Communications in Physics

The ZnS:Cu nanopowders were synthesized by the wet chemical method with Cu concentrations of 0.1, 0.15, 0.2, 0.3 and 0.4{\%}. The microstructure of samples was investigated by the X-ray diffraction (XRD) measurement. The results show that the prepared samples belong to the Wurtzite structure with the average particle size of about 3--7 nm. The highest luminescence intensity of ZnS:Cu nanopowders corresponds to sample with Cu concentration of 0.2{\%}. To investigate the effect of polyvinylacohol (PVA) on the structure of ZnS:Cu, we have prepared the polyvinylacohol (PVA)-capped ZnS:Cu thin films with a Cu concentration of 0.2{\%} by dip-coating method. The PVA did not affect the microstructure of ZnS nanomaterials. The optical properties of samples were studied by measuring the absorption and the photoluminescence spectra in the wavelength range from 300 nm to 900 nm at room temperature. The value of direct band gap is about 3.8 eV. The dependence of the photoluminescence (PL) spectra of samples on the exciting power density, their time-resolved-luminescence spectra were also investigated.

In the last few years, perovskite solar cells have attracted enormous interest in the photovoltaic community due to their low cost of materials, tunable band gap, excellent photovoltaic properties and easy process ability at low temperature. In this work, we fabricated hole-conductor-free carbon-based perovskite solar cells with the monolithic structure: glass/FTO/bl-TiO\(_{2}\)/(mp-TiO\(_{2}\)/mp-ZrO\(_{2}\)/mp-carbon) perovskite. The mixed 2D/3D perovskite precursor solution composed of PbI\(_{2}\), methylammonium iodide (MAI), and 5-ammoniumvaleric acid iodide (5-AVAI) was drop-casted through triple mesoporous TiO\(_{2}\)/ZrO\(_{2}\)/carbon electrode films. We found that the isopropyl alcohol (IPA) solvent vapor annealing strongly influenced on the growth of mixed 2D/3D perovskite on triple mesoscopic layers. It resulted in the better pore filling, better crystalline quality of perovskite layer, thus the improved stability and efficiency of perovskite solar cell was attributed to lower defect concentration and reduced recombination.

It has been shown that exposure to radiation of LED sources of light with an emission band maximum at about 465 and 520 nm having substantially identical damaging effects on animal cells in culture, that are in a logarithmic growth phase and preincubated with pigment. Photobiological effect is caused by photodynamic processes involving singlet oxygen generated by triplet excited sensitizer. Mono-exponential type dependence of cell survival on the energy dose indicates that it is bilirubin that acts as a sensitizer but not its photoproducts. The inclusion of bilirubin in the cells, where it is primarily localized in the mitochondria cells, it is accompanied by multiple amplification photochemical stability compared to pigment molecules bound with albumin.

Polycrystalline CuInS\(_{2}\) (CIS) absorber films for solar cells were prepared by spray pyrolysis of aqueuos solution of copper chloride, indium chloride and thiourea onto heated glass substrates. By optimizing the spray parameters, such as reducing/increasing the temperature of the substrate and molar ratio of Cu/In in the spraying solution, the optical characteristics of films, which are well matched to the solar spectrum, were identified. In all cases, those CIS thin films were of p-type conductivity. Transmission measurements were performed to examine the optical properties of the films; the absorption coefficient and the optical band gap of the films were calculated by transmission spectra. The absorption spectra of the films showed that this compound is a direct band gap one and its gap varied between 1.30 - 1.78 eV. Those thin films were analyzed by X-ray diffraction in order to understand the effect of layers structure on their optical properties.

Designing quantum protocols with unit success probability is highly desirable from a viewpoint of the overall resource cost. In this work, we propose a new deterministic protocol for joint remote preparation of the most general two-qubit state using the same quantum/classical resource as in [An et al., Phys. Lett. A {\bf 375} (2011) 3570] and, at the same time, retaining the passive role of the receiver as in [Xiao et al., J. Phys. B: At. Mol. Opt. Phys. {\bf 44} (2011) 075501], which employs a different kind of nonlocal resource. From a practical point of view, this protocol proves most suitable in situations when only Einstein- Podelsky-Rosen pairs are supplied and the receiver is not capable of performing any measurements nor controlled-NOT gates.

We apply the coherent potential approximation to study the three-component Falicov - Kimball model, in which single-component and two-component fermionic particles are mixed in an optical lattice. In the model, the heavy single-component fermionic particles are localized while the light two-component fermionic particles can hop in the lattice. At half-filling, two transitions from an insulator via a metallic state to a Mott insulator are found with increasing the particle correlations. By contrast, at third-filling, only one transition from the metallic state to the Mott insulating phase is observed for strong repulsive interactions. Our results are consistent with those obtained by the dynamical mean field theory as well as by the slave boson mean field approach.

The ferromagnetic transition temperature (Tc) of a two band model for diluted magnetic semiconductors (DMS) is calculated by using the coherent potential approximation (CPA). It is shown that Tc is strongly parameter dependent on density of the carriers, magnetic coupling constants, and the hopping terms. The maximal Tc of the two band model is found when both impurity bands fully overlap and this value is approximately twice larger than the highest Tc obtained in the single band model.

The fluorescence quantum yield or the efficiency of the fluorescence process is defined as the ratio of the number of photons emitted to the number of photons absorbed. In this report the experimental method to determinate photo luminescence (PL) quantum yield (QY) of CdSe quantum dot will be described. The experimental condition which depends on QY will be investigated. The QY values of CdSe which were prepared at Nano Materials Physics Laboratory Research Center for Dielectric and Advanced Matters Physics Pusan National University will be carried out and compared with the commercial CdSe sample.

e present a new study of archival ALMA observations of the CO(2-1) line emission ofthe host galaxy of quasar RX J1131. The quasar, at redshift z S ∼0.654, is lensed by a foreground galaxy at z L ∼0.30. Particular attention is paid to the mechanism of gravitational lensing. A simple lens model, shown to well reproduce the optical images obtained by the Hubble Space Telescope, is applied to the ALMA CO(2-1) images, providing a tool to understand the uncertainties attached to the evaluation of the source brightness and kinematics. Uncertainties attached to the process of data reduction are carefully evaluated. Evidence for the robustness of previously published results is obtained. A system of polar coordinates is introduced to better match the specificity ofthe imaging process. It provides particularly clear evidence for rotation of the gas contained in the galaxy. A simple rotating disc model is shown to give an excellent overall description of the morpho-kinematics of the source. It gives evidence for a hot spot of emission located near the quasar, overlapping the caustic and corresponding to an enhancement of emission by a factor ∼2.5. The possible presence of a companion galaxy suggested by some previous authors is not confirmed. The rotation curve is studied with reference to the predictions of the disc model. De-tailed comparison between model and observations gives evidence for a more complex dynamics than implied by the model. Doppler velocity dispersion within the beam size in the image plane is found to contribute 60±10 km s −1 to the line width. It accounts for the observed line width when a2- σ cut is applied to the data. However, when using a less severe cut, a significant amount of turbulence may be accommodated, preventing a reliable evaluation of the contribution of turbulence to the line width.

Ba1-xCaxTiO3 material samples with x changing from zero to 1 were fabricated by the solid state reaction method at a temperature of 1200 oC in the ambient atmosphere. Crystalline structure of the material samples was recorded and identified by X-ray diffraction and Raman scattering. Analyzing the X-ray patterns found that Ba can be completely substituted by Ca with the concentration lower than 11 at%. The frequency dependence of the impedance (C) and AC conductance (G) of all the samples were recorded in a frequency range lower than 10 MHz by using an impedance analyzer HP 4192A. It was found that in the low frequency range lower than 1 MHz the dielectric constant and its loss decrease as Ca substituted for Ba. Besides an abnormal in the frequency dependence of the dielectric constant was observed for all samples in the higher frequency range up to 10 MHz.