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Revealing the impact of laser-induced breakdown on a gas flow
摘要： Laser-induced breakdown spectroscopy (LIBS) is an optical, and thus non-contact, but not non-invasive, measurement technique. Investigating the impact of laser-induced breakdown on a gas flow, combined LIBS and particle image velocimetry (PIV) measurements are performed. In the considered laminar air flow, the induced velocity field disturbance has an extent of about 0.7 cm with magnitudes up to 0.9 m s?1. As a further result, the combination of LIBS with other measurement techniques or high-speed LIBS measurements are found to require a minimal time delay of about 500 μs in order to ensure influence of the preceding LIBS pulse on the considered gas flow of about 10 % relative velocity deviation. For a reduction to 0 % relative velocity deviation a time delay of about 20 ms is estimated for the investigated flow. Smaller time delays may occur in turbulent flows or flows with higher velocities.
关键词： laser-induced breakdown spectroscopy,Flow diagnostics,particle image velocimetry
更新于2025-09-19 17:13:59
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Improving the Detection Sensitivity for Laser-Induced Breakdown Spectroscopy: A Review
摘要： Laser-induced breakdown spectroscopy (LIBS) is fast, on-line, causes little sample damage, and can be applied in remote field locations. In recent years, LIBS has been widely used in many fields of scientific research for element detection. Further application of LIBS is limited by the strong matrix effect, poor repeatability, and relatively weak detection sensitivity. The detection sensitivity is an important factor and needs to be improved for LIBS detection of minor or trace elements in samples. A variety of methods have been developed to improve detection sensitivity of LIBS. In this invited review paper, we discuss improvements in the LIBS detection sensitivity achieved with physical enhancement methods, chemical enhancement methods, mathematical methods, and combinations of multiple methods. We discuss the enhancement mechanisms, sensitivity improvements, configurations, and effects of key factors for various methods. The advantages, disadvantages, and real-time capabilities of these methods are reviewed. Finally, new trends and future perspectives for LIBS as an efficient analytical tool are discussed.
关键词： mathematical method,physical enhancement,laser-induced breakdown spectroscopy,chemical enhancement,detection sensitivity
更新于2025-09-19 17:13:59
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EXPRESS: Signal Enhancement Evaluation of Laser Induced Breakdown Spectroscopy of Extracted Animal Fats Using a Principal Component Analysis Approach
摘要： In this work, principal component analysis (PCA) was utilized to analyze laser-induced breakdown spectroscopy (LIBS) signals of extracted chicken fat, lamb fat, beef fat, and lard froze using two different freezing methods. The frozen samples were ablated using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with a wavelength of 1064 nm, 170 mJ pulse energy, and 6 ns pulse duration to produce plasma on target surfaces. The samples were ablated using 30–60 shots of the laser beam at different spots. Stronger LIBS signals from extracted chicken fat and lamb fat were obtained with liquid nitrogen (LN2) method. However, LIBS signals obtained from the freezer freezing method were found to be stronger for extracted beef fat and lard. The PCA was then used to visualize the LIBS spectra of extracted animal fats into a score plot. Data points of each extracted animal fat were divided into three groups representing LIBS spectra collected at the early, middle and end part of the ablation process. The score plot revealed that the data points of the three groups of frozen extracted animal fats using the LN2 method were more closely clustered than those frozen in the freezer. Good discrimination with 97% of the variance was achieved between extracted the chicken fat, lamb fat, beef fat ,and lard using the LN2 method in the 3D score plot. LIBS signals of extracted animal fats produced from the LN2 method were found to be more stable than those from the freezer method.
关键词： Laser induced breakdown spectroscopy,LIBS,PCA,principal component analysis,liquid,animal fat,plasma
更新于2025-09-19 17:13:59
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Temporal Evolution of Polarization Resolved Laser-Induced Breakdown Spectroscopy of Cu
摘要： Polarization-resolved laser-induced breakdown spectroscopy based on a temporal investigation of polarized Cu plasma emission is presented by a gated detector with a width of 10 ns and a delay time range of 10 ns–2 μs. Polarization-resolved spectra show that the delay time plays a crucial role in plasma polarization for both continuum and discrete emissions. The polarization degree of continuum emission is shown to be stronger than the polarization degree of discrete emissions at delay times less than 500 ns, while this trend is inverse in a delay time range of 750 ns–1 μs. The mechanism for polarized continuum emission is proposed to have dynamic polarizability of a core, while the polarized discrete emission is driven by the interaction of the plasma with the surrounding environment. The latter may lead either to a deviation of plasma from local thermodynamic equilibrium or generation of self-magnetic fields.
关键词： Polarization-resolved laser-induced breakdown spectroscopy,Polarization,Laser-induced breakdown spectroscopy,Local temperature equilibrium,Self-generated magnetic field
更新于2025-09-16 10:30:52
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Multivariate determination of 10B isotopic ratio by laser-induced breakdown spectroscopy using multiple BO molecular emissions
摘要： Measurements of boron isotopic ratios have been investigated using LIBS, and combined LIBS and Molecular laser-induced fluorescence (MLIF). Mixtures of various ratios of research grade H3 11BO3 and H3 10BO3 in pellet form were interrogated with a Q-switched Nd:YAG laser operating at 532 nm. The resulting plasma was examined for their BO molecular bands in the 254–262 nm and 266–276 nm wavelength ranges. A minimum of three band heads of the β system B2Σ → X2Σ transitions were identified. The rovibronic isotopic shifts of the corresponding bands were measured and were conclusively compared to the literature. MLIF was applied to LIBS emission lines covering 253–271 nm to enhance some band heads, selectively. Both LIBS and LIBS-MLIF emissions were subject to multivariate statistical analysis to predict 10B isotopic ratios. Two PLS regression calibration models were examined to better examine the effects, sensitivity, accuracy of the laser-produced plasma excitation modalities based models through the figure of merit. For the full calibration set (21 samples), the root mean square error of cross-validation (RMSECV), the pseudo univariate LOD (LODpu) and the LOD interval ([LODmin, LODmax]) for 10B isotopes were improved from 1.61%, 4.81%, [2.64%, 3.49%] 10B isotopic ratio, respectively for LIBS to 0.98%, 2.40%, [2.19%, 2.81%] 10B isotopic ratio, respectively for LIBS-MLIF. However, using a random subset of the samples (14) as a calibration set and the rest as a test set, the root mean square error of prediction of 10B isotopic ratio in the test set improved from 2.95% to 1.16% 10B isotopic ratio, respectively for LIBS and LIBS-MLIF; and the LOD interval improved from [2.45%, 2.69%] to [1.88%, 2.12%] 10B isotopic ratio when calculated with cross-validated residual variance. Moreover, the prediction error of a test set improved from 2.95% for LIBS to 1.16% for LIBS-MLIF.
关键词： Molecular laser-induced fluorescence,LIBS-MLIF,Limit of detection interval,Laser-induced breakdown spectroscopy,Boron isotopes,Molecular band
更新于2025-09-16 10:30:52
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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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Influence of laser wavelength on self-absorption effect in laser-induced breakdown spectroscopy
摘要： Self-absorption effect seriously affects the accuracy of the quantitative analysis in laser-induced breakdown spectroscopy (LIBS), confining the further development of the technology. In this study, three laser wavelengths at ultraviolet (355 nm), visible light (532 nm), and infrared (1064 nm) were selected to study the influence of laser wavelength on self-absorption effect in LIBS. The effect of the laser wavelength the on spectral stability was also investigated. The results showed that when the wavelength was 1064 nm compared with the wavelength of 355 nm and 532 nm, the full widths at half maximum (FWHMs) of aluminum (Al) I 396.2 nm were reduced by 39% and 23%, the FWHM of potassium (K) I 766.5 nm were reduced by 58% and 22%. In addition, the laser wavelength was also closely related to the stability of the spectral intensity. In comparison with the laser wavelengths of 532 nm and 1064 nm, the best spectral repeatability occurred when the laser wavelength was 355 nm. The relative standard deviation (RSD) of the K I 766.5 nm was only 2.5%. The results indicate that laser wavelength affects the self-absorption effect and spectral stability of LIBS, which means selecting an appropriate laser wavelength can reduce self-absorption and improve stability.
关键词： Laser-induced Breakdown Spectroscopy,Self-absorption,Laser wavelength,Relative standard deviation
更新于2025-09-16 10:30:52
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Detection of heavy metal containment of soil pollution due to waste of paper industry using Nd:YAG laser induced breakdown spectroscopy
摘要： Detection of heavy metal containment of soil pollution has been made by using laser-induced breakdown spectroscopy (LIBS). A pulsed Nd:YAG laser (1064 nm, 8 ns, 200 mJ) was focused on to a soil sample, which is prepared in the form of pellet, at atmospheric pressure. Emission spectra taken from the waste-contaminated soil and uncontaminated soil were obtained. Plasma emissions are then detected using a multichannel analyzer (OMA) to obtain the emission line spectrum that represents the content of atoms and molecules in the target material. The spectrum is recorded and compared with the spectrum of reference standards of atoms, ions and molecules (National Institute of Standards and Technology/NIST) so that the atomic and molecular content in the sample can be known. From the results of the study it was found that there are elements of heavy metals in the form of Fe, Cd, and Mg in polluted soils.
关键词： LIBS,laser-induced breakdown spectroscopy,soil pollution,heavy metal,Nd:YAG laser
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