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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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Quantitative spatially resolved <i>post-mortem</i> analysis of lithium distribution and transition metal depositions on cycled electrodes <i>via</i> a laser ablation-inductively coupled plasma-optical emission spectrometry method
摘要： Diminishing the loss of performance of lithium ion batteries (LIBs) is a challenge that is yet to be ful?lled. Understanding of deterioration processes and mechanisms (i.e., so-called aging) requires analytically accurate examination of aged cells. Changes in the distribution of lithium or transition metals in the LIB cells can in?uence their cycle and calendar life signi?cantly. As electrochemically treated cells and especially their electrodes do not age homogeneously and the local electrochemistry (e.g. deposition patterns) is strongly dependent on surface properties, bulk analysis is not a satisfactory investigation method. Therefore, a surface sensitive method, namely laser ablation-inductively coupled plasma-optical emission spectrometry (LA-ICP-OES) is presented. LIB cells with lithium metal oxide LiNi1/3Co1/3Mn1/3O2 (NCM111) as cathode material and graphite as anode material are investigated using a 213 nm Nd:YAG laser.
关键词： graphite,aging,laser ablation-inductively coupled plasma-optical emission spectrometry,NCM111,LA-ICP-OES,LIBs,Nd:YAG laser,lithium ion batteries
更新于2025-09-19 17:13:59
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Investigating heliuma??deuterium synergies in plasma-exposed tungsten using laser ablation techniques
摘要： This article describes the application of laser ablation based techniques to quantify the depth-dependent concentrations of gaseous species below a tungsten surface. In this work, we use a Quantel QSMART Nd:YAG 60 mJ, 5 ns frequency doubled laser that operates at a 532 nm wavelength, which we couple to an MVAT energy modulator to decrease the laser energy to 1.8 mJ. We use this laser to ablate tungsten and then characterized the resulting laser-induced plasma via laser-induced breakdown spectroscopy (LIBS). The ablated gases are pumped into a quadropole mass spectrometer to perform laser ablation mass spectroscopy (LAMS). The coupled LIBS–LAMS technique is demonstrated using a polycrystalline tungsten specimen that was helium ion implanted with variable helium ion energies to create an approximately 200 atomic parts per million ?at-top concentration pro?le. LIBS–LAMS measurements are then performed on polycrystalline tungsten exposed to helium only, deuterium only, or 90% deuterium-10% helium plasmas on the linear plasma device PISCES/A using either a 75 or 250 eV bias voltage. The LIBS–LAMS measurements clearly indicate that exposure to helium during mixed deuterium–helium plasma exposure leads to an increased near surface deuterium concentration but reduces deuterium permeation below the tungsten surface.
关键词： plasma surface interactions,LIBS,helium,LAMS
更新于2025-09-19 17:13:59
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Quantification of elemental composition of Granite Gneiss collected from Neelum Valley using calibration free laser-induced breakdown and energy-dispersive X-ray spectroscopy
摘要： Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) has been employed for elemental analysis of Granite Gneiss, rock sample, collected from Neelum Valley of Azad Jammu & Kashmir, Pakistan. The sample was irradiated with focused laser beam from Q-switched Neodymium Yttrium Aluminum Garnet laser, having 532 nm wavelength and pulse width of 5 ns, and the emission spectrum was recorded with a spectrometer. Overall, ten elements viz. Si, Al, K, Fe, Sr, Ca, Mg, Na, Li, and H were identified by inspecting the characteristic emission lines. Out of ten detected elements, seven elements fulfilling the criteria of calibration-free technique, namely: Si, Al, K, Fe, Sr, Ca, and Mg, were quantified. Sample was also analyzed by employing energy-dispersive X-ray spectroscopy (EDX) and the results confirmed the presence of all those elements in the sample that were detected by LIBS, except Li and H. For the most abundant element Si in the Granite Gneiss sample, a significant agreement of two techniques for the quantitative results is obtained. Both the techniques have confirmed that Granite Gneiss consists mainly of Si with abundance of 72.75% and 71.30% by weight as measured by CF-LIBS and EDX, respectively. Findings of study show that for the elements with minor concentrations, quantitative results as measured with both techniques were not in close agreement.
关键词： EDX,elemental analysis,Granite Gneiss,CF-LIBS
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
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Quantitative analysis of Pb in soil by femtosecond-nanosecond double-pulse laser-induced breakdown spectroscopy
摘要： The effects of inter-pulse delay on the quantitative analysis of femtosecond-nanosecond double-pulsed laser-induced breakdown spectroscopy (fs-ns DP-LIBS) for assessing Pb in soil have been systematically studied in this work. A femtosecond pulse laser was focused to produce a filament, which was used to ablate the soil sample and produce an appreciable amount of aerosol particles ejected from the soil surface at a low density. Scattering images of the soil particles ejected from the soil surface were obtained, and the soil particles were found to have a delay of 800 μs. After an inter-pulse delay, a nanosecond Nd:YAG laser re-ablated the soil particles and obtained a spectral enhancement and a narrow line width. The quantitative analysis based on DP-LIBS for Pb in soil was strongly dependent on the inter-pulse delay time. With an inter-pulse delay time of 10 μs for DP-LIBS, the R-square factor (R2), relative standard deviation (RSD), root mean square error of cross-validation (RMSECV), and limit of detection (LOD) were 99.42%, 2.99%, 0.42 wt.%, and 8.13 mg/kg, respectively. These findings demonstrate that DP-LIBS can be applied as an efficient spectroscopic tool to improve the quantitative analysis of Pb heavy metal in soil.
关键词： fs-ns DP-LIBS,quantitative analysis,limit of detection,Pb heavy metal
更新于2025-09-19 17:13:59
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Stratigraphic analysis of historical wooden samples from ancient bowed string instruments by laser induced breakdown spectroscopy
摘要： One of the most hotly debated subjects in lutherie circles is the composition of the finishing layers applied by the violinmakers of the past on their valuable bowed string instruments. These are often composed of several organic and inorganic materials, variously mixed and overlaid. During the last decade many analytical strategies were put in place in order to correctly identify these materials. The most used are surely non- and micro-invasive spectroscopic techniques (e.g. XRF, EDX, FTIR) integrated, when possible, with the imaging and tomographic ones with a multi-analytical approach. In this work, Laser-Induced Breakdown Spectroscopy (LIBS) and Optical Coherence Tomography (OCT) were tested together on laboratory mockups and historical bowed string instruments in order to identify and characterize the materials composing the finishing layers of these selected artworks.
关键词： Spectroscopy,LIBS,OCT,Violins,Musical instruments,Stratigraphy,Tomography
更新于2025-09-19 17:13:59
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Improvement of classification accuracy of stainless steel alloys by laser-induced breakdown spectroscopy based on elemental intensity ratio analysis
摘要： Laser-induced breakdown spectroscopy (LIBS) is a useful technique for accurate sorting of metal scraps by chemical composition analysis. In this work, a method for intensity-ratio-based LIBS classification of stainless steel applicable to highly fluctuating LIBS signal conditions is proposed. The spectral line pairs for intensity ratio calculation were selected on the consideration of elemental concentration and upper levels of emission lines. It is demonstrated that the classification accuracy can be significantly improved from that of full spectra principal component analysis or intensity-based analysis. The proposed method is considered to be suited for an industrial scrap sorting system that requires minimal maintenance and low system price.
关键词： intensity ratio,laser-induced breakdown spectroscopy (LIBS),stainless steel,classification
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