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Wyszukujesz frazę "78.15.+e" wg kryterium: Temat


Tytuł:
An optical study to estimate orientational order parameter on some benzylideneaminophenylbenzoate liquid crystals
Autorzy:
Subhan, C.
Jeevan Kumar, R.
Panduranga, P.
Jayashreeand, B.
Fakruddin, K.
Powiązania:
https://bibliotekanauki.pl/articles/1070607.pdf
Data publikacji:
2016-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
42.79.Kr
78.15.+e
61.30.Gd
Opis:
The birefringence technique has been used for the evaluation of order parameter in the nematic phase along with the density measurements, which are needed for the calculation of molecular polarizabilities of the compounds. Birefringence and density studies have been carried out on the three liquid crystalline compounds viz.(1) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-butoxybenzoate(2) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(decycloxy)benzoate and(3) (E)-4-((4-hexyloxy)benzylidene)amino)phenyl 4-(tridecycloxy)benzoate.Using birefringence and density data the molecular polarizabilities are evaluated by two different internal field models due to Vuks and Neugebauer. The mean molecular polarizability of the compounds is also evaluated by employing modified Lippincott δ-function model. The results reveal that both the theoretical and experimental values obtained are very near to each other.
Źródło:
Acta Physica Polonica A; 2016, 129, 3; 284-288
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structural and optical properties of boron nitride grown by MOVPE
Autorzy:
Dąbrowska, A.
Pakuła, K.
Bożek, R.
Rousset, J.
Ziółkowska, D.
Gołasa, K.
Korona, K.
Wysmołek, A.
Stępniewski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1160531.pdf
Data publikacji:
2016-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Gh
78.30.Fs
78.20.-e
Opis:
Boron nitride layers were grown on sapphire substrate by metal organic vapor phase epitaxy system that was originally designed for growth of GaN. Structures were characterized by scanning electron microscopy, atomic force microscopy, the Raman spectroscopy, absorption and time resolved photoluminescence. Presented results confirm successful deposition of BN layers and gives information about basic properties of the material. The Raman line at 1370 cm^{-1} and absorption edges at 5.6-5.9 eV were observed which is related to hexagonal phase.
Źródło:
Acta Physica Polonica A; 2016, 129, 1a; A-129-A-131
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Pulsed Laser Power Annealing on Structural and Optical Characteristics of ZnSe Thin Films
Autorzy:
Aly, S.
Akl, Alaa
Howari, H.
Powiązania:
https://bibliotekanauki.pl/articles/1401905.pdf
Data publikacji:
2015-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.-z
68.55.jd
68.55.ag
78.70.Ck
81.15.Dj
78.20.-e
Opis:
Samples of ZnSe of the same film thickness (320 nm) have been thermally evaporated on unheated quartz substrates using high purity powder. The prepared films were subjected to pulsed laser annealing of two different powers. X-ray diffraction studies revealed that the as-deposited samples were polycrystalline cubic (zinc-blende type) structure. As the annealing power increases, the crystallinity of ZnSe films was improved with preferential orientation along the (111) direction parallel to the substrate surface. Microstructural characterizations have been evaluated using the Debye-Scherrer formula. The absorption coefficient as well as the energy gap for the as-deposited and the annealed samples were also reported.
Źródło:
Acta Physica Polonica A; 2015, 128, 3; 414-418
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of the Diffused Reflectance and Microstructure for the Phase Transformation of $KNO_{3}$
Autorzy:
Hafez, M.
Yahia, I.
Taha, S.
Powiązania:
https://bibliotekanauki.pl/articles/1398861.pdf
Data publikacji:
2015-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.05.cp
64.60.-i
61.43.Gt
78.20.-e
72.15.Eb
Opis:
Optical, micro-structural, thermal and electrical properties of the investigated potassium nitrate ($KNO_{3}$) samples were characterized by various techniques such as X-ray analysis, scanning electron microscopy, UV-VIS-NIR absorption and differential scanning calorimetry. The presence of structural phase transition is checked by differential scanning calorimetry, electrical and X-ray analysis measurement. The thermal energy required for such transformation is calculated and found to be 46.2 J/g. The activation energies of the electrical conduction for $KNO_{3}$ were found to be 0.236 eV for phase II and 0.967 eV for phase I. The optical band gaps of $KNO_{3}$ for the higher photon energy are calculated and equal to 5.03 and 5.01 eV for II and I phases, respectively and at lower photon energy, the values are equal to 3.84 and 3.80 eV for II and I phases, respectively. The data which leads to the interpretation of electronic spectra of potassium nitrate is possible to assume that the long wavelength part of absorption band corresponds to n-π* transition. Then, the short-wavelength part is probably due to the transition in a higher excited state of symmetry π-π*. The mean values of crystalline sizes are determined by scanning electron microscopy analysis. Such information can considerably aid in understanding the process of transformations near the phase crystal modifications at 129°C.
Źródło:
Acta Physica Polonica A; 2015, 127, 3; 734-740
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Boric Acid Content on the Structural and Optical Properties of MnS Films Prepared by Spray Pyrolysis Technique
Autorzy:
Bedır, M.
Öztaş, M.
Çelik, S.
Özdemır, T.
Powiązania:
https://bibliotekanauki.pl/articles/1205283.pdf
Data publikacji:
2014-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Rs
78.28.-e
61.72.Vv
61.05.cp
68.55.Jk
Opis:
Boron doped MnS films were obtained by the spray pyrolysis method using the boric acid ($H_3BO_3$) as dopant source at a substrate temperature of 350°C. The spray pyrolysis method has a wide range of application areas with a low cost well-suited for the manufacture of solar cells. The properties of boron doped MnS films were investigated as a function of doping concentration. The X-ray analysis showed that the films were polycrystalline fitting well with a hexagonal structure and have preferred orientation in the [002] direction. The optical band gap of the undoped and boron doped MnS films were found to vary from 3.38 to 3.20 eV. The changes observed in the energy band gap and structural properties of the films related to the boric acid concentration are discussed in detail.
Źródło:
Acta Physica Polonica A; 2014, 126, 3; 840-844
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
First-Principles Calculations of Structural, Electronic, Optical, and Thermodynamic Properties of CdS, CdTe and Their Ternary Alloys $CdS_{1-x}Te_{x}$ (0.0 ≤ x ≤1.0)
Autorzy:
Ameri, M.
Mesbah, S.
Al-Douri, Y.
Bouhafs, B.
Varshney, D.
Ameri, I.
Powiązania:
https://bibliotekanauki.pl/articles/1364167.pdf
Data publikacji:
2014-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.15.E-
63.20.dk
04.25.-g
78.66.Hf
73.61.At
Opis:
Using first-principle method, we investigate the structural, electronic, optical, and thermodynamic properties of the $CdS_{1-x}Te_x$ semiconductor alloys using generalized gradient approximation for the exchange-correlation potential calculation. The ground state properties are determined for the bulk materials (CdS and CdTe) in cubic phase. Quantities such as the lattice constants and bulk modulus of interest are calculated. Detailed comparisons are made with published experimental and theoretical data and show generally good agreement. The calculated lattice constants scale linearly with composition (Vegard's law). The microscopic origins of the bowing parameter were explained using the contributions from volume deformation, charge transfer and structural relaxation approach. The refractive index and optical dielectric constant for the alloys of interest were calculated by using different models. In addition, the thermodynamic stability of the alloys was investigated by calculating the critical temperatures of alloys.
Źródło:
Acta Physica Polonica A; 2014, 125, 5; 1110-1117
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nanostructure Formation during Amorphous Carbon Films Deposition
Autorzy:
Rutkuniene, Z.
Vigricaite, L.
Grigonis, A.
Powiązania:
https://bibliotekanauki.pl/articles/1366053.pdf
Data publikacji:
2014-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.uj
81.15.-z
78.20.-e
82.80.Gk
Opis:
Influence of Cu particles for the carbon nanostructures formation during a-C:H films deposition by plasma enhanced chemical vapor deposition method from pure acetylene gas plasma were analyzed in this work. Silicon wafer and Cu target were simultaneously bombarded by $Ar^{+}$ ions for the Cu particles deposition on the silicon before a-C:H films formation. It was obtained that hydrogenated silicon carbide forms on this defected Si/Cu surface during the first stage of carbon film deposition. Structure of a:C-H films and conditions of nanostructures formation depended on substrate temperature and Cu concentration in the film, then deposition time was 300 s.
Źródło:
Acta Physica Polonica A; 2014, 125, 6; 1303-1305
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis, Structural and Optical Properties of Mo-Doped ZnO Thin Films
Autorzy:
Mekki, A.
Tabet, N.
Powiązania:
https://bibliotekanauki.pl/articles/1219233.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.15.Aa
78.20.-e
61.05.cp
61.05.cj
Opis:
Transparent zinc oxide thin films doped with molybdenum have been prepared using a DC reactive magnetron sputtering on glass substrates from metallic ZnMo target. The three films, called A, B, and C, had 1.9 at.% Mo, 2.8 at.% Mo and 4.7 at.% Mo, respectively. The composition of the films was determined by X-ray photoelectron spectroscopy. The analysis of Mo 3 $d_{5/2}$ core level spectra indicated that Mo exist in the films in $Mo^{6+}$ oxidation state irrespective of the Mo content in the film. The X-ray diffraction spectrum of film A showed a texture along the 002 orientation, while that of film B showed two peaks, one at $θ ≈ 34.5°$ and the other at $≈ 36.5°$ corresponding to 002 and 101 orientations, respectively. Film C showed two small peaks corresponding to 100 and 110 orientations. Optical measurements showed that all three films had a transmittance of about 80%. The energy band gap showed a linear increase as Mo concentration increases from 3.29 eV to 3.38 eV. The atomic force microscopy image of film A showed a homogeneous morphology of the surface of the film, while the atomic force microscopy images of films B and C showed an inhomogeneous one.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 365-367
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermo-Optical Parameters of Amorphous a-C:N:H Layers
Autorzy:
Pieczyńska, E.
Jaglarz, J.
Marszalek, K.
Tkacz-Śmiech, K.
Powiązania:
https://bibliotekanauki.pl/articles/1377543.pdf
Data publikacji:
2014-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.60.Fs
78.20.-e
78.20.Ci
78.20.N-
78.30.Ly
81.05.U-
81.15.Gh
Opis:
Thermo-optical properties of hydrogenated amorphous carbon nitride layers (a-C:N:H) deposited on crystalline silicon by plasma assisted chemical vapour deposition were studied. The layers were characterized by the Fourier transform infrared spectroscopy and their chemical composition, i.e. [N]/[C] ratio, was determined by energy dispersive X-ray technique. The optic measurements were made by spectroscopic ellipsometer Wollam M2000 equipped with a heated vacuum chamber. The measurements of ellipsometric angles were carried out during heating the sample from room temperature to 300°C. Refractive index, extinction coefficient and the layer thicknesses were calculated by fitting the model of the layer to the ellipsometric data. The results confirm that at about 23°C the layer properties are changed. The measured thermo-optical parameters, dn/dT and dk/dT, show abrupt change from negative to positive values which can be explained by structure graphitization. Simultaneously, the bandgap decreases from 2.5 to 0.7 eV and the layer thickness drops to about 50% of the initial value.
Źródło:
Acta Physica Polonica A; 2014, 126, 6; 1241-1245
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of Modified Interference Wedge Method in Measurements of Indices of Refraction and Birefringence of Nematic Liquid Crystals
Autorzy:
Kowiorski, K.
Kędzierski, J.
Raszewski, Z.
Kojdecki, M.
Herman, J.
Miszczyk, E.
Piecek, W.
Powiązania:
https://bibliotekanauki.pl/articles/1399015.pdf
Data publikacji:
2013-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.15.+e
Opis:
Wedge cell filled with a homogeneously oriented nematic liquid crystal was exploited as an interference wedge to measuring indices of refraction. Interference fringes from the wedge were observed in polarised light in reflection or transmission mode of a polarisation microscope to determining ordinary and extraordinary indices of refraction or birefringence (i.e. anisotropy of both indices). The interference fringes close to wedge apex were uniform and could be well described in two-beam interference approximation. The refractive indices were computed with using simple formulae involving only distances between subsequent fringes in a cell filled with the liquid crystal and an empty reference cell. Several new highly-birefringent nematic mixtures produced in the Military University of Technology were investigated. The 6CHBT nematic was used as the reference material.
Źródło:
Acta Physica Polonica A; 2013, 124, 6; 946-948
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behavior of $Co^{2+}$ Cations in the Aqueous and Alcoholic Solution of $CoCl_2 \cdot 6H_2O$
Autorzy:
Petkova, P.
Nedkov, V.
Powiązania:
https://bibliotekanauki.pl/articles/1399687.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.15.+e
78.40.Dw
Opis:
We investigated the optical properties of $Co^{2+}$ cations in the aqueous and alcoholic solution of $CoCl_2 \cdot 6H_2O$ at room temperature. We measured the absorption spectra of these solutions in the spectral region 395-800 nm. The Racah parameters and the exchange integrals of the aqueous complex $[Co(H_2O)_6]^{2+}$ are calculated. The parameters $D_{t}$ and $D_{s}$ are also calculated on the basis of our experimental data. The parameters δ σ and δπ which are connected with the symmetry of this complex are also determined.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 207-208
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of Optical Properties of Ag, Cu, and Co Nanoparticles Synthesized in Organic Medium
Autorzy:
Kaminskienė, Ž.
Prosyčevas, I.
Stonkutė, J.
Guobienė, A.
Powiązania:
https://bibliotekanauki.pl/articles/1400397.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.15.+e
78.20.Bh
78.20.Ci
42.25.Bs
Opis:
The surface plasmon resonance evaluation of colloidal metal nanoparticles, synthesized in organic medium, is reported in this work. Metal salts were dissolved in dioxane/AOT solution and reduced by hydrazine hydrate under vigorous stirring. Optical properties of obtained colloidal nanoparticles were investigated by UV-VIS spectroscopy. Theoretical predictions of optical properties of metal nanoparticles were made by means of the Mie theory and the Drude free-electron model. Geometrical parameters and distribution of metal nanoparticles in colloidal solutions were characterized by atomic force microscopy. The results show that Ag, Cu, and Co nanoparticles, synthesized in organic medium distinguish plasmonic properties. Surface plasmon resonance bands were obtained in all cases: Ag - at 430 nm, Cu - at 570 nm, Co - at 350 nm (SPR1) and 430 nm (SPR2). Comparing theoretical evaluation of nanoparticles size with atomic force microscopy analysis, we can assume that our calculations are accurate. It was found that dominating nanoparticles diameter in Ag colloidal solution is ≈ 150 nm, in Cu colloidal solution is ≈ 70 - 80 nm and in Co colloidal solution is ≈ 150 nm. It can be concluded that nanoparticles with enhanced plasmonic properties synthesized in organic medium can be widely used in order to increase efficiency of various optical elements.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 111-114
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Optical Aspects of Thermally Evaporated Lead Oxide Thin Films
Autorzy:
Aly, S.
Kaid, M.
El-Sayed, N.
Powiązania:
https://bibliotekanauki.pl/articles/1399301.pdf
Data publikacji:
2013-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
77.55.-g
81.15.-z
78.20.-e
78.20.Ci
78.40.-q
Opis:
The optical properties of lead oxide samples prepared using thermal evaporation technique on unheated glass substrates with different film thicknesses have been studied. The structural characteristics of a lead oxide sample was investigated using X-ray diffraction and it is confirmed to be in the amorphous state. The optical properties of the prepared films were studied by transmittance and reflectance measurements, and the integrated transmittance ($T_\text{UV}$, $T_\text{VIS}$ and $T_\text{Sol}$) in ultraviolet, visible and solar regions was calculated and found to be affected by film thickness. The dependence of absorption coefficient on wavelength was also reported. The energy gap was calculated and has been observed around 3.7 eV.
Źródło:
Acta Physica Polonica A; 2013, 124, 4; 713-716
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:
Equimolecular Mixture of Calamitic and Bent-Core Thiobenzoates
Autorzy:
Chruściel, J.
Wantusiak, B.
Ossowska-Chruściel, M.
Powiązania:
https://bibliotekanauki.pl/articles/1419573.pdf
Data publikacji:
2012-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.30.-v
64.70.M-
78.15.+e
Opis:
This article reports on the new results on phase transitions, mesomorphic and electro-optical properties of new equimolecular mixture of calamitic and bent-core thiobenzoates. Two following liquid crystals were the components of the binary mixture: (S)-(+)-4-(1-methylheptyloxy)biphenyl 4'-octylthiobenzoate (MHOBS8) having rode-like, calamitic-chiral molecules possessing among others ferroelectric smectic C (SmC*) and bis [4-(4'-octylphenylthiocarbonyl)phenyl] isophtalates from a homologous series of banana-shaped thioesters, referred to as IFOS8, where n = 8 denoted the number of carbon atoms in terminal alkyl chains in both mesogens, synthesized by us. The IFOS8 compound has two enantiotropic phases: B2 with antiferroelectric order and B6. The mesomorphic properties were investigated by means of three complementary methods: differential scanning calorimetry, polarized light optical microscopy, and transmitted light intensity. Electro-optical measurements were also carried out.
Źródło:
Acta Physica Polonica A; 2012, 122, 2; 375-377
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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