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Determination of copper-based mineral species by laser induced breakdown spectroscopy and chemometric methods
摘要： The direct identification of mineral species in raw rocks was performed using laser induced breakdown spectroscopy (LIBS). A total of 162 sulfide rocks with mineralogical relevance in the copper industry were analyzed. These contained bornite (Cu5FeS4), chalcocite (Cu2S), chalcopyrite (CuFeS2), covellite (CuS), enargite (Cu3AsS4), molybdenite (MoS2), and pyrite (FeS2). The samples were collected from different mining locations to account for sample variability. Unsupervised multivariate methods like principal component analysis (PCA) and dendrogram analysis were explored, while supervised pattern recognition techniques, such as soft independent modelling of class analogy (SIMCA), partial least squares discriminant analysis (PLS-DA), K-nearest neighbor (KNN), decision tree analysis and artificial neural networks (ANNs) were compared. The sensitivity test performed on the LIBS data shows that the models KNN, SIMCA, PLS-DA and ANN achieve an average classification accuracy of 96.2, 98.1, 90.6 and 100%, respectively. In contrast, the robustness test of the models SIMCA and PLS-DA yields accuracies of 97.7 and 98.8%, respectively. The correct identification of very similar species in terms of their elemental composition such as bornite/chalcopyrite and chalcocite/covellite is also achieved.
关键词： mineral species,chemometrics,Laser induced breakdown spectroscopy,LIBS,multivariate methods,copper industry,pattern recognition
更新于2025-09-12 10:27:22
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Understanding the laser-induced aerosol ablation of sub-micron liquid particles <i>via</i> size-resolved spectral and image analyses
摘要： Laser-induced breakdown spectroscopy of aerosols is associated with large signal variability and lower sampling rates. In this study, aerosol ablation and signal variability associated with aerosol size were studied by size-resolved spectral and image analyses of submicron sized particles using a high-density stream of monodisperse liquid aerosols. The rise in the particle size from 0.16 mm to 0.96 mm for a similar aerosol mass concentration showed a size-dependent intensity increase. The initial increase in the analyte emission was due to the enhanced analyte concentration inside the plasma volume, whereas for larger aerosols, the stronger ablation of the larger liquid particles resulted in elevated emission intensity. The electron number density increased from 1.6 (cid:1) 1017 cm(cid:3)3 to 2.6 (cid:1) 1017 cm(cid:3)3 with an increase in the particle size; however, the temporal delay of number density was faster for the larger particles due to higher plasma–ambience interaction. The analyte signal variation reduced to 3%, calculated using ensemble averaging, for particles larger than 0.5 mm. Plasma image analysis showed that the signal variation stemmed from inhomogeneity in the initial breakdown process and grew with the increasing delay. The variation in the plasma image area increased from 8% to 16% for 0.16 mm particles and 12% to 28% for 0.96 mm particles at the respective delays of 0 and 3 ms. Thus, two di?erent sources of signal variability were determined. For smaller particles, the major source of variation was the variable sample scarcity inside the plasma, whereas for larger particles, plasma variation contributed more to the analyte signal variability from the beginning.
关键词： Laser-induced breakdown spectroscopy,plasma,submicron particles,aerosols,signal variability
更新于2025-09-12 10:27:22
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On the application of bootstrapping to laser-induced breakdown spectroscopy data
摘要： The analysis of laser-induced breakdown spectroscopy (LIBS) data heavily relies on statistical approaches. Recently, the application of another well-established statistical tool has started gaining prominence in LIBS analysis: bootstrapping. In the present work, we investigate the impact of bootstrapping on LIBS data collected by various data acquisition strategies and provide some insights into the application of this powerful statistical tool. We show that bootstrapping primarily affects the standard deviation of the recorded spectra, while barely affecting the mean values. This limits the applicability of bootstrapping to specific cases which are briefly discussed.
关键词： statistical analysis,laser-induced breakdown spectroscopy,bootstrapping,LIBS,data acquisition strategies
更新于2025-09-12 10:27:22
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Classification of Ceramic Tableware by Laser Induced Breakdown Spectroscopy and Chemometrics
摘要： Ceramics manufactured in Brazil and in other countries were analyzed by laser induced breakdown spectroscopy (LIBS). The LIBS spectra were employed to identify the origin of the tableware as produced in Brazil or abroad using soft independent modeling of class analogy (SIMCA) and linear discriminant analysis (LDA). Three sets of spectral variables were evaluated aiming at discrimination of the ceramics: the entire LIBS spectrum, a set of selected spectral ranges, and the maximum of emission intensity of the elements Al, Ca, Mg, Si, Na and Ti. The results for the three sets of variables show good performance, achieving correct classification from 88.6 to 94.3%, and 86.7 to 100% for the external training and test, respectively.
关键词： laser induced breakdown spectroscopy (LIBS),chemometrics,soft independent modeling of class analogy (SIMCA),linear discriminant analysis (LDA),Ceramic tableware classification
更新于2025-09-12 10:27:22
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Feasibility study of gross calorific value, carbon content, volatile matter content and ash content of solid biomass fuel using laser-induced breakdown spectroscopy
摘要： Rapid determination of the solid biomass fuel properties is essential for optimizing the combustion process of biomass. In this work, a feasibility study on using laser-induced breakdown spectroscopy (LIBS) in conjunction with partial least squares (PLS) for simultaneous measurement of gross calori?c value, carbon content, volatile matter content and ash content was carried out for 66 wood pellet samples. The best quantitative analysis results were obtained with the PLS model based on spectra that combined baseline correction with Z-score standardization. The root mean square error of prediction (RMSEP) of the gross calori?c value, carbon content, volatile matter content and ash content were 0.33 MJ/kg, 0.65%, 1.11% and 0.38% respectively, while the average standard deviation (ASD) were 0.08 MJ/kg, 0.15%, 0.43% and 0.16% respectively.
关键词： Gross calori?c value,Carbon content,Solid biomass fuel,Ash content,Volatile matter,Laser-induced breakdown spectroscopy (LIBS)
更新于2025-09-12 10:27:22
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Laser based analysis of transition metal boride thin films using liquid standards
摘要： In this work the use of two laser assisted direct solid sampling methods, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), and laser induced breakdown spectroscopy (LIBS) for the determination of the stoichiometry of novel diboride based materials is reported. To overcome the need for certified reference materials or matrix matched standards, which were usually required for quantitative investigations with LA-ICP-MS or LIBS, in this work liquid standards are employed. For LA-ICP-MS the concept of self-aliquoting micro-grooves and for LIBS conventional dried droplets were used. As a model for application of the developed analytical procedures the ternary system W1-xTaxB2-z was used. Fabrication of W1-xTaxB2-z thin films with varying stoichiometry was performed via magnetron sputtering. Reference compositions were obtained by liquid digestion of the samples and subsequent ICP-OES measurement. Both laser-assisted methods enabled fast and spatially resolved measurements, although the LA-ICP-MS method generally yielded more accurate results. It was shown that the method can easily be adapted for the stoichiometry determination of systems with different elemental composition.
关键词： laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS),liquid calibration,Laser-induced breakdown spectroscopy (LIBS),borides,thin films
更新于2025-09-11 14:15:04
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Influence of sample temperature on the laser-induced breakdown spectroscopy of molybdenum-tungsten alloy
摘要： The analytical capabilities of laser-induced breakdown spectroscopy (LIBS) for in-situ elemental analysis of nuclear materials at elevated temperatures were estimated. A certified molybdenum-tungsten alloy (Mo 70 wt.% and W 30 wt.%) was chosen as a replacement for the high Z impurities deposited on plasma facing components (PFCs) in tokamak. The influence of sample temperature (Ts) on the optical emission of laser-induced molybdenum-tungsten plasma was investigated with nanosecond infrared (1064 nm) laser pulse. LIBS experiments were carried out in a wide temperature range from 20 to 410 ℃. Surface morphology and depth profiling of the ablated crater for the different temperature conditions were performed. A noticeable dependence of signal emission intensity on Ts has been found. An increase in Ts leads to an increase in the spectral line emissions. In the laser ablation process, the ablation rate, plasma temperature and electron density increase significantly with Ts. In addition, the reflectivity of the alloy surface drops dramatically once oxidation occurs. The decrease of surface reflectivity leads to a greater laser energy coupled to the target and a higher LIBS signals. These results will help improve the LIBS quantitative analysis of high Z impurities in tokamak device.
关键词： LIBS,plasma emission,molybdenum-tungsten alloy,sample temperature,Laser-induced breakdown spectroscopy
更新于2025-09-11 14:15:04
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Application of Laser-Induced Breakdown Spectroscopy to Real-Time Elemental Monitoring of Iron and Steel Making Processes
摘要： Steel industry is the irreplaceable foundation in heavy industries, which have been developed and improved. The advanced monitoring methods including detection and control technology contribute to its development of iron and steel manufacturing processes. With the development of the measurement techniques, laser-induced breakdown spectroscopy (LIBS) has been developed and applied for many industrial fields of elemental monitoring due to the non-contact, fast response, high sensitivity, real-time and multi-dimensional features. The elemental measurement methods in steel industry were summarized and compared in this paper. LIBS measurements of raw material, smelting processes, products, slag, etc. have been reviewed in detail. Challenges for the future of LIBS application in iron and steel making processes have also been discussed. LIBS has a high potential to improve the detection ability of elemental analyses and to promote the on-line monitoring characteristics in iron and steel making plants.
关键词： real-time,elemental monitoring,iron and steel making processes,laser-induced breakdown spectroscopy
更新于2025-09-11 14:15:04
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Vacuum ultraviolet laser induced breakdown spectroscopy for detecting sulphur in thermally aged transformer insulation material
摘要： Spatially resolved and temporally integrated vacuum ultraviolet laser induced breakdown spectroscopy (VUV LIBS) was used for contaminant analysis in thermally aged oil impregnated pressboard (OIP) insulation material from high voltage transformers. The signature of copper sulphide contamination was obtained through detection of Cu and S emission lines. The plasma emission also contained highly ionized Oxygen and Carbon emission lines. S emissions were found to be strong in the VUV region in contrast to the UV-VIS region. The concentration of sulphur was found to increase with the duration of ageing of the OIP material.
关键词： copper sulphide,laser induced breakdown spectroscopy,Oil impregnated pressboard,vacuum ultraviolet,VUV,LIBS
更新于2025-09-11 14:15:04
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Spatially resolved polymer classification using laser induced breakdown spectroscopy (LIBS) and multivariate statistics
摘要： Synthetic polymers and plastics have become one of the most important materials in our modern world and everyday life with all kinds of applications mainly due to their wide range of excellent and tuneable properties. Several novel materials consisting of multiple different synthetic polymers or composite materials like natural-fiber-reinforced polymer composites have already been reported in literature. Additionally, materials consisting of multiple synthetic polymers already found their way in our daily lives (e.g. double-sided adhesive tape). With emerging materials consisting of different structured synthetic polymers, the need for analytical methods characterizing these kinds of sample also arises. Conventionally, analytical techniques such as FT-IR or Raman spectroscopy are used for polymer classification. Although, these techniques offer laterally resolved investigations they lack the possibility of analyzing depth profiles. In this work, we present laser induced breakdown spectroscopy (LIBS) as a novel and powerful analytical method for spatially resolved polymer classification. As a feasibility study, two exemplary structured synthetic polymer samples (2D structured and multilayer system) have been analyzed using LIBS and the spatial distribution of 5 different synthetic polymers, namely acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polyethylene (PE), polyacrylate (PAK) and polyvinylchloride (PVC) have been successfully classified using multivariate statistical approaches (principal component analysis (PCA) and k-means clustering). Spatially resolved classification results were validated by comparing the obtained distribution of the 2D structured sample to the elemental distribution of a contamination present in one of the synthetic polymers. Classification of the polymeric multilayer system was validated by comparing the obtained results to a microscopic cross-section. It was shown that LIBS cannot only be used to investigate 2D structured polymer samples but also for direct analysis of depth profiles. Besides synthetic polymer classification, LIBS provides simultaneous analysis of the elemental composition of the sample, which increases the total amount of information accessible with only one measurement.
关键词： Polymer classification,Depth profiling,Spatially resolved analysis,Multivariate statistics,Laser induced breakdown spectroscopy (LIBS)
更新于2025-09-11 14:15:04