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1

Reflectivity spectra of some conducting BETS salts

100%

Kaplunov M. G. , Kushch N. D. , Krasnikova S. S.

Materials Science Poland

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2004

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tom Vol. 22, No. 4

359--364

EN

We have measured the polarized reflectivity spectra of three BETS-based organic metals with the a-phase structure: a-(BETS)2NH4Hg(SCN)4 (I), a-(BETS)2TlHg(SeCN)4 (II), and a-(BETS)2Cu5I6 (III) in the range of 600-6500 cm-1. The spectra exhibit a metallic-type reflection with the plasma edge about 4000-5000 cm-1 and high reflectivity at low frequencies. The electron-vibrational bands observed in the range of 1200-1400 cm-1 are due to the interaction of the intramolecular vibrational modes of BETS with conduction electrons.

2

Disorder-induced natural quantum dots in InAs/GaAs nanostructures

100%

Babiński A.

Opto-Electronics Review

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2018

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tom Vol. 26, No. 1

73--79

EN

Properties of excitons confined to potential fluctuations due to indium distribution in the wetting layer which accompany self-assembled InAs/GaAs quantum dots are reviewed. Spectroscopic studies are summarized including time-resolved photoluminescence and corresponding single-photon emission correlation measurements. The identification of charge states of excitons is presented which is based on results of a theoretical analysis of interactions between the involved carriers. The effect of the dots’ environment on their optical spectra is also shown.

3

First-principles calculations to investigate structural, electronic and optical properties of (AlSb)m/(GaSb)n superlattices

80%

Caid M. , Rached D.

Materials Science Poland

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2020

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tom Vol. 38, No. 2

320--327

EN

The structural, electronic and optical properties of (AlSb)m/(GaSb)n (m-n: 1-1, 2-2, 1-3 and 3-1) superlattices are investigated within the density functional theory (DFT) by using the last version of the first principles full potential linear muffin tin orbital method (FP-LMTO) as implemented in LmtART 7.0 code. The exchange and correlation potential is treated by the local density approximation (LDA) for the total energy calculations. Our calculations of the band structure show that the superlattices (n ≠ 1) have a direct band gap Γ-Γ. The optical constants, including the dielectric function ϵ(w), the refractive index n(w) and the reflectivity R(w) are calculated and discussed.

4

Structural and optical properties of nanostructured bismuth oxide

80%

Ali R. S.

International Letters of Chemistry, Physics and Astronomy

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2014

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tom Vol. 15

64--72

EN

Thin films of bismuth oxide have been prepared utilizing vacuum evaporation. XRD anyalysis reveal that all the films were tetragonal polycrystalline structure with a preferred orientation along (002) plane. SEM images indicate that the grain size fall in the category of nanosize. AFM results assure that the nanonstructure behavior of thin films. Optical studies show that these films have a direct transition with optical energy gap equal to 2.5 eV.

5

Zinc Oxide nanoparticles synthesis by use of aqueous extracts of Muntingia calabura L.

80%

Manokari M. , Shekhawat M. S.

World News of Natural Sciences

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2019

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tom 22

31-40

EN

Biological synthesis of metal nanoparticles gained worldwide interest due to their rapid, non-toxic, economical, single-step technique and eco-friendly alternative. Green-chemical approach of production of Zinc Oxide (ZnO) nanoparticles (NPs) has been exploited in the field of medicine, food packaging, nano-optical and electrical devices. Muntingia calabura is a multipotent medicinal plant with astounded biological activities and phytoconstituents. The nanoparticles obtained using aqueous extracts of various parts of M. calabura were characterized with UV-VIS spectroscopy to obtain information concerning the optical properties of synthesized ZnO nanoparticles. The proposed green and economical method could be used for large scale production of nanostructures because of its advantages over other physical and chemical methods.

6

Simulation of optical spectra of novel Tl4CdI6 and Tl4HgI6 optoelectronic crystals

80%

Franiv V. , Bovgyra O. , Kushnir O. , Franiv A. , Plucinski K. J.

Optica Applicata

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2014

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tom Vol. 44, nr 2

317--326

EN

The results of calculations using local density approximation and generalized gradient approximation: the total energy depending on the volume of the unit cell, the distribution of the total density of states and the partial contributions of electronic orbitals in the band structure of Tl4CdI6 and Tl4HgI6 crystals are shown in this paper. The spectra of the real part of the dielectric permittivity, the spectra of the imaginary part of permittivity, the reflection spectra and the absorption coefficient of both crystals are obtained using the Kramers–Kronig method. A comparative analysis of theoretical calculations with experimental data is carried out. Substantial influence of electron–phonon broadening is shown.

7

On the possibility of using arc plasma melting technique in preparation of transparent yttria ceramics

80%

Kruk A. , Jany B. R. , Owczarczyk K. , Madej D.

Optica Applicata

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2019

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tom Vol. 49, nr 2

355--364

EN

A state-of-the-art fabrication of Y2O3 transparent ceramic by arc plasma synthesis using commercial micron-size powders is reported. The morphological observations of the surface by scanning electron microscope shows that a dense microstructure can be obtained. Arc melted samples are made of a white core and transparent layer. X-ray diffraction studies and also Raman spectroscopy confirm that only one phase occurred in the core and in the transparent layer, and that the physicochemical difference exists. The obtained Y2O3 shell ceramics have pores but also relative low absorbance in the VIS-NIR region after double side polishing. The optical band gap and the refractive index are reported. It is concluded that arc plasma melting allows obtaining quickly (10 minutes) dense and highly transparent polycrystalline samples, especially in the VIS-IR spectral region.

8

Electronic and optical properties of Mn–S co-doped anatase TiO2 from first-principles calculations

80%

Wu G. , Zheng S. K. , Yan X.

Materials Science Poland

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2016

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tom Vol. 34, No. 1

38--44

EN

The electronic and optical properties of Mn–S co-doped anatase TiO2 were calculated using the plane-wave-based ultrasoft pseudopotential density functional method within its generalized gradient approximation (GGA). The calculated results show that the band gap of Mn–S co-doped TiO2 is larger than that of the pure TiO2, and two impurity bands appear in the forbidden band, one of which above the valence band plays a vital role for the improvement of the visible light catalytic activity. The Mn–S co-doped anatase TiO2 could be a potential candidate for a photo catalyst because of its enhanced absorption ability of visible light.

9

The influence of corrosion process on spectral properties of glassy coatings

80%

Siwulski S. , Nocuń M.

Optica Applicata

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2008

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tom Vol. 38, nr 1

217-223

EN

Glassy enamels are characterized by high chemical durability. Their chemical resistance properties, however, differ from those observed for conventional oxide glasses. This is because of their specific chemical composition and microstructure determined by enamel technology. In longer periods of exploitation in corroding conditions glassy coatings deteriorate continuously, the most significant changes taking place in the near-surface region. The main goal of this work was to establish the influence of chemical corrosion on spectral properties of glassy coatings. Changes in microstructure, gloss and reflectance were studied using electron microscopy and reflectance spectroscopy. It was confirmed that enamels based on pigments have higher durability than enamels coloured by ion dyes.

10

Optical Characterization of NiO Doped Fe2O3 thin Films Prepared by Spray Pyrolysis Method

80%

Chiad S. S.

International Letters of Chemistry, Physics and Astronomy

|

2015

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tom Vol. 45

50--58

EN

In this paper, the Fe2O3 thin film were prepared with various ratios doping of NiO by spray pyrolysis method on glass substrate temperature 400 ºC. The initial solution was including a 0.1 M/L for both NiCl2 and FeCl3 diluted with redistilled water and a few drops of HCl. The effect of NiO-doping on optical properties were studied. UV-Visible spectrophotometer in the range of (300-900) nm used to determine absorbance spectra. The transmittance increased with increasing NiO content in NiO:Fe2O3 thin films, same behavior of extinction coefficient and skin depth. The energy gap increased from 2.45 eV before doping to 2.86 eV after 3% NiO-doping. While the reflectance, absorption coefficient, and refractive index are decreased with increasing NiO content in Fe2O3 thin films.

11

Energy transfer from Cr3+ to Nd3+ and NIR luminescence of Nd3+ in lead borate glasses

80%

Pisarska J.

Optica Applicata

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2008

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tom Vol. 38, nr 1

203-210

EN

Energy transfer processes from Cr3+ to Nd3+ and NIR luminescence of Nd3+ ions at 1.06 žm in Cr-Nd co-doped lead borate glasses have been investigated. The spectroscopic investigation indicates that Cr3+ ions are located at strong-field and weak-field sites. Replacing PbO by PbF2 in lead borate glasses slightly influences the energy transfer processes between Cr3+ and Nd3+ and NIR luminescence of Nd3+ ions. The energy transfer process occurs in both oxide and oxyfluoride glass systems, which may be due to the thermally induced population of the 4T2 excited state of Cr3+ ions and the participation of lattice phonons.

12

Adequate determination of micro and macro properties of optical nano-crystals

80%

Šetrajčić J. P.

Opto-Electronics Review

|

2017

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tom Vol. 25, No. 4

303--310

EN

The main problem in theoretical analysis of structures with strong confinement is the fact that standard mathematical tools: differential equations and Fourier’s transformations are no longer applicable. In this paper we have demonstrated that the method of Green’s functions can be successfully used on low-dimension crystal samples, as a consequence of quantum size effects. We can illustrate a modified model through the prime cubic structure molecular crystal: bulk and ultrathin film. Our analysis starts with standard exciton Hamiltonian with definition of commutative Green’s function and equation of motion. We have presented a detailed procedure of calculations of Green’s functions, and further dispersion law, distribution of states and relative permittivity for bulk samples. After this, we have followed the same procedures for obtaining the properties of excitons in ultra-thin films. The results have been presented graphically. Besides the modified method of Green’s functions we have shown that the exciton energy spectrum is discrete in film structures (with a number of energy levels equal to the number of atomic planes of the film). Compared to the bulk structures, with a continual absorption zone, in film structures exist resonant absorption peaks. With increased film thickness differences between bulk and film vanish.

13

Fe2O3&ensp thin Films Prepared by Spray Pyrolysis Technique and Study the Annealing on its Optical Properties

80%

Abass K. H.

International Letters of Chemistry, Physics and Astronomy

|

2015

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tom Vol. 45

24--31

EN

Fe2O3 thin films that doped by NiO were obtained on glass substrates by the chemical spray pyrolysis technique, and annealed at 450 ºC and 500 ºC. The effect of annealing on optical properties was studied by recording the absorbance spectra using UV-Visible spectrophotometer. The refractive index decreases with increasing annealing temperature, such as an optical band gap that decreases from 2.68 eV before annealing to 2.58 eV after annealing of 500 ºC. Absorption coefficient and extinction coefficient increase with increasing annealing temperature.

14

Ab-initio calculation of band structure and linear optical properties of SbSI in para- and ferroelectric phases

80%

Akkus H. , Mamedov A.

Open Physics

|

2007

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tom 5

|

nr 1

25-34

EN

An ab-initio pseudopotential calculation has been performed by using density functional methods within the local density approximation (LDA) to investigate the band structure and optical properties of the ferroelectric-semiconductor SbSI in the para- and ferroelectric phases. It has been shown that SbSI has an indirect gap in both phases (1.45 eV and 1.49 eV in the para- and ferroelectric phases respectively) and that the smallest direct gap is at the S point of the Brillouin zone (1.56 eV and 1.58 eV in the para- and ferroelectric phases respectively). Furthermore, it is shown that first-order phase transition, from the paraelectric phase to the ferroelectric phase (the transiton temperature is about 22 °C), does not change the nature of the band gap. Moreover, the linear frequency dependent dielectric function, including self-energy effects, has been calculated along the c-polar axis in the para- and ferroelectric phases.

15

Controllable synthesis of ZnO nanostructures by a simple solution route

80%

Wang J. , He S. , Zhang S. , Li Z. , Yang P. , Jing X. , Zhang M. , Jiang Z.

Materials Science Poland

|

2009

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tom Vol. 27, No. 2

477--484

EN

Flower-shaped ZnO nanostructures, composed of ZnO nanorods, and sphere-shaped ZnO nanoclusters, composed of ZnO nanosheets, were synthesized by reacting zinc acetate dehydrate with sodium hydroxide and polyethylene glycol-20000 (PEG-20000) at 180 °C for 4 h in solution. The thickness of individual nanosheets is about 40-60 nm. The nanorods are of hexagonal shape with sharp tips, and have basic diameters of ca. 450-550 nm. The ZnO nanostructures were characterized by scanning electron microscropy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared, and Raman scattering measurements. The results demonstrated that the synthesized products are single crystalline with wurtzite hexagonal phase, the sphere-shaped ZnO grew in the [100] direction and the flower-shaped ZnO grew in the [001] direction.

16

Electronic and gas sensing properties of soluble phthalocyanines

80%

Pochekailov S. , Rais D. , Nešpůrek S. , Rakušan J. , Karásková M.

Materials Science Poland

|

2009

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tom Vol. 27, No. 3

781--795

EN

Some optical and electrical properties of 3-diethylamino-1-propylsulfonamide substituted zinc and metal-free phthalocyanines are presented. These materials are sensitive to NO2 even at concentrations as low as 0.1-2.5 ppm. Electrical conductivity and photoconductivity were used as the detection methods.

17

Synthesis in aqueous phase and characterization of silver nanorods and nanowires

80%

Zhou J. , Zhou G. , Wang R. , Lu M.

Materials Science Poland

|

2009

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tom Vol. 27, No. 1

73--78

EN

Silver nanorods and nanowires have been synthesized via a chemical process in aqueous phase by using ascorbic acid as a reducing agent and anionic surfactant dodecyl benzene sulfonic acid sodium (SDBS) as a capping agent. The products were characterized by X-ray diffraction (XRD) techniques and transmission electron microscopy (TEM). Experimental results indicated that the concentration of ascorbic acid played a critical role in the formation of the silver nanorods and nanowires. The optical properties were investigated. The prepared nanostructures displayed a very strong absorption band at room temperature.

18

Tert-butyl esters of 2,3-diaryl-3-arylaminopropanoic acids - stereoselective synthesis, isolation, spectroscopic and structural elucidation

80%

Tasheva D. , Zareva S.

Polish Journal of Chemical Technology

|

2011

|

tom 13

|

nr 3

12-17

EN

A series of seven substituted tert-butyl esters of 2,3-diaryl-3-arylaminopropanoic acids has been synthesized, isolated, spectroscopically and structurally elucidated. An influence of the substituents on the spectroscopic characteristics and conformations is discussed using the data of the linear-polarized IR- (IR-LD), UV-spectroscopy and 1H-NMR. Theoretical quantum chemical calculations are carried out, with a view to explaining and supporting the experimental optical properties and the electronic structure. The stereoselective synthesis of the corresponding diastereoisomers is optimized, thus giving good yields (62-72%) and purity of the compounds

19

Inherent optical properties and particulate matter distribution in summer season in waters of Hornsund and Kongsfjordenen, Spitsbergen

80%

Sagan S. , Darecki M.

Oceanologia

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2018

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tom No. 60 (1)

65--75

EN

Two Spitsbergen fjords, Hornsund and Kongsfjorden, are known for being under different hydrological regimes. The first is cold, separated from warm Atlantic water by East Spitsbergen Current, while Kongsfjorden is frequently penetrated by relatively warm Atlantic water. On the other hand, both are under strong influence of water discharge from glaciers and land freshwater input. During the period of observation in both fjords a dominant water mass was Surface Water, which originates mainly from glacial melt. The presence of suspended matter introduced with melt water in Surface Water is reflected by highest values of light attenuation and absorption coefficients recorded in areas close to glacier both in Hornsund and Kongsfjorden. In Hornsund the maximum light attenuation coefficient cpg(555) was 5.817 m−1 and coefficient of light absorption by particles ap(676) = 0.10 m−1. In Kongsfjorden the corresponding values were 26.5 m−1and 0.223 m−1. In Kongsfjorden suspended matter of the size class 20-200 μm dominated over fractions smaller than 20 μm while in Hornsund dominating size fraction was 2-20 μm. The results provide an evidence of considerable range of variability of the optical properties mainly due to glacial and riverine runoff. The scale of variability of particulate matter in Kongsfjorden is bigger than in Hornsund. Most of the variability in Hornsund can be attributed to glaciers discharge and a presence of particles of mineral origin, while in Kongsfjorden the organic and mineral particles contribute almost equally to defining the optical properties of water.

20

Role of nitrogen in carrier confinement potential engineering and optical properties of GaAs-based quantum wells heterostructures

80%

Pucicki D. , Bielak K. , Dawidowski W. , Ściana B. , Tłaczała M.

Optica Applicata

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2016

|

tom Vol. 46, nr 2

255--263

EN

In this work, the authors present the results of optical characterization of GaAs-based multiple quantum well heterostructures, together with energy band structure analysis. The optical properties were investigated by applying photoluminescence spectroscopy. Structures with GaInNAs, GaInAs and GaNAs multiple quantum wells emitting around 1 μm, grown by atmospheric pressure metalorganic vapor phase epitaxy, were compared in this work. The role of nitrogen in quantum well carriers confinement potential was analysed. The photoluminescence intensities of the samples were correlated with the analysis of energy band structures and the overlaps of the carriers’ wave functions. In addition, the main carrier activation energies were estimated based on photoluminescence temperature dependence and the Arrhenius plots analysis. It was deduced that the thermal photoluminescence decay is most probably related to the escape of electrons whereas the holes, independently of the potential well depth, are additionally confined by the local inhomogeneities or by the Coulomb interaction with the confined electrons.