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Progress in Research and Application of Micro-Laser-Induced Breakdown Spectroscopy
摘要： The technique of micro-laser-induced breakdown spectroscopy (μLIBS) usually refers to analyzing the surface of the sample using a compact focused laser beam in the optical microscope range. Compared to conventional laser-induced breakdown spectroscopy (LIBS), it can provide more abundant form, structure, and content information on a smaller, less sample condition. Hence, the application field is very wide. In this paper, the basic status of μLIBS in the selection of laser source and the structure of optical path system is introduced, and its application in metal, semiconductor, animal and plant fields is reviewed. The existing problems and potential development direction is pointed out.
关键词： Segregation,Ablation crater,Laser-induced breakdown spectroscopy,Review,Microanalysis
更新于2025-09-19 17:13:59
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Copper particle contamination detection of oil-immersed transformer using laser-induced breakdown spectroscopy
摘要： The deterioration of transformer oil caused by particle contamination, especially copper particle, seriously affects the safe operation of oil-immersed transformers. Therefore, it is very important for the detection of metal particles in transformer oil. A new method based on laser-induced breakdown spectroscopy (LIBS) was first applied in the transformer oil diagnosis field. By screening out effective spots, the correlation between Cu particle concentration and LIBS signal was obtained after testing a set of oil samples with concentration range from 0.54 to 12.4 μg/g; the calibration curves of Cu I 324.75 nm / CN 358.6 nm and Cu I 327.39 nm /CN 358.6 nm were therefore established. The results shown high linearity, and the determination coefficient R2 of the two calibration curves in range from 0.54 to 3.1 μg/g were superior to 0.99. The limit of detection (LOD) inferred from Cu I 324.75 nm /CN 358.6 nm fitting curve was 0.77 μg/g and met the critical value specified by industry standards. Due to its flexibility, it can be used as a new-type of particle concentration detection method for transformer oil.
关键词： copper particle,filter paper substrate,transformer oil,laser-induced breakdown spectroscopy
更新于2025-09-19 17:13:59
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Chlorine and sulfur determination in water using indirect laser-induced breakdown spectroscopy
摘要： The detection sensitivity of chlorine (Cl) and sulfur (S) elements is poor using direct laser-induced breakdown spectroscopy (LIBS) because of the high ionization energy of Cl and S. Therefore, a new technique, namely indirect laser-induced breakdown spectroscopy (ID-LIBS), was proposed to improve the detection sensitivity of Cl and S elements. The method detected Cl in water by indirectly detecting the excess silver (Ag) after the precipitation reaction of Ag and chloride. Similarly, the method indirectly detected S in water by detecting the excess barium (Ba) after the precipitation reaction of Ba and sulfate, due to Ag and Ba with low ionization energy and easy excitation. The lines of Ag I 546.5 nm and Ba I 553.5 nm were detected. The R2 values of 0.999 and 0.997 were obtained for Cl and S, respectively. The limit of quantitation (LoQ) was 2 mg/L for Cl and 5 mg/L for S. The detection sensitivity was improved by about three orders of magnitude compared to using Cl I 822.17 nm and S I 921.28 nm. The results showed that the technique of indirect LIBS can achieve the sensitive detection of Cl and S in water indicating that the technique has tremendous potential for element analysis of water.
关键词： Indirect LIBS,Water analysis,Laser-induced breakdown spectroscopy,Determination
更新于2025-09-19 17:13:59
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A singularity free and derivative free approach for Abel integral equation in analyzing the laser-induced breakdown spectroscopy
摘要： In order to make a detailed analysis of the laser-induced breakdown spectroscopy (LIBS), we present a new approach which has advantages of singularity free and derivative free for solving the Abel integral equation. After presenting the model describing the LIBS, a collocation method is applied and two main steps are introduced. First, the Abel integral equation is transformed to a singularity free and derivative free integral equation. Then, by expanding the solution of the integral equation to a polynomial of degree n, the solution can be approximated by a linear system established by the collocation method. Our approach is suitable for dealing with LIBS problem for any form of the measured intensity. In particular, the method is insensitive to the noisy intensity data. A convergence analysis is also given to show the validity of the method and numerical examples are provided to show its efficiency and accuracy.
关键词： spectrum,laser-induced breakdown spectroscopy (LIBS),Abel integral equation,plasma
更新于2025-09-19 17:13:59
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Laser-Induced Breakdown Spectroscopy and Principal Component Analysis for Classification of Spectra from Gold-Bearing Ores
摘要： Laser-induced breakdown spectroscopy (LIBS) and principal component analysis (PCA) were applied to the classification of LIBS spectra from gold ores prepared as pressed pellets from pulverized bulk samples. Obtained for each sample were 5000 single-shot LIBS spectra. Although the gold concentrations in the samples were as high as 7.7 μg/g, Au emission lines were not observed in most single-shot LIBS spectra, rendering infeasible the application of the usual ensemble-averaging approach for spectral processing. Instead, a PCA approach was utilized to analyze the collection of single-shot LIBS spectra. Two spectral ranges of 21 nm and 0.15 nm wide were considered, and LIBS variables (i.e., wavelengths) reduced to no more than three principal components. Single-shot spectra containing Au emission lines (positive spectra) were discriminated by PCA from those without the spectral feature (negative spectra) in a spectral range of less than 1 nm wide around the Au(I) 267.59 nm emission line. Assuming a discrete gold distribution at very low concentration, LIBS sampling of gold particles seemed unlikely, therefore, positive spectra were considered as data outliers. Detection of data outliers was possible using two PCA statistical parameters, i.e., sample residual and Mahalanobis distance. Results from such a classification were compared with a standard database created with positive spectra identified with a filtering algorithm that rejected spectra with an Au intensity below the smallest detectable analytical LIBS signal (i.e., below the LIBS limit of detection). The PCA approach successfully identified 100% of the data outliers when compared with the standard database. False identifications in the multivariate approach were attributed to variations in shot-to-shot intensity and the presence of interfering emission lines.
关键词： gold ores analysis,Laser-induced breakdown spectroscopy,PCA,data outliers,principal component analysis,LIBS
更新于2025-09-19 17:13:59
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EXPRESS: Evaluation of a Thermoelectric Cooler as a Sample Pre-Treatment Method for Laser Induced Breakdown Spectroscopy (LIBS) Analysis of Liquid Samples
摘要： In this study, the performance of a thermoelectric cooler (TEC) as a simple and easy-to-assemble freezing instrument has been evaluated. Experiments were carried out using samples with different viscosity ranging from 44.07 to 16,965.80 mPas. The analysis on sodium component of the samples by direct laser irradiation of frozen samples showed emission enhancement and higher signal-to-noise ratio (SNR) compared to that of liquids. This work also focused on using chemometrics methods such as principal component analysis (PCA) to compare the PC score separation and clustering pattern between frozen and liquid samples. The PCA was constructed by dividing the samples into two different categories: (i) type (paste, cream, gel and oil); and (ii) viscosity (more than and less than 10000 mPas). The frozen samples showed a more established separation and clustering compared to that acquired from the liquid samples. However, poorer clustering pattern of some frozen samples could be due to the heat transfer during laser–sample interaction inducing surface melting and splashing. The average LIBS spectra were taken at as many different surface areas as possible to ensure the sample surface always maintain similar freezing temperature. This work showed that the TEC pre-treatment method had improved the LIBS measurement of the liquid samples.
关键词： viscosity,liquid sample,LIBS,Laser induced breakdown spectroscopy,thermoelectric cooler
更新于2025-09-19 17:13:59
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Laser-induced breakdown spectroscopy as a tool for homogeneity measurements in medicine tablets
摘要： In this work, we have used laser-induced breakdown spectroscopy (LIBS) in the analysis of commercial tablets. The samples were mainly composed of dipyrone, an analgesic and fever reliever consumed worldwide. At first, the physical parameters, temperature and electronic density of the plasma were calculated throughout the Boltzmann plot and Saha equation respectively, and the McWhirter criterion was achieved, which allows us to assert that the minimum criterion for local thermodynamic equilibrium is presented in the plasma generated. After that, the tablets’ homogeneity was assessed using the whole LIBS spectra combined to correlation statistic methods, such as principal components analysis (PCA) and hyperspectral images. The results show high homogeneity, R > 0.996, at the surface and some heterogeneity in the bulk. LIBS was also applied for major active pharmaceutical ingredients C, Na and Mg identification.
关键词： dipyrone tablets,homogeneity,laser-induced breakdown spectroscopy (LIBS)
更新于2025-09-19 17:13:59
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Improved measurement on quantitative analysis of coal properties using laser induced breakdown spectroscopy
摘要： It is of great significance to realize the rapid or online analysis of coal properties for combustion optimization of thermal power plants. In this work, a set of calibration schemes based on laser-induced breakdown spectroscopy (LIBS) was determined to improve the measurement on quantitative analysis of coal properties, including proximate analysis (calorific value, ash, volatile content) and ultimate analysis (carbon and hydrogen). Firstly, different normalization methods (channel normalization and normalization with the whole spectral area) combined with two regression algorithms (partial least-squares regression [PLSR] and support vector regression [SVR]) were compared to initially select the appropriate calibration method for each indicator. Then, the influence of de-noising by the wavelet threshold de-noising (WTD) on quantitative analysis was further studied, thereby the final analysis schemes for each indicator were determined. The results showed that WTD coupled SVR can be well estimated calorific value and ash, the root mean square error of prediction (RMSEP) were 0.80 MJ kg?1 and 0.60%. Coupling WTD and PLSR performed best for the measurement of volatile content, the RMSEP was 0.76%. For the quantitative analysis of carbon and hydrogen, normalization with the whole spectral area combined with SVR can get better measurement results, the RMSEP of the measurements were 1.08% and 0.21%, respectively. The corresponding average standard deviation (RSD) for calorific value, ash, volatile content, carbon and hydrogen of validation sets were 0.26 MJ kg?1, 0.57%, 0.79%, 0.47% and 0.08%, respectively. The results demonstrated that the selection of appropriate spectral pre-processing coupled with calibration strategies for each indicator can effectively improve the accuracy and precision of the measurement on coal properties.
关键词： partial least-squares regression (PLSR),quantitative analysis,normalization,Laser-induced breakdown spectroscopy (LIBS),coal properties,support vector regression (SVR),wavelet threshold de-noising (WTD)
更新于2025-09-19 17:13:59
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Diagnostics of laser induced plasmas at late delay times
摘要： The study of the diagnostics of plasmas produced by laser is not always possible without enough of data, usually a precise record of several lines meeting certain spectroscopic conditions is needed. In this work, a method of diagnosing plasmas was implemented in sufficiently late postbreakdown times, where it is no longer possible to apply known methods (e.g. Boltzmann plot for the estimation of kT). Through an iterative algorithm that uses the parameters obtained by traditional methods at early times (LIBS typical delay time), and a minimum number of lines visible in the later times. Using the late times that are typical to the plasma’s final life stage, an evolution of the temperature and electronic density of the plasma is studied. The LTE condition was also verified by McWhirter's criterion.
关键词： temperature,Laser Induced Breakdown Spectroscopy,density electronic,Plasma diagnostic,molecular emission.
更新于2025-09-19 17:13:59
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Express: Time-Gated Single-Shot Picosecond Laser-Induced Breakdown Spectroscopy (ps-LIBS) for Equivalence-Ratio Measurements
摘要： Time-gated picosecond laser-induced breakdown spectroscopy (ps-LIBS) for the determination of local equivalence ratios in atmospheric-pressure adiabatic methane–air flames is demonstrated. Traditional LIBS for equivalence-ratio measurements employ nanosecond (ns)-laser pulses, which generate excessive amounts of continuum, reducing measurement accuracy and precision. Shorter pulse durations reduce the continuum emission by limiting avalanche ionization. Furthermore, by contrast the use of femtosecond lasers, plasma emission via picosecond-laser excitation has high signal-to-noise ratio (S/N), allowing single-shot measurements suitable for equivalence-ratio determination in turbulent reacting flows. We carried out an analysis of the dependence of the plasma emission ratio Hα (656 nm)/NII (568 nm) on laser energy and time-delay for optimization of S/N and minimization of measurement uncertainties in the equivalence ratios. Our finding shows that higher laser energy and shorter time delay reduces measurement uncertainty while maintaining high S/N. In addition to atmospheric-pressure flame studies, we also examine the stability of the ps-LIBS signal in a high-pressure nitrogen cell. The results indicate that the plasma emission and spatial position could be stable, shot-to-shot, at elevated pressure (up to 40 bar) using a lower excitation energy. Our work shows the potential of using ps-duration pulses to improve LIBS-based equivalence-ratio measurements, both in atmospheric and high-pressure combustion environments.
关键词： time-resolved spectroscopy,combustion diagnostics,Laser-induced breakdown spectroscopy,picosecond phenomena,LIBS
更新于2025-09-19 17:13:59