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Discrimination of wood species using laser-induced breakdown spectroscopy and near-infrared reflectance spectroscopy
摘要： A new method is proposed for the discrimination of wood species by combining near-infrared reflectance spectroscopy (NIRS) and laser-induced breakdown spectroscopy (LIBS) and using chemometrics for data analysis. The method was applied to the analysis of 42 samples from six different species: Amburana cearensis, Copaifera lucens, Phyllocarpus riedelii, Cariniana legalis, Bowdichia virgilioides, and Aspidosperma pyricollum. The spectra from both techniques were merged on a single data matrix and pretreated by standard normal variate (SNV) and Savitzky– Golay first derivative with smoothing. Principal component analysis was applied to the exploratory data analysis and showed a clear formation of sample groups according to the wood species only when the data from both analytical techniques and the data pretreatment were used. Sample discrimination using partial least squares discriminant analysis was proved possible, but with an average misclassification of about 10%. Sample grouping and discrimination were shown to be probably related to different concentrations of iron, copper, zinc, and/or sodium (affecting the LIBS spectra) and lignin, water, cellulose, and/or hemicellulose (affecting the NIRS spectra).
关键词： wood species discrimination,laser-induced breakdown spectroscopy,near-infrared reflectance spectroscopy,chemometrics
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
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Simultaneous quantitative analysis of four metal elements in oily sludge by laser induced breakdown spectroscopy coupled with wavelet transform-random forest (WT-RF)
摘要： Determination of toxic metal elements in oily sludge is meaningful to treatment, migration, improvement, monitoring, and repair of oily sludge, and an accurate and rapid analytical technology is urgent necessary to quantitative detect the toxic metal elements in oily sludge. In this study, a novel method based on laser-induced breakdown spectroscopy (LIBS) technique coupled with wavelet transform-random forest (WT-RF) was proposed to perform quantitative analysis of four toxic metal elements (Cu, Zn, Cr and Ni) in 16 oily sludge samples. In order to facilitate LIBS measurement, the 16 initial oily sludge samples with a water-oil mixed state were subjected to a drying treatment at 150 °C for 5 h, and then ground and passed through a 100 mesh to sift. The 16 oily sludge samples were sliced and collected LIBS spectra, and 11 samples were selected as calibration sets, and rest samples were set as test sets. The raw spectra were first preprocessed by wavelet transform (WT) method, and then the input variables for RF calibration model were selected and optimized based on variable importance. Finally, the WT-RF model with the optimal input variables was constructed to quantitative analysis four toxic metal elements concentration in the oily sludge. The predictive performance of WT-RF model was compared with the RF, partial least squares (PLS) and WT-PLS models. The results indicates that WT-RF model shows a better predictive ability than the other three models for prediction of potential toxic metal concentration in oily sludge, and the best determination coefficient (R2) value of four elements (Cu, Zn, Cr and Ni) were 0.9756, 0.9758, 0.9772, 0.9768, the root mean square error (RMSE) were 0.0358%, 0.0365%, 0.0446% and 0.0344%, and the relative standard deviation (RSD) were 0.0908, 0.0929, 0.0797 and 0.0628. Therefore, LIBS technique combined with WT-RF method is a promising method for the rapid prediction of the toxic metal elements in oily sludge.
关键词： Oily sludge,Laser-induced breakdown spectroscopy,Quantification,Random forest
更新于2025-09-11 14:15:04
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Laser-induced breakdown spectroscopy characterization of tree rings from the Popocatépetl volcano area, Mexico
摘要： Laser-induced breakdown spectroscopy (LIBS) was used to monitor macro- and micro-nutrients in pine trees exposed to two mayor activity periods of the Popocatépetl volcano in Mexico. Due to the high spatial resolution achieved with LIBS, a separate analysis of earlywood and latewood was performed. An increased concentration of potassium was found in earlywood, while calcium and sodium decreased. Besides, it was observed a similar temporal behavior for elements belonging to the same chemical group. The alkali earth metals Ca, Mg and Sr showed decreasing trends through the investigated years while alkali metals Na and K remain nearly constant. LIBS was able to detect signi?cant changes in Ca, Mg, Na and Sr intensities coincident with the 1919 Popocatépetl's eruptive period and after the volcanic activity starting at the end of 1999. Temporal evolution of the emission intensities is in agreement with the elemental composition obtained with inductively coupled plasma optical emission spectrometry.
关键词： Dendrochemistry,Laser-induced breakdown spectroscopy,Tree rings,Popocatépetl volcano
更新于2025-09-11 14:15:04
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Investigation on the dynamic characteristics of LIBS for heavy metal Mn in liquid matrix
摘要： Laser-induced breakdown spectroscopy in composition analysis of materials has many advantages over other analytical methods.Based on our Laser Induced Breakdown Spectroscopy (LIBS) survey system of heavy metals in the mixed solution and the optimum experimental parameters, we measured the integrated intensities of partial spectral lines of Mn when the ICCD gate delay time and the sample ?ow rate were ranged from 500ns to 2500ns, 35ml/min to 55ml/min respectively. With increasing the time delay, the electron temperature of the plasma decreases gradually, the electron density decreases ?rstly,then the change amplitude tends to be ?at.As the ?ow rate continue increasing,the electron temperature of plasma increases ?rstly, then the change tends to be ?at, the electron density increase gradually.The element particle density ratio of Mn at ?rst ionization state to ground state and Mn at ?rst ionization state are also obtained respectively. Finally, by comparing the experimental value of spectral line intensity ratio of Mn with the calculated value, the nonexistent conditions of local thermal equilibrium and self-absorption of laser plasma are veri?ed.It provides the suppuration for forward quantitative analysis of the trace heavy metal elements in liquid matrix.
关键词： Liquid matrix,Laser induced breakdown spectroscopy,Elements particle density ratio,Electron temperature,Electron density
更新于2025-09-09 09:28:46