UV-vis Absorption Spectrometer Research Articles

Superior Conductivity of Transparent ZnO/MoS2 Composite Films for Optoelectronic and Solar Cell Applications.

The use of transparent conductive oxides in optoelectronics created a revolution where new-generation materials with high transmittance, low sheet resistance values, durability, and portability can be achieved without decreasing efficiency or increasing costs. Transparent ZnO/MoS2 sandwich-structured conductive composite films were produced in this study via the sol-gel method, which is considered the most efficient method due to its simple process and low cost. The crystal structure properties of ZnO/MoS2 were characterized via X-ray diffraction (XRD) patterns. The crystal sizes of ZnO films doped with different amounts of MoS2 were determined. A UV-visible absorption spectrometer was used to perform the spectroscopic analysis of the film. The area under the absorption curve and the full width of the half-maxima of absorbance data were calculated. Using these values, the optimum amount of MoS2 was determined for the best additive distribution. In addition, in order to determine the best transparent conductive material, resistance values measured via the four-point probe method were compared for different MoS2 additive amounts. The optical and electrical characterizations of transparent ZnO/MoS2 conductive oxide films were investigated. According to the parameters obtained via UV-vis spectroscopy, XRD, and four-point probe measurements, the most effective dispersion that exhibits a low width ratio and high resonance ratio was found for ZnO/MoS2 with a doping amount of 4 mg, the crystallite size of the films was found to be within the range of 21.5 and 24.6 nm, and these observations demonstrated a figure-of-merit value of more than 4.8 × 10-2 with respect to these sandwich-structured films. Compared to the values of previous studies on various transparent ZnO-doped conductive oxide materials, it is possible to claim that these new films have a structure that is very similar to the transparent conductivity characteristics of other films, and they may even be superior relative to some MoS2 amounts.

Smartphone-enabled colorimetric determination of silver ions exploiting the peroxidase-mimetic behavior of bowl-shaped Pd3Pt nanocrystals

Excessive silver ions (Ag+) pose significant risks to both human health and the environment, necessitating the rapid and sensitive detection of Ag+ in aqueous systems to ensure public health and environmental safety. In this study, we present a novel and expeditious colorimetric methodology for Ag+ detection, employing bowl-shaped Pd3Pt nanocrystals as an effective probe. The distinctive bowl-like structure of Pd3Pt provides an abundance of catalytic active sites, endowing them with peroxidase-like activity. Upon exposure to hydrogen peroxide, these Pd3Pt nanobowls facilitate the oxidation of the colorless substrate 3,3′,5,5′-tetramethylbenzidine (TMB), resulting in the formation of the blue product oxTMB, which exhibits a pronounced characteristic absorption peak at 652 nm. By virtue of the metal affinity and electrostatic attraction between Ag+ ions and Pd3Pt nanobowls, Ag+ species effectively adsorb onto the nanobowls surface, preferentially occupying the catalytic active sites and impeding the production of the blue oxTMB product. Based on this mechanism, we have established a novel colorimetric approach for the quantitative determination of Ag+, enabling facile Ag+ detection using either a UV–vis absorption spectrometer or a smartphone as the detection instrument. The developed method demonstrates an impressive detectable range spanning 1–100 nmol/L, accompanied by a detection limit of 0.72 nmol/L. Notably, this technique boasts several desirable attributes, including rapid detection, simplified operational procedures, heightened sensitivity, and commendable selectivity. Moreover, we have successfully applied this method to assess Ag+ levels in water samples procured from diverse sources, further attesting to its practical utility and versatility.

Modulating the fluorescence properties of carbon dots by varying the stoichiometric ratios of citric acid and urea during the synthesis

Varying the ratios of citric acid and urea during the synthesis of carbon dots (CDs) provides a strategy to modulate their fluorescence properties. The impact of different precursor ratios on the resulting CDs' size, surface chemistry, and structure was investigated using X-ray diffraction (XRD) analysis and confirmed through transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to study the influence of precursor ratios on the types and densities of surface functional groups. The optical properties of the CDs were examined using a UV–visible absorption spectrometer, photoluminescence excitation (PLE) spectra, and photoluminescence spectroscopy (PL). Smaller CDs generally exhibit higher energy emissions, resulting in bluer light, while larger CDs tend to emit lower energy light, appearing redder. By adjusting the precursor ratios, it is possible to induce shifts in fluorescence emission, leading to CDs with different fluorescence colours. Furthermore, the antimicrobial activity of CDs against bacterial pathogens was assessed, and their potential for promoting plant growth was explored by coating seeds with concentrated and diluted CDs solutions.

Nonlinear optical and quantum chemical studies of Palladium benzimidazole Schiff base complex

This article presents the linear and nonlinear optics and density functional theory studies of a Palladium complex with a benzimidazole-based Schiff base. Linear absorption of the complex has been studied using a UV–Vis absorption spectrometer. Optical nonlinearity and thereby the optical limiting performance of the complex has been deliberated experimentally using a Z-scan method with a continuum wave laser of wavelength 532 nm. The NLO investigation of the complex demonstrated significant nonlinear absorption (βeff = 4.64–27.23 × 10−2 cm/W) with an imaginary part of nonlinear optical susceptibility of the third-order (Imχ(3) = 1.28–7.49 × 10−5 esu) and nonlinear refraction (n2 = 5.46–12.3 × 10−7 cm2/W) with real part of nonlinear optical susceptibility of the third-order (Reχ(3) = 3.55–8.00 × 10−5 esu). The large nonlinear absorption displayed superior optical power limiting characteristics with a threshold and clapping level of 115 W/cm2 and 35 W/cm2respectively. Theoretical studies are performed for Palladium benzimidazole Schiff base complex within Density Functional Theory (DFT) framework, using hybrid exchange-correlation B3LYP with basis set LANL2DZ. DFT-based descriptors are computed viz. energy gap between HOMO-LUMO, electronegativity, electrophilicity index, molecular hardness, and softness. Result reveals that the bond length between Pd–O is small as compared to Pd–Cl and Pd–N.

Performance of the new biological small- and wide-angle X-ray scattering beamline 13A at the Taiwan Photon Source.

Recent developments in the instrumentation and data analysis of synchrotron small-angle X-ray scattering (SAXS) on biomolecules in solution have made biological SAXS (BioSAXS) a mature and popular tool in structural biology. This article reports on an advanced endstation developed at beamline 13A of the 3.0 GeV Taiwan Photon Source for biological small- and wide-angle X-ray scattering (SAXS-WAXS or SWAXS). The endstation features an in-vacuum SWAXS detection system comprising two mobile area detectors (Eiger X 9M/1M) and an online size-exclusion chromatography system incorporating several optical probes including a UV-Vis absorption spectrometer and refractometer. The instrumentation and automation allow simultaneous SAXS-WAXS data collection and data reduction for high-throughput biomolecular conformation and composition determinations. The performance of the endstation is illustrated with the SWAXS data collected for several model proteins in solution, covering a scattering vector magnitude q across three orders of magnitude. The crystal-model fittings to the data in the q range ∼0.005-2.0 Å-1 indicate high similarity of the solution structures of the proteins to their crystalline forms, except for some subtle hydration-dependent local details. These results open up new horizons of SWAXS in studying correlated local and global structures of biomolecules in solution.

The Preparation of Nano Silver by Chemical Reduction Method

A silver nanostructures prepared by using chemical reduction method. The silver nanoparticles were prepared with diameters of about (20 nm). Numerous techniques had been used to study the optical, structural like the UV-Vis absorption spectrometer, Ttransmission Electron Microscopy (TEM), Field-Emission Scanning Electron microscope (FESEM), and X-ray diffraction (XRD). The practical results exhibited the absorption spectrum of the prepared nanoparticles at (357 nm), it was found that there is a relationship between the positions of the optical absorption peak and the size of the silver nanoparticles. The analysis of TEM results showed the presence of nanoparticles in the range (20 nm). The analyzing of XRD results explained the crystal structure for silver nanoparticles. It is found a cubic unit cell have a lattice constants (a = 4.0855 Å), with the Miller indices were (111), (002), (002), and (113).

Luminescence properties and energy transfer of Eu3+/Tb3+ co‐doped glass ceramics containing Na3Gd(PO4)2

AbstractTb3+‐doped and Eu3+/Tb3+ co‐doped transparent glass ceramics containing Na3Gd(PO4)2 crystal phase were prepared by melt crystallization. The types of crystals, grain size, and optical transmittance of the samples were investigated by X‐ray diffraction (XRD), scanning electron microscope (SEM), and UV visible absorption spectrometer. The effect of different heat treatment time on grain size, crystal morphology, and light transmittance was also studied. The luminescence performance of transparent glass ceramics was systematically studied by the excitation spectrum, emission spectrum, and the fluorescence lifetime. The optimal doping concentration of Tb3+ doped and Eu3+/Tb3+ co‐doped were determined. When the mole percent concentration of Tb4O7 was 0.4%, the strongest green light was obtained at 546 nm (5D4 → 7F5). Meanwhile, the energy transfer process between Eu3+ and Tb3+ was discussed. Under the excitation of 374 nm, white light can be obtained by adjusting the concentration ratio of Eu3+ and Tb3+.

Synthesis of Fe<sub>3</sub>O<sub>4</sub>/MIL-101 material and evaluation of photocatytic activity

In the present work, results synthesis of Fe3O4/MIL-101 material and evaluation of photocatytic activity under visible light region. Characterization of Fe3O4/MIL-101 was investigated by using techniques including X-ray diffraction pattern (XRD), scanning electron microscopy (SEM), IR spectra and UV-visible absorption spectrometer. Evaluation of the photocatalytic activity of Fe3O4/MIL-101 material on the conversion of blue methylen solution under degradation in the visible light region.

FABRICATION AND CHARACTERIZATION OF DYE-SENSITIZED SOLAR CELLS BASED ON MUREXID DYE AND INORGANIC CdS:Mn THIN FILMS

In this study, dye-sensitized solar cells (DSSCs) were designed utilizing Murexid dye as an absorbing material and manganese doped cadmium sulfide (CdS:Mn) thin films as transparent layers. The CdS:Mn thin films were synthesized on tin doped indium oxide coated glass substrates (ITO) at 90 ºC using chemical bath deposition method (CBD). The Mn-doping process was carried out at concentrations of 0%, 2%, 4% and 6% (in molar ratio of manganese ions to cadmium ions). The structural, morphological and optical properties of the CdS:Mn thin films were examined using x-ray diffractometer (XRD), atomic force microscope (AFM) and UV–visible absorption spectrometer. The effect of the nanoparticle size on the cell performance of DSSC was investigated by J-V curves. The results regarding electrical measurements indicated that the maximum efficiency of 3.40%. Our experimental results suggested that this heterojunction can be a good candidate for DSSCs.

Preparation of Carbon Dots with High-Fluorescence Quantum Yield and Their Application in Dopamine Fluorescence Probe and Cellular Imaging

Carbon dots represent a kind of fluorescent nanomaterial and have broad application prospects in the field of biosensing and optoelectronics. Here, we explored carbon dots with a high-fluorescence quantum yield rate synthesized from L-cysteine and citric acid by the microwave-assisted method. The characteristics of the carbon dots were studied using a transmission electron microscope, an X-ray diffractometer, X-ray photoelectron spectra, a UV-Vis absorption spectrometer, a FTIR spectrometer, and a fluorescence spectrophotometer. The obtained carbon dots exhibited a high-fluorescence quantum yield (up to 85%), which is due to the combination of amidogens and sulfydryl with carbon dots, and hence bring the improved fluorescence property. We used carbon dots for in vitro imaging of CRL-5822 cells and human umbilical vein endothelial cells, which showed the low inhibitory rate (0.8%) of cells for 48 h with good biocompatibility demonstrated by the cell viability assay. The image of cells can be observed clearly under UV light. The Stern-Volmer equation was introduced to describe the quenching effect between the fluorescence intensity of carbon dots and the concentration of aqueous dopamine (DA).

The oxidation of UF4 in FLiNaK melt and its electrolysis

The oxidation of UF4 in LiF–NaF–KF (FLiNaK) melt with oxygen sparging was conducted at 823 K and analyzed by in situ infrared spectrometer, UV–Vis absorption spectrometer, and other characterizations with thermodynamic calculations, indicating UF4 was converted to UO2F2 with the following reaction mechanism: 2UF4 (l) + O2(g) + 2H2O(g) = 2UO2F2(l) + 4HF(g). Cyclic voltammetry measurements showed that the reduction of UO22+ in oxidized melt exhibited two steps both with one exchanged electron: UO22+ + e− → UO2+ and UO2+ + e− → UO2. By potentiostatic electrolysis, the product of UO2 was obtained with nanoscale triangular sheet structure.

Detection of nitrite based on fluorescent carbon dots by the hydrothermal method with folic acid.

A fluorescent carbon dots probe for the detection of aqueous nitrite was fabricated by a one-pot hydrothermal method, and the transmission electron microscope, X-ray diffractometer, UV–Vis absorption spectrometer and fluorescence spectrophotometer were used to study the property of carbon dots. The fluorescent property of carbon dots influenced by the concentration of aqueous nitrite was studied. The interaction between the electron-donating functional groups and the electron-accepting nitrous acid could account for the quenching effect on carbon dots by adding aqueous nitrite. The products of the hydrolysis of aqueous nitrite performed a stronger quenching effect at lower pH. The relationship between the relative fluorescence intensity of carbon dots and the concentration of nitrite was described by the Stern–Volmer equation (I0/I − 1 = 0.046[Q]) with a fine linearity (R2 = 0.99). The carbon dots-based probe provides a convenient method for the detection of nitrite concentration.

Femtosecond Laser Fabricated Ag@Au and Cu@Au Alloy Nanoparticles for Surface Enhanced Raman Spectroscopy Based Trace Explosives Detection

Herein we present results from our detailed studies on the fabrication of Ag@Au and Cu@Au alloy nanoparticles (NPs) using the femtosecond laser ablation in liquid technique. The NPs were obtained by ablating the pure Ag, Cu targets (bulk) in HAuCl4 (5 mM) solution. The absorption properties of the obtained NPs colloids were characterized using UV-Visible absorption spectrometer and their size, shape, and crystallinity were investigated using the XRD, FESEM and TEM techniques. The fabricated NPs were utilized for sensing of explosive molecules such as 2, 4, 6-trinitrophenol (PA), 2, 4-dinitrotoluene (DNT) and a common dye methylene blue (MB) using the surface enhanced Raman spectroscopy (SERS) technique. The detection limit in terms of weight was as low as few nano-grams in the case of nitroaromatic explosive compounds (PA, DNT) and few picograms in the case of a common dye molecule (MB). Typical enhancement factors achieved were estimated to be ~104, ~105 and ~107, respectively, for PA, DNT, and MB. The significance of the present work lies in exploring the performance of the prepared NPs being used as SERS substrates for explosives detection using a portable Raman instrument. Such capability enables one to carry the spectrometer to the point of interest in the field and evaluate any hazardous samples within a short period of time.

Thermo-physical properties of cooling water-based nanofluids containing TiO2 nanoparticles modified by Ag elementary substance for crystallizer cooling system

For enhancing the thermal performance of the crystallizer cooling water and also to achieve stable and uniform suspension, TiO2 nanoparticle modified with (3-mercaptopropyl) triethoxysilane (MPS) coupled Ag nanoparticle was added to the cooling water. Other than the investigation on the thermal performance, rheological properties were also investigated, both prior and post nanoparticle addition. The XRD, FT-IR spectrometer and TEM were used to study the morphology and properties of TiO2-Ag nanoparticles. Simultaneously, UV–vis absorption spectrometer and zeta potential were used to confirm the stability of the prepared nanofluids. Furthermore, the temperature dependent thermal conductivity study with different volume fractions carried out for TiO2-Ag cooling water-based nanofluids reported considerable enhancement. Based on researching rheological property, TiO2-Ag nanofluids are found to be promising to the research of crystallization cooling water. Moreover, experiment results have been compared with classical models and new formulas were rebuilt for thermal conductivity and viscosity. This study will play a significant role in the study of the heat transfer of crystallizer cooling water.

Effect of transition metal ions on luminescence of MOFs

Three kinds of metal-organic framework materials (MOF-5, MLI-101(Cr), UiO-66) are synthesized, which are based on transition metal (Zn, Cr, Zr) as the center ions, and terephthalic acid (H2BDC) as organic ligand. At the same time, three kinds of MOFs were characterized and analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectrometer (UV-Vis), and fluorescence spectrometer (PL). This article analyzes the fluorescence effects of these three MOFs and investigates the role of different transition metal ions in MOF luminescence. The results show that the ionic radii of Zn2 + and Zr4 + are similar, which are 0.074 nm and 0.072 nm, respectively. MOF-5 and UiO-66 have similar fluorescence effects, both of which emit blue-violet light. However, MIL-101 (Cr) fluorescence centers on Cr3 + with an ionic radius of 0.0651 nm emits yellow-green light, which is different from the foregoing MOFs. Therefore, the ionic radius of the transition metal has an important effect on the fluorescence effect of the MOF. For larger ionic radii, the fluorescence of MOF is generally in the blue-violet square region.

Fluorescence detection for H2PO4 - based on carbon dots/Fe3+ composite

A novel fluorescent probe for H2PO4- was designed and fabricated based on the carbon dots/Fe3+ composite. The carbon dots were synthesized by an established one-pot hydrothermal method and characterized by transmission electron microscope, X-ray diffractometer, UV-Vis absorption spectrometer and fluorescence spectrophotometer. The carbon dots/Fe3+ composite was obtained by aqueous mixing of carbon dots and FeCl3, and its fluorescence property was characterized by fluorescence spectrophotometer. The fluorescence of carbon dots was quenched by aqueous Fe3+ cations, resulting in the low fluorescence intensity of the carbon dots/Fe3+ composite. On the other hand, H2PO4- reduced the concentration of Fe3+ by chemical reaction and enhanced the fluorescence of the carbon dots/Fe3+ composite. The Stern-Volmer equation was introduced to describe the relation between the relative fluorescence intensity of the carbon dots/Fe3+ composite and the concentration of H2PO4-, and a fine linearity (R2=0.997) was found in the range of H2PO4- concentration of 0.4-12 mM.

Calix[4]arene based dipodal receptor nanohybrids for selective determination of chloride ions in aqueous media

A chemical sensor based on p-tert butyl calix[4]arene has been synthesized and characterized using an assortment of spectroscopic techniques such as 1H NMR, 13C NMR, and elemental analysis. For sensor application, organic nanoparticles (N1) of 1 have been primed by implementing re-precipitation technique, which were further employed for preparing organic-inorganic hybrid (H1) by decorating N1 with gold nanoparticles. Both N1 and H1 were characterized using UV–visible, fluorescence, and DLS studies. Photo-physical changes due to anion binding with H1 were scrutinized using UV–visible absorption spectrometer and found it to promptly and selectively recognize Cl− ions in aqueous media. Thus, H1 can be effectively used for recognition of Cl− ions in aqueous media over a wide pH range, in samples of real time importance with a detection limit of 2.84×10−9M with a linear detection range up to 50μM.

Photoelectrochemical-type sunlight photodetector based on MoS2/graphene heterostructure

We have fabricated a novel sunlight photo-detector based on a MoS2/graphene heterostructure. The MoS2/graphene heterostructure was prepared by a facile hydrothermal method along with a subsequent annealing process followed by a substrate-induced high selective nucleation and growth mechanism. The microstructures and morphologies of the two-dimensional MoS2/graphene heterostructure can be experimentally confirmed by x-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and a UV–vis absorption spectrometer. Photoresponse investigations performed by a photoelectrochemical (PEC) measurement system indicate that the synthesized MoS2/graphene heterostructure shows superior photoresponse activities under the illumination of sunlight in contrast with bare MoS2 and graphene. The improved photoresponsivity can be attributed to the enhanced light absorption, strong light–matter interaction and the extremely efficient charge separation of the heterostructure. The structure and performances of the MoS2/graphene heterostructure suggest promising applications in the field of photonics and optoelectronics.

Temperature and frequency dependence on electrical properties of polyaniline/Ni(1−x)CoxFe2O4 nanocomposites

Two nanocomposites of polyaniline (PANI) varying in their percentage composition of Ni(1−x)CoxFe2O4 nanoparticle (20%, 10% w/w of fine powders) were prepared by in-situ chemical oxidative polymerization method with and without ultrasonic treatment. The spinel ferrite nanoparticles of chemical composition Ni(1−x)CoxFe2O4 were prepared by auto combustion method. The structure and morphology of PANI and nanocomposites were characterized by X-ray diffraction (XRD) and High resolution transmission electron microscopy (HRTEM). The chemical structure of Ni(1−x)CoxFe2O4 nanoparticles and its composites were characterized by using Fourier transform infrared (FTIR), UV–visible absorption spectrometer and XRD techniques. Dielectric properties of nanocomposites at different temperature have been performed in the frequency range of 50Hz to 5MHz. Dielectric constant, dielectric loss and AC conductivity of PANI/Ni(1−x)CoxFe2O4 nanocomposites are significantly increasing with increase in ferrite content due to the polaron/bipolaron formation. The optical absorption experiments of PANI/Ni(1−x)CoxFe2O4 nanocomposite illustrate a direct transition with an energy band gap of Eg around 1.7.

Colorimetric detection of dichlorvos using polydiacetylene vesicles with acetylcholinesterase and cationic surfactants

Widespread use of dichlorvos in agriculture has posed serious concern for food and water contamination. A new colorimetric method for the detection of dichlorvos based on polydiacethylene and acetylcholinesterase inhibition is developed. The blue-to-red color transition of poly(10,12-pentacosadynoic acid) vesicles can be induced by myristoylcholine which is enzymatically hydrolyzed by acetylcholinesterase to myristic acid and choline to prevent the color transition. In the presence of dichlorvos, the hydrolytic activity of the enzyme is inhibited that the blue-to-red color transition is restored with a linear correlation to the dichlorvos concentration. Using UV–vis absorption spectrometer, the limit of dichlorvos detection is 6.7ppb. A naked eye detection of 50ppb dichlorvos is achievable by using dimiristoylphosphatidylcholine to the diacetylene mixed lipid vesicles.