Optical Absorption Method Research Articles

ИССЛЕДОВАНИЕ ФИЗИКО-ХИМИЧЕСКИХ ОСОБЕННОСТЕЙ СТРОЕНИЯ И ЭЛЕКТРОННЫХ СВОЙСТВ СОПОЛИАРИЛЕНЭФИРКЕТОНОВ

In this work model compounds for copolymers of polyarylene ether ketones (co-PAEK) were modeled and analyzed, and optical and electrophysical studies were carried out. Quantum chemical calculations of the structures were carried out using the density functional theory (DFT) method in the B3LYP/6-31+G(d) approximation. The optical properties of the films were studied using the optical absorption method in the UV-visible region. The study of the current-voltage characteristics and time dependences was carried out on the MPI ETS50 probe station.

Effects of growth temperature on structural and electrical properties of in-rich InAlN–GaN heterostructures by radio-frequency metal–organic molecular beam epitaxy

In-rich InAlN is a promising nitride semiconductor alloy for high-efficiency solar cells and wide-range light-emitting diodes due to its tunable bandgap from 0.7 to 6.2 eV. However, incomplete characterization has led to inconsistent fundamental properties in some studies. The aim of this study was to comprehensively investigate the structural, optical, and electrical properties of In-rich InAlN films grown on GaN/Al2O3 templates by RF-MOMBE at various temperatures. The methodology involved state-of-the-art metrology techniques, such as high-resolution x-ray diffraction (HRXRD), scanning electron microscopy (FE-SEM), Hall effect measurements, and transmission electron microscopy (TEM). The results showed that all InxAl1-xN films were epitaxially grown on the GaN/Al2O3 template, with the indium composition (x) decreasing with increasing growth temperature. Furthermore, phase separation of the In-rich InAlN films occurred at high growth temperatures(>550 °C), resulting in a relatively smooth surface. The optical absorption method measured the band-gap of the InxAl1-xN films, which ranged from 1.7 to 1.9 eV for x values between 0.77 and 0.91. The mobility and carrier concentrations of all In-rich InAlN films were measured at ∼60−277 cm2 V−1-s−1 and 2–7 × 1019 cm3 in the growth temperature of range 450 °C–610 °C, respectively. In conclusion, our comprehensive characterization using advanced metrology methods provides valuable insights into the properties of In-rich InAlN films, which can inform future optimization of these materials for various applications.

Spectroscopic Properties of Pb2+-Doped BaF2 Crystals

Various concentrations of PbF2-doped BaF2 crystals were grown by the Bridgman method using a shaped graphite heater. The room temperature optical absorption spectra showed two UV absorption bands (labeled A and D), characteristic of the Pb2+ ions. The structure of the bands was analyzed using the Gaussian multi-peak fitting. The distribution of the Pb2+ ions along the crystals and the effective segregation coefficient were studied using the optical absorption method. The obtained effective segregation coefficient was >1. The Pb2+ ions were not uniformly distributed along the samples. High intensity emission bands were observed in the near UV domain and the visible region.

The structural, optical properties, surface and electrical properties of vanadium pentoxide (V2O5) films produced at different substrate temperatures

Vanadium pentaoxide (V2O5) coatings generated by ultrasonic spray pyrolysis on glass substrates at various temperatures have been investigated. The XRD analysis revealed polycrystalline V2O5 films with an orthorhombic structure. The optimal orientation of V2O5 films is the peak direction (101) for substrate temperatures 300 °C, 350 °C, 450 °C, and (110) for substrate temperatures 400 °C, according to structural analyses. The optical characteristics were investigated using a UV–VIS spectrofotometer. As the temperature of the substrate increased, the transmittance of the films increased by up to 42 %. Using the optical absorption method, the optical band gaps of the films were estimated. It can be shown that when the substrate temperature rises, the optical band gap values decrease. The increase in substrate temperature caused porous structures to emerge, as well as the formation of region borders, as shown in SEM pictures. The electrical properties of films were searched by four probe technique It was seen that the resistivity values of the V2O5 films produced by the ultrasonic spray pyrolysis method decreased as the substrate temperature increased, thus the conductivity values increased.

Synthesis and structural characterization of Cd(II) complexes based on acetylene dicarboxylate: A 1-D polymer as a precursor to CdO nanoparticles

Two new compounds, [Cd(adc)(L)(H2O)3]2 (1), [Cd(adc)(bipy)2.H2O]n (2) (Where L = N, N′-bis-pyridin-4-ylmethylenehydrazine, adc = acetylene dicarboxylate and bipy = 2,2’-bipyridine) have been isolated in good yields and structurally characterized by IR, single-crystal X-ray diffraction, and thermogravimetric analysis. Direct thermolysis of complex 2 at 500 °C for 1 h under an ambient atmosphere yielded CdO nanoparticles. The nanoparticles were characterized for their size and structure by powder X-ray diffraction, scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (TEM). TEM images show the formation of nanorods as well as nanospheres. The optical band gap determined by the optical absorption method was found to be 3.8 eV.

Role of growth pressure on Structural, optical and electrical properties of indium Nitride thin films prepared by modified activated reactive evaporation

The effect of deposition conditions on the crystal structure and optical and electrical properties of Indium Nitride (InN) films deposited by modified reactive evaporation have been investigated. Substrates are kept at the electrode and thereby subjected to low-energy nitrogen ion bombardment.The effects of pressure on the structural, morphological, and optical properties of the films on Si (100) and glass substrates are investigated by X-ray diffraction analysis, scanning electron microscopy, energy-dispersive X-ray analysis, and UV–Vis transmittance, Photoluminescence, and Raman spectroscopy. All the films show a preferential c-axis orientation with c- lattice constant found decreasing up to 8 mTorr. The bandgap measured from the photoluminescence and optical absorption method shows similar characteristics. Raman spectra reveal broad and asymmetric line shapes for E2(high) and A1(LO) modesdue to the small phonon correlation length. The Indium oxide phase was detected for the film grown at 25 mTorr which alsodeteriorates its electrical and optical properties.

Application of gas analyzers for the control of fuel in the air environment of rocket and space industry enterprises

The presented work shows the necessity of organization of individual instrumental control of the content of rocket fuel and its products in the air of rocket-space industry enterprises. No accurate analysis of gas analyzers presented on the Russian market, providing individual instrumental control of concentrations of heptyl and its derivatives in the workplace air is available. Therefore, the task of express, automatic, selective and simultaneous monitoring of heptyl vapors and derivatives of its transformation in the air of industrial premises by one instrument and replacing the imported gas analyzers remains urgent. It is shown that the solution of the posed problem is possible on the basis of the optical absorption method. The requirements to be met by the gas analyzer are formulated. Approximate wavelengths at which simultaneous measurement of concentrations of heptyl and its derivatives in an air sample is possible have been determined. The ways of realization of individual gas analyzers having small mass-size characteristics are outlined. Structural schemes for infra-red gas analyzers have been proposed: multi-channel; single-channel (with frequency modulation of radiation). Tasks for further research are formulated.

Fabrication of ZnO/CuO Hybrid Nanocomposite for Photocatalytic Degradation of Brilliant Cresyl Blue (BCB) Dye in Aqueous Solutions

Here in the present study, we report the synthesis of ZnO nanoparticles, ZnO/CuO(3%), ZnO/CuO(5%), and ZnO/CuO(10%), nanocomposites using simple precipitation method with variation of CuO content and the activities of prepared samples were investigated for degradation of Brilliant Cresyl Blue (BCB) dye under visible light conditions in aqueous solutions. The structural, morphology, optical and compositional characteristics of fabricated samples were characterized by using Fourier Transform Infra-Red (FTIR) Spectroscopy, Field Emission Scanning Electron Microscopy combine electron dispersive spectroscopy (FESEM-EDS) and UV-vis spectroscopy. FESEM images show that ZnO nanoparticles are polygon like shape structure while ZnO/CuO have polygon and sheet shape structures. XRD patterns reflect the high crystalinity and purity of samples. The optical band gap values determined from optical absorption method indicate that band gap energy decreased with increase of CuO content in ZnO. The catalytic efficiency of the ZnO/CuO hybrid nanocomposite was observed to be higher than the ZnO nanoparticles under similar reaction conditions, 97.30% of Brilliant Cresyl Blue (BCB) dye was degraded after 100 min of irradiation of visible light radiation using the ZnO/CuO(5%) hybrid nanocomposite. The higher efficiency of ZnO/CuO compare to ZnO may be due to increased surface area and decreased band gap energy. The kinetic study of the photoctalytic degradation displayed that hybrid ZnO/CuO degrdaded dye with high rate constant k (34.88x10-3 min -1) compare to ZnO (k, 7.00x10-3 min-1). The optimization of reaction conditions of photodegradation process were attained by the variation in reaction factors such as pH, dye concentration, catalyst amount, and reaction time.

Structural and optical properties of CBD synthesised CdO thin films: influence of Ni incorporation

ABSTRACT The effect of nickel doping on different properties of thin films prepared by chemical bath deposition (CBD) routes was very much important for detailed study of doped metal oxides. The structural and optical characterisation of the deposited films was done using X-ray diffraction, EDX, UV-Vis spectroscopy, etc. XRD patterns of the samples indicate that both undoped and Ni-doped CdO thin films have polycrystalline cubic cadmium oxide structure. Details analysis of XRD patterns confirms an enhancement in grain size and lowering in average microstrain due to nickel doping. The optical absorption method is used to determine the optical band gap of undoped and Ni-doped CdO thin films and the measured value was in the range of 2.26–2.60 eV. The E g values of the CdO films decrease with the increase of dopant content in the film. It is estimated that the optical band gap and grain size of the CdO film can be controlled by doping with nickel atoms.

The Essence and Application of the Optical Absorption Method for Quantitative and Qualitative Analysis of Radiation Defects in Optical Crystals

Today ionic crystals are widely used in devices for various purposes. In X-ray spectral optics they are widely used as crystal monochromators; ionic crystals are used in optical devices where lenses and transparent optical media (light filters) are made of optically pure materials - ionic crystals. In general, the main positive feature of these materials is transparency regarding the transmission of radiation in the visible region of the spectrum (transmittance of about 0.9) and neutrality - that is, approximately the same reaction of the medium to different spectral ranges of radiation. Ionic crystals are also widely used in detectors (scintillators, ionizing radiation dosimeters) and lasers. They are also widely used in acousto-optics and electrical engineering (lines of electrical signals delay, which gain efficiency due to the relatively small absorption of ultrasonic waves, and, therefore, it is possible to work with a wide sequence of signals probing the crystal). It is known that when ionizing radiation passes through ionic crystals, color centers appear in them, which can change the spectral composition of radiation both in the UV region and in the visible range. For example, the simplest configurations of color centers (F-centers) lead to the appearance in optical materials of additional absorption bands localized on the wavelength axis with a maximum at the wavelength lmax = 248 нм , but more complex configurations of radiation damage in solids already lead to the appearance of absorption bands at wavelengths in the visible range. This already presents some difficulties for developers and designers of relevant equipment, as changes in the spectral composition of radiation passing through the optical system of the device can lead, for example, to loss of efficiency of the selected radiation receiver, the main characteristic of which is primarily spectral sensitivity. Taking into account possible changes in the spectral composition of radiation is an important and urgent task of modern optical instrumentation. The purpose of this work is the analysis and justification of a method that takes into account structural changes in externally irradiated ionic crystals.

Electrochemical detection of fucosidase activity in human serum

AbstractLiver cancer is one of the most common malignant tumors globally and is the second leading cause of cancer deaths in Taiwan. The activity of α‐fucosidase (AFU) in the human body has been confirmed by many clinical studies and experiments to be applicable in the early diagnosis of primary liver cancer. Herein, an electrochemical method for determining AFU activity was developed based on measuring p‐nitrophenol (pNP), which is a product of the reaction between AFU and p‐nitrophenyl‐α‐L‐fucopyranoside. The electrochemical detection of pNP in serum samples exhibited a wide linear range (2.5–250 μM), which corresponds to approximately 2.5–250 U/L AFU. The recovery of AFU measured upon enzyme addition to standard serum was 97–110%. Moreover, no potential interferants had a significant effect on pNP quantification. In contrast, an optical absorption method was subject to interference by the serum color. Further, the linear range for pNP was only 2.5–50 μM and the recovery of AFU was 165–219%. The performance of this absorption method could lead to a misjudgment of the disease course. Therefore, the electrochemical method for AFU activity determination has greater potential for use in clinical applications.

Charge transfer complexes of atenololdrug with some dihydrxyanthraquinone and dihydroxybenzoquinone derivatives:Molecular structures, spectral, and quantitative studies.

Atenolol (ATN) is -blocker medication widely used in the clinic to treat hypertension. In this study, complexation of ATN with three different acceptors, namely alizarin (AZ), alizarin red S (AZR), and 2,5-dihydroxy-p-benzoquinone (DHBQ) was investigated spectrophotometrically. It was found that ATN formed charge transfer (CT) complexes with AZ, AZR, and DHBQ in MeOH. The CT reaction conditions between ATN and each acceptor were comprehensively investigated. Moreover, the formation constants and other related spectrophysical parameters were determined. The stoichiometry of 1:1 ratio was established for all studied complexes in MeOH using different methods. The optical band gap (Eg), which corresponds to the minimum energy required for the transition, was calculated by the optical absorption method. The values of Eg were found to be 2.02, 2.07, and 2.25 eV for the [ATN-AZ], [ATN-AZR], and [ATN-DHBQ] complexes, respectively. Solid complexes of ATN with these acceptors were effectively prepared and isolated. New bands in the FTIR spectra of the complexes were detected as a result of complexation. Additionally, the appearance of signals corresponding to the reactants in 1H NMR spectra of the products confirmed the formation of ATN complexes. In addition to the CT reactions between ATN and each acceptor, both FTIR and 1H NMR analyses suggested the existence of proton transfer reactions. Based on the fast complexation of ATN with the studied acceptors in MeOH, three direct, simple, and sensitive spectrophotometric methods were developed for the quantitative determination of ATN in its pure form and in pharmaceutical formulations. Validation studies confirmed the remarkable accuracy and precision of the developed methods without any interference from tablet excipients.

Growth and characterization of ErF3 doped BaF2 crystals

ErF3 doped BaF2 crystals were obtained using the vertical Bridgman technique. Five crystals, with 0.05, 0.08, 0.1, 0.2 and 0.5 mol% ErF3 added to the starting material, have been investigated. The optical absorption spectra reveal the characteristic bands of the Er3+ ions. The distribution of Er3+ ions along the crystals was studied using the optical absorption spectrum of every samples (14–18 slices) cleaved from the as-grown crystals. The Er3+ ions are not uniform distributed along the BaF2 crystals. The segregation coefficient, k, was calculated using the so-called optical absorption method and the Scheil relationship between the dopant concentration and crystal growth conditions. The calculated segregation coefficient of the Er3+ ions ranges from 0.76 to 0.98, for ions with trigonal (C3v) sites, and from 0.6 to 0.86 for clusters, depending on the ErF3 concentration. In the investigated temperature range, only one type of dielectric relaxation has been observed. This relaxation, with activation energy of 0.54 eV is associated with trigonal NNN type (C3v) centers. The charge compensating defects were discussed taking into account both the optical absorption spectra and the calculated number of NNN dipoles whose relaxation were observed.

Recognition and adsorption characteristics of tramadol hydrochloride molecules in molecular imprinted poly(MAA-co-EGDMA)

A simple method for adsorption and recognition of tramadol-HCl in molecular imprinted poly (methacrylic acid-co-ethylene glycol dimethacrylate); poly (MAA-co-EGDMA), is described. Seven tramadol imprinted polymers (TIPs) were synthesized based on tramadol hydrochloride as the template molecule, methacrylic acid (MAA) as a functional monomer, ethylene glycol dimethacrylate (EGDMA) as a crosslinker, chloroform as a porogenic solvent and benzoyl peroxide (BP) as an initiator. Other seven non-imprinted polymers (NIPs) were prepared with the same compositions as the TIPs without the template molecule. A simple method for determination of Tramadol concentration by optical absorption method was described. The effects of crosslinker and functional monomer concentration, soaking time and the pH on the adsorption efficiency of tramadol by the polymers were studied. TIPs exhibited more adsorption affinity than their NIPs counterparts as they acquired recognition sites to capture the tramadol molecules. The TIP polymer with 15 mmol EGDMA and 1.15 mmol MAA stirred for 3h at 7 pH tramadol solution showed 90% adsorption capability for the tramadol, while the corresponding NIP sample showed 55.6% adsorption. SEM images showed the presence of (micro/meso/macro) pores in such TIP sample.

A comprehensive investigation on Ag-doped ZnO based photodiodes with nanofibers

The morphological, optical and electrical properties of undoped Zinc Oxide (ZnO) and 0.5% and 2% Ag-doped ZnO based Photodiodes were investigated. ZnO samples, which were deposited on p-type Si semiconductor substrates using spin a coating method, were produced by sol–gel method. The morphological properties of the ZnO films were investigated by atomic force microscopy. The results revealed that thin films are in nanofiber like structure that nanofiber spread homogeneously on the substrate. Additionally, the permittivity, absorbance, reflectivity and bandgap energy values were calculated by using the UV measurement results. The optic bandgaps of the films were also calculated by the optical absorption method. Each sample shows permittivity properties in the visible region; samples show absorption properties in the region where the applied wavelength is smaller than 400 nm. Reflecting boundaries were shift to higher boundaries with increased dopant effect. The transmittance of samples was found low in the UV region, but it shows higher characteristics which are between 78 and 88% in the visible region. To investigate the electrical properties of produced thin films, Current–Voltage, Capacitance–Voltage, Conductance–Voltage characteristics and Current–Time measurements were obtained in different illumination intensities. It was seen that the samples show photoconductive performance.

TOOL CONTROL THE CONCENTRATION OF CARBON DIOXIDE IN THE FLUE GAS BOILERS BASED ON THE OPTICAL ABSORPTION METHOD

The methodology for controlling the concentration of carbon dioxide in flue gases from boilers is an optical absorption method with improved metrological characteristics. Studies done in the article, provided the new, scientifically-based theoretical and practical results that are essential for improving the accuracy at the required speed process, control the carbon dioxide concentration in dual gas boilers based on the optical absorption method with compensation effect on the factors optical converter.

Design and Construction of Optical System to Detect of Ammonia Gas

The idea of research is the detection of gases using the transmitter and receiver system for electromagnetic radiation in the IR region using the optical absorption method. As a result of the interaction of the light with the gas molecules can be detect and measure gas pressure adoption absorption method. It was chosen best absorption band between (1.4-1.6) um at the wavelength 1.5 um to build a sensor for accurate measurement of ammonia gas which is characterized by precision, where he was the measuring pressure range (1-6) bar. The importance of the oil industry has been focusing on this kind of scientific research for the detection of ammonia gas.

Study on the effect of Zn2+ doping on optical and electrical properties of CuO nanoparticles

The present work outlines the synthesis of CuO and Zn-CuO nanoparticles via microwave combustion method using urea as a fuel. The structural, optical and electrical properties of the CuO and Zn-CuO nanoparticles were systematically characterized through UV–Visible spectroscopy (UV–Vis), Field-emission scanning electron microscopy (FE-SEM), Photoconductivity technique (I-V study), X-ray diffraction studies (XRD), Transmission electron microscopy (TEM) and Energy dispersive analysis X-rays spectrometer (EDAX). The average crystalline size and micro-strain of pure CuO and Zn-CuO nanoparticles were calculated using Debye-Scherrer and William-Hall (W-H) plot methods. The crystalline size was found to be decreased with increase in the concentration of Zn2+ up to 6 mol% and a further increase in the Zn2+ concentration resulted in the formation impurity phase. Field emission scanning electron micrographs show the monoclinic rod-like structure of CuO and Zn-CuO nanoparticles. Energy dispersive X-ray spectra display the existence of Zn2+ in Zn-CuO nanoparticles. The optical band gap values of CuO and Zn-CuO nanoparticles were determined by optical absorption method and the results show a slight decrease in the optical band gap with Zn2+ doping. Electrical properties of CuO and Zn-CuO films were performed using I-V characterization studies and the results shown that the enhancement of photocurrent is more in UV-light as compared to dark.

Distribution of Yb3+ and Yb2+ Ions along YbF3‐Doped BaF2 Crystals

AbstractBaF2 crystals doped with 0.05, 0.1, and 0.2 mol% YbF3 are grown using vertical Bridgman method. Transparent crystals, ≈5–6 cm in length, ≈10 mm in diameter, are obtained in vacuum using a shaped graphite furnace. The absorption spectra reveal the characteristic absorption bands of the Yb3+and Yb2+ ions in the as‐grown crystals. The distribution of ytterbium ions along the crystals and the effective segregation coefficient of the Yb3+ and Yb2+ ions in the BaF2 host are determined by using the optical absorption method. The crystals are cleaved from the bottom to the top into 10–17 slices of ≈2 mm thickness. The optical absorption spectrum of every slice is recorded. The dopant distribution along the crystal is estimated studying the absorption spectrum of every slice. Two well‐shaped and strong characteristic bands, 968 nm and 352 nm, respectively, are chosen. The Yb3+ and Yb2+ ions are not uniformly distributed along the BaF2 crystals. The calculated effective segregation coefficients of the Yb3+ range from 0.7 to 0.84 and from 0.66 to 0.82 for Yb2+ ions.

Al-doped ZnO as a multifunctional nanomaterial: Structural, morphological, optical and low-temperature gas sensing properties

In this study, zinc oxide thin films doped with Al at different atomic ratios (0.1%, 0.5%, 1%, 2%, 5%) were prepared using sol-gel spin coating method. Crystal structure, surface morphology, optical properties of the films and their response to ammonia gas were examined. XRD results showed that the ZnO thin films had a hexagonal polycrystalline structure. It was concluded from the calculation of the crystal size and lattice constant of the films that the produced samples were a nanomaterial. Scanning electron microscope (SEM) and atomic force microscope (AFM) images of the samples revealed that the morphology was composed of nanostructured particles and a cluster structure made of the combination of these particles. The optical band gap (Eg) of the prepared films were found within the range of 3.251 eV–3.342 eV by using the optical absorption method. Characteristics of susceptibility against ammonia gas were evaluated depending on the Al dopant. The obtained results showed that the gas response along with the structural, morphological, and optical properties of ZnO thin films changed with Al dopant. The produced thin film samples can be used as a sensor for the detection of ammonia gas in various industrial branches.