Laser-induced Breakdown Spectroscopy Research Articles

Full correction of the self-absorption of laser-induced plasma beryllium emissions via sample preparation

Self-absorption effect is always encountered in laser-induced breakdown spectroscopy (LIBS) and immediately distorts the calibration curves especially for the elemental determination of complex materials. With the aim to provide an expeditious approach for LIBS measurements susceptible to self-absorption effect, an exploratory study for sample preparation by powder mixing is implemented, and the self-absorption of laser-induced plasma beryllium emissions is investigated as a function of the dilution factor. For comparison, boric acid and wax powder are separately used as typical binding agent to mix with beryl powder to produce two sets of pressed pellets with sequential gradient of beryllium content variation. For the resonant lines most prone to self-absorption of Be II emission doublet at 313.042 nm and 313.107 nm, the beryllium spectral line shapes can be directly regulated and improved in the case of both sets of pellets as the dilution factor increases. In addition, the self-absorption effect for the strongly emitting beryllium spectral lines is further assessed by calculating the self-absorption coefficients based on the radiation transport equation. With regard to the both types of binder as diluent, when the dilution factor for beryl increases to 10 with a weight percent of 0.386% for beryllium in the pellet, the SA values may exponentially increase in general to around 0.8 and eventually asymptotically approaches to 1 without exception. Thus the self-absorption effect of laser-induced beryl plasma emissions can be readily overcome with sample preparation by powder mixing. By contrast with laser pulse irradiance in the present work, the dilution factor for powder mixing plays a dominant role in eliminating self-absorption effect. This research proposes a potentially effective approach to reduce self-absorption in laser-induced plasma emissions.

Characteristics of laser induced plasma near a flat gas-liquid interface and its effect on the performance of laser induced breakdown spectroscopy (LIBS) detection

Moving the laser focus to the vicinity of the gas-liquid interface is the key point for many new enhanced and new methods to improve the quality of spectral signals in water Laser induced breakdown spectroscopy (LIBS) detection. Understanding the generation and evolution characteristics of the plasma induced by pulsed laser near the gas–liquid interface is of great significance for the establishment of evolution models and improvement of these new LIBS methods. In this paper, a set of slow horizontal flow auxiliary system is established to provide an ideal flat gas–liquid two-phase interface experimental condition. Experimental research on vertical incidence flat system was conducted using techniques such as time-resolved imaging, plasma characterization diagnosis, and spectral analysis. And the detection capabilities of the system were also tested. The characteristics and mechanisms of LIBS near the gas-liquid two-phase interface were investigated with the laser incident on the sample along the vertical direction. Simulation of the laser beam focusing process and observation of laser beam spot images show that the shift of plasma generation position relative to the focal point results from the refraction of the laser beam entering the solution from the air and the ‘interface effect’ of propagation on the vertical direction. Moreover, the plasma forms only the optical power density surpasses the breakdown threshold. In this work, plasma with smaller size, rounder shape, stronger radiation, higher temperature, and higher density can be produced when the focus position is in the liquid column 0.3 mm away from the upper interface. Simultaneously, for example, the Mg ion line at 285.213 nm, the obtained spectral intensity to signal-to-background ratio reaches the maximum value, and a better spectral signal can be obtained, which is 2–4 times of other positions, and the detection limits of the elements Na, Mg, and Ca also reach the lowest level, with 1.6–2.4 times of the detection limit of other focusing positions for Mg and 1.4–1.7 times for Ca, respectively.

Reassociation of Skeletal Remains Using Laser-Induced Breakdown Spectroscopy.

A major challenge in forensic anthropology and bioarcheology is the development of fast and effective methods for sorting commingled remains. This study assesses how portable laser-induced breakdown spectroscopy (LIBS) can be used to group skeletal remains based on their elemental profiles. LIBS spectra were acquired from the remains of 45 modern skeletons, with a total data set of 8388 profiles from 1284 bones. Spectral feature selection was conducted to reduce the spectral profiles to the peaks exhibiting the highest variation among individuals. Emission lines corresponding to 9 elements (Ca, P, C, K, Mg, Na, Al, Ba, and Sr) were found important for classification. Linear discriminant analysis (LDA) was concurrently used to classify each spectral profile. From the 45 individuals, each LIBS spectrum was successfully sorted to its corresponding skeleton with an average accuracy of 87%. These findings indicate that variation exists among the LIBS profiles of individuals' skeletal remains, highlighting the potential for portable LIBS technology to aid in the sorting of commingled remains.

Application and Research Progress of Laser-Induced Breakdown Spectroscopy in Agricultural Product Inspection.

The quality and safety of agricultural products are of paramount importance in ensuring the health of the food supply chain. Additionally, the composition and trace elements in agricultural products significantly influence their quality and nutritional value. Therefore, the need for rapid and accurate analysis techniques for agricultural product composition is particularly crucial. In the current landscape of evolving compositional analysis technologies, Laser-Induced Breakdown Spectroscopy (LIBS) technology is emerging as a promising analytical tool with broad applications in agricultural product testing. Its characteristics of being rapid, real-time, and capable of simultaneous detection of multiple elements provide an efficient and reliable means for assessing the quality, monitoring safety, and tracing the origin of agricultural products. This technology is expected to play a significant role in controlling and managing the agricultural industry chain and can offer consumers safer and healthier agricultural products. This paper provides an overview of the research status and recent developments of LIBS technology in agricultural product testing applications in recent years. Based on the current research landscape, challenges and opportunities of applying LIBS technology in fields such as agricultural product quality and safety assessment, soil analysis, assessment of crop nutrition, detection of plant diseases, and identification of agricultural product varieties have been evaluated. Moreover, recommendations for further expanding the application of LIBS technology in the agricultural sector are proposed.

Studies of erosion-deposition of plasma-facing materials due to plasma-wall interactions in EAST tokamak

Material erosion, migration, mixing, dust formation, and co-deposition were investigated on plasma-facing materials in the experimental advanced superconducting tokamak (EAST). The test samples (TSs) of molybdenum (Mo), tungsten (W), and carbon (C) were irradiated during EAST operations. All exposed TS surfaces are modified by erosion and deposition processes resulting in the formation of thin layers containing a mixture of PFCs (Mo, W, Cu, Cr, Fe) and light elements (Li, C, Ca, N, O). The majority of chemical species are in a layer of thickness <650–900 nm. The particle size and structure of co-deposition were observed on each TS. Depth profiling by laser-induced breakdown spectroscopy (LIBS) suggests the presence of local and global impurities on the TSs resulting from the plasma-wall interaction (PWI). The processes involved in the PWI that caused erosion of EAST materials are heat flux and high energy excited impurity particles. The material is sputtered from the first wall plasma-facing components. Erosion and deposition processes occur simultaneously in the EAST. The migrated impurities get deposited globally on remote surfaces. A crack was observed in one of the W TSs due to a high heat load. The spectral intensity of co-deposition and substrate continuously changed during successive laser shots.

Sensitivity, precision, and accuracy of fs-LIBS for heavy metal detection in flowing aqueous solutions.

This investigation employs femtosecond laser-induced breakdown spectroscopy (fs-LIBS) to measure the concentrations of chromium (Cr), lead (Pb), and copper (Cu) in flowing aqueous solutions. The fs pulsed laser excites the water, generating plasma in a dynamic setting that prevents liquid splashing-a notable advantage over static methods. The flowing water column maintains a stable liquid level, circumventing the laser focus irregularities due to liquid-level fluctuations. Calibration curves, based on a linear function, reveal limits of detection (LODs) as low as 0.0179 μg/mL for Cr, 0.1301 μg/mL for Pb, and 0.0120 μg/mL for Cu. The reliability of the experiment is confirmed by R2 values exceeding 0.99. These findings offer valuable insights for the analysis of trace heavy metals in flowing aqueous solutions using fs-LIBS, demonstrating the technique's potential for environmental monitoring.

Identification of Dendrobium Using Laser-Induced Breakdown Spectroscopy in Combination with a Multivariate Algorithm Model.

Dendrobium, a highly effective traditional Chinese medicinal herb, exhibits significant variations in efficacy and price among different varieties. Therefore, achieving an efficient classification of Dendrobium is crucial. However, most of the existing identification methods for Dendrobium make it difficult to simultaneously achieve both non-destructiveness and high efficiency, making it challenging to truly meet the needs of industrial production. In this study, we combined Laser-Induced Breakdown Spectroscopy (LIBS) with multivariate models to classify 10 varieties of Dendrobium. LIBS spectral data for each Dendrobium variety were collected from three circular medicinal blocks. During the data analysis phase, multivariate models to classify different Dendrobium varieties first preprocess the LIBS spectral data using Gaussian filtering and stacked correlation coefficient feature selection. Subsequently, the constructed fusion model is utilized for classification. The results demonstrate that the classification accuracy of 10 Dendrobium varieties reached 100%. Compared to Support Vector Machine (SVM), Random Forest (RF), and K-Nearest Neighbors (KNN), our method improved classification accuracy by 14%, 20%, and 20%, respectively. Additionally, it outperforms three models (SVM, RF, and KNN) with added Principal Component Analysis (PCA) by 10%, 10%, and 17%. This fully validates the excellent performance of our classification method. Finally, visualization analysis of the entire research process based on t-distributed Stochastic Neighbor Embedding (t-SNE) technology further enhances the interpretability of the model. This study, by combining LIBS and machine learning technologies, achieves efficient classification of Dendrobium, providing a feasible solution for the identification of Dendrobium and even traditional Chinese medicinal herbs.

Enhancing analytical merits of laser-induced breakdown spectroscopy of hydrogen isotopes using an orthogonal double-pulsing scheme

Accurate detection and quantification of hydrogen isotopes in solid materials are vital for diverse applications, including fusion energy, hydrogen storage, and tritium production. Laser-induced breakdown spectroscopy (LIBS) is a well-established, rapid, standoff method for this purpose, but it faces challenges related to the analytical merits required for isotopic analyses. In this study, we enhance the analytical and detection capabilities of traditional single-pulse LIBS by implementing an orthogonal double pulsing approach, focusing on the analysis of a range of 2H concentrations in Zircaloy-4 substrates (acting as a proxy for 3H). The double-pulse experiments employed an orthogonal re-heating configuration with two nanosecond Nd:YAG lasers. We systematically evaluated critical parameters affecting the signal intensity in double-pulse LIBS, including interpulse delay, ambient gas pressure, and heating laser energy. Our results demonstrate that employing an orthogonal double-pulse scheme significantly enhances 2Hα emission while minimizing line broadening and self-absorption, ultimately improving the technique's analytical capabilities.

Erratum to: Effect of ambient pressures on laser-induced breakdown spectroscopy signals

Erratum to: Effect of ambient pressures on laser-induced breakdown spectroscopy signals

Real-time in situ detection of petroleum hydrocarbon pollution in soils via a novel optical methodology

Petroleum hydrocarbon (PHC) contamination in soils is considered one of the most serious problems currently, of which the detection and identification is a fairly significant but challenging work. Conventional methods to do such work usually need complex sample pretreatment, consume much time and fail to do the in-situ detection. This paper set out to create a novel systematic methodology to realize the goals accurately and efficiently. Based on laser-induced breakdown spectroscopy (LIBS) and self-improved machine learning methods, the innovative methodology only uses extremely simple devices to do the real-time in situ detection and identification work and even realize the quantitative analysis of pollution level accurately. In the study, clean soils mixed with petroleum were served as polluted samples, clean soils to be the blank group for comparison. Based on the elemental information from the spectra obtained by LIBS, machine learning methods were improved and helped optimized the algorithm to identify the PHC polluted soil samples for the first time. Furthermore, a novel model was designed to perform the quantitative analysis of the concentration of PHC pollution in soils, which can be applied to detect the degree of PHC contamination in soils accurately. Finally, the harmful volatile component of the PHC polluted soils was also successfully and identified despite its extremely minimal content in the air. The newly-designed methodology is novel and efficient, which has extensive application prospect in the real-time in situ detection of petroleum hydrocarbon pollution.

Quantification of Zr in simulated dissolver solution of U–Zr fuel by laser-induced breakdown spectroscopy

Abstract Estimation of Zr in fresh and irradiated metal alloy fuel is important. The homogeneous dissolver solution represents the fuel composition better compared to a highly heterogeneous solid pellet. The present study employs LIBS to determine Zr in the simulated dissolver solution. Four different compositions of U–Zr samples where the Zr/U ratio varies from 0.04 to 0.18 % are analyzed by LIBS with an in-house designed liquid sample cell. A good correlation coefficient is achieved for the measurements in the calibration plot. The results for identifying non-overlapping peaks, calibration plot, precision, deviation, and detection limit are discussed in detail. Two set of solid samples, an oxide pellet and metal alloy with similar Zr/U composition, are also analyzed by LIBS. The results obtained from these three set of samples are inter-compared, and the reason for getting a better Zr/U intensity ratio for a dried coating of sample on aluminium for a given composition is explained.

Stark Broadening, Boltzmann Plot Methods for Calculating Plasma Parameters by Laser-Induced Breakdown Spectroscopy for Gold Target

In this investigation, a spectroscopic optical emission test was used to investigate the characteristics of gold plasmas that were produced in the surrounding environment using an Nd: YAG system at a wavelength of 1064[Formula: see text]nm and had an energy output that varied from 400 to 600[Formula: see text]mJ. The emission spectrum profiles of (Au) were analyzed and recorded using a spectrometer to aid in the extraction of vital plasma features (i.e., [Formula: see text] and [Formula: see text]). Plasma temperature was determined using the Boltzmann plot method, and electron density was determined using the Stark broadening method. The temperature was between (0.91 and 0.94)[Formula: see text]eV, while the electron density ranged between (4.79 and 5.26) [Formula: see text][Formula: see text]cm[Formula: see text]. The rest of the plasma parameters were calculated by the mathematical equations of the method used (Boltzmann Plott).

Rapid Determination of Cr3+ and Mn2+ in Water Using Laser-Induced Breakdown Spectroscopy Combined with Filter Paper Modified with Gold Nanoclusters.

Excessive emissions of heavy metals not only cause environmental pollution but also pose a direct threat to human health. Therefore, rapid and accurate detection of heavy metals in the environment is of great significance. Herein, we propose a method based on laser-induced breakdown spectroscopy (LIBS) combined with filter paper modified with bovine serum albumin-protected gold nanoclusters (LIBS-FP-AuNCs) for the rapid and sensitive detection of Cr3+ and Mn2+. The filter paper modified with AuNCs was used to selectively enrich Cr3+ and Mn2+. Combined with the multi-element detection capability of LIBS, this method achieved the simultaneous rapid detection of Cr3+ and Mn2+. Both elements showed linear ranges for concentrations of 10-1000 μg L-1, with limits of detection of 7.5 and 9.0 μg L-1 for Cr3+ and Mn2+, respectively. This method was successfully applied to the determination of Cr3+ and Mn2+ in real water samples, with satisfactory recoveries ranging from 94.6% to 105.1%. This method has potential application in the analysis of heavy metal pollution.

Exploring Rare Earth Elements in complex microscopic mineral phases: Inputs from μLIBS imaging

Understanding the distribution and concentration of Rare Earth Elements (REE) within various minerals and ores is crucial in mineralogy and geology for comprehending the micro-scale processes that contribute to the formation of REE-bearing minerals. Laser Induced Breakdown Spectroscopy elemental imaging emerges as a valuable tool due to its spatial resolution (15 μm) and ability for blind and rapid identification of elements within thin rock sections. Geological samples from the metamorphic core of the Zagros orogen (Iran) prepared as thin rock sections have been analyzed by LIBS imaging. Mineralogical phases have been determined from LIBS images of major elements. We first found that the distribution of Yttrium and REEs varies depending on the metamorphic stage. Then, while garnets may exhibit zoning in Mn, we observed that not all of them incorporate Yttrium. Finally, we demonstrated that REEs carriers include bastnaesite (Y Ce La F) and xenotime-like minerals primarily composed of Y with varying amounts of Yb, Gd, and Nd. We also demonstrated that the REEs minerals can exhibit either millimetric size when embedded within andalusite phases, or micrometric size when randomly scattered throughout the matrix. And we have also observed that some samples feature abundant Y-enriched Zircon phases. This study demonstrates that μLIBS imaging enables drawing a comprehensive picture of geological samples down to the micrometric scale. It has become a key technique in this field, providing access to the mineralogy of REE minerals, which is paramount for optimizing the final exploitation process compared to other analytical techniques.

Relativistic atomic structure calculations of Li-like ions used for plasma diagnostic studies

We have carried out atomic structure calculations using systematically enlarged multiconfiguration Dirac-Fock wavefunctions of Li-like ions of the most prominent plasma impurities (Ar, Ti, Fe, Ni, Kr and W) found in presently working tokamaks. Relativistic Breit interaction and quantum electrodynamic (QED) corrections such as vacuum polarization and self-energy corrections are also included in the calculations prior to the evaluation of low lying energy levels, transition probabilities, oscillator strengths and line strengths. Selective radiative data for electric dipole and magnetic quadrupole transitions are also reported. Special emphasis is given in the computations of fundamental quantities such as oscillator strengths as they are widely used in atomic data and analysis structure (ADAS) databases to evaluate quantities such as effective collision strengths. Present computed values are compared with existing available results on NIST database and few similar earlier computations and a good agreement has been found. We believe that the detailed atomic data with the relativistic and QED corrections will assist in spectroscopic studies such as accurate line identification and plasma modelling work in tokamak plasma, laser induced breakdown spectroscopy (LIBS), highly charged ions clocks and astrophysical observations.

Laser-induced breakdown spectroscopy for helium detection in beryllium coatings

Laser Induced Breakdown Spectroscopy (LIBS) method is considered to be a promising tool for analyzing the retention of hydrogen isotopes (D and T) and helium (He) on the first walls and divertor regions of future fusion reactors. Helium will be produced in DT reactions but could also be used in the initial non-nuclear phases of DEMO concepts. The present study investigates the He detection by LIBS method in the Be coatings simulating the deposits on the divertor plasma-facing components of JET while the results are also relevant for He detection in the deposits of other wall materials. The study was carried out in a vacuum vessel filled with 2–40 mbar argon background gas. It was shown that 2.8 at. % of He was confidently detectable by LIBS at optimized measurement conditions and the estimated limit of detection at used experimental conditions is approximately 0.7 at. %. The intensity of the He emission line at 587.56 nm was the strongest at the center of the laser-induced plasma plume. The He line intensity increased with the pressure of Ar gas but the broadening of the He line and the increase of the background emission and noise set an upper limit to the Ar background pressure usable for He detection. The application of the calibration-free LIBS procedure resulted in the overestimation of the He/Be ratio by several orders of magnitude. The overestimation can be explained by the deviation of LIBS plasma from the local thermodynamic equilibrium, which is caused by the very high excitation energy of He atoms.

Ensemble methods for quantification of potassium oxide in ChemCam Mars and laboratory spectra

In this paper we test new approaches for predicting the amount of element oxides in rock samples from the ChemCam instrument suite onboard the NASA Curiosity rover by focusing on K2O. Using the expanded dataset compiled by Gasda et al. (2021) with and without the Earth to Mars (E2M and NoE2M) transformation discussed in Clegg et al. (2017) we trained blended submodels using the “double blending” technique and compared these to ensemble methods (Random Forest, ExtraTrees, and Gradient Boosting Regression). We found that ensemble methods performed similar to blended submodels when looking at RMSE-P on the laboratory spectra and provided significant advantages when looking at spectra coming from Mars. For the full model, blended submodels achieved an RMSE-P of 0.62 and 0.60 (E2M and NoE2M respectively) while Gradient Boosting Regression resulted in a slightly improved RMSE-P of 0.59 and 0.60. More importantly, by employing a local RMSE-P estimation technique where model performance is evaluated based on nearby test samples we found that using ensemble methods can lower the quantification limit for K2O from the current value of ≈0.6 wt% to ≈0.08 wt% using Extra Trees and Random Forest. This would allow for a much larger range of K2O values to be quantified on Mars with greater certainty given that most targets seen on Mars tend to have <1 wt% K2O. Finally, we used both Mean Decrease in Impurity (MDI) and permutation importance techniques to investigate the wavelengths used by the ensemble methods and found that they correspond to known potassium emission lines. This suggests that ensemble methods can provide an easier to train and improved alternative to blended submodels for predicting potassium compositions from Laser Induced Breakdown Spectroscopy (LIBS) data.

Identification of the optical isomers using laser induced breakdown spectroscopy combined with machine learning

Identification of the optical isomers using laser induced breakdown spectroscopy combined with machine learning

Elemental Analysis and Classification of Nicotine Pouches Using Machine Learning Assisted Laser Induced Breakdown Spectroscopy

Elemental Analysis and Classification of Nicotine Pouches Using Machine Learning Assisted Laser Induced Breakdown Spectroscopy

Analysis and classification of individual ambient aerosol particles with field-deployable laser-induced breakdown spectroscopy platform

Analysis and classification of individual ambient aerosol particles with field-deployable laser-induced breakdown spectroscopy platform