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The catalytic reduction of methylene blue (MB) by metal nanoparticles and subsequent reoxidation is widely recognized and often referred to as a ''redox reaction.'' The reduction mechanism of MB has been extensively studied and is well understood but its reoxidation has received little attention. Here we report an experimental study on the reoxidation dynamics of MB reduced by silver nanoparticles (Ag NPs). Ag NPs synthesized using the Pulsed Laser Ablation (PLAL) technique are used to reduce MB in the presence of the reducing agent NaBH4. The reduction/reoxidation dynamics are monitored using UV−Vis spectroscopy through the decrease/increase of characteristic MB absorbance peak and color switching between methylene blue and leucomethylene (LMB). The influence of the various volumetric concentrations of Ag NPs and NaBH4 on reoxidization dynamics of reduced MB is investigated. The reoxidation of reduced MB exhibited almost linear growth over time for different concentrations of both Ag NPs and NABH4 used in the reduction process. Higher NaBH4 concentrations appeared to decelerate the reoxidation process, while the concentration of Ag NPs had no discernible impact on the reoxidation rate. The reduction of reoxidized MB after adding additional amounts of Ag NPs and NaBH4 revealed that Ag NPs remained stable in the reaction medium but NaBH4 deteriorated. Therefore, the deterioration of the NaBH4 is identified as the major cause of the reoxidation of the reduced MB. A series of reduction-reoxidation experiments using chemically synthesized Ag NPs indicated that MB reoxidation is not limited to laser-synthesized Ag NPs.

This paper presents the fractional generalized q-deformed sinh-Gordon equation. The fractional effects of the temporal derivative of the proposed model are studied using a conformable derivative. The analytical solutions of the governing model depend on the specified parameters. The resulting equation is studied with two integration architectures: the sine-Gordon expansion method and the modified auxiliary equation method. These strategies extract hyperbolic, trigonometric, and rational form solutions. For appropriate parametric values and different values of fractional parameter α, the acquired findings are displayed via 3D graphics, 2D line plots, and contour plots. The graphical simulations of the constricted solutions depict the existence of bright soliton, dark soliton, and periodic waves. The considered model is useful in describing physical mechanisms that possess broken symmetry and incorporate effects such as amplification or dissipation.

This paper presents the investigations toward the direct use of bentonite clay (Al2H2O6Si) nanoparticles to act like a saturable absorber (SA) for the Q-switched pulse operation of an erbium-doped fiber laser (EDFL). The measured results reveal that with the incorporation of bentonite clay nanopowder as a SA, an EDFL is realized with a Q-switching mechanism starting at a pump power of 30.8 mW, and a Q-switched emission wavelength was noticed at 1562.94 nm at 142 mW pump power. With an increased pump from 30.8 mW to 278.96 mW, the temporal pulse parameters including minimum pulse duration and maximum pulse repetition rates were reported as 2.6 µs and 103.6 kHz, respectively. The highest peak power, signal-to-noise ratio, output power and pulse energy were noticed to be 16.56 mW, 51 dB, 4.6 mW, and 47 nJ, respectively, at a highest pump power of 278.96 mW. This study highlights the significance of bentonite clay (Al2H2O6Si) nanoparticles as a potential candidate for a saturable absorber for achieving nonlinear photonics applications.

Laser-induced breakdown spectroscopy (LIBS) technique was utilized to investigate the green mineral fluorite (CaF2) samples. The LIBS experiment was implemented by using Nd: YAG Laser system and a linear array CCD detector coupled with an Avantes spectrometer in an air atmosphere. The emission spectra of ten various fluorite samples were studied. The molecular bands correspond to the green B2Σ+-X2Σ+ and orange A2Π-X2Σ systems of diatomic CaF-molecule, specifically at Δν = -1, 0, +1 sequences and the CaO diatomic molecule between 618 nm and 630 nm were detected. It was observed that the CaF-diatomic molecular emission bands exhibited stronger optical emission compared to the fluorine (F) atomic lines. Chemical composition (wt.%) analysis was acquired using CF-LIBS methodology under optically thin and local thermodynamic equilibrium (LTE) conditions. Our CF-LIBS studies revealed that Ca (50–60%) and F (30–40%) were the major elements, while C (3–5%) and O (2–5%) were minor elements present in all samples. For comparison, we employed energy-dispersive X-ray (EDX) technique to study the essential elemental composition (wt.%). The results achieved from CF-LIBS were found to be in good agreement to that obtained from the EDX technique. To validate CF-LIBS results, the calibration curve method was employed using the validated samples (S3, S5, and S7). Furthermore, we utilized a principal component analysis (PCA) technique on the LIBS spectral data to classify the fluorite samples.

Coupled nonlinear Schrödinger type equation is used to represent the transmission of optical signals in birefringent fibers. These types of equations are significant models for a vast range of disciplines, including fluids, nonlinear optics, the theory of deep ocean waves etc. In this manuscript, coupled nonlinear Schrödinger type equation is investigated by using two techniques namely, the G′/(bG′+G+a)-expansion method and the modified Jacobi elliptic expansion schemes. Furthermore, modulation instability analysis is performed on our model. The extracted solutions show dark, Kink and singular solitons behaviors, which are depicted graphically by using surface and line plots. The obtained solutions are unique and novel. The employed integration techniques are widely used to examine exact solutions of various partial differential equations.

Phosphate exists concurrently in multiple waste streams. Embedded nickel oxide in polyvinyl alcohol (NiO/PVA) was doped by silver nanoparticles (Ag) to generate an Ag-doped NiO/PVA nanocomposite structure prepared by multiple laser ablation process technique for removing phosphate. Different techniques were used to characterize the physicochemical properties of the substance. The characterization results of the prepared nanocomposites showed that NiO and Ag were successfully integrated into the PVA structure. They confirmed the production of hybrid nanocomposites by a reduction in the peak height due to intramolecular and intermolecular interactions with Ag nanoparticles from Raman spectra. Also, the shift in the absorbance transition characteristic and the appearance of vibrational motions of NiO and Ag confirmed the successful interaction between PVA, Ag, and NiO. After that, in the adsorption study, the most important aspect of the investigation was a series of phosphate adsorption tests from aqueous solutions, which showed that the efficiency of the adsorption process is dependent on the concentrations of the adsorbate and adsorbent, the pH, the reaction time, and the temperature. The results indicate that the current Ag-doped NiO/PVA nanocomposite adsorbent has the capacity to control phosphorus contamination in water.

NiO-CNTs nanocomposite was prepared by the decoration of CNTs by NiO nanoparticles via eco-friendly pulsed laser ablation method based on nanosecond Nd:YAG laser to be applied in the removal of methyl orange (MO) dye. The preparation and the decoration of NiO nanoparticles were carried out in a single step without any by-product via pulsed laser ablation method. The nanocomposite was characterized by different analytical techniques such as FT-IR, TEM, XRD, Raman spectroscopy, XPS, and EDX. These techniques confirmed the formation of NiO in the nanoscale range (spherical shape) with a particle size of about 20 nm without the formation of any other by-product. Moreover, the examination of the interaction between NiO nanoparticles and CNTs showed a shift in their peaks, while the examination of its surface showed an increase in the amounts of defects and appearance of spherical shape from NiO on the surface of CNTs. Then, the efficiency of removal MO was investigated in visible light in the absence of any reducing agent with the assistance of the prepared nanocomposite to investigate the capability to be used as adsorbent materials. The results showed a high adsorption ability of NiO-CNTs nanocomposite against MO due to both, the large surface area of CNTs and the catalytic activity of NiO nanoparticles.

In the present study, the immediate detection of rare-earth elements (REEs) in phosphorite deposits has been reported using laser-induced breakdown spectroscopy (LIBS). Numerous emission lines corresponding to the REEs such as lanthanum (La), cerium (Ce), neodymium (Nd), samarium (Sm), and ytterbium (Yb), have been detected in the emission spectra of phosphorite-induced plasma plume. For the quantitative analysis, we employed the calibration-free LIBS (CF-LIBS), and Energy Dispersive X-ray (EDX) spectroscopy techniques. The results obtained using the CF-LIBS technique show excellent agreement with that obtained by EDX. Besides principal component analysis (PCA) was employed by incorporating the LIBS spectral data of rare earth phosphorite rocks samples containing La, Ce, Nd, Sm, and Yb emission lines. The first three PCs were observed using LIBS spectral data set showing a covariance (interpretation rate) up to 76.3%. This study suggests that LIBS yields a quick and very reliable qualitative and quantitative analysis of REEs in any geological ore sample.

Chalcogenide glasses are promising contenders for use in radiation shielding applications because of their remarkable radiation shielding properties, such as transparency and good thermal stability. In the current study, the shielding parameters for gamma rays and neutrons are estimated for different compositions of Se75−x–Te25–Agx (0 ≤ x ≤ 10 mole %) chalcogenide glasses using the Phy-X/PSD online software. We referred to the investigated Se75−x–Te25–Agx (x = 0, 2, 4, 6, 8, and 10 mole %) glasses by coded abbreviations as (STA1, STA2, STA3, STA4, STA5 and STA6 respectively). The linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), effective atomic number (Zeff), effective electron density (Neff), half-value layer (HVL), tenth-value layer (TVL), mean free path (MFP), energy absorption buildup factor (EABF), and exposure buildup factor (EBF) in the photon energy range of 0.15–15 MeV. The specified energy range (0.015–15 MeV) corresponds to the energies emitted from radioactive sources such as (241Am, 55Fe, 133Ba, 60Co, 109Cd, 131I, 152Eu, 22Na, and 137Cs) which may be used in medical, industrial, and nuclear facilities where workers may frequently be exposed to harmful radiations. In the current work, we investigate shielding materials to protect people from radiation-related harm. Furthermore, the fast neutron removal cross section (FNRCS) is estimated. The findings refer to increasing the Ag content results in an enhancement in the shielding characteristics for the glass under investigation. The lowest Zeff values (36.657–37.465) occur at a photon energy of 0.02 MeV; the Zeff values then increase to reach their maxima (43.259–44.347) at a photon energy of 0.06 MeV. The MFP, TVL, and HVL values decrease with increasing Ag content, especially in the intermediate and high photon energy ranges. The results show low HVL and MFP values compared with those obtained for traditional and commercial glasses, especially in the intermediate and high photon energy ranges. The Zeff values increase as the Ag content increases. The FNRCS values are in the range of 0.083–0.092 cm−1 for the investigated glasses. The FNRCS values of these glasses are higher than those of some commercial glasses. The most performance sample for radiation shielding between the investigated glasses is STA6 corresponds to the higher concentration of Ag.

In a dense wavelength division multiplexed (DWDM) system, extended Gerdjikov–Ivanov (GI) equation has been explored for kerr law nonlinearity using two different techniques. The employed techniques are effective for identifying exact results including their dynamic characteristics. To explore exact solutions of the governing equation unified method has been applied which is one of the best analytical techniques. These analytical solutions are in form of polynomial as well as rational function. By assigning the specific values to the parameters, dark and bright soliton has been extracted. Afterwards, for phase characterization, the equation has been studied using bifurcation. The system has been first turned into a planer dynamical system, and subsequently into a Hamiltonian system. Then the equilibrium points has been derived. The different phase portrait is plotted by simply giving parameters various values.

This study explores the effects of Si and Si-P heteroatoms doping and co-doping on a monolayer graphene surface through density functional analysis. The results suggest that doping with Si and co-doping with Si-P significantly alters the bonding arrangement of the atoms surrounding the graphene sheet. Additionally, the surface of the graphene material had a high concentration of electrons in both Si doping and Si-P co-doping, based on electron population analysis. The HOMO–LUMO gap of graphene sheets was found to decrease in the following order: pristine graphene sheet > Si-doped graphene sheet > Si-P co-doped graphene sheet. Furthermore, a TD-DFT study revealed that the absorption wavelength of Si and Si-P co-doped graphene systems had a greater shift to a lower range compared to pristine graphene. The order of decreasing absorption wavelength is Si-P co-doped graphene, Si doped graphene, and pristine graphene. These materials are suggested to have a high potential for photodetector applications due to their broad absorption range.

In this present work, we demonstrated a spectral characterization of copper–iron (Cu-Fe) alloy using optical emission spectroscopy. The Cu-Fe alloy plasma was generated on the target sample surface by directing the laser pulse of Q-switched Nd: YAG of the second harmonic (2ω) with a 532 nm optical wavelength. The optical emission spectrum was acquired using five miniature spectrometers that lie within the wavelength range of 200–720 nm. The emission plasma was characterized by validating the local-thermodynamical equilibrium (LTE) as well as optically thin (OT) plasma condition. In addition, the LTE condition was verified using the McWhirter criterion, and the OT condition was validated by comparing theoretically calculated intensity ratios with experimental ones. Plasma parameters, including electron number density as well as plasma temperature, were estimated. In the first stage, the plasma temperature was estimated using the Boltzmann-plot method and the two-line method. The average calculated value of the plasma temperatures were 8014 ± 800 K and 8044 ± 800 K using the Boltzmann-plot and two-line methods, respectively. In the second stage, electron number density was estimated using the Saha–Boltzmann equation and stark-broadening method (SBM). The average number density calculated from the SBM was 2.73×1016 cm−3 and from the Saha–Boltzmann equation was 3.9×1016 cm−3, showing a good agreement. Finally, the comparative compositional analysis was performed using CF-LIBS, Boltzmann Intercept Method, EDX, and ICP-AES, which showed good agreement with that of the standard composition.

The sensitivity of luminescent Boltzmann thermometers is restricted by the energy difference between the thermally coupled excitement levels of trivalent lanthanides, and their values further decrease with increases in temperature, rendering their use at high temperatures difficult. Here, we demonstrate how to overcome this sensitivity limitation by employing multiparameter and multilevel cascade temperature readings. For this purpose, we synthesized Dy3+:Y2SiO5, a phosphor whose emission is known to begin quenching at very high temperatures. Its photoluminescence-emission features, later used for thermometry, consisted of two blue emission bands centered around 486 nm and 458 nm, and two bands centered around 430 nm and 398 nm, which were only visible at elevated temperatures. Next, we performed thermometry using the standard luminescence-intensity ratio (LIR) method, which employs the 4F9/2 and 4I15/2 Dy3+ levels’ emissions and the multilevel cascade method, which additionally uses the 4G11/2 level and overlapping intensities of 4I13/2, 4M21/2, 4K17/2, and 4F7/2 levels to create two LIRs with a larger energy difference than the standard LIR. This approach yielded a sensitivity that was 3.14 times greater than the standard method. Finally, we simultaneously exploited all the LIRs in the multiparameter temperature readings and found a relative sensitivity that was 30 times greater than that of the standard approach.

Abstract In the framework of the Born–Oppenheimer (BO) method, we illustrate our ab-initio spectroscopic study of the of silver hydride molecule. The calculation of 48 electrons for this system is very difficult, so we have been employed a pseudo-potential (P.P) to reduce the big number of electrons to two electrons of valence, which is proposed by Barthelat and Durant. This allowed us to make a configuration interaction (CI). The potential energy curves (PECs) and the spectroscopic constants of AgH have been investigated for Σ+, Π and Δ symmetries. We have been determined the permanent and transition dipole moments (PDM and TDM), the vibrational energies levels and their spacing. We compared our results with the available experimental and theoretical results in the literature. We found a good accordance with the experimental and theoretical data that builds a validation of the choice of our approach.

Herein, we investigate the performance of single- and multiparametric luminescence thermometry founded on the temperature-dependent spectral features of Ca6BaP4O17:Mn5+ near-infrared emission. The material was prepared by a conventional steady-state synthesis, and its photoluminescence emission was measured from 7500 to 10,000 cm−1 over the 293–373 K temperature range in 5 K increments. The spectra are composed of the emissions from 1E → 3A2 and 3T2 → 3A2 electronic transitions and Stokes and anti-Stokes vibronic sidebands at 320 cm−1 and 800 cm−1 from the maximum of 1E → 3A2 emission. Upon temperature increase, the 3T2 and Stokes bands gained in intensity while the maximum of 1E emission band is redshifted. We introduced the procedure for the linearization and feature scaling of input variables for linear multiparametric regression. Then, we experimentally determined accuracies and precisions of the luminescence thermometry based on luminescence intensity ratios between emissions from the 1E and 3T2 states, between Stokes and anti-Stokes emission sidebands, and at the 1E energy maximum. The multiparametric luminescence thermometry involving the same spectral features showed similar performance, comparable to the best single-parameter thermometry.

A graphene oxide (GO)/poly 3-methyl aniline (P3MA) photodetector has been developed for light detection in a broad optical region: UV, Vis, and IR. The 3-methyl aniline was initially synthesized via radical polymerization using an acid medium, i.e., K2S2O8 oxidant. Consequently, the GO/P3MA composite was obtained through the adsorption of GO into the surface of P3MA. The chemical structure and optical properties of the prepared materials have been illustrated via XRD, FTIR, SEM, and TEM analysis. The absorbance measurements demonstrate good optical properties in the UV, Vis, and near-IR regions, although a decrease in the bandgap from 2.4 to 1.6 eV after the composite formation was located. The current density (Jph) varies between 0.29 and 0.68 mA·cm−2 (at 2.0 V) under dark and light, respectively. The photodetector has been tested using on/off chopped light at a low potential, in which the produced Jph values decrease from 0.14 to 0.04 µA·cm−2, respectively. The GO/P3MA photodetector exhibits excellent R (and D) values of 4 and 2.7 mA·W−1 (0.90 × 109 and 0.60 × 109 Jones) in the UV (340 nm) and IR (730 nm) regions, respectively. The R and D values obtained here make the prepared photodetector a promising candidate for future light detection instruments.

In the present work, the rapid identification of elements and their relative chemical composition in various Peganum harmala seed samples were investigated using a calibration-free laser-induced breakdown spectroscopy technique (CF-LIBS). A pulsed Nd:YAG laser-source with a 5 ns pulse-duration, and 10 Hz pulse repetition rates providing 400 and 200 mJ energy at 1064 and 532 nm wavelength, respectively, was focused on the Peganum harmala seed samples for ablation. A LIBS 2000+ spectrometer within the wavelength range (200 to 720 nm), emission-spectra were recorded. The measured spectra of the Peganum harmala sample gives spectral lines of Carbon (C), Magnesium (Mg), Lithium (Li), Sodium (Na), Calcium (Ca), Silicon (Si), Iron (Fe), Strontium (Sr), Copper (Cu), Potassium (K), and Lead (Pb). A CF-LIBS technique has been employed for the compositional study of the elements exist in the Peganum harmala seed samples. The measured results demonstrate that C, Mg, and Ca are found to be major elements in the Peganum harmala seed samples with compositions of ~36.64%, ~24.09%, and ~19.03%, respectively. Along with the major elements, the elements including Li, Na, Si, K, Fe, and Sr were identified as minor elements with compositions of ~2.87%, ~2.33%, ~3.72%, ~7.17%, ~2.83%, and ~1.14%, respectively. Besides Cu (~8.07 μg/g), and Pb (~1.10 μg/g) elements were observed as trace elements exist in the Peganum harmala seed samples. Furthermore, the electron number density including the plasma excitation-temperature were calculated using the stark-broadening line profile method and the Saha–Boltzmann plot method, respectively. The plasma parameters versus laser-irradiance and the distance from the sample were further investigated. Moreover, a principal component analysis (PCA) method was also utilized to the spectral data obtained by using LIBS to discriminate various seed samples with four classes, namely, α, β, γ, and Δ. Three principal-components (PCs) calculated from eigenvalues of score matrix described 87.6%, 4.6%, and 2.5% of total variance for PC1, PC2, and PC3, respectively. The LIBS spectral data variance covered by the initial 3 PCS was found as ~94.7% of total variance. The PCA results have successfully demonstrated the different classes of the Peganum harmala seed samples based on the different doping compositional ratios of the Zn element. This study confirmed the feasibility and ability of LIBS and PCA for the rapid analysis of Peganum harmala seed samples. Finally, the results achieved using CF-LIBS were incorporated with those obtained from the XRF and EDX analytical techniques.

Herein, an optoelectronic device synthesized from a CuFeO2/CuO/Cu nanocomposite was obtained through the direct combustion of Cu foil coated with Fe2O3 nanomaterials. The chemical, morphological, and optical properties of the nanocomposite were examined via different techniques, such as XRD, XPS, TEM, SEM, and UV/Vis spectrophotometer. The optical reflectance demonstrated a great enhancement in the CuFeO2 optical properties compared to CuO nanomaterials. Such enhancements were clearly distinguished through the bandgap values, which varied between 1.35 and 1.38 eV, respectively. The XRD and XPS analyses confirmed the chemical structure of the prepared materials. The produced current density (Jph) was studied in dark and light conditions, thereby confirming the obtained optoelectronic properties. The Jph dependency to monochromatic wavelength was also investigated. The Jph value was equal to 0.033 mA·cm−2 at 390 nm, which decreased to 0.031 mA·cm−2 at 508 nm, and then increased to 0.0315 mA·cm−2 at 636 nm. The light intensity effects were similarly inspected. The Jph values rose when the light intensities were augmented from 25 to 100 mW·cm−2 to reach 0.031 and 0.05 mA·cm−2, respectively. The photoresponsivity (R) and detectivity (D) values were found at 0.33 mA·W−1 and 7.36 × 1010 Jones at 390 nm. The produced values confirm the high light sensitivity of the prepared optoelectronic device in a broad optical region covering UV, Vis, and near IR, with high efficiency. Further works are currently being designed to develop a prototype of such an optoelectronic device so that it can be applied in industry.

ZnO/MWCNTs nanocomposite has significant potential in photocatalytic and environmental treatment. Unfortunately, its photocatalytic efficacy is not high enough due to its poor light absorbance and quick recombination of photo-generated carriers, which might be improved by incorporation with noble metal nanoparticles. Herein, Ag-doped ZnO/MWCNTs nanocomposite was prepared using a pulsed laser ablation approach in the liquid media and examined as a degradable catalyst for Rhodamine B. (RhB). Different techniques were used to confirm the formation of the nanostructured materials (ZnO and Ag) and the complete interaction between them and MWCNTs. X-ray diffraction pattern revealed the hexagonal wurtzite crystal structure of ZnO and Ag. Additionally, UV-visible absorption spectrum was used to study the change throughout the shift in the transition energies, which affected the photocatalytic degradation. Furthermore, the morphological investigation by a scanning electron microscope showed the successful embedding and decoration of ZnO and Ag on the outer surface of CNTs. Moreover, the oxidation state of the formed final nanocomposite was investigated via an X-ray photoelectron spectrometer. After that, the photocatalytic degradations of RhB were tested using the prepared catalysts. The results showed that utilizing Ag significantly impacted the photo degradation of RhB by lowering the charge carrier recombination, leading to 95% photocatalytic degradation after 12 min. The enhanced photocatalytic performance of the produced nanocomposite was attributed to the role of the Ag dopant in generating more active oxygen species. Moreover, the impacts of the catalyst amount, pH level, and contact time were discussed.

The laser-induced breakdown spectroscopy (LIBS) technique was performed on polymers to study the neutral and ionic emission lines along with the CN violet system (B2Σ+ to X2Σ+) and the C2 Swan system (d3 Пg–a3 Пu). For the laser-based emission analyses, the plasma was produced by focusing the laser beam of a Q-switched Nd: YAG laser (2ω) at an optical wavelength of 532 nm, 5 ns pulse width, and a repetition frequency of 10 Hz. The integration time of the detection system was fixed at 1–10 ms while the target sample was positioned in air ambiance. Two organic polymers were investigated in this work: nylon and nylon doped with ZnO. The molecular optical emission study of nylon and doped nylon polymer sample reveals CN and C2 molecular structures present in the polymer. The vibrational emission analysis of CN and C2 bands gives information about the molecular structure of polymers and dynamics influencing the excitation structures of the molecules. Besides, it was further investigated that the intensity of the molecular optical emission structure strongly depends on the electron number density (cm−3), excitation temperature (eV), and laser irradiance (W/cm2). These results suggest that LIBS is a reliable diagnostic technique for the study of polymers regarding their molecular structure, identification, and compositional analysis.

We report a quantitative analysis of various plant-biochar samples (S1, S2 and S3) by utilizing a laser-induced breakdown spectroscopy (LIBS) technique. For LIBS analysis, laser-induced microplasma was generated on the target surface by using a focused beam through a high-power Nd: YAG laser and optical emission spectra were recorded using a charged coupled device (CCD) array spectrometer, with wavelength ranges from 200 nm to 720 nm. The spectroscopical analysis showed the existence of various ingredients, including H, Li, Ca, Na, Al, Zn, Mg, Sr, Si, and Fe, along with a CN molecular emission band due to B2Σ+ − X2Σ+ electronic transition. By assuming conditions of the plasma is optically thin and in LTE, calibration-free laser-induced breakdown spectroscopy (CF-LIBS) was utilized for the compositional analysis of the ingredients present in the three plant-biochar samples. To lower the uncertainties, we used an average composition (%) of the three plant-biochar samples. The quantitative study of the plant-biochar samples was also achieved using the energy dispersive X-ray (EDX) technique, showing good agreement with the CF-LIBS technique. In addition, statistical analysis, such as principal component analysis (PCA), was performed for the clustering and classification of the three plant-biochar samples. The first three PCs explained an overall ~91% of the variation in LIBS spectral data, including PC1 (58.71%), PC2 (20.9%), and PC3 (11.4%). These findings suggest that LIBS is a robust tool for rapid measurement of heavy as well as light elements, such as H, Li, and nutritional metals in plant-biochar samples.

In this research, we studied the performance analysis of inductively coupled radiofrequency plasma “RF-ICP” torch used in multi-material processing. A 2D numerical model built with COMSOL Multiphysics was used to study the discharge behavior and evaluate the overall efficiency transmitted into the plasma system. The temperature and velocity flow of the plasma were investigated. The numerical results are consistent with previous experimental studies. The temperature and velocity profiles are represented under a wide range of RF power and for different sheath gas flow rates. With increasing power, the radial peak temperature typically shifts towards the wall. The resistance of the torch rises whereas the inductance diminishes with increasing RF power. The overall dependency of the coupling efficiency to the RF power is also estimated. The stabilization of the plasma flow dependency to the sheath swirl flow was investigated. The incorporation of Helium (0.02%) into an Argon gas was established to minimize the energy lost in the sidewall. The number and spacing of induction coil numbers affects the temperature and flow field distribution. A valuable approach to designing and optimizing the induction plasma system is presented in the proposed study. The obtained results are fundamental to specify ICP torch design criteria needed for multi-material processing.

Zinc oxide thin film (ZnO thin film) and a silver-doped zinc oxide nanocomposite thin film (Ag/ZnO thin film) were prepared by the technique of the pulsed laser deposition at 600 °C to be applicable as a portable catalytic material for the removal of 4-nitrophenol. The nanocomposite was prepared by making the deposition of the two targets (Zn and Ag), and it was analyzed by different techniques. According to the XRD pattern, the hexagonal wurtzite crystalline form of Ag-doped ZnO NPs suggested that the samples were polycrystalline. Additionally, the shifting of the diffraction peaks to the higher angles, which denotes that doping reduces the crystallite size, illustrated the typical effect of the dopant Ag nanostructure on the ZnO thin film, which has an ionic radius less than the host cation. From SEM images, Ag-doping drastically altered the morphological characteristics and reduced the aggregation. Additionally, its energy band gap decreased when Ag was incorporated. UV spectroscopy was then used to monitor the catalysis process, and Ag/ZnO thin films had a larger first-order rate constant of the catalytic reaction K than that of ZnO thin film. According to the catalytic experiment results, the Ag/ZnO thin film has remarkable potential for use in environmentally-favorable applications.

We have investigated, in a previous work, the transition dipole moments (TDM) of the 13 1Σ+ states of the (SrK)+ molecular ion by using the ab initio method based on the pseudo-potential approach. The radiative lifetimes for all vibrational levels of A and C1Σ+ have been calculated by using such transition dipole moments curves. We have included the bound-free emissions probabilities further to the bound–bound transitions. The bound-free emissions probabilities have been determined exactly, using the Franck–Condon approach, and then included in the total radiative lifetime. An important change has been observed for the higher excited vibrational levels in these lifetimes when the approximate evaluation breaks down. For the first time, the radiative lifetimes associated with the Aand C1Σ+ excited state have been studied here.

Al2O3-poly(vinyl alcohol) nanocomposite (Al2O3-PVA nanocomposite) was generated in a single step using an eco-friendly method based on the pulsed laser ablation approach immersed in PVA solution to be applicable for the removal of Ni(II) from aqueous solution, followed by making a physicochemical characterization by SEM, XRD, FT-IR, and EDX. After that, the effect of adsorption parameters, such as pH, contact time, initial concentration of Ni(II), and medium temperature, were investigated for removal Ni(II) ions. The results showed that the adsorption was increased when pH was 5.3, and the process was initially relatively quick, with maximum adsorption detected within 90 min of contact time with the endothermic sorption process. Moreover, the pseudo-second-order rate kinetics (k2 = 9.9 × 10−4 g mg−1 min−1) exhibited greater agreement than that of the pseudo-first-order. For that, the Ni(II) was effectively collected by Al2O3-PVA nanocomposite prepared by an eco-friendly and simple method for the production of clean water to protect public health.

In this work, we report the results of the compositional analysis of an aluminum gallium arsenide (AlGaAs) sample using the calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique. The AlGaAs sample was doped with three various concentrations of gallium (Ga), arsenic (As), and aluminum (Al), as reported by the manufacturer, and the CF-LIBS technique was employed to identify the doping concentration. A pulsed Q-switched Nd: YAG laser capable of delivering 200 and 400 mJ energy at 532 and 1064 nm, respectively, was focused on the target sample for ablation, and the resulting emission spectra were captured using a LIBS 2000+ spectrometer covering the spectral range from 200 to 720 nm. The emission spectra of the AlGaAs sample yielded spectral lines of Ga, As, and Al. These lines were further used to calculate the plasma parameters, including electron temperature and electron number density. The Boltzmann plot method was used to calculate the electron temperature, and the average electron temperature was found to be 5744 ± 500 K. Furthermore, the electron number density was calculated from the Stark-broadened line profile method, and the average number density was calculated to be 6.5 × 1017 cm−3. It is further observed that the plasma parameters including electron temperature and electron number density have an increasing trend with laser irradiance and a decreasing trend along the plume length up to 2 mm. Finally, the elemental concentrations in terms of weight percentage using the CF-LIBS method were calculated to be Ga: 94%, Al: 4.77% and As: 1.23% for sample-1; Ga: 95.63%, Al: 1.15% and As: 3.22% for sample-2; and Ga: 97.32%, Al: 0.69% and As: 1.99% for sample-3. The certified concentrations were Ga: 95%, Al: 3% and As: 2% for sample-1; Ga: 96.05%, Al: 1% and As: 2.95% for sample-2; and Ga: 97.32%, Al: 0.69% and As: 1.99% for sample-3. The concentrations measured by CF-LIBS showed good agreement with the certified values reported by the manufacturer. These findings suggest that the CF-LIBS technique opens up an avenue for the industrial application of LIBS, where quantitative/qualitative analysis of the material is highly desirable.

We report feedback-induced frequency oscillations using a power-split-ratio through asymmetric dual-loop optical feedback (Loop I: ~2.2 km and Loop II: ~20 m) subject to a self-mode-locked two-section QDash laser emitting at 1550 nm and operating at 21 GHz repetition rate. To assess the suppression of frequency resonances, three chosen combinations of feedback power (Loop I: −27.27 dB and Loop II: −19.74 dB, Loop I: −22 dB and Loop II: −22 dB, and Loop I: −19.74 dB and Loop II: −27.27 dB) through asymmetric dual-loop optical feedback have been studied. Based on the chosen coupling strength, an optimum feedback ratio that yields better side-mode suppression has been identified. Our results demonstrate that side-mode suppression can be achieved by the fine adjustment of coupling power through either cavity of dual-loop feedback configurations. Furthermore, we have further demonstrated that frequency fluctuations from the RF spectra can be filtered by carefully selecting the delay phase of the second cavity. Our experimental findings suggest that semiconductor mode-locked lasers based on dual-loop feedback configurations can be used to develop noise oscillations free from integrated photonic oscillators for potential applications in telecommunications, multiplexing, and frequency-comb generation.

A three-dimensional numerical modelling of a time-dependent, turbulent thermal plasma jet was developed to synthetize silicon nanopowder. Computational fluid dynamics and particle models were employed via COMSOL Multiphysics®v. 5.4 (COMSOL AB, Stockholm, Sweden) to simulate fluid and particle motion in the plasma jet, as well as the heat dependency. Plasma flow and particle interactions were exemplified in terms of momentum, energy, and turbulence flow. The transport of nanoparticles through convection, diffusion, and thermophoresis were also considered. The trajectories and heat transfer of both plasma jet fields, and particles are represented. The swirling flow controls the plasma jet and highly affects the dispersion of the nanoparticles. We demonstrate a decrease in both particles’ velocity and temperature distribution at a higher carrier gas injection velocity. The increase in the particle size and number affects the momentum transfer, turbulence modulation, and energy of particles, and also reduces plasma jet parameters. On the other hand, the upstream flame significantly impacts the particle’s behavior under velocity and heat transfer variation. Our findings open the door for examining thermal plasma impact in nanoparticle synthesis, where it plays a major role in optimizing the growth parameters, ensuring high quality with a low-cost technique.

We investigated structure optimization, mechanical stability, electronic and bonding properties of the nanolaminate compounds Ti2PbC, Zr2PbC, and Hf2PbC using the first-principles calculations. These structures display nanolaminated edifices where MC layers are interleaved with Pb. The calculation of formation energies, elastic moduli and phonons reveal that all MAX phase systems are exothermic, and are intrinsically and dynamically stable at zero and under pressure. The mechanical and thermal properties are reported with fundamental insights. Results of bulk modulus and shear modulus show that the investigated compounds display a remarkable hardness. The elastic constants C11 and C33 rise more quickly with an increase in pressure than that of other elastic constants. Electronic and bonding properties are investigated through the calculation of electronic band structure, density of states, and charge densities.

We report theoretical studies based on density functional theory within spin-orbit coupling to explore electronic structures, lattice dynamical properties of ZrSbTe and HfSbTe. With spin−orbit coupling included, our findings reveal that ZrSbTe and HfSbTe exhibit a semiconducting behavior with narrow indirect band gaps of 0.10 eV, and 0.15 eV, respectively. Besides, the lattice dynamical properties revealed that the explored materials based on antimonide−tellurides are dynamically stable. On the basis of electronic structures, the thermoelectric properties were computed using the Landauer-Buttiker formula by considering both electron and phonon contributions in the transport properties calculation. We employed Green’s-function method based on the Green-Kubo-Mori formula, where the thermoelectric properties such as the electrical conductivity σ and thermopower α were estimated in terms of the correlation functions. The present work could be viewed as a significant amendment of the electronic nature of ZrSbTe and HfSbTe that were reported to be metallic in literature.