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This paper presents a self-consistent multi-dimensional mathematical model and a numerical approach for simulating the low-temperature plasma induced by the femtosecond laser filament. Addressing limitations in current models, we analyze key aspects of the laser plasma behavior, including plasma generation, detailed chemical kinetics, energy exchange channels, total energy balance, and hydrodynamics. The developed model and LOTASFOAM code are applied to study the temporal and spatial decay of the plasma produced by a femtosecond laser pulse in pure nitrogen at atmospheric pressure. The paper also includes a discussion on the spatial and temporal dynamics of electronically excited states of nitrogen in the decaying laser plasma. [ABSTRACT FROM AUTHOR]

Conventional time-of-flight methods can be used to determine carrier mobilities for photovoltaic cells in which the transit time between electrodes is greater than the RC time constant of the device. To measure carrier drift on sub-ns timescales, we have recently developed a two-pulse time-of-flight technique capable of detecting drift velocities with 100-ps time resolution in perovskite materials. In this method, the rates of carrier transit across the active layer of a device are determined by varying the delay time between laser pulses and measuring the magnitude of the recombination-induced nonlinearity in the photocurrent. Here, we present a related experimental approach in which diffractive optic-based transient grating spectroscopy is combined with our two-pulse time-of-flight technique to simultaneously probe drift and diffusion in orthogonal directions within the active layer of a photovoltaic cell. Carrier density gratings are generated using two time-coincident pulse-pairs with passively stabilized phases. Relaxation of the grating amplitude associated with the first pulse-pair is detected by varying the delay and phase of the density grating corresponding to the second pulse-pair. The ability of the technique to reveal carrier diffusion is demonstrated with model calculations and experiments conducted using MAPbI3 photovoltaic cells. [ABSTRACT FROM AUTHOR]

Castor oil‐based polyurethane has been researched for its utility in heavy metal adsorption. To improve the adsorptive performance, the polymer can be incorporated with cellulose—a renewable and widely available biopolymer. The aim of this research was to synthesize a film composite prepared from castor oil‐based polyurethane and cellulose for adsorptive removal of aqueous Cd and Pb. One‐shoot synthesis method was employed by mixing cellulose filler with castor oil and toluene diisocyanate (TDI). Characterization was carried out by FT‐IR, SEM, TGA, DSC, and contact angle analyses. Batch adsorption was carried out for the Cd and Pb with variations in contact time and initial pH, before analyzed for the adsorptive performance using 1064 nm Nd:YAG laser spectroscopy. The resulted adsorbents had improved thermal stability, and lower hydrophobicity. Adsorption of Pb and Cd increased 2 and 35 times after the addition of 0.1 g cellulose, respectively. Batch adsorption test revealed that the optimum conditions are 120‐min contact time and pH of 9 and 7 (for Cd and Pb, respectively). In conclusion, incorporation of cellulose could modify the characteristics of castor oil‐based polyurethane film and improve the adsorption of Cd and Pb. [ABSTRACT FROM AUTHOR]

Copyright of Chinese Journal of Inorganic Analytical Chemistry / Zhongguo Wuji Fenxi Huaxue is the property of Beijing Research Institute of Mining & Metallurgy Technology Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We regulate the particle size and crystallographic facet of single-crystal (SC) Li(Ni,Mn) 2 O 4 (LNMO) cathode materials via flux-selective molten salt method. By simply adjusting Li 2 MoO 4 or LiI as sintering aids, we synthesized size controlled SC particles, both small and large, and comparatively investigated their electrochemical behavior focusing on the lithiation/delithiation reactivity in conjunction with the particle size and surface planes. Considering the growth mechanism of a SC particles with a specific crystal plane, such particle size control is not determined solely by the synthetic condition but must also consider the interfacial energy of the crystal planes in conjunction with the fluxes what we used. While the initial charge capacity is similar, the given cathode using a small SC LNMO (using LiI) with uniform particle sizes (≤5 μm) exhibits outstanding rate capability with stable capacity retention under changing current density, which indicates stable lithium transport during the repetitive electrochemical reactions. The dependency of the impedance response with change in the electrode resistances as well as the stability during the cycle reactions in conjunction with the post-mortem Li distribution by using laser-induced breakdown spectroscopy as a function of porosity change and cell degradation are thoroughly discussed from the standpoint of regulated particle property. [ABSTRACT FROM AUTHOR]

ABSTRACT The focus of this research is to use the thermal ablation properties of a Nd:YAG infrared laser to highlight the thermal damage caused by the extinction of the plasma, which leads to the disappearance of the spectra of certain polymers as the laser energy increases. The study involved testing five commonly used polymers: polytetrafluoroethylene (PTFE) also known as Teflon, polyoxymethylene (POM), polyvinyl chloride (PVC), Bakelite, and polyamide. Laser induced breakdown spectroscopy (LIBS) analysis was used to qualitatively analyze the plasma generated from the polymer samples, identifying the excited species present in each of the five polymers. Wavelength dispersive X‐ray fluorescence (WDXRF) analysis of the polymer samples further confirmed the identification of these excited species. The results obtained from the spectra recorded at different laser energies in an air environment showed that the saturation observed in the plasma, induced by increasing laser energy, is not consistently observed for all polymers. This plasma extinction phenomenon in certain polymers is attributed to thermal effects when using an infrared (IR) laser as a heating source. [ABSTRACT FROM AUTHOR]

Rare earth elements (REEs) hold significant industrial, scientific, and modern technological worth. This study focused on detecting and quantifying REEs in various geological ore samples. These samples were collected from different REE-bearing locations recommended by geological experts. The analysis was conducted using laser-induced breakdown spectroscopy (LIBS) and laser ablation time-of-flight mass spectrometry (LA-TOF-MS). In this work, LIBS methodology was employed using three different configurations: standard LIBS, LIBS with an applied magnetic field, and LIBS with both an applied magnetic field and target sample heating within an optimal temperature range. Elements from the REE group, specifically lanthanum (La), cerium (Ce), and neodymium (Nd), were identified and quantified. To detect, quantify, and validate the results from LIBS and LA-TOF-MS, we utilized an array of analytical techniques—Energy-Dispersive X-ray Spectroscopy (EDX), Energy-Dispersive X-ray Fluorescence Spectrometer (ED-XRF), and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Interestingly, the quantitative results for REEs (La, Ce, and Nd) in the ore samples obtained using the LIBS technique with various configurations were found to be in agreement with those from LA-TOF-MS, EDX, XRF, and ICP-OES. In addition, LIBS enables detailed microchemical imaging, allowing the map of the spatial distribution of elements within the mineral–ore matrix. The high-resolution microscale elemental mapping of REEs was accomplished using the emission lines Ce (II) at 446.0 nm, La (II) at 492.1 nm, and Nd (II) at 388.8 nm. By integrating multiple analytical techniques, our study enabled the construction of a complete elemental distribution map, providing new insights into the geochemical processes and mineral composition of rare earth ores, while advancing geochemistry and contributing valuable data for rare earth resource exploration. [ABSTRACT FROM AUTHOR]

In this investigation, a spectroscopic optical emission test was used to investigate the characteristics of gold plasmas that were produced in the surrounding environment using an Nd: YAG system at a wavelength of 1064 nm and had an energy output that varied from 400 to 600 mJ. The emission spectrum profiles of (Au) were analyzed and recorded using a spectrometer to aid in the extraction of vital plasma features (i.e., T e and n e ). Plasma temperature was determined using the Boltzmann plot method, and electron density was determined using the Stark broadening method. The temperature was between (0.91 and 0.94) eV, while the electron density ranged between (4.79 and 5.26) × 1 0 1 7 cm − 3 . The rest of the plasma parameters were calculated by the mathematical equations of the method used (Boltzmann Plott). [ABSTRACT FROM AUTHOR]

We report the standoff/remote identification of post-consumer plastic waste by utilizing a low-cost and compact standoff laser-induced breakdown spectroscopy (ST-LIBS) detection system. A single plano-convex lens is used for collecting the optical emissions from the plasma at a standoff distance of 6.5 m. A compact non-gated Czerny–Turner charge-coupled device (CCD) spectrometer (CT-CCD) is utilized to analyze the optical response. The single lens and CT-CCD combination not only reduces the cost of the detection system by tenfold, but also decreases the collection system size and weight compared to heavy telescopic-based intensified CCD systems. All the samples investigated in this study were collected from a local recycling plant. All the measurements were performed with only a single laser shot which enables rapid identification while probing a large number of samples in real time. Furthermore, principal component analysis has shown excellent separation among the samples and an artificial neural network analysis has revealed that plastic waste can be identified within ∼10 ms only (testing time) with accuracies up to ∼99%. Finally, these results have the potential to build a compact and low-cost ST-LIBS detection system for the rapid identification of plastic waste for real-time waste management applications. [ABSTRACT FROM AUTHOR]

Nanoparticle-enhanced laser-induced breakdown spectroscopy (NELIBS) represents a promising tool for detecting trace elements. This work improves NELIBS by substituting metal nanoparticles with nano-silica particles to achieve rapid detection of Cs elements at low concentrations. This substitution effectively prevents cluster formation and simplifies the experiment preparation process. The research optimizes factors such as target movement speed, nanoparticle concentration, and nanoparticle size to identify the optimal experimental parameters. Comparative analysis of the 3D morphology of laser ablation areas with and without nanoparticles reveals that evenly distributed nano-silica particles on the target surface provide the most effective colloidal particle lens array (CPLA) effect, and increasing the roughness of the target surface thereby enhancing the quality of laser ablation. With a laser frequency of 10 Hz, optimal characteristic spectral signals are achieved when the target movement speed exceeds 2 mm/s. Under conditions of a concentration of 0.1 mg/mL and an average particle size of 50 nm, the greatest enhancement effect on Cs element LIBS characteristic spectral signals is observed. Consequently, the limit of detection (LOD) and the limit of quantitation (LOQ) of elemental Cs by LIBS technology are reduced to 0.45 mg/L and 1.51 mg/L, respectively, facilitating real-time detection of Cs element at low concentrations. In addition, the nano-silica particles have also had a certain enhancement effect on the spectral signal of elemental properties in the target, proving that enhancing the LIBS characteristic spectral signal using nano-silica particles is a feasible method. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) quantitative analysis is susceptible to matrix effects, especially in samples with significant differences in texture, such as soil and coal. Adding additional information such as the physicochemical properties of the sample and plasma images based on the original spectrum is an effective measure to reduce substrate effects. In this study, a new strategy to mitigate the impact of matrix effects and a high-accuracy quantification method for elements in soil by LIBS called PCA-GS-ELM are proposed. No additional equipment is required to obtain auxiliary information. Principal component analysis (PCA) is employed to extract spectral differences between different samples, and the differential spectrum is combined with the original spectrum to form the generalized spectra (GS), which is then input into the extreme learning machine (ELM) model. The model is trained to simultaneously focus on the element characteristic spectral lines and matrix differences between samples. In the experiment, a self-developed portable high-frequency LIBS is used. In the quantitative analysis of six major elements in 13 soil samples, the PCA-GS-ELM method has significantly improved accuracy. The RMSEP for Si, Al, Ca, Fe, Mg, and Ti is 0.946, 0.278, 0.394, 0.08, 0.169, and 0.034 wt%, respectively. The results demonstrate that the proposed generalized spectral method can mitigate matrix effects and enhance the performance of multivariate analysis methods. [ABSTRACT FROM AUTHOR]

The detection of impurities in diatomite is a critical issue during the silicon extraction process. Impurities can significantly impact the properties of silicon, compromising the performance of Si solar cells. In the present work, we applied a sensitivity-improved calibration-free LIBS measurement approach to assess the quality of diatomite. Based on the recording of two spectra with different delays between the laser pulse and the detector gate, the method enables the quantification of major, minor, and trace elements. The limits of detection for minor and trace elements were evaluated. Furthermore, we investigated the morphology and properties of the diatomite surface using Energy-Dispersive X-ray Spectroscopy and Scanning Electron Microscopy analysis. This research contributes to process optimization in the fabrication of electronic grade silicon from diatomite for photovoltaic technology and other applications. [ABSTRACT FROM AUTHOR]

For the construction of the international linear collider, mass production of niobium (Nb) superconducting cavities is essential. In the surface treatment of the Nb cavities, on-site analysis of electropolishing solution composed of hydrofluoric acid and sulfuric acid is desired. In this work, we analyzed the electropolishing solutions containing from 1.0 g L-1 to 10.0 g L-1 Nb by surface-enhanced laser-induced breakdown spectroscopy (surface-enhanced LIBS) that needs only a microvolume sample and simple operations. The sample solution was trapped on porous silicon (Si) fabricated by metal-assisted etching (metalassisted chemical etching) through a wiping process. Nb emission lines were detected with low laser energy irradiation (2.0 mJ per pulse) onto the substrate. A regression model was built by partial least squares regression, and the Nb concentrations of test samples were predicted with a mean absolute error of approximately 0.4 g L-1. To the best of our knowledge, this is the first report that applied LIBS to the analysis of the highly toxic electropolishing solution. The proposed method would be helpful for the quality control of surface treatment and the efficient use of solution. [ABSTRACT FROM AUTHOR]

As a kind of plant with complex chemical composition, the different compositions of tobacco determine the quality of tobacco, which in turn determines the quality of its cigarette products, so high-precision and rapid identification of different brands of cigarettes is of great significance for combating the market of counterfeit and shoddy cigarettes and safeguarding people's life and health. Traditional cigarette detection methods are time-consuming and subjective, and the analysis results are not objective and precise enough, whereas this study proposes a combination of cavity-constrained laser-induced breakdown spectroscopy (LIBS) and gray wolf optimization algorithm optimized bidirectional long short-term memory (GWO-BiLSTM) networks for classifying and identifying cigarette samples of 10 different brands. The signal-to-noise ratio and enhancement factor of the spectral intensity signal, LIBS plasma temperature and density are compared for different sizes of cavity constraints, and an optimal spectral enhancement size of 5 mm in both cavity height and diameter is selected. Comparing four different spectral downscaling methods, namely, principal component analysis (PCA), robust principal component analysis (RPCA), linear discriminant analysis (LDA), and t-distribution-stochastic neighborhood embedding (t-SNE), the LDA downscaling model is selected to achieve effective downscaling of the LIBS spectral data. By comparing the classification performance of the three models, the long short-term memory (LSTM) network, bidirectional long short-term memory (BiLSTM) network, and GWO-BiLSTM network, the GWO-BiLSTM model can achieve a classification accuracy of up to 98.31% in the test set. The results show that the classification method for different brands of cigarettes proposed in this study can effectively solve the technical pain points of traditional tobacco detection methods and provide a technical means to prevent the circulation of counterfeit cigarettes. [ABSTRACT FROM AUTHOR]

As a remote and in situ diagnostic technique for the first wall of tokamaks, laser-induced breakdown spectroscopy (LIBS) has shown promising potential for depth profile analysis of deposition layers on plasma-facing components (PFCs). However, due to the complexity of the interface of deposition layers and the limitations of laser profiles, achieving an accurate deposition layer thickness is often more difficult for an in situ LIBS system in tokamaks. In previous studies, a Laser Profile & Interface Roughness model (LPIR model), which considers the laser beam profile and interface roughness factors, has been developed to identify the interface of deposition layers. In this study, the effect of ablation rates from different materials in the deposited layers on the accuracy of their thickness has been investigated. The depth profiling of a Ni-Cu-Ni-Cu multilayer sample, which has a four-layer structure, has been carried out using the LIBS technique under different focusing conditions as well as various laser pulse energies, with the pressure maintained at 10-5 mbar. The LPIR model was used to reconstruct the depth distribution profile of the Ni-Cu-Ni-Cu multilayer sample and quantify the interfacial positions of the deposited layers. A layer thickness correction method for multilayer sample is proposed based on the dependence of the ablation rates of different layers on laser fluence. The correction ability has been evaluated based on the relative errors between the calculated and the scanning electron microscope (SEM) values for different layer thicknesses. The relative errors of the corrected layer thicknesses are all significantly improved, and the accuracy of the layer thicknesses has been substantially improved. The proposed method will not only help us better understand the LIBS depth profiling of multilayer samples under different laser fluence conditions, but it will also further improve the accuracy of the layer thickness analysis of multilayer samples. This result is of positive significance for the application of in situ LIBS diagnostics in plasma-wall interaction (PWI) studies. [ABSTRACT FROM AUTHOR]

The poor spectral stability of laser-induced breakdown spectroscopy (LIBS) seriously affects its analytical performance, which is a key obstacle to its further development. To overcome this challenge, an improved spectral standardization method based on plasma image-spectrum fusion (ISS-PISF) was proposed in this study. This method, for the first time, considers and quantifies the influence of plasma morphology on spectral intensity based on the line-integrated intensity formula of LIBS spectra. It recognizes that the spectral fluctuations mainly stem from variations in total number density, plasma temperature, electron number density, and plasma morphology. Therefore, ISS-PISF innovatively utilizes easily accessible features from plasma images and spectra to eliminate the influence of these four plasma parameters, thereby improving the spectral stability and analytical performance of LIBS. To validate the effectiveness of this method, the spectra of aluminum alloy samples obtained under complex detection conditions simulated by varying laser energy and defocusing amount were analyzed. After correction by ISS-PISF, the R2 for Mg I 516.73 nm, Mn II 294.92 nm, and Si I 288.16 nm improved to 0.990, 0.976, and 0.961, and the average RMSE of the validation set decreased by 46.154%, while the average STD of the validation set decreased by 37.405%. These experimental results indicate that this study provides a simple, effective, and physically supported spectral standardization method, which contributes to the further promotion and application of LIBS. [ABSTRACT FROM AUTHOR]

An experimental study on the packing thickness (PT) dependent plasma emission caused by laser ablating thin-layer microgranular samples in air was conducted using three sets of size-selected copper grains (median size d50 = 53 mm, 72 mm, and 100 mm, respectively). For each size-selected case, the PT parameter was tuned from 0.15 to 1.00 mm through varying the amount of grains packed into a vessel with a steel bottom wall and the emission spectra of laser-induced plasma were measured at various PT. It is found that there is a striking threshold phenomenon in the measured behavior of PTdependent plasma emission. Specifically, when PT is less than a threshold PTth, the emission intensity exhibits an exponential decreasing with incremental thickness; however, when it exceeds PTth, the emission intensity becomes almost constant. It is also found that the PTth slightly depends on grain size but the ratio of PTth to d50 seems to be size independent. Combining the mechanical fundamentals of granular materials, we interpreted the findings by considering a PT-dependent effect of the vessel's bottom on the formation circumstance of a laser-induced plasma. This work has practical significance in assessing a threshold thickness above which laser-induced breakdown spectroscopy, as an analytical technique to quantify elements embedded in microgranular materials, is viable regardless of PT difference. [ABSTRACT FROM AUTHOR]

Double-pulse laser-induced breakdown spectroscopy (DP-LIBS) is the most effective LIBS signal enhancement method widely used in various fields. Due to adding an extra laser pulse, DP-LIBS experiments have more possibilities for research. Since the proposal of DP-LIBS technology in 1998, researchers have devoted themselves to much research on DP-LIBS. Research on DP-LIBS has been more common and innovative in the last 5 years. This review aims to comprehensively analyze DP-LIBS's experimental research and application, focusing on the various studies conducted in this area. The latest advancements in DP-LIBS experiments are summarized, including the instruments studies (such as geometric configurations, experimental parameters, and conditions). It also discusses the mechanism of DP-LIBS and its combination with other enhancement methods and spectroscopies. Moreover, the application of DP-LIBS is categorized into five domains: geological exploration and environmental monitoring, metallurgical industry, energy industry, biological application, and other applications. The applications of DP-LIBS in various fields are further elaborated. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the relationship between the plasma temperature in remote laser-induced breakdown spectroscopy (LIBS) experiments and the hydrophobic properties of silicone rubber insulators (SIRs). Contact angle and LIBS measurements were conducted on both artificially-aged (accelerated aging) and field-aged SIRs. This study reveals a clear connection between plasma temperature and the properties of aged SIRs on artificially-aged SIR specimens. Specifically, the plasma temperature exhibits a consistent increase with the duration of the accelerated aging test. The hydrophobicity of the artificially-aged SIRs was assessed by performing contact angle measurements, revealing a decrease in the hydrophobicity with increased aging test duration. Furthermore, we extended our investigation to the study of nine field-aged SIRs that had been in use on 150 kV overhead transmission lines for 0 to 21 years. We find that the laser absorption and hardness of the material do not relate to the plasma temperature. In summary, we observe a direct connection of plasma temperature to both contact-angle measurements and operation time of the in-service insulators. These results strongly suggest the potential use of LIBS for remotely evaluating the hydrophobicity and aging degree of silicone rubber insulators, thus assessing their real-time on-site operational quality. [ABSTRACT FROM AUTHOR]

Intumescent fireproof coatings protect steel structures and cables by forming a thick, fire-resistant layer under high temperatures. These coatings can deteriorate over time, impacting their fire resistance. Current testing methods are largely lab-based, lacking in-service evaluation platforms. Laser-Induced Breakdown Spectroscopy (LIBS) is emerging as a promising in situ detection technology but is influenced by low air pressure in high-altitude areas. This study investigates how air pressure affects LIBS signals in intumescent coatings on galvanized steel. Using pressures between 35 and 101 kPa, a linear model was developed to correlate laser pulses to ablation depth for characterizing coating thickness. Results show that spectral intensity decreases with lower air pressure. However, a strong linear relationship persists between laser pulses and ablation depth, with a fitting accuracy above 0.9. The coating thickness is identified by the number of laser pulses required to detect the Zn spectral line from the underlying galvanized steel. As air pressure decreases, the ablation depth increases. The study effectively models and corrects for air pressure effects on LIBS data, enabling its application for field detection of fireproof coatings. This advancement enhances the reliability of LIBS technology in assessing the fire performance of these materials, providing a reference for their in situ evaluation and ensuring better fire safety standards for building steel structures and cables. [ABSTRACT FROM AUTHOR]

The performance of aluminum alloys can be affected by the element of magnesium. Therefore, it is necessary to realize fast and accurate quantitative analysis of magnesium in aluminum alloys. Herein, high repetition rate spark discharge assisted laser-induced breakdown spectroscopy based on microchip lasers (HRR SD-LIBS) was applied to quantitatively analyze magnesium elements in aluminum alloys. Baseline correction was performed using the moving median method to obtain the net spectral data. Multivariate calibration models such as back-propagation neural network (BP), support vector machine (SVM), and random forest (RF) were established, respectively. Compared with the conventional univariate calibration model, the correlation coefficients (RP²) of BP,SVM and RF models increased from 0. 810 to 0.985, 0.997 and 0.994, while the root mean square error (RMSEP) decreased from 0.283 to 0.059 8, 0.041 0 and 0.054 2, the average relative error decreased from 26.62% to 3.13%, 2.82%, and 3.61%. It indicated that machine earning combined microchip laser-based HRR SD-LIBS significantly improved the quantitative analysis ability of LIBS. In conclusion, it is promising to achieve portable, fast, and accurate quantitative elemental analysis of alloy sample and other materials. [ABSTRACT FROM AUTHOR]

Cubic gauche nitrogen (cg-N) has received wide attention for its exceptionally high energy density and environmental friendliness. However, traditional synthesis methods for cg-N predominantly rely on high-pressure techniques or the utilization of nanoconfined effects using highly toxic and sensitive sodium azide as precursor, which substantially restrict its practical application. On the basis of the first-principles simulations, we found that adsorption of potassium on the cg-N surface exhibits superior stabilization compared to sodium. Then, we chose safer potassium azide as precursor for synthesizing cg-N. Through plasma-enhanced chemical vapor deposition treatment, the free-standing cg-N was successfully synthesized without the need for high-pressure and nanoconfined effects. It demonstrated excellent thermal stability up to 760 K, and then rapid and intense thermal decomposition occurred, exhibiting typical thermal decomposition behaviors of high-energy-density materials. The explosion parameters were also measured using laser-induced plasma spectroscopy. Our work has substantially promoted the practical application of cg-N as HEDMs. [ABSTRACT FROM AUTHOR]

A high‐throughput experimental approach is developed to assess the correlations between chemical composition, structure and conduction properties of inorganic solid ionic conductors. This approach covers the preparation of a large number of samples by combinatorial synthesis, followed by fast characterization of the material library. The approach is primarily based on combinatorial synthesis by magnetron co‐sputtering and the characterization of thin film samples where lithium phosphorus oxynitride (LiPON) is chosen as a case study. A library of 76 LiPON materials is prepared in one experiment from the reactive co‐sputtering of LiPO3 and Li3PO4 in a N2 atmosphere. A specific sample design allows conducting thickness and impedance measurements, Raman spectroscopy, then fast and spatially‐resolved chemical analysis by Laser‐Induced Breakdown Spectroscopy (LIBS) on each material. Particular developments are devoted to this technique to achieve quantitative analysis of lithium in thin films. The materials cover a wide range of compositions with 0.95

One of the most significant medicinal plants used to treat numerous illnesses is Swertia chirayita. The present study demonstrated the compositional analysis of the Swertia chirayita (S. chirayita) plant using an emerging and non-destructive laser-induced breakdown spectroscopy (LIBS) technique. Mg, Ca, K, Fe, Sr, Cr, and Na were verified as necessary elements by the optical emission investigations, while Al, Ti, Si, Ba, Mn, and Li were non-essential. Using the Boltzmann plot technique with stark broadening parameters, plasma temperature and electron number density were calculated in the range of (10,000–12,000) K ±1000 K and (1.5–1.8) × 1017 cm-3, respectively. Finally, compositional analysis was carried out using calibration-free (CF-LIBS) analysis and results were compared with ICP-MS. It was observed that the concentration of Ca and Fe is higher than other detected elements. All the toxic elements are found to be within the safe limit. So, this medicinal plant can be used to cure a variety of diseases that arise due to the deficiency of these elements. [ABSTRACT FROM AUTHOR]

AbstractFood fraud has serious consequences including reputational damage to businesses, health and safety risks and lack of consumer confidence. New technologies targeted at ensuring food authenticity has emerged and however, the penetration and diffusion of sophisticated analytical technologies are faced with challenges in the industry. This review is focused on investigating the emerging technologies and strategies for mitigating food fraud and exploring the key barriers to their application. The review discusses three key areas of focus for food fraud mitigation that include systematic approaches, analytical techniques and package-level anti-counterfeiting technologies. A notable gap exists in converting laboratory based sophisticated technologies and tools in high-paced, live industrial applications. New frontiers such as handheld laser-induced breakdown spectroscopy (LIBS) and smart-phone spectroscopy have emerged for rapid food authentication. Multifunctional devices with hyphenating sensing mechanisms together with deep learning strategies to compare food fingerprints can be a great leap forward in the industry. Combination of different technologies such as spectroscopy and separation techniques will also be superior where quantification of adulterants are preferred. With the advancement of automation these technologies will be able to be deployed as in-line scanning devices in industrial settings to detect food fraud across multiple points in food supply chains. [ABSTRACT FROM AUTHOR]

This current investigation explored the thermal conversion process of castor wood into biochar, which was subsequently harnessed for removing naproxen from pharmaceutical industrial effluent via adsorption. Surface composition analyses conducted through scanning electron microscopy–energy dispersive X‐ray, laser‐induced breakdown spectroscopy, and Fourier‐transform infrared studies unveiled the presence of nano MgO particles within the adsorbent material. Employing optimization techniques such as response surface methodology facilitated a refined approach to batch study. The optimized conditions for batch naproxen sodium (NPX) adsorption on nano‐MgO‐modified biochar were identified as pH 4, 1.5 g/L adsorbent dosage, and a 120‐min contact time maintaining a constant NPX concentration of 10 mg/L. The adsorption capacity was calculated to be 123.34 mg/g for a nano‐magnesium oxide‐modified castor wood biochar (modified biochar) and 99.874 mg/g for pristine castor wood biochar (pristine biochar). Fenton's reagents comprising 15 mM of FeSO4 (7H2O) and 25 mM of H2O2 have been scrutinized under conditions of pH 3.0, a reaction time of 30 min, a temperature of 30°C, and stirring at 120 rpm, followed by batch adsorption treatment. The COD, NH3–N, NO3−, PO43−, and NPX removal percentages was found to be 90%, 87%, 79%, 80%, and 90%, respectively. Thus nano MgO‐modified biochar holds promise of treatment of pharmaceutical effluent. [ABSTRACT FROM AUTHOR]

Oral cancer is the most common malignancy in many developing countries, such as India, due to increased consumption of smokeless tobacco. The trace elemental components in commercially packaged forms of tobacco can play a significant role in the pathogenesis of oral cancer. To qualitatively assess the trace elements in various types of commercially packaged forms of tobacco using laser-induced breakdown spectroscopy (LIBS). Two popular varieties of 'Paan masala' that contained a mixture of slaked lime with areca nut, catechu, and other flavouring agents (tobacco was absent) and four types of packaged tobacco were obtained from 'Paan' shops. The contents in the packets were made into pellets using a hydraulic press and subjected to elemental analysis using LIBS. A ten-trial experiment was carried out on all six pellets. The National Institute of Standards and Technology (NIST) database was used to assess the emission lines. The elements obtained from commercially packaged tobacco and Paan masala were similar: calcium (Ca), iron (Fe), aluminium (Al), nickel (Ni), and chromium (Cr). Substances that cause DNA damage and carcinogenesis are inorganic elements such as nickel. Our study revealed that carcinogens such as nickel are present in the commercially packaged forms of tobacco and 'Paan masala' samples. [ABSTRACT FROM AUTHOR]

Real-time Fe content monitoring in iron ore slurry is crucial for evaluating concentrate quality and enhancing mineral processing efficiency. Laser-induced breakdown spectroscopy (LIBS) is a promising technique for the online monitoring of elemental content at industrial sites. However, LIBS measurements are hampered by the matrix effect and the self-absorption effect, limiting the precision of linear analytical processes. To overcome this, we propose to introduce a nonlinear processing unit based on the S-transform to incorporate nonlinearity into the data analysis process. This approach integrates a feature selection unit based on the spectral distance variable selection method (SDVS), a nonlinear processing unit based on the S-transform (ST), and a partial least squares regression model (PLS). To demonstrate the improvement in accuracy achieved through nonlinear processing, a comparative analysis involving five models, Raw-PLS, SDVS-PLS, ST-PLS, SDVS-ANN, and SDVS-ST-PLS, is conducted. The results reveal a significant improvement in the performance of the SDVS-ST-PLS model, effectively facilitating the successful application of the LIBSlurry analyzer to the mineral flotation process. [ABSTRACT FROM AUTHOR]

AbstractThe accuracy of quantitative analysis in soil laser-induced breakdown spectroscopy (LIBS) is frequently compromised by self-absorption. Eliminating this influence is imperative for attaining reliable results. To mitigate the impact of self-absorption upon the determination of Cr in soil, a novel correction model based upon plasma temperature (SAT) is reported grounded in column density-Saha-Boltzmann (CD-SB) theory. This approach calculates plasma temperature using self-absorption spectra, thereby providing a foundation for line intensity calibration. Initially, the electron number density was determined using the full width at half maximum (FWHM) of the Hα 656.27 nm line. Subsequently, the column density of particles at lower energy levels and the plasma temperature were ascertained. Finally, a multi-line method was employed to correct for self-absorption. In comparison to the LIBS calibration curve procedure, the SAT model effectively rectifies self-absorption in the analysis of soil by significantly enhancing the linear determination coefficients (R2) of the Cr I 425.43 nm and Cr I 427.48 nm lines from 0.9569 and 0.9578 to 0.9869 and 0.9819, respectively. The model also reduces the exponential self-absorption factors by 2.1806 and 0.9919, respectively. The results demonstrate that the SAT model effectively rectifies self-absorption, thereby enhancing the accuracy for the quantitative analysis of soil. [ABSTRACT FROM AUTHOR]

This study discusses potential toxic elements detection in conventional nail polish, including Cr and Pb. The noteworthy results highlight well‐established potential risks of elevated Cr and Pb concentrations. These elements are not allowed in the European Union. Implementing the minimum spanning tree (MST) approach and the isolation forest algorithm effectively clustered samples. Forty‐five samples were analyzed, and four clusters were identified. Two presented six samples with high concentrations of Fe (Cluster 1 with four samples) and Cr and Pb (Cluster 2 with two samples). The other 39 samples presented low concentrations of the determined elements (Co, Cr, Cu, Fe, Ni, and Pb). Cadmium, Zn, and Mn were not detected in any of the analyzed samples. Furthermore, integrating energy‐dispersive x‐ray fluorescence (ED‐XRF) and laser‐induced breakdown spectroscopy (LIBS) enabled fast direct analysis of nail polish samples, streamlining a swift and reliable data acquisition process. This research underscores the importance of ongoing vigilance and monitoring of potential health hazards associated with nail polish formulations, especially in regions with regulatory restrictions on certain elements. The study examined toxic elements in nail polish, particularly Cr and Pb, which are banned in the EU. Using MST and isolation forest algorithms, 45 samples were analyzed, revealing four clusters: one with high Fe concentrations and another with high Cr and Pb. The remaining samples had low concentrations of Co, Cr, Cu, Fe, Ni, and Pb. Cd, Zn, and Mn were undetected. ED‐XRF and LIBS facilitated rapid analysis. The research emphasizes monitoring health hazards in nail polish formulations. [ABSTRACT FROM AUTHOR]

This research explores the use of laser-induced breakdown spectroscopy to detect elements in water residue. This research focuses on inducing plasma on pelletized water residue samples via a pulsed Neodymium-doped yttrium aluminum garnet (Nd:YAG) nanosecond laser with a wavelength of 1064 nm and energy of 100 mJ. The LIBS measurements were performed without and with a magnetic field of 0.8 T. Magnetic discs were used to create a magnetic field of 0.8 T. The presence of different elements (Ca, Mg, Fe, Cr, Mn, As, C, Li, Sr, Ba, Ti, K, O, N, and Si) was confirmed by examining the plasma emission spectra obtained from LIBS analysis. The results show that LIBS successfully detected toxic and heavy metals in water residues. Notably, the presence of a magnetic field affects the plasma properties such that the electron temperature and electron number density increase with increasing magnetic field. The Joule heating effect and the magnetic confinement effect are responsible for the increase in the plasma properties. The improved spectroscopic outcomes are associated with the magnetic confinement of water residue plasma, supported by the affirmation of thermal beta βt, which is less than one for all samples. [ABSTRACT FROM AUTHOR]

A group of wall painting fragments discovered at Ulpia Traiana Sarmizegetusa, an important Roman archeological site located in the former Roman province of Dacia (Romania), have been investigated with the aim of defining the material composition of their pictorial layers and exploring the pictorial technology used. In order to preserve the integrity of the murals and minimize sampling, an array of non- and micro-invasive techniques has been employed, including X-ray fluorescence, laser-induced breakdown spectroscopy, Fourier transform infrared spectroscopy, and hyperspectral imaging. In accordance with previous studies, the identified color palette was mainly based on iron-rich earth pigments (red and yellow ochres, green earth) and carbon-based blacks (soot/charcoal, bone black). Egyptian blue, lazurite, some lead-based pigments, and potentially indigo were also identified (in complex mixtures) on the uppermost paint layers, typically applied a secco over the a fresco background. The presence of expensive pigments and the existence of a red preparatory drawing, documented for the first time in the region, indicate that the original wall paintings had elaborate schemes and, secondly, reflect the patron's wealth and social status. Hyperspectral imaging was able to retrieve some faded paint layers in certain cases, helping to recover lost decorative details, an indicator of a more complex polychromy compared to what we see today. The obtained results add important contributions to the limited corpus of data regarding the technical know-how of decorative polychrome painting on plaster found in Roman archeological sites in Romania. [ABSTRACT FROM AUTHOR]

One of the inherent limitations associated with laser-induced breakdown spectroscopy (LIBS) in the identification of elements lies in the strength of the emission signals. Several approaches exist to enhance the emission capacity of LIBS. In this particular investigation, our focus was on amplifying the signal intensity of LIBS through the utilization of two techniques. These techniques include the application of a low-power electric field within the zone where plasma is formed, in conjunction with the utilization of nanoparticles on the surface of the sample. Specifically, our analysis involved the examination of samples consisting of metallic Zn powder as the matrix element, with the incorporation of small quantities of Ca in the form of CaCO3. The combination of these two methods resulted in unprecedented outcomes, demonstrating a 3.5-fold increase in samples containing 0.05% w/w of CaCO3 when subjected to an electric field of 60 V/cm, while bearing nanoparticles on their surface. [ABSTRACT FROM AUTHOR]

One of the necessary ways to achieve the efficient, clean utilization of coal resources is to reduce the amount of coal gangue in raw coal to ensure the development of clean, low-carbon, and green energy in China. The application of conventional coal gangue separation equipment is severely limited due to the large investment in early construction, high production costs, and large water consumption and waste in production. Intelligent coal gangue separation equipment has the advantages of fast speed, high precision, strong modularity, and integration scalability. It also has the advantages of low operation cost and energy consumption, convenient operation and maintenance, and no water use. All of that could effectively improve the utilization rate of coal resources and expand the economic benefits of enterprises. The application of high-speed, high-precision, and anti-interference online element rapid analysis technology in intelligent coal gangue separation equipment will become an inevitable trend of equipment development in the future with the continuous improvement of coal product demand. Online rapid element analysis technology includes laser-induced breakdown spectroscopy, dual-energy X-ray, and transient neutron activation analysis. Improving and applying more high-speed, high-precision algorithms such as partial least squares and Monte Carlo library least squares in the future are important. [ABSTRACT FROM AUTHOR]

Objectives: Inadequate resection margins of less than 5 mm impair local tumor control. This weak point in oncological safety is exacerbated in bone-infiltrating tumors because rapid bone analysis procedures do not exist. This study aims to assess the bony resection margin status of bone-invasive oral cancer using laser-induced breakdown spectroscopy (LIBS). Materials and methods: LIBS experiments were performed on natively lasered, tumor-infiltrated mandibular cross-sections from 10 patients. In total, 5,336 spectra were recorded at defined distances from the tumor border. Resection margins < 1 mm were defined as very close, from 1–5 mm as close, and > 5 mm as clear. The spectra were histologically validated. Based on the LIBS spectra, the discriminatory power of potassium (K) and soluble calcium (Ca) between bone-infiltrating tumor tissue and very close, close, and clear resection margins was determined. Results: LIBS-derived electrolyte emission values of K and soluble Ca as well as histological parameters for bone neogenesis/fibrosis and lymphocyte/macrophage infiltrates differ significantly between bone-infiltrating tumor tissue spectra and healthy bone spectra from very close, close, and clear resection margins (p < 0.0001). Using LIBS, the transition from very close resection margins to bone-infiltrating tumor tissue can be determined with a sensitivity of 95.0%, and the transition from clear to close resection margins can be determined with a sensitivity of 85.3%. Conclusions: LIBS can reliably determine the boundary of bone-infiltrating tumors and might provide an orientation for determining a clear resection margin. Clinical relevance: LIBS could facilitate intraoperative decision-making and avoid inadequate resection margins in bone-invasive oral cancer. [ABSTRACT FROM AUTHOR]

A support vector machine regression (SVMR) model that integrates data preprocessing was devised for the determination of Mo in molybdenum ores. To eliminate the negative effects of spectral fluctuations and improve the computational efficiency, the model processes original measurements through the following steps: denoising via wavelet transform smoothing (WTS), debaselining via adaptive iteratively reweighted penalized least squares (airPLS), main characteristic peak extraction, elimination of abnormal spectral data via the box plot method, and normalization via min-max scaling. In this study, 255 characteristic peaks were selected from 17,916 spectral datasets, and the total number of datasets after removing the outliers was 491. The calibration curve approach was used to establish a univariate model. The limit of detection of Mo was 0.0080 wt%. The R2 value of the calibration curve was 0.6675. Linear regression (LR) and SVMR were used to establish a multivariate analysis model. Compared to that of the calibration curve approach, the determination coefficients (RP2) of LR and SVMR increased from 0.8034 to 0.9859 and 0.9941, respectively. The range of relative errors (REP) decreased from 0.21%–67.66% to 0.48%–18.46% and 2.65%–7.44%, respectively; the mean absolute error (MAEP) was decreased from 0.0173 wt% to 0.0048 and 0.0039 wt%, respectively; and the root mean square error (RMSEP) decreased from 0.0243 wt% to 0.0065 and 0.0042 wt%, respectively. These results indicate that the integration of SVMR with data preprocessing is suitable for the determination of Mo in molybdenum ores. [ABSTRACT FROM AUTHOR]

NdFeB magnetic materials are the most commonly used rare earth magnets. In the production and processing of the NdFeB magnetic materials, it is necessary to conduct quality control on crude samples of magnetic materials to reduce production costs. Laser induced breakdown spectroscopy (LIBS) is a technique to obtain the spectrum of elements by exciting plasma on the surface of the sample with a high energy laser. An LIBS rare-earth magnet on-line measuring instrument for crude sample detection of magnetic materials is designed and developed. The instrument meets the requirements for product quality control in workshop production. The spectra of 7 kinds of NdFeB crude material samples were obtained by the LIBS instrument. To improve the classification accuracy, the algorithm in the instrument supporting software was used. Appropriate stoichiometric methods were selected, and a sliding window minimum removal base method was independently designed to further optimize the classification accuracy. The optimal ratio was determined by discussing the proportion of data sets, and the accuracy and stability were compared by cross-validation. Finally, stoichiometric method parameters were optimized. The overall optimization improves the classification accuracy from 87.14% to 99.05%. It is verified that the LIBS rare earth magnet online measuring instrument can effectively classify and detect NdFeB rare earth magnets, providing a fast, convenient, accurate and economical testing method for quality control in magnetic material workshops [ABSTRACT FROM AUTHOR]

The main purpose of this work is to thoroughly describe sensitivity and resolution enhancement by systematically optimizing key parameters in laser-induced breakdown spectroscopy analysis. Simultaneous analysis of biogenic (C, P, Mg, and Ca) and contaminating (Pb) elements, which are commonly detected in selected biotic matrices (mammal teeth), was performed. Hydroxyapatite reference pellets were utilized as model matrices, which successfully reflect human dental tissue. The optimization involved precise adjustments of the used laser wavelengths (1064, 532, and 266 nm), relative defocus of the laser pulse, ablation pulse energies, and gate delays for collecting characteristic spectra. In addition, for Ca analysis, the signals of different ionization line types (Ca I 364.44 nm; Ca II 370.60 and 396.85 nm) were compared; in the case of Pb analysis, the limits of detection were established for each used laser wavelength, and the revealed differences were discussed in detail. We intend to demonstrate the benefits of rapid, low-cost analysis and also the importance of measurement parameters used in biotic sample testing. [ABSTRACT FROM AUTHOR]

The current work proposes developing the wavefront-enhanced laser-induced-breakdown spectroscopy (WELIBS) approach using a crystalline quartz slide instead of the crystalline silicon wafer. Such substitution widens the application of WELIBS in the UV, visible, and IR laser wavelength ranges, not only the IR, as in the case of the silicon wafer. A Shack--Hartmann wavefront sensor (SHWFS) has been used to prove the capability of the crystalline quartz slide to convert the wavefront shape from quasi-Gaussian to a flat-top one in different ranges of wavelengths. The analytical performance of the novel WELIBS arrangement with the crystalline quartz slide has been studied using a pure zinc target, which showed a pronounced enhancement in the intensity of the spectral lines (two to sixfold) compared to the conventional LIBS technique for the three laser wavelengths the IR (1064 nm), the green (532 nm), and the UV (355 nm). Furthermore, seven certified bronze alloy samples have been used to study the achieved analytical improvement of the novel WELIBS analytical performance by testing its capability of estimating the limit of detection (LOD) of different minor elements. From the WELIBS and LIBS spectra of the bronze alloys, calibration lines of Zn, Sn, and Pb have been plotted to estimate the limit of detection for each element. The LOD for WELIBS was half that of LIBS. WELIBS with the quartz slide for beam shaping is superior to WELIBS with the Si wafer since it can be used with different laser wavelengths and not only the IR and provides similar, or better, analytical enhancement than the conventional LIBS. [ABSTRACT FROM AUTHOR]

Studying the elemental composition of aerosol particles on a single particle level is of importance when determining the internal and external mixing state of the aerosol population. We present a field-deployable platform for the elemental analysis of ambient single particles using laser-induced breakdown spectroscopy (LIBS). The platform utilizes a wideband spectrometer for simultaneous multi-element detection and size-amplification-aided aerosol charging (SAAC) for efficient particle focusing via a linear electrodynamic quadrupole (LEQ). Carefully designed emission collection system allows minimization of the plasma background emission, which allows us to use short gate delays for increased yield of analyte emission. Performance evaluation with a set of well-defined salt aerosols show excellent capability in determining the relative mass percentage and absolute mass of elements spanning multiple orders of magnitude on a single particle level. Limits of detection for Mg, Na and K were determined to be approximately 2 fg, 40 fg, and 70 fg, respectively. An outdoor aerosol sample was analyzed in the size range of 1–3 µm in diameter, and the particles were classified into distinct categories based on their elemental composition. The maximum analysis speed is about 20 particles per minute and the minimum detectable particle size is, depending on the constituent elements, about 300–800 nm. Emission signals of Al, B, C, Ca, Cu, Fe, K, Mg, Na, Si, and Ti were detected during the measurements of generated or outdoor aerosols. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) is a powerful elemental detection and quantification technique widely employed across various disciplines, including science, engineering, construction, and medicine. This comprehensive review focuses on the recent advancements and challenges in utilizing LIBS for corrosion detection, specifically emphasizing reinforced concrete structures. While LIBS has demonstrated its reliability in corrosion assessment, its adoption as a standardized method is not yet widespread. Identifying and quantifying contaminant elements in targeted structures are crucial steps in corrosion investigation. This review reveals how LIBS can effectively extract elemental contaminants and their relative intensities from samples, establishing correlations with the degree of corrosion. Given that corrosion rate is time-dependent, rapid and accurate techniques like LIBS are essential for timely measurements, enabling multiple instantaneous assessments of contaminant levels. Various calibration techniques and accuracy-enhancing methods are discussed, including calibration curves, chemometrics, and dual-pulsed LIBS approaches for measuring constituent elements. Furthermore, a range of applications for LIBS in concrete technology, cement paste analysis, soil investigations, fluid analysis, and quality control in cement factories are explored. By providing an in-depth understanding of LIBS capabilities and its potential as a reliable and rapid approach for corrosion rate detection in different materials, this study offers valuable insights to researchers, engineers, and industry professionals in pursuing effective corrosion assessment methodologies. [ABSTRACT FROM AUTHOR]

High levels of heavy metal contamination in soil present substantial threats to human health and the environment, leading to severe health problems such as neurotoxicity, cancer, kidney issues, chronic obstructive pulmonary disease, and reduced life expectancy. This research aims to identify and analyze heavy metals in soil samples collected from Superfund sites in North Birmingham, Alabama, specifically in affected areas with zip codes 35207 and 35217 and control area 35214. These affected areas were previously used for mining, coal-fired power plants, coke furnaces, smelting, and other potential sources of heavy metal pollution. Laser-induced breakdown spectroscopy (LIBS) was employed to study 60 soil samples systematically collected from affected and control areas. We found that by using LIBS, we could detect arsenic (As), lead (Pb), and manganese (Mn) in all soil samples from the affected areas. The limit of detection (LoD) was 29.5 mg/kg for Pb, 95.5 mg/kg for As, and 327 mg/kg for Mn using specific parameters of the detection system and/or argon gas purging at atmospheric pressure. The results were compared with ICP-MS measurements to validate the accuracy of the LIBS findings. The data showed good linearity for all calibration data at relatively low concentrations and a good correlation with ICP-MS measurements. [ABSTRACT FROM AUTHOR]

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In-situ laser-induced breakdown spectroscopy (LIBS) was used for measurements on molten aluminum alloys containing 0.6 wt pct magnesium in the melt temperature range 685 °C to 790 °C. With increasing melt temperature, an exponential growth of magnesium LIBS emission signals was observed, a phenomenon that has previously been attributed to the presence of Mg vapor above the melt surface. Here we show how this temperature dependence of the magnesium signal is affected by the presence of a second alloying element in the melt. For dilute ternary aluminum alloys Al–Mg–M, with M = Si, Zn, or Sn, the change in vapor-phase contribution to the Mg signal was found to be linearly correlated with the concentration of the additional alloying element but differing in sign and magnitude. Ternary alloys containing group-II alloying elements (M = Be, Ca, or Sr), known to inhibit oxidation of the melt, were also studied. The presence of these elements had a strongly reducing effect on the vapor-phase component of the Mg LIBS signal. We attribute this decrease to the formation of Be, Ca, or Sr-containing oxides that effectively inhibit the transport of Mg from the melt to the surface and into the vapor phase. [ABSTRACT FROM AUTHOR]

Abstract Oral cancer is the most common malignancy in many developing countries, such as India, due to increased consumption of smokeless tobacco. The trace elemental components in commercially packaged forms of tobacco can play a significant role in the pathogenesis of oral cancer. To qualitatively assess the trace elements in various types of commercially packaged forms of tobacco using laser-induced breakdown spectroscopy (LIBS). Two popular varieties of ‘Paan masala’ that contained a mixture of slaked lime with areca nut, catechu, and other flavouring agents (tobacco was absent) and four types of packaged tobacco were obtained from ‘Paan’ shops. The contents in the packets were made into pellets using a hydraulic press and subjected to elemental analysis using LIBS. A ten-trial experiment was carried out on all six pellets. The National Institute of Standards and Technology (NIST) database was used to assess the emission lines. The elements obtained from commercially packaged tobacco and Paan masala were similar: calcium (Ca), iron (Fe), aluminium (Al), nickel (Ni), and chromium (Cr). Substances that cause DNA damage and carcinogenesis are inorganic elements such as nickel. Our study revealed that carcinogens such as nickel are present in the commercially packaged forms of tobacco and ‘Paan masala’ samples.

The simplicity and low-cost way to improve qualitative and quantitative analytical performance has always been a crucial concern for laser-induced breakdown spectroscopy (LIBS), and many scientists have been engaged in this evolving research direction. In this review, we investigated an update on recent developments in light-field modulated operation in LIBS. It covered a brief description of LIBS, optical polarization, and beam shaping. Here, the optical polarization is divided into laser beam polarization and plasma polarization. In addition, the methodology and development of light-field modulated LIBS were summarized and discussed. Finally, the existing problems with light-field modulated LIBS were presented, along with some of their own insights and the future direction of their development. This review will provide a guideline for LIBS researchers with basic knowledge, which is very useful in the signal optimization of LIBS research and applications. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown spectroscopy (LIBS) is a spectroscopic analytic technique with great application potential because of its unique advantages for online/in-situ detection. However, due to the spatially inhomogeneity and drastically temporal varying nature of its emission source, the laser-induced plasma, it is difficult to find or hard to generate an appropriate spatiotemporal window for high repeatable signal collection with lower matrix effects. The quantification results of traditional physical principle based calibration model are unsatisfactory since these models were not able to compensate for complicate matrix effects as well as signal fluctuation. Machine learning is an emerging approach, which can intelligently correlated the complex LIBS spectral data with its qualitative or/and quantitative composition by establishing multivariate regression models with greater potential to reduce the impacts of signal fluctuation and matrix effects, therefore achieving relatively better qualitative and quantitative performance. In this review, the progress of machine learning application in LIBS is summarized from two main aspects: i) Pre-processing data for machine learning model, including spectral selection, variable reconstruction, and denoising to improve qualitative/quantitative performance; ii) Machine learning methods for better quantification performance with reduction of the impact of matrix effect as well as LIBS spectra fluctuations. The review also points out the issues that researchers need to address in their future research on improving the performance of LIBS analysis using machine learning algorithms, such as restrictions on training data, the disconnect between physical principles and algorithms, the low generalization ability and massive data processing ability of the model. [ABSTRACT FROM AUTHOR]

Laser-induced breakdown and subsequent plasma are produced in ambient air in the proximity of an aqueous surface using a Nd:YAG Q-switched laser at 1064 nm with a pulse width of 9 ns and a delivered focused input energy of 170 mJ. The distance between the focal point of a 10 cm convex lens and the aqueous surface is 4 mm with laser propagation perpendicular to the surface. Using an intensified CCD camera attached to a 1-m spectrometer, spatial and wavelength-resolved plasma emission data are obtained for delay times after breakdown ranging from 50 ns to 10 μs with a gate window typically 5 ns. Plasma electron density is determined by applying Lorentzian fitting and FWHM extraction to three Stark-broadened spectral lines: N II 3P-3Do multiplet (593.85 nm), Hα (656.27 nm), and the Na D doublet (589.00 and 589.59 nm). One-dimensional spatially resolved measurements of the total emission intensity and electron density are obtained by binning the camera image along the laser axis in intervals of 250 μm and are reported as a function of time from 50 ns to 10 μs. Two plasmas are ignited from a single laser pulse; one from laser breakdown at the water surface and the other a few nanoseconds later from laser-induced air breakdown at the focal point of 4 mm above the water surface. Comparisons between the evolution of the air plasma near and far from the water surface are presented along with data for the water surface plasma itself. [ABSTRACT FROM AUTHOR]

Temperature plays a crucial role in influencing the mechanical properties of materials. Accurately measuring the temperature of devices is essential for understanding the evolution of their mechanical properties under stress and evaluating their health and lifespan. However, traditional methods encounter challenges in measuring transient temperatures and lack sufficient time-resolution capability, particularly when it comes to the rapid temperature changes at the solder interface during the switching process of power devices. In this paper, based on the close correlation between the intensities of the characteristic spectral lines of the laser-induced elements and the temperatures, a method of measuring the surface temperatures with the time-resolved capability of the order of microsecond is proposed, and a quantitative relationship between the surface temperatures of the sample and the spectral characteristics is established. The findings demonstrate that an increase in the surface temperature of the material results in enhanced intensity and signal-to-noise ratio of laser-induced plasma spectra. This enhancement is influenced by the spectral acquisition delay and gate width. To establish a quantitative relationship between surface temperature and spectral properties, back propagation-artificial neural network (BP-ANN) and partial least squares (PLS) are employed for fitting and calibration. The fitted models can achieve linear correlation coefficient indexes exceeding 0.99. Notably, the BP-ANN fitted model exhibites a small fitting bias, with a root mean squared error (RMSE) of 2.582 and a correctness rate of 98.3%. The method provides an effective means for transient temperature measurement of objects and gives a strong support for the assessment of the health status of the soldering interface of power devices.