Papers by Keyword: Optical

Abstract: The Rhodamine 6G fluorescent dye, It was dissolved at a concentration in ethanol of 6*10-6 M, was investigated an active laser medium in this work, and its optical and spectral properties were investigated. The fluorescent Rhodamine 6G dye, which was dissolved in ethanol at a concentration 6*10-6 M, was investigated an active laser medium in this work, and its optical and spectral properties were investigated. The chemical reduction process was also used to create gold nanoparticles at concentration of 0.01 M. Three concentrations of gold nanoparticles (2.5, 5, and 7.5%) w/v were added to the Rhodamine 6G dye solution in order to examine how they affected the dye's optical and spectral characteristics. Optical and spectral properties Rhodamine 6G dye sample were analyzed both before to following the addition of gold nanoparticles. After adding gold nanoparticle the dye, the results indicated a shift toward lower wavelengths (red shift) and an increase in optical parameters, with the exception of transmittance. Fluorescence intensity, radiative lifetime, quantum yield, stoke shift, and fluoresce cent lifetime were among the spectrum characteristics. The relative fluorescence intensity dropped after the nanoparticles were applied.

Abstract: In the presented work the features of formation of metal-fullerene films of the systems Al-C₆₀, Au-C₆₀, Cu-C₆₀, Ti-C₆₀ from atomic-molecular flows in vacuum were investigated, the processes of surface resonance plasmon absorption and diffusion were studied. It is shown that electron microscopy, optical, Auger-electron and X-ray spectroscopy methods are effective for the study of metal-fullerene films. The combination of different methods of spectroscopy and electron microscopy allowed to establish the dependence of the grain size of the films, the shift of the position of the plasmon absorption maximum, diffusion parameters on the ratio of metal and fullerene components, to establish the fact of formation of the chemical compound Cu₆C₆₀.

Abstract: Preparing of Sb₂S₃ precursor by sol gel method and the post selenization is a simple and low-cost method for preparing Sb₂(S, Se)₃. In the preparation process of this method, the number of spin-coating of Sb₂S₃ precursor determines the film thickness, structure, and S/Se ratio. In this work, the effects of different spin-coating times (1 to 5) on the structure, optical and electrical properties of the film were studied. The results showed that when the number of spin-coating increased from 1 to 5, the thickness of the film increased from 0.24 μm to 1.17 μm. When spin-coating twice, the strongest diffraction peak of the film changed from (120) to (230); as the spin-coating frequency continued to increase, the film gradually exhibited Sb₂S₃ characteristics, accompanied by a small amount of Sb₂O₃ impurities. In addition, excessive spin-coating cycles can cause large voids to appear on the surface of the film. From the UV-visible spectrum, it can be seen that as the thickness of the film increases, the light absorption also gradually improve, and the band gap increases from 1.34 eV to 1.66 eV. The Mott-Schottky test showed that the prepared thin films were all P-type semiconductor. When spin-coated twice, the carrier concentration of the thin film reached 5.8×10¹⁵cm^-3.

Abstract: Cd_1-0.06Mn_0.06Te epitaxial thin films were synthesis on glass substrates by the Molecular Beam Condensation (MBC) method in the vacuum evaporation equipment УВН-71-ПЗ with steam-oil pumping and nitrogen trap at working pressure of residual gas (1÷2)x10^-4 Pa. By using additional source of Te vapor and controlling temperature, it has been determined the optimum conditions for obtaining Cd_1-0.06Mn_0.06Te epitaxial films with a perfect structure, clean and smooth surface, without of second phase inclusions. XRD investigations showed that Cd_1-0.06Mn_0.06Te epitaxial films grow on glass substrates on the (111) plane of the face-centered cubic lattice with the lattice parameter of a = 6.481 Å. Effect of γ-irradiation on XRD spectra of Cd_1-0.06Mn_0.06Te epitaxial films reveals that, XRD patterns of initial and γ-irradiated samples did not show any phase transformations, however there is a variation in relative intensities of diffraction peaks. It has been found that Cd_1-0.06Mn_0.06Te epitaxial films with a film thickness of d=15 µm, absorb light up to a wavelength of λ=765 nm and at λ>765 nm the absorption begins to gradually decrease and then the material becomes transparent. The obtained results indicate that Cd_1-0.06Mn_0.06Te epitaxial films absorb light quanta in the visible and infrared spectral regions. Iirradiation of Cd_1-0.06Mn_0.06Te epitaxial films with γ rays at low irradiation doses leads to a change in the optical parameters, the profile of the spectrum curves and the intrinsic absorption edge. In additions to experimental studies, a theoretical ab initio calculations of band structure (BS) of ideal and defective semiconductors of Cd_1-0.06Mn_0.06Te has been also carried out by using Density Functional Theory (DFT) method via Atomistix ToolKit computer program. The band gap energy has been calculated as E_g = 1.6 eV for ferromagnetic (FM) and E_g = 1.7 eV for antiferromagnetic (AFM) state of Cd_1-0.06Mn_0.06Te compound. The results of theoretical calculations on the band gap energy of ideal and defective Cd_1-0.06Mn_0.06Te semiconductors are in a good agreement with experimental findings.

Abstract: This study examines the mechanical and microstructural characteristics of magnesium nanocrystalline (nc) AZ61 alloy, which is produced using the SPS and mechanical milling processes. The results are presented and discussed. Using optical microscopy, it has been shown that the powders underwent twining, and after eight hours of milling, the subgrain boundaries developed, defining the grains with a nanometer size of 60 nm. The AZ61 alloy was sintered by spark plasma sintering at temperatures between 465⁰ to 565⁰ degrees Celsius. It has been noted that the grains in pure magnesium magnesium AZ61 alloys are uniformly dispersed, have few pores, and have particle boundaries throughout the SPS process. The mechanical parameters of the AZ61 alloy, namely hardness, compressive strength, and corrosion resistance, increase with increasing sintering temperature by approximately 725MPa, 298 MPa, and 0.18 mm.y-1.

Abstract: Strontium Oxide (SrO) nanoparticles have a specific structure, and excellent optical, mechanical, and thermal properties, within direct bandgap semiconductors applications. SrO impact on the optical and electrical properties of newly (PVA-PEG/ SrO) nanocomposite were investigated. The electrical properties were measured at 100 Hz – 6 MHz frequencies. An increase in frequency caused a reduction in the dielectric loss (δ) and dielectric constant (ɛ). ɛ value revealed an improvement with an increased loading ratio of SrO. The optical properties of the (PVA-PEG/SrO) nanocomposite showed a reduction in the energy gap values. In contrast, the absorption, extinction coefficient, absorption coefficient, optical conductivity, refractive index, and dielectric constant (imaginary, real) increased with the increased concentration of SrO NPs.

Abstract: During the last two decades, over more than five million research papers (articles, reviews, communications etc.) were published on nanocomposite materials. Most of them are excellent contributions that already mingle the readers’ and researchers’ interests; thus gaining many citations. This mini-review is focused on advancement in next-generation nanocomposite materials based on optical and sensing applications; and their practical execution. Some recent novel developments will be highlighted and future trends will be discussed. Nowadays, nanocomposite has ended up one of the most popular materials with potential usage in various scope, including packaging, automotive and aerospace industry, batteries with higher power output, flexible batteries, making lightweight sensors, in photocatalysis and making tumours easier to look at and to eliminate. New materials, viz. designed polymers, metal oxides, alloys, chalcogenides, nanostructured and hierarchical carbons, regularly induced researchers and engineers; to test and compare them with existing sensors of multifarious sorts. Nanocomposites not only offers’ the new technology and business opportunities in all sectors of the industry but also it tender innovations and new openings for all divisions.

Abstract: CdS thin films have been grown on glass substrate at 250^o C employing pulsed laser deposition method. The effect of laser pulses number on the crystalline structure, surface morphology, optical properties, and films thickness have been studied. XRD analysis shows that the CdS films have polycrystalline and hexagonal nanostructure with three notable peaks along (100), (002), and (101) planes and preferentially orientated along (101). The crystallite size of the preferred orientation was in the range of (21.4 - 27.3 nm). With small pulses number, XRD pattern confirms the formation of CdO with three peaks (111), (200), and (220). Theses peaks gradually reduce with the increasing of the pulses. The absorbance of the films is in the visible part of the spectrum. The band gap of the synthesized films reduces by rising the number of laser pulses. AFM studies indicate that the grain size and surface roughness increase with the film thickness. Due to the good crystalline structure and optical properties of the film of the highest thickness, it has been grown on a wafer silicon substrate for solar cell applications measurements. Hall measurements indicate low resistivity of 0.3×10-2 (Ω.m) and high conductivity of 3.3×10+2 (Ω.m)-1. The efficiency of the n-CdS/ p-Si junction has been calculated to be 3.4 % using I-V characteristic measurement. Keywords: pulsed laser, thin films, structural, optical, morphology, solar cell measurements

Abstract: Multi-sensor remote sensing data can significantly improve the interpretation and usage of large volume data sources. A combination of satellite Synthetic Aperture Radar (SAR) data and optical sensors enables the use of complementary features of the same image. In this paper, SAR data is injected into optical image using a combining fusion method based on the integration of wavelet Transform and IHS (Intensity, Hue, and Saturation) transform. Not only to preserve the spectral information of the original (MS) image, but also to maintain the spatial content of the high-resolution SAR image. Two data sets are used to evaluate the proposed fusion algorithm: one of them is Pleiades, Turkey and the other one is Boulder, Colorado, USA. The different fused outputs are compared using different image quality indices. Visual and statistical assessment of the fused outputs displays that the proposed approach has an effective translation from SAR to the optical image. Hence, enhances the SAR image interpretability.

Abstract: Oleic acid (OA) and octadecylamine (ODA) capped lead sulphide (PbS) nanoparticles were prepared at 150, 190 and 230 °C. X-ray diffraction patterns indicates that the synthesized PbS nanoparticles were in the rock cubic salt crystalline phase. The particle sizes of the as-prepared PbS nanoparticles are in the range 2.91–10.05 nm for OA-PbS(150), 24.92–39.98 nm for ODA-PbS(150), 9.26 – 29.08 nm for OA-PbS(190), 34.54 – 48.04 nm for ODA-PbS(190), 17.96–88.07 nm for OA-PbS(230) and 53.60 – 94.42 nm for ODA-PbS(230). SEM images revealed flaky and agglomerated spherical like morphology for the nanoparticles. The energy bandgap of the PbS nanoparticles are in the range 4.14 – 4.25 eV, OA-PbS(230) have the lowest bandgap of 4.14 eV while ODA-PbS(150) have the highest bandgap of 4.25 eV. The PbS nanoparticles were used as photocatalyst for the degradation of Rhodamine B and OA-PbS(150) showed efficiency of 44.11% after 360 mins. Cyclic voltammetry of the PbS nanoparticles showed a reversible redox reaction and linear Randles-Sevcik plots indicates electron transfer process is diffusion controlled.