Ultraviolet-visible Transmission Research Articles

Transitions of nitrogen optical centers induced by femtosecond laser pulses in treated natural diamond

Diamond is a unique optical material with ultra-hard lattice, which properties can be altered by optically active doping defects combined with carbon interstitials and vacancies. Direct laser writing by focused ultrashort laser pulses enables local modification of color centers in diamonds with excellent three-dimensional positioning accuracy, providing unique capabilities for quantum technologies, magnetometry, laser generation and photoluminescence (PL) micromarking. To shed light on currently unknown underlying atomistic transformations, we exposed electron-irradiated and annealed natural IaAB1-type diamond with an initially high content of various nitrogen-vacancy centers (NV, H3, N3 and H4) to millions of 0.2-ps, 525-nm laser pulses focused inside the sample. The modified areas were characterized by Fourier-transform infrared (FT-IR) and ultraviolet–visible transmission spectroscopy and confocal Raman/PL microspectroscopy with excitation wavelengths of 405 nm and 532 nm. We report on a local decrease in originally strong PL yield of NV, H3 and H4 centers with a monotonic dependence on both pulse energy and exposure time, as well as a rise of H1b and H1c lines in the FT-IR spectra accompanied by a drop in the concentration of H1a center. The results indicate that laser-induced processes make possible both creation and destruction of NV, H3 and H4 centers influenced by their initial concentration and the parameters of laser modification, which can be useful for adjusting of laser writing regimes for PL micromark inscription and other local modification of diamond for photonics applications.

Optical and electrical properties of Ni+2 doped nanocrystalline Bi2S3 thin films prepared by chemical bath deposition method

Nickel (Ni+2) doped nanocrystalline Bi2S3 thin films are deposited on the glass substrate from the solutions containing Bismuth Nitrate, Ethylenediamine Tetraacetic acid (EDTA) and Thioacetamide at a bath deposition temperature of 318K. The optical, surface morphological and electrical properties of Ni-doped Bi2S3 thin films prepared at three different doping concentration are investigate by using ultraviolet–visible transmission spectra (UV–Vis), Scanning electron microscopy (SEM), Energy Dispersive X-ray (EDAX) and thermo-e.m.f. techniques. The optical band gap energies are found in between 2.32-2.43 eV. The SEM images show that the prepared films are continuous, dense and distributed over the entire area with good uniformity. The electrical conductivity of the films are in the order of 10-2 Ω-1 m-1 . The films are n-type as determined from the Hot Probe method. Photoconductivity studies reveal that photocurrent increases with the increase in Ni doping concentrations. Due to the absorption of photons, free electron-hole pairs (EHP) are produce.

Sensitive detection of dextromethorphan hydrobromide based on portable Raman spectrometer and CuO@AgNPs nano composite SERS substrate

A highly sensitive surface-enhanced Raman spectroscopy approach was established for the detection of dextromethorphan hydrobromide (DXM) utilizing nano CuO modified silver nanoparticles (CuO@AgNPs) as substrate. Ultraviolet visible spectra (UV-vis), X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterized the synthesized CuO@AgNPs. UV-vis and fourier transform infrared (FT-IR) were adopted to investigate the interaction between DXM and CuO@AgNPs. The optimal experimental conditions (the dosages of CuO@AgNPs and NaCl as well as mixing time) were explored. The enhancement factor (EF) was 1.71 × 106. The linear relationship between SERS intensity and the concentration of DXM in the range of 67 – 1000 nmol L−1 was obtained as ISERS = 25.81 c + 40398.77, and the limit of detection (LOD) was 2.12 nmol L−1 (S/N = 3). The interference of K+, Mg2+, Zn2+, Ca2+, Cu2+, Fe3+, glucose, HSA, L-tryptophan, soluble starch and ibuprofen were investigated. The method was successfully applied to test DXM in serum samples. The recovery was 99.06% – 101.51% with the relative standard deviation (RSD) of 0.74% – 3.87%.

A Method of Evaluating NV centers Concentration by UV–Vis Transmittance Spectra

The ultraviolet-visible (UV-Vis) spectrum was not generally considered an available method for measuring the concentration of negatively charged nitrogen-vacancy (NV-, NV center). In this study, we propose the idea of evaluating the concentration of NV center by the slope of the UV-Vis spectrum. To establish this new method we synthesized diamonds with different NV center concentrations by the chemical vapor deposition (CVD) method. We then measured the zero-phonon line (ZPL) intensity of PL spectra at 637 nm and estimated the concentration of the NV centers as a baseline for comparison to our new UV-Vis method. The UV-Vis transmission spectra were then measured and transformed to relative absorption coefficient spectra. Slopes of the transformed UV-Vis spectra between 400 nm and 800 nm were calculated and compared with the ZPL intensities. The results show a strong positive correlation between the slopes of the absorption spectra and the ZPL intensities of PL spectra at 637 nm. Therefore, this paper demonstrates the feasibility of estimating the concentration of the NV centers from measuring the transmission UV-Vis spectrum.

Improving the Photo Electro Catalytic Degradation of Methylene Blue by Modified TiO2/ITO Photo Anodes

TiO2 photoanodes have gained significant attention for the removal of organic pollutants through photoelectrocatalytic processes, with the aim of developing a cost-effective and efficient method for improving the degradation of pollutants in surface water. This study investigated the effects of adding titanium nanooxide (Degussa P25) containing 70% anatase and 30% rutile phases on the properties of nanostructured TiO2 photoanodes prepared on glass substrates (indium tin oxide (ITO)) using sol–gel/dip coating techniques The results obtained from ultraviolet–visible transmittance spectroscopy, electrochemical (EC) impedance spectroscopy, photocurrent, and atomic force microscopy analyses revealed that the addition of Degussa P25 improved the electrical conductivity of the TiO2/ITO anode and reduced the optical bandgap from 3.50 to 3.35 eV, while the size of the titanium oxide particles decreased to about 75 nm. The EC impedance spectra measurement confirms that the addition of titanium nanooxide Degussa P25 improved the electrical conductivity for TiO2/ITO anode. The photoelectrocatalysis (PEC) performance of the TiO2 photoanodes was investigated via the degradation of methylene blue (MB) under UVA light irradiation. The AB photoanode (with the addition of Degussa P25) exhibited excellent PEC performance, with 95.9% color removal efficiency and 63% total organic carbon (TOC) removal efficiency, compared to 92% color removal efficiency and 56% TOC removal efficiency for the A photoanode (without the addition of Degussa P25). The kinetic constants (k) were 134 × 10−4, 110 × 10−4 (min−1) for A and AB anodes, respectively, and the degradation of MB followed first-order kinetics for all anodes. The A and AB anodes were compared as electrodes for the degradation of MB using PEC, photocatalysis (PC), and EC technologies. Subsequently, The A and AB anodes were utilized as electrodes to compare the performance of PEC, PC, and EC technologies for the degradation of MB. The results showed that the AB anode exhibited higher efficiency in all PC technologies, with color removal (%) efficiencies of 95.9% (PEC), 33% (PC), and 21% (EC) compared to 92% (PEC), 28% (PC), and 19% (EC) for the A anode. Additionally, the photooxidation process had a 2.1% effect on the degradation of the initial MB concentration.

The effect of thickness on structural, optical, and electrical properties deposited ZnO thin films by PLD

In this paper, the effect of film thickness on structural, electrical, and optical properties of ZnO thin films deposited by Pulsed laser Deposition (PLD) over a quartz substrate has been studied. In PLD the thickness of the deposited thin films varies from 200 nm to 300 nm by increasing the number of laser shots from 9000 shots to 12,000 shots respectively. Deposited thin films were studied by Grazing angle X-ray diffraction (Gi-XRD), Ultraviolet–Visible transmittance spectroscopy (UV–Vis), Lateral I-V measurements, Field emission scanning electron spectroscopy (FESEM), and energy dispersive X-ray spectroscopy (EDX). Gi-XRD result shows that films deposited over quartz are poly-crystalline in nature and are oriented along (002), (102), and (103) planes. FESEM analysis shows that 300 nm thick film is distributed uniformly over the surface and 200 nm ZnO thin film is distributed mainly at the center. EDX results show the presence of Zn and O elements in both deposited thin films. I-V characteristics in the dark show Schottky contact with Vc 2.9 V and 1 V for 200 nm and 300 nm thin films respectively. The optical band gap of ZnO thin films intersects at the same photo energies for both thicknesses. Tauc’s plot of both films reveals the similar optical band gap energies of 3.25 eV in both deposited films.

Structural, optical, and electronic studies of Ni doped ZnO thin films

The structural, optical, and electronic properties of Ni-doped ZnO (NZO) thin films were studied by X-ray diffraction (XRD), ultraviolet-visible transmittance spectroscopy (UV-Vis), atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR). 0, 3, 5, and 7% NZO thin films were deposited on quartz substrate by pulsed laser deposition (PLD) technique at a substrate temperature of 300oC and oxygen partial pressure of 1 mTorr. XRD results show that all deposited films were crystalline and oriented along the (002) plane with wurtzite symmetry. All deposited films also show high transmittance in the UV-Visible regime (300-800 nm). Tauc formulation was used to calculate the bandgap. NZO thins films show a lesser bandgap as compared to pure ZnO films and further with Ni concentration the bandgap was reduced from 3.20 eV (3%) to 3.11 eV (7%). AFM results revealed the uniform deposition of NZO and ZnO films over a quartz substrate and FTIR analysis shows the shifting of the Zn-O-Zn band towards higher frequency numbers with Ni concentrations. Results obtained from this study indicate that as PLD grew NZO thin films can be a promising candidate for optoelectronic application. Keywords: ZnO, PLD, XRD, Ni, UV, NZO.

Improving structural and electrical properties of p-type Al–N-doped SnO2 films with low Al content by tuning N2 concentration in sputtering gas mixture

In this study, we attempted to upgrade the structural quality of p-type Al–N-doped SnO2 films with low Al content by varying the N2 content of the gas mixture used for sputtering. The synthesised films were examined and analysed using X-ray diffraction (XRD), atomic force microscopy (AFM), field-emission scanning electron microscopy (FESEM) and X-ray dispersive spectroscopy (EDX). The crystal quality improved significantly with increasing N2 concentration. Specifically, the crystal grain size increased to 48.45 nm, while the surface roughness decreased to 1.2 nm. These improvements in the crystal quality increased the hole mobility to 17.5 cm2V−1s−1, which is higher than that (16.1 cm2V−1s−1) observed in previous works. As a result, the photocurrent of the SnO2/n-Si heterojunction under illumination also increased to a value of 25 mA. Furthermore, the presence of a (111) cubic plane in the SnO2 films confirmed that elemental N was incorporated into the SnO2 films in sufficiently large amounts. The refractive index, which is derived from the ultraviolet–visible transmittance spectra and relative to the crystal quality, varied with the amount of N-substituted elemental O in the SnO2 films. The film synthesised using the sputtering gas mixture with 70% N2 exhibited enhanced properties and is thus suitable for use in a wide variety of optoelectronic devices.

Silver nanoparticles modified by β-cyclodextrin and γ-alumina as substrate for quantitative SERS detection of netilmicin

Based on silver nanoparticles modified by β-cyclodextrin and γ-alumina (β-CD/γ-Al2O3@AgNPs), a novel and sensitive surface-enhanced Raman spectroscopy (SERS) assay for the determination of netilmicin was established. The synthesized SERS substrate of β-CD/γ-Al2O3@AgNPs was characterized by ultraviolet visible (UV–vis) spectroscopy and transmission electron microscope (TEM), and the interaction between netilmicin and β-CD/γ-Al2O3@AgNPs was also investigated by the above methods as well as Fourier transform infrared (FT-IR). The optimum experimental conditions including the type of media, amounts of β-CD/γ-Al2O3@AgNPs and NaCl and mixing time were found. The enhancement factor (EF) was 1.18 × 107 (peak at 577 cm−1). There was a good linear relationship between the concentration of netilmicin and the SERS intensity with the equation of ISERS = 136.12 c + 47201.80 (c: nmol L−1, r = 0.9975), and the linear range was 10.00–300.00 nmol L−1. The limit of detection (LOD) was 1.85 nmol L−1 (S/N = 3). The effects of some interferences including Cu2+, K+, Zn2+, Ca2+, Na+, Mg2+, glucose, l-tryptophan HSA and kanamycin were studied. This method was used to detect netilmicin in human serum samples with the recovery of 97.96%–103.52% and the RSD of 1.2%–2.1%.

C(NH2)3]2Zn(CO3)2: A Guanidinium-Templated Ultraviolet Nonlinear Optical Material.

A novel guanidinium-templated ultraviolet (UV) nonlinear optical zinc carbonate crystal, [C(NH2)3]2Zn(CO3)2 (GZCO), has been synthesized in a closed system at low temperatures. GZCO crystallizing in the tetragonal noncentrosymmetric nonpolar space group, P41212 exhibits a three-dimensional anionic framework constructed by interconnected [Zn6C6O32] 12-membered ring channels with inorganic CO3 triangles and ZnO4 tetrahedra. Notably, the anhydrous GZCO shows a very high thermal stability among guanidine-based hybrid NLO materials benefiting from the confinement effect of the organic cations within inorganic channels. The UV-visible transmittance spectrum reveals that GZCO has a short UV cutoff edge of 210 nm, corresponding to the large band gap of 5.9 eV. GZCO exhibits a mild second-harmonic generation efficiency of 0.5 × KH2PO4 with type-I phase-matching behavior.

Measurement of brown eggs freshness using non-destructive UV/VIS spectroscopy and viscosity of egg white

The present research aimed to determine the freshness of brown eggs using non-destructive ultraviolet-visible (UV/VIS) transmission spectroscopy (λ = 350-1020 nm) and viscosity measurement during storage for 7 days. As per human visual perception, the eggshell color varied from light yellow-brown to dark red-brown, distributed near the edge of the spectral locus of orange to a red region in the CIE 1931 chromaticity diagram. Quantitatively characterized luminance (CIE Y) values of the eggshell brightness were 7.77 (darkest) and 49.1 cd/cm2 (brightest). The L* value (brownness) of the eggshell increased while the a* value (redness) decreased. The correlation between luminance and transmittance values was evaluated using a linear regression model which showed a correlation coefficient of 0.92. The transmittance spectra collected daily showed a gradual increase from 36.0% (day 1) to 38.8% (day 3). The slope of this increment became steeper after day 3 and reached 50.8% (day 7). The freshness of the eggs calculated based on the transmittance value of 100% (day 1) showed an inverse relation with the storage time and was reduced by 59% (day 7). Egg white exhibited non-Newtonian shear thinning behavior and showed a reduction in viscosity by 13.7% reduction on day 7 as compared to that on day 1. Our results clearly demonstrated that the freshness of the eggs declined with an increase in storage time. This analytical method of measuring egg freshness has potential applications in designing an automatic egg selection machine, to identify stale eggs from the fresh ones on-site in small and medium egg farms by simply measuring the transmittance of eggshells of varying darkness.

Evaluating the effect of the substrate on the electrocatalytic performance of Cu2ZnSnS4 and Cu2ZnSnSe4 counter electrodes in dye-sensitized solar cells

The colloidal synthesis of Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) nanoparticles and their application as counter electrodes in dye-sensitized solar cells (DSSCs). In particular, the effect of three substrates namely; vitreous carbon (VC), indium tin oxide (ITO), and fluorine doped tin oxide (FTO) on the electrocatalytic properties as well as the overall performance of the solar cells is investigated. The CZTS and CZTSe were synthesized and characterized with X-ray diffraction, Raman, X-ray photoelectron spectroscopy, Fourier transform infrared, nuclear magnetic resonance, and ultra-violet visible spectroscopies and transmission electron microscopy for the morphologies of the nanoparticles. The CZTS and CZTSe nanoparticles were quasi-spherical in shape with an average size of 7 ± 0.60 nm and 11 ± 0.84 nm, respectively. CZTSe on glassy carbon had better electrocatalytic activity as compared to CZTS however; the DSSCs from VC were poor due to the reduced transmittance of the substrate. On ITO and FTO, CZTS performed the best. Electrochemically, CZTS had the lowest series resistance and charge transfer resistance, however, had the largest exchange current density and limiting diffusion current thereby making it the best electrocatalyst. The DSSC using CZTS–ITO gave the best performance with the power conversion efficiency of 3.62%.

Systematic Exploration of WO3/TiO2 Heterojunction Phase Space for Applications in Photoelectrochemical Water Splitting

Recent work has shown that heterojunction photoelectrodes can achieve synergistically higher water splitting activity than their parent materials. To optimize the performance in such layered systems, it is necessary to develop new methods capable of assessing heterojunction phase space. Herein, we explore WO3/TiO2 heterojunction phase space as a model system. Using chemical vapor deposition, 71 unique photoanodes were grown (15 single-layer; 56 heterojunctions). The materials were physically characterized using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy analysis, and ultraviolet–visible transmission spectroscopy. Various key performance indicators were measured. Within this WO3/TiO2 heterojunction phase space, the onset potentials ranged from ∼0.45 to ∼0.81 VRHE; the incident-photon-to-current efficiencies at 350, 375, and 400 nm ranged from ∼0.6 to ∼50.9, ∼0.1 to ∼30.0, and ∼0 to ∼15.6%, respectively; and the theoretical solar photocurrents ranged from ∼0.01 to ∼0.94 mA cm–2. Contour plots allowed us to identify regions of heterojunction phase space with high activity and establish trends. We identified an electronic barrier to charge transfer between the heterojunction layers that required a sufficiently high applied potential (≥1.0 VRHE) to be surpassed for synergetic improvements in activity to be observed. We recommend that the methods developed herein, for assessing the performance of sample libraries of heterojunction photoelectrodes, be used alongside combinatorial synthesis methods and high-throughput photoelectrochemical measurements to optimize promising heterojunction systems more rigorously and rapidly.

Low-temperature preparation of SnO<sub>2</sub> electron transport layer for perovskite solar cells

SnO<sub>2</sub> has the advantages of excellent photostability and can be prepared at low-temperature below 200 ℃. It is regarded as one of the excellent materials for the electron transport layer, and widely used in efficient and stable planar heterojunction perovskite solar cells. In this work, the low-cost, dense and uniform SnO<sub>2</sub> electron transport layer is prepared by spin coating at low temperature (150 ℃) for perovskite solar cells with a structure of FTO/SnO<sub>2</sub>/CH<sub>3</sub>NH<sub>3</sub>PbI<sub>3</sub> (MAPbI<sub>3</sub>)/Spiro-OMeTAD/Au. The crystallization and photoelectric properties of SnO<sub>2</sub> electron transport layers prepared at different concentrations (2.5%–10%) at 150 ℃, and the influences of SnO<sub>2</sub> electron transport layers on the formation of perovskite films and the performances of perovskite solar cells are discussed. By analyzing the scanning electron microscope (SEM), ultraviolet-visible light absorption spectrum (UV-Vis) and transmission spectrum of the SnO<sub>2</sub> film, it is found that the coverage and light transmittance of the substrate and band gap of the SnO<sub>2</sub> film increase as the SnO<sub>2</sub> content increases, while the absorbance decreases. By analyzing the SEM, UV-Vis, X-ray diffraction (XRD) and steady-state photoluminescence spectrum (PL) analysis of the SnO<sub>2</sub>/MAPbI<sub>3</sub> thin film, it is found that the MAPbI<sub>3</sub> deposited on the SnO<sub>2</sub> layer with a concentration of 7.5% is uniform and pinhole-free, has the largest particle size and the best crystallinity, as well as more effective charge extraction capability and transport capability. By analyzing the electrochemical impedance (EIS) and external quantum efficiency (EQE) of the device, the SnO<sub>2</sub> electron transport layer with a concentration of 7.5% has better interface contact and lower interface resistance, which is beneficial to reducing the recombination of carriers and improving the photoelectric conversion capability, The perovskite solar cells based on SnO<sub>2</sub> layer prepared with a concentration of 7.5% reaches a photoelectric conversion efficiency of 15.82% (<i>V</i><sub>oc</sub> = 1.06 V, <i>J</i><sub>sc</sub> = 21.62 mA/cm<sup>2</sup>, FF = 69.40%), After storing for 600 h in ambient air ((25±5) ℃, RH>70%) without encapsulation, its efficiency remains 92% of the initial efficiency. At the same time, we prepare flexible devices on flexible substrates (TIO/PEN) by using SnO<sub>2</sub> precursor with a concentration of 7.5%, which exhibits good photovoltaic performance and achieves a photoelectric conversion efficiency of 13.12%, and storage time for 84 d in ambient air ((30±5) ℃, RH>70%) without encapsulation, its efficiency remains 48% of the initial efficiency. The PCE retains 78% of the initial efficiency after 1000 bending cycles with a bending radius of 3 mm. The study of optimizing the concentration of SnO<sub>2</sub> has laid a foundation for improving the performance of flexible perovskite solar cells.

Determination of spectinomycin by SERS based on BSA-protected AgNPs decorated with α-CD

A surface-enhanced Raman scattering (SERS) spectroscopic method with good selectivity and high sensitivity for the determination of spectinomycin (SPT) was established based on silver nanoparticles (AgNPs) coated by bovine serum albumin (BSA) and decorated with α-cyclodextrin (α-CD). The SERS characteristic peak of SPT at 485 cm−1 was selected for quantity analysis and the enhancement factor (EF) of the detection system was 1.95 × 107. The synthesis of α-CD/Ag@BSA NPs substrate was characterized by ultraviolet visible (UV–vis) spectroscopy and transmission electron microscope (TEM). The interaction between the substrate and the drug was demonstrated by UV–vis and fourier transform infrared (FT-IR) spectroscopy, which provided a theoretical basis for the determination of SPT by SERS. The effects of experimental parameters such as α-CD/Ag@BSA NPs solution volume, NaCl volume and mixing time on SERS signal intensity were investigated. Under the optimum conditions, the determination of SPT by SERS performed a good linear relationship in the 3.33 – 1000.00 nmol L−1 concentration range for SPT (ISERS = 131.52c + 26585.53, c: nmol L−1, r = 0.996). Limit of detection (LOD) for SPT was 2.01 nmol L−1 (S/N = 3). The effects of various interfering ions and similar drug on the determination system were studied. The SERS method was successfully applied to the determination of SPT in beef and lamb samples. The relative standard deviation (RSD) of SPT in the samples was 2.27% – 4.82% (n = 5), with recovery 96.04% – 104.90%.

Effects of static magnetic field on dye extracted from Anchusa-Italica through optimization the optoelectronic properties

The dye extracted from the plant is already well used in optoelectronic applications for its easy and safe handling. This study is to demonstrate the effect of magnetized distilled water on dye extracted from Anchusa-Italica flowers. The results of its optoelectronic behavior reveal that the use of magnetized water in the extraction process results in different and better properties than processes in which ordinary water was used. The structural analysis of Anchusa-Italica dye thin-film was performed using the Fourier-transform infrared technique (FT-IR). The optical responses, such as the absorption coefficient, absorption spectra, both standard and refractive indices, and electronic properties (optical energy gap) were studied using Ultraviolet-Visible transmittance spectra range 300–900 nm. The calculated energy band gap of the dye extracted using magnetized water was decreased from 3.23 to 2.35 eV and turned into the preferred direct band gap to make a useful contribution to optical sources. The optical absorption spectra of the dye extracted using magnetized water appear to have a better efficiency compared to that extracted with ordinary water. A significant evolution in the absorption coefficient was obtained by employing magnetized water to extract the dye. The magnetized extraction process also modified the electronic transmission values (indirect to direct). The effect of magnetized water on the resonance mode and transparent indication was deduced by studying the complex refractive index. An increase appeared in the spectrum of the absorption index at a wavelength of 570 nm, whereas a small attenuation coefficient was observed as well. The important effects of magnetized dye extraction will highly benefit the field of optoelectronic applications.

Cucurbit[6]uril functionalized gold nanoparticles and electrode for the detection of metformin drug

Based on the host-guest molecular recognition capability of cucurbit[6]uril (CB[6]) modified on the gold surface, sensitive spectrophotometric and electrochemical methods for the detection of metformin (MET) have been developed. The molecular recognition between cucurbit[7]uril (CB[7]) or CB[6] and MET is initially demonstrated and the related recognition mechanism is further deliberated. First, CB[6]-modified gold nanoparticles (AuNPs/CB[6]) were synthesized and then characterized by ultraviolet visible light spectrum (UV–vis) and transmission electron microscopy (TEM). The aggregation of AuNPs/CB[6] prompted by MET triggered changes of color and the absorption spectrum, that explored for the visual identification and spectrophotometric determination of MET. Under the optimized detection conditions, the UV–vis spectrometry had a good linear relationship in the range of 6–700 µmol/L, and the detection limit was 2 µmol/L. In addition, a single-layer CB[6]-modified gold electrode (GE-CB[6]) detection system for MET was constructed. As the concentration of MET in the solution continues to increase, the charge transfer resistance (Rct) in the Nyquist diagram of the electrochemical impedance method (EIS) continues to increase. In the concentration range from 10 pmol/L to 20 nmol/L, the logarithm of the MET concentration has a good linear relationship with Rct, and the detection limit of this method is 1.35 pmol/L. Both methods have good concentration sensitivity to MET in different concentration ranges, providing a powerful tool for the detection of MET.

Optically Transparent and Toughened Poly(methyl methacrylate) Composite Films with Acylated Cellulose Nanofibers.

In this work, nanocomposites of poly(methyl methacrylate) (PMMA) with cellulose nanofiber (CNF) were prepared by a solution casting technique. CNF was modified by propionic anhydride (PA) to form surface-propionylated CNF (CNFp) to improve its compatibility with the PMMA matrix. CNF, CNFp, and acetylated CNF were compared with respect to their influence as fillers in PMMA composite films by ultraviolet–visible transmittance, haze values, tensile strength testing, and water contact angle measurement. It was demonstrated that 1 wt % of CNFp has good compatibility and uniform dispersion in the PMMA matrix, as demonstrated by the formation of a smooth surface composite film with good transparency, enhanced tensile properties, improved toughness, and lower wettability. Therefore, PMMA/CNFp composite films have great potential for use in several applications such as lightweight transparent materials, window substitutes, and see-through packaging.

Effect of lithium salt precursors on the physical properties of ZnO-Li thin films

Zinc oxide (ZnO) thin films were prepared on glass substrates with three different lithium salt precursors (acetate, chloride and nitrates) with Li/Zn atomic ratio varying between 0% and 20% using sol-gel deposition and spin-coating technique. The aim of the work was to compare the physical properties of lithium containing ZnO thin layers obtained using different Li salt precursors; in order to identify the most suitable one. The X-ray diffraction measurements showed that all 500°C annealed films were polycrystalline. The samples prepared from lithium nitrates solutions showed a preferred orientation along c-axis (002) and their crystallites sizes are much larger compared to other Li source. The ultraviolet-visible transmission spectra confirmed the good transparency of all ZnO films with an average transmission around 85 % in the visible range. The optical band gap values varied between 3.19 eV and 3.28 eV. All the results revealed that the ZnO-Li films prepared with LiNO3 exhibit the highest crystallographic quality and the best optical and electrical properties compared to C2H3LiO2 and LiCl containing precursors.

Optical, electrical, and structural properties of Ta-doped SnO2 films against substrate temperature using direct current magnetron sputtering

Ta-doped SnO2 (TTO) films were deposited at 3 × 10−3 Torr pressure from the 6 wt. % Ta2O5-doped SnO2 target at temperatures of 30–500 °C in Ar sputtering gas. The Ta dopants in the SnO2 host lattice were detected via X-ray photoemission, EDX mapping, and photoluminescence spectra. The Ta5+–Sn4+ substitution formed the OOx at VOxsites in the host lattice and the substitution occurred at deposition temperatures greater than 200 °C. The substitution leads to a decrease in the amount of VOx in the SnO2 lattice corresponding to the preferred rutile SnO2 (110) lattice reflection in the X-ray diffraction patterns. The ultraviolet-visible transmittance in visible light was approximately 80%. The lowest resistivity achieved was 2.0 × 10−3 Ω.cm, with a carrier concentration of 1.28 × 1020 cm−3 and carrier mobility of 24.5 cm2V−1s−1. The integration of the TTO-400 film with (n- and p-) Si exhibited an excellent photoelectric effect.