IR Transmission Research Articles

Synthesis of Calixarene-Capped Silver Nanoparticles for Colorimetric and Amperometric Detection of Mercury (HgII, Hg0).

Calixarene-functionalized water dispersible silver nanoparticles have been synthesized and characterized on the basis of UV–vis, IR, X-ray diffraction, and high-resolution transmission electron microscopy analysis, and their sensing properties toward metal ions have been investigated. They selectively detect Hg2+ and Hg0 in solution and vapor phases, respectively, with distinct color change. Interference study with mixture of metal ions revealed no interference from any other metal ions used in this study. Their mechanism of detection involved Hg2+-aided displacement of calixarene moiety from the surface of the functionalized nanoparticles, followed by the formation of Ag–Hg amalgam due to interaction of Hg2+ with Ag0 and also the formation of assembly of Ag0 nanoparticles by dipole–dipole interaction of the bare-surfaced nanoparticles. Electrochemical study revealed that with the aid of functionalized nanoparticles, Hg2+ can be detected amperometrically with high sensitivity. The detection limits obtained for Hg2+ by UV–vis study and amperometry are 0.5 nM (0.1 ppb) and 10 nM (2 ppb), respectively. The new material has been used to detect Hg2+ in aqueous real sample and Hg0 in soil sample.

IR filtering properties of TiAlN/Cu/TiAlN coatings

In this paper, to explore the potential infrared filtering applications of magnetron sputtered TiAlN/Cu/TiAlN coatings, we investigated the optical, morphological and surface topographical properties using UV/Vis/NIR spectrometry, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy, respectively. From IR Spectroscopy analysis, it is observed that glass/TiAlN/Cu/TiAlN structure with 10 nm thick Cu layer showed highest visible transmittance of 78% and lowest IR transmittance of 22% at 600 nm and 2500 nm wavelength, respectively. In additon the AFM topographs further indicate that the inner TiAlN seeding layer could reduce the average roughness of Cu layer to 3 nm as compared to 8 nm without seeding layer. Moreover, outer TiAlN layer demonstrates very good environmental and corrosion protection property. Based on the results and analysis, it is proposed that TiAlN/Cu/TiAlN can be used as an efficient IR reflective material with high visible transmittance.

IR spectroscopic quantification of small molecule transport and desorption phenomena in polymers

The application, continued performance, and degradation behavior of polymers often depends on their interaction with small organic or gaseous volatiles. Understanding the underlying permeation and diffusion properties of materials is crucial for predicting their barrier properties (permeant flux), drying behavior, solvent loss or tendency to trap small molecules, as well as their interaction with materials in the vicinity due to off-gassing phenomena, perhaps leading to compatibility concerns. Further, the diffusion of low Mw organics is also important for mechanistic aspects of degradation processes. Based on our need for improved characterization methods, a FTIR-based spectroscopic gas/volatile quantification setup was designed and evaluated for determination of the diffusion, desorption and transport behavior of small IR-active molecules in polymers. At the core of the method, a modified, commercially available IR transmission gas cell monitors time-dependent gas concentration. Appropriate experimental conditions, e.g. desorption or permeation under continuous flow or static gas conditions, are achieved using easily adaptable external components such as flow controllers and sample ampoules. This study presents overview approaches using the same IR detection methodology to determine diffusivity (desorption into a static gas environment, continuous gas flow, or intermittent desorption) and permeability (static and dynamic flow detection). Further, the challenges encountered for design and setup of IR gas quantification experiments, related to calibration and gas interaction, are presented. These methods establish desorption and permeation behavior of solvents (water and methanol), CO2 off-gassing from foam, and offer simultaneous measurements of the permeation of several gases in a gas mixture (CO2, CO and CH4) through polymer films such as epoxy and Kapton. They offer complementary guidance for material diagnostics and understanding of basic properties in sorption and transport behavior often of relevance to polymer degradation or materials reliability phenomena.

Syntheses, structures and immobilization of arene-ruthenium complexes bearing phosphine ligands with methoxysilyl groups

Condensation of 3-aminopropyltrimethoxysilane and chlorodiphenylphosphine in the molar ratio of 1:1 and 1:2 in the presence of Et3N in toluene afforded aminophosphine (CH3O)3Si(CH2)3NHPPh2 (L1) and bisphosphinoamine (CH3O)3Si(CH2)3N(PPh2)2 (L2) with methoxysilyl groups, respectively. Treatment of [(η6-C6H6)RuCl2]2 with L1 in refluxing tetrahydrofuran gave a mononuclear ruthenium phosphine complex [(η6-C6H6)RuCl2(κ1-P-L1)] (1). Reaction of [(η6-p-cymene)RuCl2]2 with L2 under the similar condition gave a dinuclear ruthenium phosphine complex [(η6-p-cymene)Ru(μ-Cl)3RuCl(κ2-P,P-L2)] (2). Complexes 1 and 2 were characterized by microanalyses, IR and NMR spectroscopies, and their structures were also established by single-crystal X-ray diffraction. Immobilization of complexes 1 and 2 on SBA-15, and characterization of these hybrid heterogeneous catalysts were studied by transmission electron microscopy (TEM), IR and low pressure N2 adsorption/desorption measurement. The heterogeneous catalysts were also briefly tested for transfer hydrogenation of acetophenone.

Detector performance and defect densities in CdZnTe after two-step annealing

Defects both microscale and nanoscale are play an important role in CdZnTe (CZT) device performance. Typical micro-scale defects such as Te inclusions were removed via a two-step annealing process, and their concentration was analyzed via IR transmission microscopy. In addition, transmission electron microscopy (TEM) measurement was employed to investigate the evolution of nano-scale defects after the annealing process. Dislocation and stacking faults were commonly observed defects in as-grown and annealed CZT. The line shape defects, which are possibly related to the stress field around dislocations, disappeared during the in-situ the annealing at 200–220 °C. A Frisch-grid CZT detector made via the two-step annealing process exhibited improved energy resolution and low backscattering counts in Cs-137 gamma spectra.

Dipolar coupling and molecular vibrations in ionic liquids.

It is often the case that intense, non-degenerate bands appear asymmetric in transmission IR spectra of ionic liquids, with a high-frequency shoulder adjacent to the dominant band. Moreover, the band shape is temperature dependent with lower temperatures producing greater amounts of asymmetry. The 1-alkyl-3-methylimidazolium trifluoromethanesulfonate family of ionic liquids provides an excellent illustration of this phenomenon, wherein the νs(SO3) mode of the anion is split into two components whose frequencies change with temperature. In this article, a new theoretical model is derived to explain temperature-dependent trends in the infrared spectra of these materials. According to the model, vibrationally-induced dipole moments couple with one another across the charge-organized liquid structure inherent to ionic liquids to produce transverse optical (TO) and longitudinal optical (LO) phonons. The temperature dependence of the resulting TO-LO band splitting originates from two distinct sources. First, the interaction strength between vibrationally-induced dipole moments depends on the distance separating the ions, which in turn, is directly related to the ionic liquid's density. Second, TO-LO splitting requires a significant amount of angular correlation among the ions to facilitate the propagation of optical phonons. Elevated temperatures produce smaller densities and increased amounts of disorder, both of which lead to decreased amounts of TO-LO splitting. Although the model is developed in the context of ionic liquids, the equations are broadly applicable to other materials that possess long-range structure but are not fully crystalline, such as molten salts, plastic crystalline compounds, glasses, and disordered solids.

Microwave synthesis and characterization Mg(OH)2/Gr nanocomposites in the presence of sodium dodecyl sulfate (SDS) as a stabilizer agent

This work reports, microwave synthesis and characterization Mg(OH)2/Gr nanocomposites in the presence of sodium dodecyl sulfate (SDS) as a stabilizer agent. Mg(OAc)2•4H2O and graphene powder have been used as starting reagents. Mg(OH)2/Gr nanocomposites synthesized by microwave method, particle size distribution and characterization of products were done by X-ray diffraction (XRD), Atomic force microscopy (AFM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Uv-Vis and IR spectroscopy. The results indicated that the synthesized Mg(OH)2/Gr nanocomposites have a pure crystality structure with average size 75–110 nm.

Wet-chemical preparation of TiO2-nanostructures using different solvents: Effect of CTAB concentration and tentative mechanism of particle formation

In this paper, TiO2 nanostructures (TiO2-NSs) were synthesized in a controlled way. The effects of the use of a surfactant, Cetyl trimethylammonium bromide (CTAB), and the nature of the solvent of synthesis (ethanol and toluene) on the characteristics of the final product were studied. For this, TiO2-NSs were characterized using IR spectroscopy, X-ray diffraction (XRD), Transmission and Scanning Electron Microscopy. The solid obtained, without heat treatment, presented an amorphous structure that crystallized when treated at 450 °C, giving anatase as crystalline phase, independent of the solvent of synthesis and the concentration of CTAB used. The size of the crystallite in the powders synthesized was 3–5 nm and was reduced on increasing CTAB concentration, regardless of the solvent used. Using ethanol, the primary particles had a spheroidal or needle type shape of nanometric size (<100 nm) and the agglomerates were spherical (1–5 μm), reducing in size on the addition of CTAB. On using toluene, irregular-shaped aggregates with acute edges were formed (10–20 μm), made up of primary particles nanometric (<100 nm) and with the presence of poros. Given the nature of the synthesis process, a mechanism was proposed to explain the formation of the TiO2-NSs.

Smart Home Automation System based on Arduino

&lt;p&gt;Intelligent home environments are environments that attempt to ease the user's life in different ways and make it more comfortable using the technology. This paper present the principle of realizing a home control interface based on an. Arduino UNO R3 board equipped with a programmable ATmega328 microcontroller. The sketch to be uploaded to the Arduino is written in C language. A desktop application was created in C # language to communicate with the Arduino via the serial port, thus facilitating repetitive tasks such as lighting control, opening / closing doors. A temperature / humidity sensor, an alarm (motion sensor + buzzer), garden lighting and automatic control of the TV via an IR receiver + IR transmitter have been added without forgetting manual control&lt;/p&gt;

Effect of Method of Boron Introduction into NiMo/Al2O3 Protective-Layer Catalysts on the Removal of Silicon from Diesel Fractions

NiMo/γ-Al2O3 protective-layer catalysts for removing silicon from diesel fractions were examined. The catalysts differ in the way in which boron is introduced into the support. The supports and catalysts were examined by X-ray diffraction analysis, transmission electron microscopy, IR spectroscopy, and adsorption–desorption of nitrogen. The catalysts were tested in hydropurification of the diesel fraction to which decamethylcyclopentanesiloxane was added as a model silicon compound. It was shown that introduction of boron into the support results in that the surface area of the supports and catalysts increases. If boron is introduced into pseudoboehmite, massive particles of the Ni–Mo–S phase are formed. It was found that the highest capacity for silicon is observed for the catalyst into which boron is introduced in the stage of pseudoboehmite preparation.

Catalytic performance of silicalite-1 modified HY zeolite in the hydrolysis of cellulose

A core-shell composite zeolite (HY/silicalite-1) was prepared by modifying HY zeolite with silicalite-1 and characterized by X-ray diffraction (XRD), Scanning electron microscope (SEM), Transmission electron microscope (TEM), N2 sorption and IR spectra of pyridine adsorption (Py-FTIR); the catalytic performance of HY/silicalite-1 composite zeolite in the hydrolysis of cellulose was then investigated in comparison with that of HY. The results show that the crystallization time has a significant influence on the crystal growth of the HY/silicalite-1 composite zeolite and the relative content of two components. With the optimum crystallization time of 16–24 h, a core-shell structure for the HY/silicalite-1 composite zeolite is achieved, where the silicalite-1 crystal grows over the surface of HY zeolite; with the prolongation of the crystallization time, the morphology of the composite zeolite changes from rough turbid to smooth and eventually to scale-like surface. The amount of Brönsted acid sites decreases first and then increases with the increase of the crystallization time, whereas the amount of Lewis acid sites changes in the opposite direction. In particular, the HY/silicalite-1 composite zeolite obtained with a crystallization time of 24 h exhibits excellent catalytic performance in the hydrolysis of cellulose to glucose; over it, the yield of glucose reaches 45.8% at 130°C, much higher than the value of 28.0% over the HY zeolite.

The Structure and Properties of 2,3-7,8-Dibenzpyrene-1,6-Quinone

A technique for growing 2,3-7,8-dibenzpyrene-1,6-quinone single crystals is described. Its crystal structure, IR transmission spectra, reflection spectra in the visible spectral range, results of thermal analysis, and XPS spectroscopy data are reported for the first time. The crystalline structure of this compound is described within the sp. gr. P21/n; its unit cell parameters are a = 17.4346(19) A, b = 4.8717(5) A, c = 18.263(2) A, and β = 105.857(2)°. The structure can be characterized as a herringbone stacking of flat molecules, between which weak О…H‒C interactions of carbonyl oxygen atoms and hydrogen atoms of aromatic rings exist.

Growth of large-size high-quality ZnTe bulk crystals by traveling solvent melting zone method

ZnTe crystal is a promising electro-optical crystal materials applied for THz generation and detection. However, there is still a big challenge to obtain large sized high quality ZnTe crystals. In this work, large sized ZnTe bulk crystals with Φ30 mm × 150 mm were grown by the traveling solvent melting zone (TSMZ) method. With the characterization of the optical and electrical properties of as-grown ZnTe crystals, the band gap (2.22 eV), high IR transmittance (around 60%), high resistivity (3.5 × 103 Ω·cm), low density (1.3 × 105 cm−2) and small sizes (3 μm - 5 μm) of Te inclusions in ZnTe crystals, low etch pit densities (1.5 × 105 cm−2), high peak intensity to FWHM ratio (2.5 × 104) of the LO peak in the Raman spectra were obtained. Furthermore, the THz transmission spectra was measured and the maximum transmittance is more than 40% at the range of 0.3 - 3 THz. Based on these results, high quality and large aspect ratio ZnTe bulk crystals can be obtained by the TSMZ technique. Our work has greatly facilitated the application of ZnTe crystals in THz device.

Study of Detector-Grade CdMnTe:In Crystals Obtained by a Multi-Step Post-Growth Annealing Method

A multi-step annealing method was successfully applied to inclusions reduction and resistivity improvement of CdMnTe:In (CMT:In) single crystals with high resistivity, including a Cd atmosphere annealing step followed by a Te atmosphere annealing step. After the Cd atmosphere annealing step, the density of Te inclusions was reduced distinctly, and it could be also decreased in the subsequent step of re-annealing under Te atmosphere. Both the resistivity and IR transmittance decreased notably after Cd atmosphere annealing, whereas they increased tremendously after re-annealing under a Te atmosphere. The reduction of full-width at-half-maximum (FWHM) and the increase of the intensity of the X-ray rocking curve indicated an improvement of the crystal quality. Meanwhile, after Cd atmosphere annealing, the increase of the intensity of the (D0,X) peak and the disappearance of the (A0,X) peak in photoluminescence (PL) measurements suggested further that the crystal quality was improved. The detector performance was enhanced obviously after annealing. The higher the annealing temperature, the better the performance was. The detector fabricated by CMT:In slice (Cd atmosphere annealing at 1073 K for 240 h and Te atmosphere re-annealing at 773 K for 120 h) with 9.43% energy resolution and 1.25 × 10−3 cm2/V μτ value had the best detector performance.

Flexible and transparent IWO films prepared by plasma arc ion plating for flexible perovskite solar cells

We investigated flexible W-doped In2O3 (IWO) electrodes prepared by arc plasma ion plating (APIP) as a substitute for sputtered amorphous ITO electrodes in flexible perovskite solar cells (FPSCs). In spite of the room temperature ion plating process, the APIP-grown IWO film showed a low sheet resistance of 37.14 Ohm/square, a high optical transmittance of 96.0%, high near IR transmittance, and a small bending radius of 5 mm. In addition, the IWO film shows an atomically smooth surface with a root mean square roughness of 0.83 nm due to the absence of the resputtering effect during the ion plating process. The FPSC with the ion-plated IWO electrode showed comparable performances to a commercial amorphous ITO electrode in an FPSC with an open circuit voltage (0.837 V), short circuit current (18.67 mA/cm2), fill factor (72.54%), and power conversion efficiency (11.33%). Moreover, the microstructure and interfacial structure of the APIP-grown IWO film employed in a FPSC were examined by high-resolution transmission electron microscopy and the sheet resistance of the IWO films was correlated to the FPSC performance.

Optical Properties of ZnO/Al/Ag/ZnO Multilayers as Near Infrared Cut-off Filters

Various ZnO/metal/ZnO multilayers were fabricated and their optical properties were investigated. Top and bottom ZnO layers were formed by sol-gel method and mid-metal layers were deposited by thermal evaporation for precise control of thickness. After the fabrication of ZnO/Ag/ZnO structure, the transmittance increased to 72%. Adding Al to middle Ag layer, the ZnO/Al/Ag/ZnO structure reduced the near IR transmission in half with 40% optical transmittance in entire visible region. This oxide/double metal/oxide multilayers show the huge potential for building integrated photovoltaics as near IR cut-off filters.

Dominant Role of Entropy in Stabilizing Sugar Isomerization Transition States within Hydrophobic Zeolite Pores

Lewis acid sites in zeolites catalyze aqueous-phase sugar isomerization at higher turnover rates when confined within hydrophobic rather than within hydrophilic micropores; however, relative contributions of competitive water adsorption at active sites and preferential stabilization of isomerization transition states have remained unclear. Here, we employ a suite of experimental and theoretical techniques to elucidate the effects of coadsorbed water on glucose isomerization reaction coordinate free energy landscapes. Transmission IR spectra provide evidence that water forms extended hydrogen-bonding networks within hydrophilic but not hydrophobic micropores of Beta zeolites. Aqueous-phase glucose isomerization turnover rates measured on Ti-Beta zeolites transition from first-order to zero-order dependence on glucose thermodynamic activity, as Lewis acidic Ti sites transition from water-covered to glucose-covered, consistent with intermediates identified from modulation excitation spectroscopy during in situ attenuated total reflectance IR experiments. First-order and zero-order isomerization rate constants are systematically higher (by 3-12×, 368-383 K) when Ti sites are confined within hydrophobic micropores. Apparent activation enthalpies and entropies reveal that glucose and water competitive adsorption at Ti sites depend weakly on confining environment polarity, while Gibbs free energies of hydride-shift isomerization transition states are lower when confined within hydrophobic micropores. DFT calculations suggest that interactions between intraporous water and isomerization transition states increase effective transition state sizes through second-shell solvation spheres, reducing primary solvation sphere flexibility. These findings clarify the effects of hydrophobic pockets on the stability of coadsorbed water and isomerization transition states and suggest design strategies that modify micropore polarity to influence turnover rates in liquid water.

Spectra (UV-Visible, IR transmission) of Sc3+, Fe3+ and Cu2+ tri-doped LiNbO3 crystals with various [Li]/[Nb] ratios

The Sc:Fe:Cu:LiNbO3 crystals were grown with Fe[Formula: see text](0.3 wt.%), Cu[Formula: see text](0.1 wt.%) and Sc[Formula: see text](1 mol.%) by the Czochralski method with various [Li]/[Nb] ratios (0.946, 1.05, 1.20 and 1.38). The influence of the [Li]/[Nb] ratios on the defect structure of Sc:Fe:Cu:LiNbO3 crystals was analyzed by the UV-Visible spectra and IR transmission spectra. The spectra show that the absorption edge shift to the red with [Li]/[Nb] ratios enhancing. The Sc:Fe:Cu:LiNbO3 crystals with [Li]/[Nb] ratio of 1.05 is nearly stoichiometric. A new narrow OH[Formula: see text] associated vibrational peak at 3505 cm[Formula: see text] was revealed in Sc:Fe:Cu:LiNbO3 crystals with the ratio of [Li]/[Nb] = 1.38. It is attributed to the (Sc[Formula: see text])-(OH)[Formula: see text]. The results show that the defect structure changes with the [Li]/[Nb] ratios variation.

Microwave assisted sintering of Nanostructured Infrared-Transparent Nd0.1Y1.9O3 ceramics Synthesized by a Modified Combustion Technique

Synthesis of nano particles of Nd0.1Y1.9O3 ceramics (∼15nm) by a single step auto-igniting combustion technique, followed by microwave sintering to optimum density, and their remarkable infrared transmission characteristics are presented in this paper. The XRD pattern of the as prepared sample clearly indicates that the Nd3+ ions are effectively replacing Y3+ ions in the yttria cubic structure and it matches very well with the JCPDS file no-89-5591. The size of the crystallites was calculated using Scherrer formula and they found to be in the size range of 10-19 nm and the average size of the crystallites was 15 nm. The HRTEM analysis confirms the nano nature and the well-defined lattice structure of the sample. The UV-Visible and FTIR spectroscopy were effectively used to characterise the powder and to obtain the transmittance properties of the sintered samples. Microwave heating was successfully employed to sinter the sample pellets. A soaking duration of 20 minutes at 1500°C yielded well sintered (98.8% ) translucent pellet with reduced average grain size of 500nm and it showed a transmittance of 77% in the UV-Visible region and 78% in the mid infrared region. Microwave assisted sintering of the combustion synthesized powder is therefore a promising fabrication technique, especially for infrared transparent ceramics, which considerably reduces the sintering temperature, soaking duration, the grain size and enhances the transmittance properties. These results clearly indicate that by prudently tuning the concentration of the additives, the IR transmittance properties can be improved and they can be used very effectively for the fabrication of infrared transparent windows and domes.

Visible-IR transmission enhancement through fog using circularly polarized light.

Detection range is an important factor affecting the transmission characteristics of polarized light through fog. We first selected certain spectral bands from visible to IR wavelengths that exhibit lower path loss. For both radiation fog and advection fog, these optimized wavelength ranges include 0.4-1.1μm, 1.48-1.56μm, 1.63-1.86μm, 2.03-2.18μm, and 2.39-2.45μm, and radiation fog in particular contains 3.5-4.3μm. The long-wave IR wavelengths were excluded due to higher absorption losses. We further investigated the transmission performance of circular and linear polarization in variable foggy environments, exploring the impact of the detection range in particular. Using polarization-tracking Monte Carlo simulations for varying particle size, wavelength, refractive index, and detection range, we show that circular polarization outperforms linear polarization when transmitting in both radiation and advection fog. For radiation fog, circular polarization persists longer than linear polarization for 5μm and 9μm particles over the entire optimized wavelength range from the visible to mid-wave IR (MWIR). However, linear polarization outperforms circular polarization for 1μm particles over the entire MWIR and a part of the short-wave IR (SWIR). For advection fog, circular polarization persists longer than linear polarization for all three particle sizes (10, 20, and 40μm) over the entire optimized wavelength range from the visible to SWIR. We show that circular polarization retains a higher degree of polarization and has better enhancement in some detection ranges.