Ultraviolet-visible Spectrometer Research Articles

Facile preparation of high refractive index polymer films composited with a tungstophosphoric acid

In this study, transparent, colorless polymer composites of polyvinyl alcohol (PVA) and tungstophosphoric acid (PWA) with high refractive indices were developed. The composite films were prepared on glass, using a facile spin-coating method, from an aqueous mixture of PVA and PWA without surfactants. The optical properties of the obtained films were investigated using an ultraviolet-visible absorption spectrometer and a prism coupler. Resultant PVA/PWA (90wt%) composite films exhibited high transparency (90%T) in the visible region and had a high refractive index (n=1.72). These PVA/PWA films were also compared to corresponding composite films of PVA and titanium oxide (TiO2).

A Comparative Study on Structural and Optical Properties of ZnO Micro-Nanorod Arrays Grown on Seed Layers Using Chemical Bath Deposition and Spin Coating Methods

In this study, Zinc Oxide (ZnO) seed layers were prepared on Indium Tin Oxide (ITO) substrates by using Chemical Bath Deposition (CBD) method and Sol-gel Spin Coating (SC) method. ZnO micro-nanorod arrays were grown on ZnO seed layers by using Hydrothermal Synthesis method. Seed layer effects of structural and optical properties of ZnO arrays were characterized. X-ray diffractometer (XRD), Scanning Electron Microscopy (SEM) and Ultraviolet Visible (UV-Vis) Spectrometer were used for analyses. ZnO micro-nanorod arrays consisted of a single crystalline wurtzite ZnO structure for each seed layer. Besides, ZnO rod arrays were grown smoothly and vertically on SC seed layer, while ZnO rod arrays were grown randomly and flower like structures on CBD seed layer. The optical absorbance peaks found at 422 nm wavelength in the visible region for both ZnO arrays. Optical bandgap values were determined by using UV-Vis measurements at 3.12 and 3.15 eV for ZnO micro-nanorod arrays on CBD seed layer and for ZnO micro-nanorod arrays on SC-seed layer respectively. DOI: http://dx.doi.org/10.5755/j01.ms.22.4.13443

Structural, morphological, optical and gas sensing properties of pure and Ce doped SnO2 thin films prepared by jet nebulizer spray pyrolysis (JNSP) technique

Pure and cerium (Ce) doped tin oxide (SnO2) thin films are prepared on glass substrates by jet nebulizer spray pyrolysis technique at 450 °C. The synthesized films are characterized by X-ray diffraction (XRD), scanning electron microscopy, energy dispersive analysis X-ray, ultra violet visible spectrometer (UV–Vis) and stylus profilometer. Crystalline structure, crystallite size, lattice parameters, texture coefficient and stacking fault of the SnO2 thin films have been determined using X-ray diffractometer. The XRD results indicate that the films are grown with (110) plane preferred orientation. The surface morphology, elemental analysis and film thickness of the SnO2 films are analyzed and discussed. Optical band gap energy are calculated with transmittance data obtained from UV–Visible spectra. Optical characterization reveals that the band gap energy is found decreased from 3.49 to 2.68 eV. Pure and Ce doped SnO2 thin film gas sensors are fabricated and their gas sensing properties are tested for various gases maintained at different temperature between 150 and 250 °C. The 10 wt% Ce doped SnO2 sensor shows good selectivity towards ethanol (at operating temperature 250 °C). The influence of Ce concentration and operating temperature on the sensor performance is discussed. The better sensing ability for ethanol is observed compared with methanol, acetone, ammonia, and 2-methoxy ethanol gases.

ZnO-Layered Double Hydroxide@Graphitic Carbon Nitride Composite for Consecutive Adsorption and Photodegradation of Dyes under UV and Visible Lights.

In this work, a ZnO-layered double hydroxide@graphitic carbon nitride composite (ZnO-LDH@C3N4) was synthesized via co-precipitation method with solvothermal treatment. The structure and morphology of ZnO-LDH@C3N4 composite were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopes/transmission electron microscopes (SEM/TEM), N2 adsorption/desorption, ultraviolet visible diffuse reflectance spectroscopy (UV-Vis-DRS), photoluminescence spectrometer (PL) and electrochemical impedance spectroscopy (EIS). The adsorption and photocatalytic properties of ZnO-LDH@C3N4 composite towards the organic dyes: Orange II sodium salt (OrgII, an anionic azo dye) and methylene blue (MB, a cationic azo dye) were investigated. Compared to ZnO-LDH and g-C3N4, the ZnO-LDH@C3N4 composite displayed an excellent performance in both adsorption and photocatalytic degradation of the organic dyes. Moreover, a combination of ZnO-LDH and g-C3N4 significantly improved the photocatalytic performance of ZnO-LDH and g-C3N4 under visible-light irradiation. The adsorption and photocatalytic mechanism were also investigated.

Rapid and label-free bioanalytical method of alpha fetoprotein detection using LSPR chip

Alpha fetoprotein (AFP) is a cancer marker, particularly for hepatocellular carcinoma. Normal levels of AFP are less than 20ng/mL; however, its levels can reach more than 400ng/mL in patients with HCC. Enzyme linked immunosorbent assay (ELISA) and radioimmunoassay (RIA) have been employed for clinical diagnosis of AFP; however, these methods are time consuming and labor intensive. In this study, we developed a localized surface plasmon resonance (LSPR) based biosensor for simple and rapid detection of AFP. This biosensor consists of a UV–Vis spectrometer, a cuvette cell, and a biosensor chip nanopatterned with gold nanoparticles (AuNPs). In our LSPR biosensor, binding of AFP to the surface of the sensor chip led to an increasing magnitude of the LSPR signals, which was measured by an ultraviolet-visible (UV–Vis) spectrometer. Our LSPR biosensor showed sufficient detectability of AFP at concentrations of 1ng/mL to 1μg/mL. Moreover, the overall procedure for detection of AFP was completed within 20min. This biosensor could also be utilized for a point of care test (POCT) by employing a portable UV–Vis spectrometer. Owing to the simplicity and rapidity of the detection process, our LSPR biosensor is expected to replace traditional diagnostic methods for the early detection of diseases.

Synthesis and properties of highly soluble branched polyimide based on 2,4,6-triaminopyrimidine

A series of novel soluble polyimides was synthesized from commercially available 2,4,6-triaminopyrimidine (TAP), 2,2-bis(3,4-dicarboxylphenyl) hexafluoropropane dianhydride (6FDA), α,ω-aminopropylpoly(dimethylsiloxane) and 1,3-bis(3-aminophenoxy)benzene. TAP is the branched monomer, and polymerization process had been improved in three ways by using TAP to prepare soluble polyimides. The polyimides were characterized by Fourier transform infrared spectra, proton nuclear magnetic resonance, ultraviolet–visible spectrometer analysis, wide-angle X-ray diffraction, and size-exclusion chromatography with multiangle laser light-scattering detection. The branched polyimides showed excellent solubility both in strong polar solvents and in common low-boiling point solvents. Differential scanning calorimetric and thermogravimetric analyses showed high glass transition temperatures and excellent thermal stability for branched polyimides with moderate content of TAP. Polyimide membranes were formed at relatively low temperature, and the mechanical properties were tested. These results ensure that soluble polyimides with moderate content of TAP showed outstanding combined features and are desirable candidate materials for advanced applications.

Meteoritic influence on sodium and potassium abundance in the lunar exosphere measured by LADEE

AbstractThe Lunar Atmosphere and Dust Environment Explorer (LADEE) orbited the Moon for approximately 6 months, taking data with the Lunar Dust Experiment (LDEX), Ultraviolet‐Visible Spectrometer (UVS), and Neutral Mass Spectrometer (NMS). Here we compare coincident LDEX measurements of meteoritic influx to exospheric column densities of Na and K derived by UVS. We report a strong correlation of exospheric potassium and meteoroid ejecta during the Geminids meteoroid shower, exhibiting a much stronger response than sodium. With the exception of the Geminids, we find a weak correlation between the sporadic meteoroid influx as measured by LDEX and exospheric density as measured by UVS.

Structure, Morphology, and Band Gap of Ti-V-O Mixed Oxides Processed by Coprecipitation and Calcination

Mixed oxides of Ti-V-O were co-precipitated by wet process using TiCl4 and VOCl3 as starting materials. As-precipitated gels were calcinated at 800 ◦C for 4 hours in oxygen atmosphere. Effects of vanadium content on the structural evolution, morphology, and band gap of Ti-V-O oxides were investigated. Calcination has produced mixtures of TiO2/VO2/V2O5 oxides and has allowed formation of Ti1−xVxO2. Lattice parameters of rutile TiO2 were precisely measured to investigate vanadium substitution into single rutile phase of Ti1−xVxO2 with varying vanadium content. As vanadium addition was increased, particles were coarsening rapidly during calcination. Band gap of the Ti-V-O oxides was measured using ultraviolet visible light spectrometer. A decrease of band gap down to 1.7 eV with the addition of maximum of 10 at.% of vanadium was measured, which is due to the formation of single phase of Ti1−xVxO2 as well as the formation of metallic VO2 or V2O5 particles.

Role of Bi3+ substitution on structural, magnetic and optical properties of cobalt spinel ferrite

Bismuth-doped cobalt ferrite CoBixFe(2−x)O4 with x = 0, 0.1,0.2, 0.3, 0.4, 0.5 have been prepared using powder metallurgy route. The structural, morphological, elemental, magnetic and optical properties have been investigated using X-ray diffractometer, Fourier transform infrared spectroscopy, scanning electron microscope, energy dispersive X-rays, vibrating sample magnetometer and ultraviolet–visible spectrometer, respectively. X-ray diffractometer analysis confirms the formation of single-phase cubic spinel structure. As the substitution of larger ionic radii Bi3+ ions increases in cobalt ferrite which is responsible to increase the lattice parameters and decrease the crystallite size. SEM micrographs revealed the spherical shape of the particles with the nonuniform grain boundaries. The saturation magnetization decreases and bandgap energy increases as the concentration of non-magnetic Bi3+ ions increases.

Thickness Dependent on Energy Band Gap and Electrical Conductivity of Undoped Conjugated Polymer Thin Films

Conjugated polymers have been widely used for electronic purpose applications due to their numerous advantages. This has led many researches to pay their major attention in studying on characteristics of conjugated polymer thin films. The purpose of this study was to investigate the effect of undoped conjugated polymer thin films on their optical and electrical properties. Poly(3-thiophene acetic acid), Polypyrrole and Polythiophene thin film was fabricated on ITO glass substrate by using EIS. Film thickness, energy band gap and electrical conductivity of thin films were characterized by using profilometer, ultraviolet-visible spectrometer and four point probe method respectively. The thickness of each thin film varied between 50.534 nm to 97.03 nm. The result has shown that thicker film has lower energy band gap compared to the thinner one. However the electrical conductivity showed an opposite behavior.

Eco-Friendly Synthesis and Antimicrobial Activity of Silver Nanoparticles Using Dracocephalum moldavica Seed Extract

This paper reports a novel green approach for the synthesis of silver nanoparticles (AgNPs) using aqueous seed extract of Dracocephalum moldavica (L.) under ambient conditions. Processes such as Ultraviolet-visible (UV-vis) spectrometer, field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray analysis (EDX), and transmission electron microscopy (TEM) were carry out to characterize AgNPs. The presence of AgNPs in the prepared solution was approved by a peak to occur at 443 nm. XRD pattern indicated the crystalline structure of the nanoparticles (NPs) while the FTIR spectra confirm the attendance of plant residues adsorbed by these NPs. TEM images revealed a near spherical shape of these NPs, and EDX provided the expected elemental composition. The synthesized AgNPs showed excellent antimicrobial activities against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Serratia marcescens, Staphylococcus epidermidis and Bacillus subtilis.

Design and fabrication of UV band-pass filters based on SiO2/Si3N4 dielectric distributed bragg reflectors

We have designed one kind of optical filters based on double stacks of 13.5-pairs SiO2/Si3N4 dielectric distributed Bragg reflector (DDBR) structures, to realize the passband with different central wavelengths in ultraviolet (UV) range. These SiO2/Si3N4 multi-layers have been successfully fabricated on (0001) sapphire substrates by plasma-enhanced chemical vapor deposition (PECVD). The reflectance spectra measured by the UV–visible spectrometer manifest that a series of band-pass filters with fixed passband width of ∼30nm and central passband varied from 310nm to 370nm have been obtained successfully. Besides, the other series of filters with passband width varied from 30nm to 45nm can be achieved. With good control of PECVD deposition parameters, all samples exhibit smooth surface with root mean square roughness less than 4.5nm. Moreover, cross-section scanning electron microscope (SEM) images show these DDBR structures have good periodicity in accordance with the design, indicating that these band-pass filter structures are suitable for wavelength-window-selection UV photodetectors.

Structural and optical properties of Zn doped CdO nanoparticles synthesized by chemical precipitation method

In this article, synthesis of undoped and zinc doped cadmium oxide with different zinc concentration (0, 2, and 5 wt%) using simple chemical precipitation method has been discussed. Influence of zinc dopant on crystal structure, microstructure and optical properties of the nanoparticles was investigated by means of X-ray diffractometer, field emission scanning electron microscope, ultraviolet–visible spectrometer, and photoluminescence spectrometer. Crystal structure analysis reveals that zinc doping appreciably increases the crystalline size and also it shows the polycrystalline nature of the samples. Microstructural investigation shows that the samples contain nanoparticles. Optical bandgap of the prepared samples found to vary from 2.67 to 2.61 eV for various dopant concentrations. With these specifications we can fabricate semiconductor nanocrystals and these can be used for some large scale applications of nanotechnology.

Fast spatial atomic layer deposition of Al2O3 at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays

The authors developed a high throughput (70 Å/min) and scalable space-divided atomic layer deposition (ALD) system for thin film encapsulation (TFE) of flexible organic light-emitting diode (OLED) displays at low temperatures (<100 °C). In this paper, the authors report the excellent moisture barrier properties of Al2O3 films deposited on 2G glass substrates of an industrially relevant size (370 × 470 mm2) using the newly developed ALD system. This new ALD system reduced the ALD cycle time to less than 1 s. A growth rate of 0.9 Å/cycle was achieved using trimethylaluminum as an Al source and O3 as an O reactant. The morphological features and step coverage of the Al2O3 films were investigated using field emission scanning electron microscopy. The chemical composition was analyzed using Auger electron spectroscopy. These deposited Al2O3 films demonstrated a good optical transmittance higher than 95% in the visible region based on the ultraviolet visible spectrometer measurements. Water vapor transmission rate lower than the detection limit of the MOCON test (less than 3.0 × 10−3 g/m2 day) were obtained for the flexible substrates. Based on these results, Al2O3 deposited using our new high-throughput and scalable spatial ALD is considered a good candidate for preparation of TFE films of flexible OLEDs.

Structural and physical properties of boron doped ZnO films prepared by chemical spray pyrolysis method

In this work, ZnO and boron doped ZnO (ZnO:B) thin films were produced by chemical spray pyrolysis method. ZnO and ZnO:B films were obtained onto glass substrates at 450°C by spray pyrolysis method and the physical properties of those films were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet-visible spectrometer (UV) and four probe technique. XRD measurements show that all films have hexagonal wurtzite structure and all films grow preferentially along (002) direction. Morphologies of the films were examined by using a scanning electron microscopy and it was observed that almost all films were quite intense with a regular structure. Optical measurements showed that the band gap energies of the films increased with boron concentrations. The resistances of the B-doped ZnO films were measured by four probe method and resistances of films initially decreased to its minimum 1 at% boron doping and then it increased again with increasing B concentration. It was also observed that that boron doping increased the activation energies of the films.

Optoelectronic Characterization of Ta-Doped ZnO Thin Films by Pulsed Laser Deposition.

Transparent conductive oxide of Ta-doped ZnO (TZO) film with doping amount of 3.0 wt% have been deposited on glass substrates (Corning Eagle XG) at substrate temperatures of 100 to 500 degrees C by the pulsed laser deposition (PLD) technique. The effect of substrate temperature on the structural, optical and electronic characteristics of Ta-doped ZnO (TZO) films with 3.0 wt% dopant of tantalum oxide (Ta2O5) was measured and demonstrated in terms of X-ray diffraction (XRD), ultraviolet-visible spectrometer (UV-Vis), four-probe and Hall-effect measurements. X-ray diffraction pattern shows that TZO films grow in hexagonal crystal structure of wurtzite phase with a preferred orientation of the crystallites along (002) direction and exhibits better physical characteristics of optical transmittance, electrical conductivity, carrier concentration and mobility for the application of window layer in the optoelectronic devices of solar cells, OLEDs and LEDs. The lowest electrical resistivity (ρ) and the highest carrier concentration of the as-deposited film deposited at 300 degrees C are measured as 2.6 x 10(-3) Ω-cm and 3.87 x 10(-20) cm(-3), respectively. The highest optical transmittance of the as-deposited film deposited at 500 degrees C is shown to be 93%, compared with another films deposited below 300 degrees C. It is found that electrical and optical properties of the as-deposited TZO film are greatly dependent on substrate temperature during laser ablation deposition.

Enhancement of red emission in KLa(MoO4)2:Eu3+, Bi3+ phosphor for WLEDs

A series of Bi3+–Eu3+ co-doped KLa(MoO4)2 phosphors were synthesized by a hydrothermal method. The obtained samples were characterized by power X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet visible absorption spectrometer and photoluminescence (PL) techniques. The products were pure monoclinic phase and were composed of octahedral particles. The PLE and PL spectra demonstrated that the phosphors could be excited by 395nm and 465nm, which were in good agreement with the emission wavelengths of the near-ultraviolet (near-UV) and blue LED chips, respectively, and emitted red light at about 618nm owing to 5D0→7F2 transition of Eu3+. It was found that the intensity of the red light was significantly enhanced by adding Bi3+, which was attributed to the sensitization of Eu3+ by Bi3+. The exchange interaction was the major energy transfer mechanism in KLa(MoO4)2:Eu3+, Bi3+. Besides, the lifetime and chromaticity coordinates of single-doped Eu3+ and Eu3+–Bi3+ co-doped products were compared, respectively. All the results suggest that KLa(MoO4)2:Eu3+, Bi3+ is a promising phosphor for white LEDs.

Preparation of Nanostructured Fluorine Doped Tin Oxide (FTO) by Hydrothermal Method

This study demonstrates the fabrication of nanostructured FTO by hydrothermal method. It was directly synthesized on FTO glass substrate by using pentahydrated stannic chloride (SnCl4.5H2O) and ammonium fluoride (NH4F) as precursors. Different synthesis time was applied which were 5h, 10h and 24h. The characteristics of nanostructured FTO were investigated via field emission scanning electron microscopy (FESEM), two-point probe current-voltage test and ultraviolet visible spectrometer (UV-Vis). The FESEM images revealed the growth of nanosized particles layer on the FTO substrate. The electrical properties studied have shown a degeneration of conductivity as the thickness of nanostructured layer increased. UV-Vis results showed the decrement of transmittance as the time duration increased. It was revealed through FESEM characterization that the nanostructured FTO can be improved by using dibutyltin diacetate (DBTA) as a precursor.

Electrochromic Characteristics of Polyaniline and Poly(3-Methylthiophene) Thin Films for Display

In this study, the polyaniline (PANI) and the poly(3-methylthiophene) (PMeT) of the conductive polymer electrochromic thin films had been deposited on the indium tin oxide/glass (ITO/Glass) substrate by electrochemical polymerization, respectively. The cycling stability of the electrochromic thin film prepared with the variety of the different charge densities was investigated. The electrochromic behaviors of the PMeT/ITO/Glass and PANI/ITO/Glass were performed in the electrolytes of 0.1 M lithium perchlorate (LiClO4)/propylene carbonate (PC) and 0.1 M LiClO4+0.001 M perchloric acid (HClO4)/PC, respectively. The colors of the PMeT thin film exhibited blue and red in oxidation and reduction states, respectively. And the colors of the PANI thin film exhibited green and yellow in oxidation and reduction states, respectively. Furthermore, the absorbance and transmittance (T%) of the electrochromic thin film were measured by ultraviolet-visible (UV-Visible) spectrometer in this study. Besides, in order to find the optimal manufacture conditions of the electrochromic thin film, the potentials of redox reaction and cycles were investigated by the cyclic voltammetry (CV) measurement system to analyze the cycling stability of the electrochromic thin film with the variety of the different charge densities. Finally, the reflectance (R%) of the optimal parameters of the electrochromic thin film was measured by chroma meter in this study. And the variational colors of the electrochromic thin film were observed by the chromaticity coordinates of the Commission Internationale de l'Eclairage (CIE), so that the electrochromic thin film can be applied to the filed of display.

Synthesis and characterization of Cu2ZnSnS4 nanocrystals prepared by microwave irradiation method

In this study, we report a rapid and single-step synthesis of Cu2ZnSnS4 (CZTS) nanocrystals using microwave-assisted solution method. The influence of reaction temperature and reaction time on the phase purity, crystallographic structure, morphology and optical property of CZTS particles were investigated using X-ray diffraction, Raman spectroscopy, scanning electronic microscope, transmission electron microscopy and ultraviolet–visible spectrometer. Results revealed that the single kesterite CZTS particles with no secondary phase can be obtained by preparing samples at minimal temperature of 170 °C. The sphere-like particles, each of which contains many nanocrystals, decrease effectively in size when increasing the reaction temperature from 170 to 200 °C. The CZTS nanocrystals have an optical band gap around 1.5 eV, which is optimal for photovoltaic applications. In addition, minimal reaction time of 10 min is also essential for the growth of single kesterite CZTS. Our study demonstrated that appropriate reaction temperature and reaction time are crucial for the synthesis of high-quality CZTS by microwave irradiation method.