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Influence of target temperature on femtosecond laser-ablated brass plasma spectroscopy
摘要： femtosecond LIBS, a high-temperature and low-density plasma with high emission can be generated by increasing the target temperature. The results showed that, compared with the experimental condition of 25 oC, the spectral intensity of the femtosecond LIP was enhanced with more temperature target. In addition, the electron temperature and density were calculated by Boltzmann equation and Stark broadening, indicating that the changes in the electron temperature and density of femtosecond LIP with the increase of the target temperature were different from each other. By increasing the target temperature, the electron temperature increased while the electron density decreased. Therefore, in femtosecond LIBS, a high-temperature and low-density plasma with high emission can be generated by increasing the target temperature. The increase in the target temperature can improve the resolution and sensitivity of femtosecond LIBS.
关键词： LIBS,femtosecond laser,emission enhancement,laser-induced breakdown spectroscopy,target temperature,time-resolved spectroscopy
更新于2025-09-16 10:30:52
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Laser-Induced Breakdown Spectroscopy Assisted by Machine Learning for Plastics/Polymers Identification
摘要： In the present work, Laser-Induced Breakdown Spectroscopy (LIBS) is used for the discrimination/identification of different plastic/polymeric samples having the same polymeric matrix but containing different additives (as e.g., fillers, flame retardants, etc.). For the classification of the different plastic samples, some machine learning algorithms were employed for the analysis of the LIBS spectroscopic data, such as the Principal Component Analysis (PCA) and the Linear Discriminant Analysis (LDA). The combination of LIBS technique with these machine learning algorithmic approaches, in particular the latter, provided excellent classification results, achieving identification accuracies as high as 100%. It seems that machine learning paves the way towards the application of LIBS technique for identification/discrimination issues of plastics and polymers and eventually of other classes of organic materials. Machine learning assisted LIBS can be a simple to use, efficient and powerful tool for sorting and recycling purposes.
关键词： laser-induced breakdown,polymers,LIBS,machine learning,identification of polymers,laser produced plasmas
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Laser-Induced Breakdown in Dielectrics: Strong Electron Superheating
摘要： Laser-induced breakdown hinders the operation of modern lasers, photonic elements and devices, and can be also employed as an important operational regime for high-intensity laser technology of new materials. In this report we generalize the two-temperature model of laser-matter interaction to simulate the regimes of laser-induced breakdown in dielectrics. This generalization allow us to associate the onset of breakdown with a sequence of the step-wise increase and decrease of the mean electron energy, (cid:2013)(cid:3032), and related evolution of the free electron density, (cid:1866)(cid:3032). The model set of the rate equations includes photo-ionization and recombination kinetics, radiation absorption, energy release and exchange effects defining the time evolution of (cid:2013)(cid:3032) to the band gap energy (cid:1831)(cid:3008), and critical energy of ionization, (cid:1831)(cid:3030)(cid:3045)(cid:124)1.5(cid:1831)(cid:3008). Additionally, our model includes an effect of a strong electron superheating, Δ(cid:2013)(cid:3032), above (cid:1831)(cid:3030)(cid:3045). Namely, in treating the onset of impact ionization by generated free electrons the related impact ionization rate, (cid:1875)(cid:3036)(cid:3040)(cid:3043) = (cid:2028)(cid:3035)(cid:2879)(cid:2869), is associated with the time of the electron heating to the critical energy, (cid:2028)(cid:3035) = (cid:1831)(cid:3030)(cid:3045)((cid:1856)(cid:2013)(cid:3032) (cid:1856)(cid:1872)? )(cid:2879)(cid:2869) ≈ 1 ((cid:2009)(cid:1835))(cid:2879)(cid:2869), where (cid:2009) = (cid:2026)(cid:3090) (cid:1831)(cid:3030)(cid:3045)? is the avalanch coefficient, (cid:2026)(cid:3090) is the related absorption cross-section of free electrons and I is the radiation intensity). However, when the neutral atoms start to deplet the impact ionization can be controlled by an additional collision time, (cid:2028)(cid:3030) = (cid:1856)(cid:3028)((cid:1865)(cid:3032) (cid:1831)(cid:3030)(cid:3045)? )(cid:3117)/(cid:3118)((cid:2869)(cid:2879)(cid:3041)(cid:3280) (cid:3041)(cid:3276)? )(cid:2870)(cid:3117)/(cid:3118) (where (cid:1856)(cid:3028) is the interatomic distance, (cid:1865)(cid:3032) is the electron mass and (cid:1866)(cid:3028) is the atomic density). That is, if (cid:1866)(cid:3032) ? (cid:1866)(cid:3028) and (cid:2028)(cid:3030) ? (cid:2028)(cid:3035) the impact ionization is controlled by (cid:2028)(cid:3035) and the ionizing impacts can occur at (cid:2013)(cid:3032) > (cid:1831)(cid:3030)(cid:3045)within the time (cid:2028)(cid:3030)(cid:124) 0.1 fs. However, when (cid:1866)(cid:3032) tends to (cid:1866)(cid:3028) by reaching the level of (cid:2013)(cid:3032) > (cid:1831)(cid:3030)(cid:3045) and seeking new neutral atoms the free electrons continue to experience the impacts with the ionized atoms and recombining electron-ion pairs. By making these interactions the free electrons can acquire an additional energy of Δ(cid:2013)(cid:3032) ≈ (cid:2028)(cid:3030) before producing the final ionizing impacts and loosing the energy of (cid:1831)(cid:3008).
关键词： electron superheating,impact ionization,two-temperature model,Laser-induced breakdown,dielectrics
更新于2025-09-16 10:30:52
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Feasibility Investigation for Online Elemental Monitoring of Iron and Steel Manufacturing Processes using Laser-Induced Breakdown Spectroscopy
摘要： The metallurgical industries are very important for social development. In order to improve the metallurgical techniques and quality of products, the real-time analysis and monitoring of iron and steel manufacturing processes are very significant. Laser-induced breakdown spectroscopy (LIBS) has been studied and applied for the contents measurement of iron and steel. In this paper, the remote open-path LIBS measurement was studied under different sample temperature, lens to target distance (LTD), sample angle conditions to clarify its online measurement features. The 3D profile measurement system of parallel laser beam fringes projection was also developed to measure the sample profile at different sample temperature. The measurement results demonstrated the robustness of remote open-path LIBS system and 3D profile measurement system. However, the correction is necessary to enhance the detection ability of LIBS online measurement. In order to improve the precision and accuracy of real-time elemental measurement, an innovative co-axial laser beam measurement system combining LIBS and 3D profile techniques is proposed to automatically adjust the focus unit and measure the sample components. The further study of this promising method will be developed for online application of iron and steel manufacturing processes.
关键词： remote measurement,laser-induced breakdown spectroscopy,3D profile,iron and steel manufacturing processes
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON BIOSCIENCES AND MEDICAL ENGINEERING (ICBME2019): Towards innovative research and cross-disciplinary collaborations - Bali, Indonesia (11–12 April 2019)] PROCEEDINGS OF THE 2ND INTERNATIONAL CONFERENCE ON BIOSCIENCES AND MEDICAL ENGINEERING (ICBME2019): Towards innovative research and cross-disciplinary collaborations - Laser-induced breakdown spectroscopy (LIBS) for printing ink analysis coupled with principle component analysis (PCA)
摘要： Laser-induced breakdown spectroscopy (LIBS) has been applied to perform elemental analysis of printing ink samples. Samples of black printing inks from three types of printers viz. inkjet, laser-jet, and photocopier (three different brands for each type) and one control sample (blank white A4 paper) were analysed under optimised conditions. Results revealed that the LIBS method when coupled with PCA was able to provide discriminative evidence on elemental differences among all the different printing inks. Considering its time and cost effectiveness as well as requiring only minute amount of sample with no sample pre-treatment steps, the combination of LIBS and PCA may prove useful for forensic questioned document practical caseworks.
关键词： forensic questioned document,Laser-induced breakdown spectroscopy,principle component analysis,PCA,printing ink analysis,LIBS
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Quantitative Analysis of Heavy Metal Components in Soil by Laser-Induced Breakdown Spectroscopy Based on Principal Component Analysis
摘要： The calibration curves of heavy metal elements Cd and Ni were established based on laser induced breakdown spectroscopy of standard soil and soil to be tested. The plasma excitation test was carried out on the soil by laser induced breakdown spectroscopy to obtain a plasma spectrum with a wavelength of 300-1000 nm. By comparing the characteristic peaks in the obtained spectrum with the National Institute of Standards and Technology database, it is found that the test samples contain heavy metal elements such as Cd, Cr, Cu, Hg, Ni and W, and the Cd and the measured standard soil. The main method analysis of the peak of Ni element is carried out, and the principal component regression model is established to obtain the calibration curve of Cd and Ni elements, and then the content of Cd and Ni elements in the soil to be tested is estimated. Based on the concentration of the national standard soil sample and the measured spectral intensity, the linear correlation coefficients between the predicted and actual values of the Cd and Ni element contents were established to be 1 and 0.99443. Compared with the commonly used methods, laser-induced breakdown spectroscopy can quickly detect samples to be tested, and sample pretreatment is simple and less damage to the sample.
关键词： Principal component analysis,Soil heavy metal pollution,Laser induced breakdown spectroscopy,Qualitative and quantitative analysis
更新于2025-09-16 10:30:52
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Spectral characteristics of underwater laser-induced breakdown spectroscopy at high pressure conditions
摘要： Laser-induced breakdown spectroscopy (LIBS) has been proven to be an attractive technique for the in-situ oceanic applications. However, when applying LIBS into deep-sea, the pressure effect caused by different ocean depth is inescapable and could have great influence on the LIBS signals. In this work, spectral characteristics of underwater LIBS were investigated as a function of pressure in the range of 0.1–45 MPa. A high-pressure chamber built in the laboratory was used to simulate the high-pressure environment of deep-sea. Optimal laser energy and detection delay were first determined under different pressure conditions and were shown to be independent on the external pressure. The increase in pressure has a significant impact both on the peak intensity and line broadening of the observed spectra. The peak intensity of Na, Li and K lines increases with the increasing pressure until a maximum intensity reached at 12.5 MPa. Above this value, the peak intensity decreases gradually up to 45 MPa. For Ca line, the maximum intensity was observed at 30 MPa. The line broadening keeps constant at low pressures from 0.1 to 10 MPa while it increases linearly at higher pressures, indicating a higher electron density caused by the compression effect of the high external pressure. We also compared the spectral data obtained from the high-pressure chamber and from the field sea trials, and the good consistency between the laboratory data and sea-trial data suggested the key role of pressure effect on underwater LIBS signals for the practical deep-sea applications.
关键词： high-pressure chamber,underwater laser-induced breakdown spectroscopy,deep-sea application,pressure effect,spectral characteristics
更新于2025-09-16 10:30:52
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A feature selection method combined with ridge regression and recursive feature elimination in quantitative analysis of laser induced breakdown spectroscopy
摘要： In the spectral analysis of laser-induced breakdown spectroscopy, abundant characteristic spectral lines and severe interference information exist simultaneously in the original spectral data. Here, a feature selection method called recursive feature elimination based on ridge regression (Ridge-RFE) for the original spectral data is recommended to make full use of the valid information of spectra. In the Ridge-RFE method, the absolute value of the ridge regression coefficient is used as a criterion to screen spectral characteristic, the feature with the absolute value of minimum weight in the input subset features was removed by recursive feature elimination (RFE), and the selected features were used as inputs of the partial least squares regression (PLS) model. The Ridge-RFE method based PLS model was used to measure the Fe, Si, Mg, Cu, Zn and Mn for 51 aluminum alloy samples, and the results showed that the root mean square error of prediction (RMSEP) decreased greatly compared to the PLS model with full spectrum as input. The overall results demonstrate that the Ridge-RFE method is more efficient to improve model generalization ability.
关键词： recursive feature elimination,laser-induced breakdown spectroscopy,quantitative analysis,ridge regression,feature selection
更新于2025-09-16 10:30:52
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Quantitative analysis of elemental depth on Wendelstein 7-X divertor baffle screws by picosecond laser-induced breakdown spectroscopy
摘要： Analysis of elemental distributions in plasma-facing components (PFCs) is vital for the study of material erosion, deposition, and fuel retention in Wendelstein 7-X (W7-X) stellarator operating in full 3D geometry. In this work, we report the results on the application of picosecond laser-induced breakdown spectroscopy (ps-LIBS) combined with laser-induced ablation quadrupole mass spectrometry (LIA-QMS) to quantitatively investigate the elemental depth distribution and fuel retention on the screws PFCs from the divertor ba?e of W7-X. Depth pro?les of H, C, Ti and Mo intensities on the screws with speci?c multilayer structures have been achieved by LIBS combined with LIA-QMS. A linear correlation approach has been applied for identifying the interface between the C layer and the Ti layer and shows that a laser ablation rate of (82.9 ± 0.9) nm/shot can be achieved on C layer thickness measurement by a laser energy density of 6.5 J/cm2. Moreover, quantitative H retention content on the surface of the screws with stellarator discharge plasma exposure is approximately 1.1 × 1021 atoms/m2 which is higher than approximately 3.5 × 1020 atoms/m2 on the surface of the new screw without plasma exposure. The studies well demonstrate the ability to determine elementary resolved layer thicknesses and H retention measurements by depth analysis of LIBS on PFCs exposed in W7-X.
关键词： Plasma wall interaction,Laser-induced breakdown spectroscopy,Fuel retention,Deposition layer
更新于2025-09-16 10:30:52
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Multi-elemental analysis of flour types and breads by using laser induced breakdown spectroscopy
摘要： Bread and flour are most commonly used products in human diet, which makes it susceptible to adulteration, mislabeling and addition of unpermitted amount of different flour types. The objective of this work was to evaluate the potential of employing laser induced breakdown spectroscopy to differentiate different flour types and quantify the white wheat flour addition to rye and oat flour and breads. In the principal component analysis, score plot represents pure flour types with 97.64% of the variance. In the calibration study, the measured coefficient of determination values was 0.989, 0.989, 0.992 and 0.991 for refined wheat flour: rye flour, refined wheat flour: oat flour, breads made with the blend of refined wheat: rye flour and the blend of refined wheat: oat flour, respectively. The limit of detection values were calculated as 3.82, 5.97, 4.59 and 4.92% for refined wheat flour: rye flour, refined wheat flour: oat flour, refined wheat: rye bread and refined wheat: oat bread, respectively.
关键词： Bread,Laser induced breakdown spectroscopy,Wheat flour,Partial least square
更新于2025-09-16 10:30:52