Ultraviolet-visible-near Infrared Research Articles

Synthesis and characterization of single-crystalline zinc tin oxide nanowires.

Crystalline zinc tin oxide (ZTO; zinc oxide with heavy tin doping of 33 at.%) nanowires were first synthesized using the electrodeposition and heat treatment method based on an anodic aluminum oxide (AAO) membrane, which has an average diameter of about 60 nm. According to the field emission scanning electron microscopy (FE-SEM) results, the synthesized ZTO nanowires are highly ordered and have high wire packing densities. The length of ZTO nanowires is about 4 μm, and the aspect ratio is around 67. ZTO nanowires with a Zn/(Zn + Sn) atomic ratio of 0.67 (approximately 2/3) were observed from an energy dispersive spectrometer (EDS). X-ray diffraction (XRD) and corresponding selected area electron diffraction (SAED) patterns demonstrated that the ZTO nanowire is hexagonal single-crystalline. The study of ultraviolet/visible/near-infrared (UV/Vis/NIR) absorption showed that the ZTO nanowire is a wide-band semiconductor with a band gap energy of 3.7 eV.

Quantifying the Aggregation Factor in Carbon Nanotube Dispersions by Absorption Spectroscopy

Absorption spectroscopy in the ultraviolet-visible-near infrared (UV-Vis-NIR) wavelength region has been used to quantify the aggregation factor of single-walled carbon nanotubes (SWCNTs) in liquid media through a series of controlled experiments. SWCNT bundles are dispersed in selected solvents using a calibrated ultrasonicator, which helps in determining the true amount of energy used in the exfoliation process. We also establish the selectivity of the centrifugation process, under the conditions used, in removing the nanotube aggregates as a function of the sonication time and the dispersion solvent. This study, along with the calibration of the sonication process, is shown to be very important for measuring the true aggregation factor of SWCNTs through a modified approach. We also show that the systematic characterization of SWCNT dispersions by optical spectroscopy significantly contributes to the success of dielectrophoresis (DEP) of nanotubes at predefined on-chip positions. The presence of individually dispersed SWCNTs in the dispersions is substantiated by dielectrophoretic assembly and post-DEP electromechanical measurements.

Optical Effects of Experimental Light-Activated Bleaching Procedures

The purpose of this study was to evaluate the efficiency of experimental light-activated bleaching procedures. The improved color effect may be attributed to the potential photochemical effect of light-emitting diode (LED405), organic LED (OLED), and femtosecond laser rather than to the photothermal effect of conventional lights used for tooth bleaching. Specially made pastilles of hydroxylapatite were immersed in green tea for 8 h and randomly divided into four groups (n=50) specified by the type of light source applied during a 30 min bleaching treatment: LED405, OLED, and femtosecond laser, or its absence (control group). Each group was treated with five bleaching gels: 10%, 16%, and 30% carbamide peroxide (CP), and 25% and 38% hydrogen peroxide (HP). Changes in color were determined by red-green-blue (RGB) colorimeter and ultraviolet-visible-near-infrared (UV/Vis/NIR) spectroscopy. Regardless of the applied bleaching gel, LED405 produced a larger increase in the value of RGB index than did OLED and bleaching without light activation (p<0.05). Femtosecond laser also produced significantly better results in combination with 16% CP and 38% HP. Furthermore, application of a bleaching agent with a higher concentration of peroxide boosted the value of the RGB index. Spectroscopic measurements revealed similar results, although treatments with OLED were rated relatively better than in RGB analysis. The mechanisms of light-activated bleaching procedures had a significant effect on the color change. The bleaching activation with LED405 and higher concentrations of peroxide in bleaching agents promoted better whitening effect.

Titanium Dioxide Thin Films Containing Gold-Silver Nanoclusters by Sol–Gel Technique

Abstract Pure and Au-Ag nanoclusters-doped TiO2 thin films have been synthesized by the sol–gel method and the effect of Au-Ag nanoclusters doping on their structural, morphological and optical properties was investigated by of X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), and Ultraviolet-Visible-Near infrared (UV-Vis-NIR) spectrophotometry, respectively. XRD spectrum indicated that all of TiO2 thin films were polycrystalline anatase with a body-centered tetragonal structure. SEM images show that all thin films are compact, dense and adhered well to the substrates. The maximum transmittance values of pure and TiO2 thin films are over 90% when Au-Ag nanoclusters concentration is up to 40% doping level. The optical band gap of the as-grown TiO2 thin films decreases from 3.63 to 3.31 with increasing dopant concentration. These results provide some useful references for the potential application of these thin films in device technology.

The photoresponse and photoconductivity of micron-sized C60 whiskers and sub-millimeter-sized C60 clusters

The photoresponse and photoconductivity properties of micron-sized C60 whiskers and sub-millimeter-sized C60 clusters are successfully studied by the microfabrication technologies. According to the ultraviolet-visible-near infrared (UV-Vis-NIR) absorption spectroscopic study, a highly intense absorption is observed in the UV and visible light regions, which indicates probable applications in photoelectric devices. Furthermore, a large photocurrent is measured under the illumination of white light in nitrogen (N2) atmosphere. The micron-sized C60 whiskers and the sub-millimeter-sized C60 clusters have different photoresponse curves under the same condition of measurement. A quick transformation of photoelectric response is detected in parallel multi-arranged micron-sized C60 whiskers, but the recovery of the photocurrent of self-assembly sub-millimeter-sized C60 clusters is much slower.

Effect of 14 MeV neutrons on the optical properties of CR-39 detector

This study is carried out to establish a correlation between optical absorbance and track density in CR-39 detectors exposed to different fluences of D-T (14 MeV) neutrons. This can be useful in estimating the neutron fluence and hence the dose without involving the tedious track counting procedure, especially when the track density is extremely high. Variation in the optical properties is studied using UV-VIS-NIR (ultraviolet-visible-near infrared) spectroscopic technique. The neutron-induced recoil tracks are developed by chemical etching and the track density is determined. The optical transmission spectra are obtained for pristine and neutron irradiated detectors before and after etching. A linear relationship is obtained between the track density and the optical absorbance with increasing neutron fluence. Another objective of this work is to study the effect of etching on the optical properties such as transmittance and absorbance of irradiated CR-39 detectors. The optical properties are found to be changing due to the development of tracks in the detector.

Synthesis, growth and characterization of picolinic acid hydrochloride: A novel semiorganic nonlinear optical single crystal

Nonlinear optical single crystals of picolinic acid hydrochloride (PHCL) were grown by the slow evaporation method. The grown crystal was subjected to a single crystal X-ray diffraction analysis, to confirm that it belongs to the orthorhombic structure. The Nonlinear Optical (NLO) property of the crystal is confirmed with the emission of green radiation from the crystal under the illumination of laser radiation (106.4 nm) from a Q switched Neodymium: Yttrium Aluminum Garnet (Nd: YAG) laser. The optical transmission range of the grown crystal was measured by Ultraviolet-Visible-Near Infrared (UV-VIS-NIR) with the lower cut-off wavelength as 195 nm. The mechanical strength of the grown crystal was analyzed using Vickers microhardness tester. The dielectric constant and dielectric loss of picolinic acid hydrochloride are measured in the frequency range of 50 Hz to 5 MHz at different temperatures. Key words: Crystal growth, Nonlinear Optical (NLO), optical transmission, single crystal X-ray diffraction (XRD), mechanical properties, dielectric studies.

Control of Polymer-Packing Orientation in Thin Films through Synthetic Tailoring of Backbone Coplanarity

Controlling solid-state order of π-conjugated polymers through macromolecular design is essential for achieving high electronic device performance; yet, it remains a challenge, especially with respect to polymer-packing orientation. Our work investigates the influence of backbone coplanarity on a polymer’s preference to pack face-on or edge-on relative to the substrate. Isoindigo-based polymers were synthesized with increasing planarity by systematically substituting thiophenes for phenyl rings in the acceptor comonomer. This increasing backbone coplanarity, supported by density functional theory (DFT) calculations of representative trimers, leads to the narrowing of polymer band gaps as characterized by ultraviolet-visible-near infrared (UV-vis-NIR) spectroscopy and cyclic voltammetry. Among the polymers studied, regiosymmetric II and TII polymers exhibited the highest hole mobilities in organic field-effect transistors (OFETs), while in organic photovoltaics (OPVs), TBII polymers that display intermediate levels of planarity provided the highest power conversion efficiencies. Upon thin-film analysis by atomic force microscropy (AFM) and grazing-incidence X-ray diffraction (GIXD), we discovered that polymer-packing orientation could be controlled by tuning polymer planarity and solubility. Highly soluble, planar polymers favor face-on orientation in thin films while the less soluble, nonplanar polymers favor an edge-on orientation. This study advances our fundamental understanding of how polymer structure influences nanostructural order and reveals a new synthetic strategy for the design of semiconducting materials with rationally engineered solid-state properties.

Optical and electronic properties of delafossite CuBO2 p-type transparent conducting oxide

CuBO2 delafossite was prepared by solid state reaction and calcined/sintered at 1005 °C. The optical properties of this p-type transparent conducting oxide were investigated. Its crystal structure, morphology, composition, oxygen decomposition, and optical and electronic properties were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, thermal gravimetric analysis (TGA), ultraviolet-visible-near-infrared (UV-VIS-NIR) and fluorescence spectroscopies, Seebeck coefficient, and electrical conductivity measurements. CuBO2 delafossite possesses a hexagonal space group R3¯m. TGA indicated a weight loss of 10%, which was attributed to excess oxygen. The positive Seebeck coefficient confirmed p-type behavior. Emission at 355 nm indicated a direct band type transition, and the UV-VIS-NIR spectrum indicated an optical direct gap of 3.6 eV. Activation energies for carrier production and electrical conduction were 0.147 and 0.58 eV, respectively, indicating the thermal activation of carriers. CuBO2 delafossite is a p-type transparent conducting oxide with a wide band gap and may have potential in industrial p-type electrodes.

Investigation of optical property in LiInSe2 single crystal grown by Bridgman Stockbarger method using stepper translations for mid IR laser application

Abstract LiInSe 2 polycrystalline material was synthesized in a horizontal muffle furnace with the help of a mechanical motor. LiInSe 2 single crystal has successfully been grown by modified Bridgman furnace using stepper translation. The grown crystal was subjected to various characterizations such as Powder X-ray Diffraction (XRD), Single crystal X-ray Diffraction, High Resolution X-ray Diffraction (HRXRD), Fourier transform infrared spectroscopy (FTIR), Ultraviolet–Visible-Near Infrared spectroscopy (UV–Vis–NIR), Photoluminescence and Micro Raman spectroscopy. The grown LiInSe 2 crystal was confirmed by single crystal and powder X-ray diffraction analyses. The FTIR transmission of grown LiInSe 2 single crystal was found to be around 80% which is being used in the field of mid Infrared laser, Lidar sensor, and optical parametric conversion. The band gap energy 1.85 eV was calculated from absorption spectrum. The cut off wave length is 617 nm for LiInSe 2. The photoluminescence spectrum was observed around 598 nm at ambient temperature, corresponding energy is 2.07 eV. The structural and compositional uniformities of LiInSe 2 were studied using micro-Raman scattering spectroscopy at room temperature. The insignificant change in the Full width at half maximum (FWHM) of the Г 1 ( W 1 ) measured at different regions of the crystal further reveals that the composition throughout its length is fairly uniform.

Structural and photocatalytic characteristics of TiO2 coatings produced by various thermal spray techniques

Titanium dioxide (TiO2) was elaborated by four different thermal spray techniques—(i) plasma spraying using a water-stabilized torch, (ii) plasma spraying using a gas-stabilized torch, (iii) high velocity oxy-fuel gun, and (iv) oxy-acetylene flame. The porosity of the coatings was studied by optical microscopy, nano-structural features by scanning electron microscopy (SEM), phase composition by X-ray diffraction (XRD); the microhardness, surface roughness and wear resistance were evaluated. The diffuse reflectance was measured by ultra-violet/visible/near-infrared (UV/Vis/NIR) scanning spectrophotometer. The kinetics of photocatalytic degradation of gaseous acetone was measured under a UV lamp with 365 nm wavelength. After all the applied spray processes, the transformation of anatase phase from the initial powders to rutile phase in the coatings occurred. In spite of this transformation, all the coatings exhibited certain photocatalytic activity, which correlated well with their band gap energy calculated from reflectivity. All the coatings offer relatively good mechanical properties and can serve as robust photocatalysts.

Directly assembled quantum dots on one dimension ordered TiO2 nanostructure in aqueous solution for improving photocatalytic activity

One dimension (1D) ordered titanium dioxide (TiO2) nanostructured photocatalysts sensitized by quantum dots (QDs) are fabricated. Their morphologies, crystal structures and photocatalytic properties are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and ultraviolet-visible-near infrared (UV-vis-NIR) absorption spectroscopy, respectively. Compared with the original TiO2 nanostructure, the nanostructured TiO2 sensitized by QDs exhibits a good photocatalytic activity for the degradation of methyl orange (MO). The QDs with core-shell structure can reduce the photocatalytic ability due to the higher potential barrier of carrier transport in ZnS shell layer. The results indicate that the proposed photocatalyst shows promising potential for the application in organic dye degradation.

Preparation of Heterojunction Semiconductor SnS&lt;sub&gt;2&lt;/sub&gt;/SnO&lt;sub&gt;2&lt;/sub&gt; with Enhanced Photocatalytic Properties

The Formation of Heterojunction Structure between Two Semiconductors Was Considered as an Effective Method to Enhance the Photocatalytic Activity. here, we Reported a Simple Method to Prepare SnS2/SnO2Heterojunction Photocatalysts by Annealing SnS2in Air. the Structure, Morphology, Chemical Compositions and Optical Properties of the Obtained Materials Were Characterized by the X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Energy-dispersive X-ray Spectroscopy (EDX) and Ultraviolet-visible-near Infrared (UV-Vis-NIR) Absorption Spectra. the Photocatalytic Investigations Showed the Composites Have Higher Photocatalytic Activity than the Single-phase SnS2. the SnS2Powder which Annealed at 400 °C for 60 Min Showed the Highest Photocatalytic Performance.

Facile Oxidative Conversion of TiH2 to High-Concentration Ti3+-Self-Doped Rutile TiO2 with Visible-Light Photoactivity

TiO2, in the rutile phase with a high concentration of self-doped Ti(3+), has been synthesized via a facile, all inorganic-based, and scalable method of oxidizing TiH2 in H2O2 followed by calcinations in Ar gas. The material was shown to be photoactive in the visible-region of the electromagnetic spectrum. Powdered X-ray diffraction (PXRD), transmission electron microscopy (TEM), ultraviolet-visible-near-infrared (UV-vis-NIR), diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller (BET) methods were used to characterize the crystalline, structural, and optical properties and specific surface area of the as-synthesized Ti(3+)-doped rutile, respectively. The concentration of Ti(3+) was quantitatively studied by electron paramagnetic resonance (EPR) to be as high as one Ti(3+) per ~4300 Ti(4+). Furthermore, methylene blue (MB) solution and an industry wastewater sample were used to examine the photocatalytic activity of the Ti(3+)-doped TiO2 which was analyzed by UV-vis absorption, Fourier transform infrared spectroscopy (FT-IR), and electrospray ionization mass spectrometry (ESI-MS). In comparison to pristine anatase TiO2, our Ti(3+) self-doped rutile sample exhibited remarkably enhanced visible-light photocatalytic degradation on organic pollutants in water.

Revisiting astronomical crystalline forsterite in the UV to near-IR

Optical functions (n and k) of cosmic dust species like forsterite (Mg2SiO4) are required at all wavelengths to quantify the temperature and amount of dust. Astronomers combine optical functions of forsterite and olivine in different ways, which will affect radiative transfer models. We investigated what recent updates to the ultraviolet-visible-near-infrared (UV-VIS-NIR) laboratory spectra of forsterite and the choice of forsterite n, k dataset will have on radiative transfer models. We measured the UV-VIS-NIR transmission spectra of synthetic forsterite, MgO, SiO2, olivine (Fo90), and meteoritic olivine (pallasite). We derived optical functions for these and compared the UV-IR behavior of our k, absorption cross-section 〈Cabs〉, and total flux to that of “astronomical silicate” and olivine. Laboratory-derived k is substantially lower than “astronomical silicate” k at λ ~ 0.2–5 µ m. In the IR, different laboratory n and k produce equivocal 〈Cabs〉, whereas total flux is different for “astronomical silicate” versus laboratory n, k. From 0.35–5 µ m, the choice of “forsterite” k values has the most effect on modeled quantities. For environments with significant UV flux, astronomers should use recent UV-VIS-NIR laboratory n, k.

Optical, electrical and sensing properties of In2O3 nanoparticles

In this work, various techniques such as differential scanning calorimetry-thermogravimetric analysis (DSC-TGA), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible-near infrared (UV-vis-NIR), photoluminescence (PL), >as well as electrical and sensor techniques have been used for the characterization of indium oxide (In2O3) nanoparticles. Here, we also provide insight regarding the optical and electrical characteristics of In2O3 nanostructures. The impact of highly sensitive and fast responding gas sensors using In2O3 nanostructures is also discussed. It is found that the as-prepared In2O3 powder is a pure single phase and is stable up to 800°C. The size of the particles is in the range of 12nm as determined by transmission electron microscopy (TEM). The band gap was found to vary linearly with the annealing temperature. A good sensitivity up to 400ppm was obtained for ethanol and a mechanism is proposed.

Hole Doping in Al-Containing Nickel Oxide Materials To Improve Electrochromic Performance

Electrochromic materials exhibit switchable optical properties that can find applications in various fields, including smart windows, nonemissive displays, and semiconductors. High-performing nickel oxide electrochromic materials have been realized by controlling the material composition and tuning the nanostructural morphology. Post-treatment techniques could represent efficient and cost-effective approaches for performance enhancement. Herein, we report on a post-processing ozone technique that improves the electrochromic performance of an aluminum-containing nickel oxide material in lithium-ion electrolytes. The resulting materials were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible-near-infrared (UV-vis-NIR) spectroscopy, and X-ray absorption spectroscopy (XAS). It was observed that ozone exposure increased the Ni oxidation state by introducing hole states in the NiO(6) octahedral unit. In addition, ozone exposure gives rise to higher-performing aluminum-containing nickel oxide films, relative to nickel oxide containing both Al and Li, in terms of switching kinetics, bleached-state transparency, and optical modulation. The improved performance is attributed to the decreased crystallinity and increased nickel oxidation state in aluminum-containing nickel oxide electrochromic films. The present study provides an alternative route to improve electrochromic performance for nickel oxide materials.

Studies on the Synthesis, Growth and Characterization of ([Paranitrophenyl]Imino)Benzene NLO Crystal by Sankaranarayanan-Ramasamy Method

The study of imine-bridged organics has been the hot spot synthesis of second order nonlinear optical (SONLO) and photo-responsive materials in recent years. Herein we present a study of synthesis, growth, and characterization of ([paranitrophenyl]imino)benzene (PNPIB) NLO single crystal. The title compound was synthesized in one step by Schiff base formation. PNPIB single crystal of diameter of 40 mmand length 50 mmwas successfully grown by SR method using a seed as the nucleus. The growth rate formula is derived for the SR method. PNPIB single crystals of 10 mmdiameter and 60 mmheight have been grown at an average growth rate of 3 mmper day from the point seed in a glass crystallizer. Almost 100% stable crystal conversion efficiency was achieved. The as grown PNPIB crystals were characterized using single crystal X-ray diffraction (XRD), X-ray powder diffraction (XRPD), Fourier Transform Infrared (FTIR), Ultraviolet-Visible-Near Infrared (UV-Vis-NIR), 1H & 13C NMR spectral studies, dielectric measurement and NLO studies. Single crystal XRD analysis confirms that the grown ingot belongs to the space group of P2 of monoclinic system thus exhibiting noncentrosymmetric structure. The crystalline perfection was assessed by XRPD. The powder diffraction pattern of the grown crystal has been indexed. The presence of C=N bond with intramolecular hydrogen bonding and the protonation of ions were confirmed by FTIR analysis. The UV-Vis-NIR spectrum of the crystal shows that the crystal has a cut-off at 298 nm. The 1H & 13C NMR spectra confirm the molecular structure. The dielectric behaviour was measured in the frequency range 1 KHz - 10 KHz for the temperature range from 30℃ to 170℃. The slight decrease in dielectric constant has been observed as the frequency is increased and the dielectric loss is very low for the entire frequency range. The second harmonic generation (SHG) in the crystal was observed by Kurtz powder technique.

Physical Properties of ZnSe Thin Films Depending on the Process Parameters

ZnSe thin films were grown by a co-evaporation method with various Se/Zn flux ratios. In order to characterize ZnSe thin films, we performed an investigation that utilized X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Ultra Violet–Visible-Near InfraRed (UV-VIS-NIR) measurements of the structural, optical, and morphological properties. XRD pole-figure analysis confirmed that the orientation of the ZnSe cubic (111) plane has been widely distributed throughout the ψ axis with respect to process conditions, flux rate of Se. It has been found that as long as the Se/Zn flux ratio is larger than 1.43, stable, single-phase, ZnSe thin films can be grown. Additional experimental data revealed that optical properties strongly depend on the substrate temperature and have correlation with crystallinity.

Multiwavelength Transmission Spectroscopy Revisited for the Characterization of the Protein and Polystyrene Nanoparticle Interactions

Multiwavelength transmission ultraviolet-visible-near-infrared (UV-Vis-NIR) spectroscopy is an effective technique that has not yet been fully exploited for the characterization of products of protein and particle interactions. Here, it is explored by using bovine serum albumin and National Institute of Standards and Technology-traceable particle size standard having a nominal diameter of 20 nm. Adsorption of bovine serum albumin to the particles is quantitatively ascertained through its effect on the wavelength-dependent transmission spectra of protein and particle mixtures. The experimental results demonstrate that the changes induced in the transmission spectra of protein and particle mixtures because of protein adsorption on particles are detectable and consistent with the expectations set by the light-scattering theory. The size, structure, composition, and relative concentrations of the particle populations present in the protein-particle mixtures can be quantified. Given the considerable dynamic range of multiwavelength transmission UV-Vis-NIR spectroscopy for particle analysis and its real-time measurement capabilities, this type of spectroscopy can be effectively used for the characterization of the products of protein-particle interaction and for the continuous real-time monitoring of interaction processes.