-circular ray-splitting rough billiard. Using the rough billiard without ray-splitting properties we also study the wave functions lying in the regime of Shnirelman ergodicity. The wave functions Ψ$\text{}_{N}$ of the ray-splitting billiard were measured up to the level number N=204. In the case of the rough billiard without ray-splitting properties, the wave functions were measured up to N=435. We show that in the regime of Breit-Wigner ergodicity most of wave functions are delocalized in the n, l basis. In the regime of Shnirelman ergodicity wave functions are homogeneously distributed over the whole energy surface. For such wave functions, lying both in the regimes of Breit-Wigner and Shnirelman ergodicity, the dependence of the number of nodal domains Ɲ$\text{}_{N}$ on the level number N was found. We show that in the regimes of Breit-Wigner and Shnirelman ergodicity least squares fits of the experimental data reveal the numbers of nodal domains that in the asymptotic limit N→∞ coincide within the error limits with the theoretical predictionƝ$\text{}_{N}$/N≃ 0.062. Finally, we demonstrate that the signed area distribution Σ$\text{}_{A}$ can be used as a useful criterion of quantum chaos.
Źródło:
Acta Physica Polonica A; 2006, 109, 1; 73-87
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of External Electric Field on Time of Nonlinear Optical Reorientational Effect in Nematics
Autorzy:
Bajdecki, W. K.
Karpierz, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/2035684.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.65.-k
42.70.Df
Opis:
Nonlinear reorientation phenomena in nematic liquid crystals cause extremely large refractive index changes. However, this effect is relatively slow and the determination of the time necessary to appearing or disappearing of the nonlinear effect is an important issue. In this work we present measurements of the time of increasing the nematics reorientation induced by the light beam passing through the liquid crystalline layer. The influence of external low-frequency electric field suppressing reorientation is also reported. The obtained results describing relations between time and optical power of light as well as between time and external electric field intensity are in good agreement with theory.
Źródło:
Acta Physica Polonica A; 2003, 103, 2-3; 187-193
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the High Compositional Uniformity of Thick GaAlAs Layers Grown by Liquid Phase Electroepitaxy
Autorzy:
Żytkiewicz, Z. R.
Miotkowska, S.
Powiązania:
https://bibliotekanauki.pl/articles/1923664.pdf
Data publikacji:
1992-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Df
81.10.Dn
Opis:
The results of electroepitaxial growth of thick GaAlAs layers on GaAs substrates are presented. It is experimentally proven that effective convective mixing of the solution volume results in the compositional uniformity of GaAlAs layers, even in spite of the high compositional non-uniformity of the material supplying the solutes (Al, As) to the solution during the growth of the layers. For the first time this allowed us to grow uniform GaAlAs layers with thicknesses up to 200-300 μm in a wide composition range from a small (5 g) amount of solution.
Źródło:
Acta Physica Polonica A; 1992, 82, 5; 765-768
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
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