UV-visible Wavelength Research Articles

Relevance of surface characterization of <i>Bambusa vulgaris</i> (l.) leaf extract doped iron nanoparticle

In the present study, green nano scaled zero-valent irons (nZVI) were synthesized from Bambusa vulgaris leaf extract at room temperature. The plant extract was evaluated for the presence of reducing agents (bioactive compounds) phytochemically using standard methods. nZVI was systematically characterized using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Ultraviolet-Visible (UV-Vis), and Fourier Transform Infra-Red (FT-IR) techniques. The SEM and XRD results showed that after the reduction process for 4 hr at 25oC, the iron powder obtained was a single phase of lamellar or platy α-Fe crystals with the presence of medium nanoparticles (10-100 nm) having crystal size, L ranging from 40-46 nm (42.2 nm) and particle size, D ranging from 53-70 nm (56.1 nm) for both 0.3 M and 0.9 M B. vulgaris-nZVI. It has been demonstrated that B. vulgaris leaf extract was capable of producing iron nanoparticles that shows good stability in solution and under the UV-Visible wavelength, nanoparticles exhibited quite good surface plasmon resonance behavior in the range of 220-740 nm. The FT-1R spectra revealed that the vibrational bands at 3722.76 cm-1 and 3706.4 cm-1 represented the O-H stretching due to the presence of polyphenol as a functional group in addition to tannins, saponins, and others which may be responsible for the eduction of ferrous ion (Fe3+) to zero-valent iron (Feo). This study reveals that B. vulgaris-nZVI possessing short-time synthesis protocol, anisotropism, and eco-benignity could be promising lowcost matrix for remediation (both soil and water), adsorption, catalysis, and other applications.

Wide‐Angled Pragmatic Dielectric Chiral Meta‐Platform for Spin‐ and Wavelength‐Multiplexed Holography in the Ultraviolet and Visible

Abstract A chiral meta‐optics platform that incorporates hologram‐multiplexing with low phase distortion and wide‐incident angle tolerance over the broad spectral range of the ultraviolet‐visible (UV–vis) regimes holds great potential for photonic‐encryption‐based applications, particularly in next‐generation 3D displays, high‐resolution biomedical imaging, holographic anti‐counterfeiting labeling, and multi‐channel optical communication. However, the design incorporating giant chirality from UV–vis wavelengths coupled with wide‐incident‐angle tolerance and cost‐effective fabrication is still challenging. Here, the study introduces a pragmatic multifunctional dielectric chiral meta‐platform designed for simultaneous spin‐ and wavelength‐multiplexing of optical information in the UV–vis spectrum. The unit cell comprises a dimer structure based on wide‐bandgap silicon nitride (SiNx), ensuring substantial dual‐spectrum chiro‐optical effects. The meticulously engineered chiral meta‐platform offers an incident angle tolerance of up to 40 degrees, coupled with significant chiro‐optical transmission. To demonstrate the concept, two distinct phase profiles are embedded in the meta‐platform, utilizing the spin and wavelength of incident light as keys to unlock the specific holographic information. The chiral meta‐platform is experimentally validated for oblique illumination angles, showcasing its adaptability across the UV–vis spectrum. The demonstrated meta‐device with dual‐spectrum visual encryption can be applied in various anti‐counterfeiting and security applications.

Processing natural bamboo into white bamboo through photocatalyzed lignin oxidation

Scalable and highly efficient bamboo whitening remains a great challenge. Herein, an effective bamboo whitening strategy is proposed based on photocatalyzed oxidation, which involves H2O2 infiltration and UV illumination. The as-prepared white bamboo well maintains the nature structure of natural bamboo and demonstrates high whiteness and superior mechanical properties. The absorbance value is significantly decreased to 3.5 and the transmittance is increased to 0.04 % in UV–visible wavelength range due to the removal of light-absorbing chromospheres of lignin, resulting in a high whiteness when the UV illumination time is 8 h. In addition, the white bamboo displays a high tensile strength of 30 MPa and a high flexural strength of 36 MPa due to the well-preserved lignin units (lignin preservation is about 89 %). XRD patterns and analysis show that photocatalyzed oxidation has no effect on the crystal parameters of cellulose. Compared with the traditional bamboo whitening technology, our photocatalyzed oxidation strategy demonstrates significant advantage including chemical and time conservation, high efficiency, environment friendliness, and mechanical robustness. This highly efficient and environmentally friendly photocatalyzed oxidation strategy for the fabrication of white bamboo may pave the way of bamboo-based energy-efficient structural materials for engineering application.

2D Growth of BiSCl as Anisotropic Photodetector with Ultrahigh Responsivity and Detectivity

AbstractBiSCl, which shares the anisotropic chain‐like lattice configuration with the BiVXVIYVII (XS, Se; YCl, Br, I) family displays high photoelectric conversion efficiency in the UV–vis wavelength region. The current difficulty in 2D growth restricts the investigation of device performance and further integration. Herein, an epitaxial growth strategy for 2D BiSCl is proposed based on the principle of sharing a chloridion layer at the BiSCl/BiOCl interface. The interfacial atomic arrangement is carefully revealed using atomic resolved AC‐TEM(Spherical Aberration High Transmission Electron Microscope) and demonstrated by calculations based on density functional theory. Benefiting from its compatibility with PS‐assisted large‐scale transfer technology, the photoelectric performance is evaluated by constructing a standard symmetrical photoconductor and Graphene‐BiSCl Schottky junction device. High responsivity (1.71 × 104 A W−1) and detectivity (5.9 × 1016. Jones) are achieved at 405 nm, and robustness is shown in a broadband spectrum, which manifested prominent anisotropic photoelectric behavior and great potential in weak‐light detection. These results elucidate the photoelectric applications of BiSCl semiconductors and the structural design of the BiVXVIYVII family.

Constructing diverse switchable circularly polarized luminescence via a single azobenzene polymer film

Recently circularly polarized luminescence (CPL) materials have attracted significant interest. Introducing reversible dynamic property to these materials has been a key focus in cutting-edge fields, such as in high-level information encryption. Here, we provided a novel and general strategy involving handedness-selective filtration and ground-state chiral self-recovery (CSR) in double film system to address this issue. Based on this strategy, we achieved CPL switch through the reversible modulation of ground-state chirality including absorption and scattering circular dichroism (CD) signals over the full UV-visible wavelength range (365-700 nm) in a single azobenzene polymer (PAzo) film. More importantly, by flexibly changing the type of fluorescent films, it is convenient to achieve general excited-state CSR, that is reversible switching of full-color including ideal white (CIE coordinate (0.33, 0.33)), as well as room-temperature phosphorescent CPL. All these CPL signals without almost any intensity decay after three cycles of on-and-off switching. Experimental results indicated that the trans-cis isomerization and ordered rearrangement of azobenzene units in PAzo film were the fundamental reasons for realizing CPL switching. Finally, based on this system we achieved dynamic visual encryption and decryption process including multiple decryption methods. This study provides an effective method for constructing a universally applicable chiroptical switch in excited state.

Responsivity Surge in MAPbI3:PC61BM/Au/ZnO Sandwich‐Structured Photodetector

AbstractThe low gain in the presence of a single transverse external electric field limits the application of metal‐semiconductor‐metal (MSM) photodetectors. Here, a longitudinal built‐in electric field by spin‐coating CH3NH3PbI3:PC61BM on the electrode region of an Au/ZnO MSM photodetector, which constitutes a vertically crossed composite electric field with a transverse external electric field, is constructed. In this case, the transverse electric field collects the electrons, and the longitudinal electric field separates them. Based on this novel electric field structure, carrier multiplication at lower voltage conditions is achieved. Compared to the low voltage, there is a significant amplification effect when the voltage reaches 7 V. The responsivity is increased ≈270 times for UV–vis wavelengths, escalating from ≈0.02 to ≈5.4 A W−1. This study provides a novel carrier transport control scheme for high‐gain perovskite‐based photodetectors.

Biosynthesis and Characterization of Zinc Oxide Nanoparticles (ZnO-NPs) Utilizing Banana Peel Extract

In recent years, there has been a significant focus on the green synthetization of metal oxide nanoparticles due to their environmentally friendly features and cost-effectiveness. The aim of this study is to biosynthesize zinc oxide nanoparticles (ZnO NPs) through a green method, utilizing crude banana peel extract as reducing and capping agents, to characterize the synthesized ZnO NPs and test their antibacterial activity. ZnO NPs were biosynthesized using the peel extract of banana with various concentrations of zinc acetate dihydrate salt, followed by annealing at 400 °C for 2 h. The synthesized ZnO NPs were characterized using UV–visible spectroscopy (UV-Vis), scanning electron microscopy (SEM), dynamic light scattering (DLS), attenuated total reflectance–Fourier-transform infrared (ATR-FTIR), and X-ray diffraction (XRD). Also, its antibacterial efficiency against different bacterial strains was tested. ZnO NPs were biosynthesized successfully using the extract of Musa Acumniata (cavendish) fruit peel with a UV-Vis wavelength range of 344 to 369 nm and an electrical band gap ranging from 3.36 to 3.61 eV. The size varied from 27 ± 4 nm to 89 ± 22, and the negative zeta potential (ζ) ranged from −14.72 ± 0.77 to −7.43 ± 0.35 mV. ATR-FTIR analysis showed that the extract phytochemical functional groups were present on ZnO NPs. XRD results confirm the formation of a highly pure wurtzite hexagonal structure of ZnO NPs. Moreover, the best obtained size of ZnO NPs was selected for the antibacterial tests, giving the highest inhibition growth rate against Staphylococcus epidermidis (98.6 ± 0.9%), while the lowest rate was against Pseudomonas aeruginosa (88.4 ± 4.4%). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were reported and compared to previous studies. The unique properties of greenly synthesized ZnO NPs and their antibacterial activity have potential for reducing environmental pollution and the use of antibiotics, which may contribute to solving the problem of bacterial resistance. Therefore, studies that aim to design an applicable dosage form loaded with biosynthesized ZnO NPs might be conducted in the future.

Investigation and structural of phosphate glasses at low photon energy through: optical and attenuation properties

This paper presents a novel low-cost phosphate glass preparation by using the melt quenching technique. It was investigated for use in diagnostic protective applications. The range of UV-VIS wavelength is used to estimate the optical energy gap. The MAC denotes the mass attenuation coefficients of the present glass were computed at low photon energies between 15 and 200 KeV using the MIKE program. The manufactured glasses parameters viz; the mean free path, half value layer, tenth value layer, effective atomic number, effective electron density, and linear attenuation coefficient denotes as follows; 𝑀𝑀𝑀𝑀𝑀𝑀, 𝐻𝐻𝐻𝐻𝐻𝐻, 𝑇𝑇𝑇𝑇𝑇𝑇, 𝑍𝑍𝑒𝑒𝑒𝑒𝑒𝑒, 𝑁𝑁𝑒𝑒𝑒𝑒𝑒𝑒, 𝑎𝑎𝑎𝑎𝑎𝑎 𝐿𝐿𝐿𝐿𝐿𝐿 were determined. Furthermore, the molar volume, oxygen molar volume, and optical packing density of fabricated glass were assessed. The third-order susceptibility (χ(3) and non-linear refractive index of the present glass were determined. From previous results, it can be concluded that the glass has unique attenuation characteristics, therefore, can be used for radiation protection at low energy 15 to 200 KeV.

RP-HPLC Estimation of Clobetasol Propionate and Salicylic Acid using Quality by Design Approach

ABSTRACT: The RP-HPLC method for CLOP and SA estimation from bulk and pharmaceutical dosage from has been developed and validated. For analytical methods to be robust, current ICH guidelines, Q8 to Q11 were suggested use of analytical quality by design (AQbD) includes adoption of current systematic approaches. The proposed method was optimized and developed using Taguchi orthogonal design. The RP-HPLC method parameters were optimized by box- Behnken design. The stationary phase used C18 Princeton column (150mm × 4.6mm × 5µm) with acetonitrile: 0.05M phosphate buffer (pH 2.5, adjustment with by ortho - phosphoric acid) as mobile phase at ratio of 60:40v/v, 1.0 ml/min of flow rate along with UV-Visible wavelength of detection 240 nm. The linearity over concentration 5-15 µg/ml for CLOP and 600-1500 µg/ml for SA (r2 =0.9969 for CLOP and 0.9943 for SA) was found. The retention time for SA was 2.2 min. and CLOP 7.0 minute. The % recovery was found to be 98.0.3 SA and 97.84 or CLOP. As per ICH analytical method validation guidelines [Q2 (R1)], the RP-HPLC method was validated.

DC-driven subatmospheric glow discharges in the infrared-stimulated

This paper presents a conceptual framework for experimental research combined with numerical analysis on direct current (DC) glow discharges in microscale planar gas discharge-semiconductor systems (GDSS). In the experimental section, several structural and elemental analyses, including SEM, EDAX, AFM, and near-infrared absorption spectra measurements were carried out for compound semiconductor zinc selenide (ZnSe) cathode sample. Argon (Ar) was charged into the plasma reactor cell of GDSS at pressures of 100 Torr subatmospheric and 760 Torr atmospheric, respectively, by a vacuum pump- gas filling station. Glow discharge light emissions from plasma, excited under three different intensity levels (dark, weak, strong) of infrared beam illumination on ZnSe cathode electrode, were measured by using a phomultiplier tube that is sensitive to UV–Visible wavelengths. In the numerical analysis section, simulation studies were carried out on the two-dimensional gas discharge-semiconductor microplasma system (GDSµPS) cell models using the finite-element method (FEM) solver COMSOL Multiphysics DC plasma program. Calculations and predictions were based on mixture-averaged diffusion drift theory and Maxwellian electron energy distribution function. GDSµPS cell was modeled in a square chamber with planar anode/cathode electrode pair coupled at a 50 μm discharge gap. Single side of ZnSe cathode was finely micro-digitated to increase the effective surface area for enhanced electron emission to the gas discharge cell. The electrical equivalent circuit (EEC) of the proposed model was driven by 1.0 kV DC voltage source. Binary Ar/H2 gas medium in a mixture of 3:2 molar ratio was introduced to the gas discharge chamber at constant 200 Torr subatmospheric pressure. Simulations were run for normal glow discharges to exhibit the electrical fast transient glow discharge behaviours from electron field emission state to self-sustained normal glow discharge state by numerically solving the electron density (ED), electron current density (ECD) and electric potential distribution (EPD) parameters.It is figured out that binary Ar/H2 gas discharge model can undertake a major role in shaping and controlling the spatiotemporal response to transient electro-optical behavior of microplasma-based artificial electromagnetic materials configured for high-efficiency infrared-to-visible wavelength conversion applications.

Anticancer Potential of Gold doped ZnO Nanoparticles Fabricated using Root Extract of Kigelia africana (Lam.) Benth. against Lung (A549), Melanoma (A375) and Epidermoid (A431) Cancer Cells

This study presents a simple, biocompatible and eco-friendly Au-doped ZnO nanoparticles were fabricated by employing root aqueous extract of Kigelia africana (Lam.) Benth. root as reducing, stabilizing and capping agent. The nanoparticles were identified by showing characteristic UV-visible wavelength maxima at 361 nm (ZnO NPs) and 569 nm (Au NPs). The nanoparticles possess polycrystalline structure with circular to oval in shape having 34 nm size that contains ~24.74 % and ~52.16 % of Au and Zn content. The FT-IR analysis confirmed the functional groups correspond to terpenoids, flavonoids and phenolics present in aqueous root extract of of Kigelia africana (Lam.) were actively participated in nanoparticles capping. The cytotoxic applicability of fabricated nanoparticles was assessed by performing MTT assay against human lung cancer (A549) cells, melanoma cancer (A375) cells and skin or epidermoid cancer (A431) cells. The nanoparticles were proved to show potential anticancer activity with IC50 concentration of 206.13 µg/mL, 152.73 µg/mL and 295.49 µg/mL against A549, A375 and A431 cell lines respectively. The IC50 concentration of nanoparticles in DPPH assay was noticed as 43.75 µg/mL, whereas 33.95 µg/mL and 81.10 µg/mL respectively noticed for standard and aqueous root extract suggest that the nanoparticles possess potential antioxidant capability. Based on findings, it was suggested that the fabricated Au-doped ZnO NPs were treated as promising biocompatible candidate that can having remarkable applicability in therapeutic applications.

The implementation of dust mineralogy in COSMO5.05-MUSCAT

Abstract. Mineral dust aerosols are composed of a complex assemblage of various minerals depending on the region in which they originated. Given the different mineral composition of desert dust aerosols, different physicochemical properties and therefore varying climate effects are expected. Despite the known regional variations in mineral composition, chemical transport models typically assume that mineral dust aerosols have uniform composition. This study adds, for the first time, mineralogical information to the mineral dust emission scheme used in the chemical transport model COSMO–MUSCAT. We provide a detailed description of the implementation of the mineralogical database, GMINER (Nickovic et al., 2012), together with a specific set of physical parameterizations in the model's mineral dust emission module, which led to a general improvement of the model performance when comparing the simulated mineral dust aerosols with measurements over the Sahara region for January–February 2022. The simulated mineral dust aerosol vertical distribution is tested by a comparison with aerosol lidar measurements from the lidar system PollyXT, located at Cape Verde. For a lofted mineral dust aerosol layer on 2 February at 05:00 UTC the lidar retrievals yield a dust mass concentration peak of 156 µg m−3, while the model calculates the mineral dust peak at 136 µg m−3. The results highlight the possibility of using the model with resolved mineral dust composition for interpretation of the lidar measurements since a higher absorption in the UV–Vis wavelengths is correlated with particles having a higher hematite content. Additionally, the comparison with in situ mineralogical measurements of dust aerosol particles shows that more of them are needed for model evaluation.

Geostationary Environment Monitoring Spectrometer (GEMS) polarization characteristics and correction algorithm

Abstract. The Geostationary Environment Monitoring Spectrometer (GEMS) is the first geostationary earth orbit (GEO) environmental instrument, onboard the Geostationary Korea Multi-Purpose Satellite–2B (GEO-KOMPSAT-2B) launched on 19 February 2020, and is measuring reflected radiance from the earth's surface and atmosphere system in the range of 300–500 nm in the ultraviolet–visible (UV–Vis) region. The radiometric response of a satellite sensor that measures the UV–Vis wavelength region can depend on the polarization states of the incoming light. To reduce the sensitivity due to polarization, many current low earth orbit (LEO) satellites are equipped with a scrambler to depolarize the signals or a polarization measurement device (PMD) that simultaneously measures the polarization state of the atmosphere, then utilizes it for a polarization correction. However, a novel polarization correction algorithm is required since GEMS does not have a scrambler or a PMD. Therefore, this study aims to improve the radiometric accuracy of GEMS by developing a polarization correction algorithm optimized for GEMS that simultaneously considers the atmosphere's polarization state and the instrument's polarization sensitivity characteristics. The polarization factor and axis were derived by the preflight test on the ground as a function of wavelengths, showing a polarization sensitivity of more than 2 % at some specific wavelengths. The polarization states of the atmosphere are configured as a look-up table (LUT) using the Vector Linearized Discrete Ordinate Radiative-Transfer model (VLIDORT). Depending on the observation geometry and atmospheric conditions, the observed radiance spectrum can include a polarization error of 2 %. The performance of the proposed GEMS polarization algorithm was assessed using synthetic data, and the errors due to polarization were found to be larger in clear regions than in cloudy regions. After the polarization correction, polarization errors were reduced close to zero for almost all wavelengths, including the wavelength regions with high peaks and curvatures in the GEMS polarization factor, which sufficiently demonstrates the effectiveness of the proposed polarization correction algorithm. From the actual observation data after the launch of GEMS, the diurnal variation for the spatial distribution of polarization error was confirmed to be minimum at noon and maximum at sunrise/sunset. This can be used to improve the quality of GEMS measurements, the first geostationary environmental satellite, and then contribute to the retrieved accuracy of various Level-2 products, such as trace gases and aerosols in the atmosphere.

Effect Of Microwave In The Green Synthesis Of Colloidal Bismuth Nanoparticles

In this study, bismuth nanoparticles were synthesized and prepared using citrus aurantifolia green synthesis method. The effect of microwave heating was examined. Citrus aurantifolia was used to reduce metal ions and nanoparticle formation due to the presence of various biomolecules needed. microwave was chosen because it can accelerate and form more stable nanoparticles. Bismuth nanoparticles were successfully synthesized with UV-Vis wavelength at 276 nm and nanoparticle average size is 4.66 nm. This result also shows a better TEM result image when with microwave because there is no impurity from bioreductor.

Metasurface Absorbers with Film-Coupled Au Nanoclusters to Achieve Broadband and Polarization-Independent Absorption of UV-Vis Light.

Metasurface absorbers (MAs) have attracted widespread interest in the recent study of subwavelength artificial optical metasurfaces, although most reported MAs suffer from the actualities of costly and time-consuming fabrications, narrow working bandwidth, polarization-dependent responses, etc., somewhat limiting their practical applications. Herein, we introduce a facile and low-cost method to fabricate MAs with excellent absorption performances via the self-assembly of synthesized Au nanoclusters (NCs) on a Au film spaced by a nanoscale-thick dielectric SiO2. Interestingly, the proposed MAs with well-designed Au film-coupled Au NCs (i.e., an appropriate surface coverage of Au NCs and the compatible thickness of the SiO2 spacer) exhibited a measured average absorbance above 90% within a broad UV-vis wavelength band (200-800 nm). In addition, owing to the MAs' topological symmetry, their UV-vis absorption behaviors presented polarization insensitivity with the incident light angles ranging from 20 to 50°. It has been demonstrated that the excited different surface plasmon resonance modes between Au NCs and the adjacent Au film were vital; in addition, the light-trapping effects from "V"-shaped structures of Au NCs were favorable for the designed MAs with enhanced light absorption. We believe that such MAs and the potential self-assembly fabrication strategy may facilitate scalable optical applications such as photothermalvoltaics, ultraviolet protection, optical storage, and sensing.

Bimetallic oxide Mg-Cu nanoparticles synthesis and application in photometric sensing of trypsin in the presence of tap water, ammonia, and glutamine

The concentration of biomolecules such as trypsin and ammonia in bodily fluids are indicators of health conditions including pancreatic diseases and acute liver failure respectively. The maximum UV-Visible intensity and wavelength shifts of Mg-Cu bimetallic oxide nanoparticles (BNPs) were found to be proportional to changes in trypsin and ammonia concentration. The BNPs could selectively detect trypsin in tap water containing ions, ammonia, and glutamine at concentrations as low as 0.0003%v/v. The synthesis of Mg-Cu BNPs was accomplished by ablating a mixture of Mg and Cu powders and Mg and Cu colloids using a Nd:YAG 1064 nm laser in isopropanol alcohol and HCl. The BNPs demonstrated higher optical absorbance intensity in the UV-Visible range compared to their monometallic constituents, making them more suitable for use in biochemical sensing of trypsin and ammonia. The BNPs exhibited a massive 730-fold increase in electrical conductivity compared to monometallic Mg nanoparticles (0.001 mS/cm vs. 0.73 mS/cm). Field emission scanning electron microscopy was used to visualize the NP morphologies, revealing pyramidal and quasi-spherical BNPs with diameters as small as 5 nm.

Detection of Uric Acid in UV-VIS wavelength Regime

Background: Current techniques for uric acid (UA) detection are time consuming and therefore, need to improve the detection methods like absorption.
 Objective: There was a need to establish a technique that has low integration time for detection of UA using absorption technology.
 Methods: we measured the concentrations of UA using the ultra violet visible (UV/Vis) spectrophotometer in the wavelength regime (190-1100 nm).
 Results and Conclusion: In this work, the proposed spectroscopic technique can detect each concentration and interpret into an absorption value in a constant UV/Vis regime. This technique acquires the data in ~ 3 seconds (a quick integration time). Our phantom showed a close value as reported in the text.

Infrared to Visible Upconversion Photoluminescence from Nd-doped Yttria Ceramic for Optical Applications

Upconversion photoluminescence (UCPL) attracts great attention in the field of optics and solid state lightening applications. Thus, in order to understand the underlying mechanisms of UCPL, this work reports on the spectral and kinetic properties of up and down conversion photoluminescence (PL) from Nd-doped Y2O3 ceramic. The energy transition levels and the possible excitation mechanisms are discussed. Nd-doped Y2O3 nanocrystals have been prepared via co-precipitation method then subjected to sintering process for ceramic production. The X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements have been used to reveal the formation of nanocrystals and the crystal phase of the prepared Nd-doped Y2O3 powders. It is found that the PL down conversion (DCPL), from ceramic sample, demonstrates well-resolved narrow emission lines related to the near-infrared transitions in Nd ions, when excited by different UV–visible wavelengths. On the other side, a visible upconversion PL (UCPL) has been detected under excitation by a 1064-nm pulsed laser. In addition, the UCPL together with the photoluminescence excitation (PLE) results have been used to confirm the proposed energy levels for the upconversion process. Moreover, the excitation power dependence of the UCPL and time-resolved photoluminescence (TRPL) have been measured in order to determine the dominant excitation mechanism responsible for the upconversion. our findings suggest that the excited state absorption mechanism (ESA) is likely the possible mechanism of UCPL process in rare earth (Nd) single-doped Y2O3 ceramic.

Effect of Al Concentration on Structural, Optical and Electrical Properties of (Gd, Al) Co-Doped ZnO and Its n-ZnO/p-Si (1 0 0) Heterojunction Structures Prepared via Co-Sputtering Method

Heterojunction structures of n-ZnO/p-Si were prepared through the growth of undoped ZnO and (Gd, Al) co-doped ZnO films onto p-type Si (1 0 0) substrates, using a co-sputtering method. The structural and optical properties of the Gd-doped ZnO films were studied as a function of different Al doping concentrations. The X-ray diffraction profiles indicated that the films had a nanocrystalline structure of ZnO with a (0 0 2) preferential orientation. An increase in the Al doping concentration deteriorated the (0 0 2) diffraction peak intensity. The transmittance measurements in the UV-Vis wavelength range indicated that the film's optical gap increased with increase in Al doping concentration. The heterojunction parameters were evaluated using the current-voltage (I-V) characterization carried out of the fabricated n-ZnO/p-Si heterostructure, in dark conditions at room temperature. From these measurements, the n-ZnO-based DMS/p-Si heterojunction diode with the use of (Gd, Al) co-doped ZnO film showed the lowest leakage current of 1.28 × 10-8 A and an ideality factor η of 1.11, close to the ideal diode behavior of η = 1, compared to the n-Gd-doped ZnO/p-Si and n-undoped ZnO/p-Si heterojunction diodes.

The optical properties behavior of modify poly(methyl methacrylate) nanocomposite thin films during solar energy absorption

Herein, nanoparticles (Co3O4, Cr2O3, CuO, and TiO2) doped PMMA were fabricated via casting method. The PMMA nanocomposite thin films have been prepared with a fixed concentration of 4 g from PMMA to make PMMA thin films, they were modified with amine cluster. These thin films were doped by a fixed concentration, 0.01 gm, of various nanomaterials (Co3O4, Cr2O3, CuO, and TiO2) to make the nanocomposite thin films of PMMA. The thin film samples were examined by UV–Visible wavelength between (250–1350 nm). The optical properties, optoelectronic features, and oscillator strength were investigated. The reflectance and transmittance values were decreased for all the nanocomposite thin films of PMMA. The absorption coefficient ranged between (99.8–92.0%) for all samples. The direct energy gap decreased from 4.65 eV for the blank PMMA and it with Co3O4 to 2.10 eV, also, for the indirect energy gap decreased from 4.2 eV for the blank PMMA and it with Co3O4 to 2.8 eV due to the modified and doped PMMA. The optoelectronic features such as dielectric of high frequency and effective mass increased, oscillator strength decreased, dispersion energy and effective energy of single oscillator increased in comparison to blank PMMA. The oscillator strength for these thin films were increased also. These nanocomposite thin films are suitable to enhance the photostability performance from UV light and drastic weather are needed especially for underwater, aerospace, and applications for air transport, in addition, fabricated shields from UV energy, light-emitting diodes, lasers sensors, memory devices, harvesting light, and converting-light devices.