Laser-induced Breakdown Spectroscopy Technique Research Articles

Effect of single and double pulse laser-induced breakdown spectroscopy towards steel alloy in different gaseous media

In recent years, laser-induced breakdown spectroscopy (LIBS) technique showed its promising for material analysis, quality control, forensic science, and environmental safety monitoring. Besides, due to its rapid measurement capability and minimal sample-preparation requirements, it is a widely recognized elemental analysis approach used in a variety of study domains. The current work compares spatially resolved single (SP) and double pulse (DP), especially orthogonal DP, setups for LIBS to examine and enhance the limit of detection (LOD) in duplex stainless steels alloy. Using the Boltzmann plot method and the Stark broadening mechanism, the electron temperature and density of local arc plasma are highlighted due to single pulse and orthogonal pre-pulse double pulse configurations. With delay time, the circumstances of arc plasma's local thermodynamic equilibrium (LTE) of emission spectral lines are investigated. The experimental results show that there are significant increases in the spectral intensities of the Fe lines in double pulse LIBS under Ar-gas compared to those under He-gas. Internal standardization was used to create calibration curves for the spectral lines of Cr, Cu, and Mn in the alloy sample for the both studied media. It demonstrated that argon outperforms helium in determining the elemental composition of steel alloys. Furthermore, LOD for SP-LIBS and DP-LIBS in both media were calculated, which showed a higher detection LOD for DP-LIBS in the presence of Ar-gas compared to that in He-gas.

Imaging the elemental distribution within human malignant melanomas using Laser-Induced Breakdown Spectroscopy

The diagnosis of malignant melanoma, often an inconspicuous but highly aggressive tumor, is most commonly done by histological examination, while additional diagnostic methods on the level of elements and molecules are constantly being developed. Several studies confirmed differences in the chemical composition of healthy and tumor tissue. Our study presents the potential of the LIBS (Laser-Induced-Breakdown Spectroscopy) technique as a diagnostic tool in malignant melanoma (MM) based on the quantitative changes in elemental composition in cancerous tissue. Our patient group included 17 samples of various types of malignant melanoma and one sample of healthy skin tissue as a control. To achieve a clear perception of results, we have selected two biogenic elements (calcium and magnesium), which showed a dissimilar distribution in cancerous tissue from its healthy surroundings. Moreover, we observed indications of different concentrations of these elements in different subtypes of malignant melanoma, a hypothesis that requires confirmation in a more extensive sample set. The information provided by the LIBS Imaging method could potentially be helpful not only in the diagnostics of tumor tissue but also be beneficial in broadening the knowledge about the tumor itself.

Quantifying of Radioactive Elements in Soil, Water and Plant Samples using Laser Induced Breakdown Spectroscopy (LIBS) Technique

In this study, the laser-induced breakdown spectroscopy (LIBS) technique was applied to detect radioactive elements on surface soil, plant leaves (Tamarindus indica), and flow water collected from Bala, Mayo-Kebbi Quest, Chad. The survey process indicates that the samples contain radioactive elements U, Fr, Ce, Ac, Cm, Tb, and Pm. The concentrations of the detected elements in samples were determined using the calibration curve method, while the plasma temperatures (Texc) and electron density (Ne) of the detected radioactive elements were calculated from Boltzmann linear plots. Except for uranium, all elements in the soil sample had amounts below the acceptable limit. The concentration of uranium in soil samples ranges from 0.024236 to 0.23439 ppm, with a safety limit of 0.03 ppm. The average plasma temperature Texc for uranium (U) is 700, while the electron density Ne is 500 cm-3 .

Effect of Femtosecond Ultraviolet and Infrared Laser Wavelength on Plasma Characteristics of Metals, Ceramics and Glass Samples Using Femtosecond Laser-Induced Breakdown Spectroscopy.

In this work, we present studies on the effect of laser wavelengths on the laser-induced plasma characterization using a femtosecond (fs) ytterbium-doped potassium-gadolinium tungstate (Yb:KGW) laser. Plasma plumes of copper, steel, ceramics, and glass samples were induced using a multiple shot of 200 fs laser pulses with 1030 nm and 343 nm wavelengths at fixed laser fluence () and analyzed using the laser-induced breakdown spectroscopy (LIBS) technique. Time-resolved fs-LIBS measurements were performed on the same set of samples and under the same experimental conditions. For the calculation of plasma parameters, the set of spectral lines of Cu(I) (for copper sample), Fe(I) (for steel sample), and Ca(I), K(I) (for glass and ceramics samples) were observed. The plasma electron temperature and density were evaluated from the Boltzmann plots and Stark-broadening profiles of the plasma spectral lines, assuming the local thermodynamic equilibrium condition. Time-resolved plasma temperature and electron density for fs-LIBS using ultraviolet (UV) and infrared (IR) laser wavelengths were analyzed and no significant dependence on fs laser wavelength was observed for any of the samples. However, for all samples the signal-to-noise ratio (SNR) significantly increased using UV laser radiation: copper (), steel (), glass (), and ceramics (). Therefore, by using a fs UV laser wavelength for laser-induced breakdown spectroscopy experiments, for certain materials the SNR and at the same time the limit of detection can be significantly enhanced.

Determination of heavy elements collected from the tropical river water by laser-induced breakdown spectroscopy (LIBS) technique: probable experimental approaches and challenges

Determination of heavy elements collected from the tropical river water by laser-induced breakdown spectroscopy (LIBS) technique: probable experimental approaches and challenges

Rare earth elements and radioactive elements in black sands from the Konkan and Malabar coasts of India

ABSTRACT The objective of the present work is to demonstrate the ability of the laser-induced breakdown spectroscopy (LIBS) technique for quick detection and quantification of rare earth elements (REEs) and radioactive elements in the black sands at selected locations of the Konkan coast (Goa) and Malabar coast (Kerala) in India. Several REEs such as Ce, Nd, Sm, Dy, Ho, Tm, Gd, and Th have been detected in the LIBS spectra. Calibration-free LIBS method has been used to calculate the concentration of REEs and radioactive elements. The experimental result shows that the concentration of REEs such as Sm, Dy, Ho, and radioactive element Th is maximum in the sands collected from Thiruvananthapuram (Kerala) beach and minimum in the Baga (Goa) beach. The reliability of the results (qualitative and quantitative) obtained by the LIBS method has been examined by other spectroscopic techniques like XRF and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and found to be in close agreement. The multivariate approach (principal component analysis) has been applied to discern the samples based on their spectral data. Photoacoustic spectroscopy and XRD technique are used to detect compounds/minerals of REEs. The relative hardness, degree of crystallinity (DOC), and crystallite size have been calculated.

Rapid Assessment of Extractability of Macronutrients from Yerba Mate (Illex paraguariensis) Leaves Based on Laser-Induced Breakdown Spectroscopy

Leaves of yerba mate plant (Ilex paraguariensis) have a wealth of nutrients, ingested by people who drink them in the hot water infusion popularly known as mate. In the present work, the laser-induced breakdown spectroscopy (LIBS) technique was applied for the first time to analysis of the extractability of macronutrients, including Mg, Ca, Na, and K, in commercial samples of yerba mate. Powdered samples from leaves’ material were used to simulate the infusion process in the laboratory. To carry out LIBS analysis, the emission spectra were measured before and after the infusion from the samples prepared in pellets. The spectral data were processed and analyzed by a specially designed algorithm. A coefficient of extractability was calculated for each of the investigated macronutrients in the range 34–76%, showing a good correlation with the corresponding elemental concentrations leached into the water infusion, determined by Atomic Absorption Spectroscopy. The obtained results demonstrated the feasibility of our approach for the rapid analysis of extractable macronutrients present in yerba mate leaves.

LIBS combined with SG-SPXY spectral data pre-processing for cement raw meal composition analysis.

Rapid testing of cement raw meal plays a crucial role in the cement production process, so there is an urgent need for a fast and accurate testing method. In this paper, a method based on the Savitzky-Golay (SG) smoothing and sample set partitioning based on joint x-y distance (SPXY) spectral data pre-processing is proposed to improve the accuracy of the laser-induced breakdown spectroscopy (LIBS) technique for quantitative analysis of cement raw meal components. Firstly, the spectral data is denoised by SG smoothing, which effectively reduces the noise and baseline variations in the spectra. Then, the denoised data is divided into sample sets by combining the SPXY sample division method, which improves the efficiency of data analysis. Finally, the delineated data set is modeled for quantitative analysis by a back-propagation (BP) neural network. Compared to the modeling effect of the four oxide contents of CaO, S i O 2, A l 2 O 3, and F e 2 O 3 in the Hold-Out method, the correlation coefficient (R) was improved by 26%, 10%, 17%, and 4%, respectively. The root mean square error (RMSE) was reduced by 47%, 33%, 43%, and 21%, respectively. The mean absolute percentage error (MAPE) was reduced by 63%, 60%, 36%, and 51%, respectively. The results show that there is a significant improvement in the model effect, which can effectively improve the accuracy of quantitative analysis of cement raw meal composition by LIBS. This is of great significance for the real-time detection of cement raw meal composition analysis.

CF-LIBS based elemental analysis of Saussurea simpsoniana medicinal plant: a study on roots, seeds, and leaves.

The plant Saussurea Simpsoniana, which has been used in traditional medicine for its biocompatibility and abundant nutrients, offers a wide range of remedies. Local communities effectively utilize medicines derived from the plant's roots to treat various ailments such as bronchitis, rheumatic pain, and abdominal and nervous disorders. In this study, we present an elemental analysis of the chemical composition (wt%) of this medicinal plant using the laser-induced breakdown spectroscopy (LIBS) technique. In the air atmosphere, an Nd:YAG (Q-switched) laser operating at a wavelength of 532nm is utilized to create plasma on the sample's surface. This laser has a maximum pulse energy of approximately 400mJ and a pulse duration of 5ns. A set of six miniature spectrometers, covering the wavelength range of 220-970nm, was utilized to capture and record the optical emissions emitted by the plasma. The qualitative analysis of LIBS revealed the presence of 13 major and minor elements, including Al, Ba, C, Ca, Fe, H, K, Li, Mg, Na, Si, Sr, and Ti. Quantitative analysis was performed using calibration-free laser-induced breakdown spectroscopy (CF-LIBS), ensuring local thermodynamical equilibrium (LTE) and optically thin plasma condition by considering plasma excitation temperature and electron number density. In addition, a comparison was made between the results obtained from CF-LIBS and those acquired through energy-dispersive X-ray spectroscopy (EDX) analysis.

A chemically functionalized glass support for gold and silver metallic nanoparticle analysis with LIBS

For the first time ever, the LIBS technique has been applied for the metal nanoparticle analysis, using a novel custom-designed silane-functionalized sample support for LIBS-based metallic nanoparticle analysis.

Investigating the Relationship between Zinc Deficiency andRenal Failure using Laser-Induced breakdown Spectroscopy(LIBS)

Kidney failure is a common health problem affecting millions of people worldwide, and zinc deficiency is a major contributor to this condition. In this study, the use of a laser-induced breakdown spectroscopy (LIBS) technique for the diagnosis of renal failure in zinc-deficient individuals was validated. The study was conducted by analyzing plasma samples collected from individuals with renal failure and zinc deficiency using the LIBS technique. Then the plasma parameters, such as electronic temperature and electron density, were analyzed and their equations were derived. To identify the characteristic spectral lines of elements in blood samples and compare them with those of healthy individuals. The results showed that the plasma parameters of individuals with renal failure and zinc deficiency were significantly different from those of healthy individuals. This study demonstrates the potential of the LIBS technique as a non-invasive diagnostic tool for renal failure in zinc-deficient individuals.

Extended total number density compensation for uranium determination by laser-induced breakdown spectroscopy

BackgroundVariations in plasma properties among spectra and samples lead to significant signal uncertainty and matrix effects in laser-induced breakdown spectroscopy (LIBS). To address this issue, direct compensation for plasma property variations is considered highly desirable. However, reliably compensating for the total number density variation is challenging due to inaccurate spectroscopic parameters. For reliable compensation, a total number density compensation (TNDC) method was presented in our recent work, but its applicability is limited to simple samples because of its strict assumptions. In this study, we propose a new pre-processing method, namely extended TNDC (ETNDC), to reduce signal uncertainty and matrix effects in the more complex analytical task of uranium determination. ResultsETNDC reflects the total number density variation with a weighted combination of spectral lines from all major elements and incorporates temperature and electron density compensation into the weighting coefficients. The method is evaluated on yellow cake samples and combined with regression models for uranium determination. Using the typical validation set and line combination, the mean relative standard deviation (RSD) of U II 417.159 nm in validation samples decreases from 4.92% to 2.27%, and the root mean square error of prediction (RMSEP) and the mean RSD of prediction results decrease from 4.81% to 1.93% and from 1.92% to 1.56%, respectively. Furthermore, the results of 10 validation sets and 216 line combinations show that ETNDC outperforms baseline methods in terms of average performance and robustness. SignificanceFor the first time, ETNDC explicitly addresses the temperature and electron density variations while compensating for the total number density variation, where the inaccurate spectroscopic parameters are avoided by fitting related quantities using concentration information. The method demonstrates effective and robust improvement in signal repeatability and analytical performance in uranium determination, facilitating accurate quantification of the LIBS technique.

Rapid Authentication and Detection of Olive Oil Adulteration Using Laser-Induced Breakdown Spectroscopy.

The adulteration of olive oil is a crucial matter for food safety authorities, global organizations, and consumers. To guarantee olive oil authenticity, the European Union (EU) has promoted the labeling of olive oils with the indices of Protected Designation of Origin (PDO) and Protected Geographical Identification (PGI), while food security agencies are also interested in newly emerging technologies capable of operating reliably, fast, and in real-time, either in situ or remotely, for quality control. Among the proposed methods, photonic technologies appear to be suitable and promising for dealing with this issue. In this regard, a laser-based technique, namely, Laser-Induced Breakdown Spectroscopy (LIBS), assisted via machine learning tools, is proposed for the real-time detection of olive oil adulteration with lower-quality oils (i.e., pomace, soybean, sunflower, and corn oils). The results of the present work demonstrate the high efficiency and potential of the LIBS technique for the rapid detection of olive oil adulteration and the detection of adulterants.

Application of laser-induced breakdown spectroscopy for the analysis of pig bones

An application of the laser-induced breakdown spectroscopy technique (LIBS) for the elemental analysis of pig shoulder bone samples is reported. Measurements were performed using a compact laboratory-made LIBS system based on the TEA CO2 laser and time-integrated signal detection. The recorded spectra consisted of well-defined atomic and single-charged ionic lines of bone matrix elements (Ca and P) and other constituent elements (e.g. Mg, Zn, Na, K, and C) with a good signal-to-noise ratio suitable for chemical analysis. Based on the elemental composition of bone samples measured by inductively coupled plasma emission spectroscopy, limits of detection (LOD) of LIBS analysis were estimated for several elements. LOD ranged from 2.2 ppm (K) to 16 ppm (Zn). Carbon and Hα spectral lines were used for plasma diagnostics by measuring Stark widths. Optical profilometry was used to assess the capability of LIBS for depth profile analysis. For laser fluence between 13.0 and 18.2 J cm−2, the ablation rate per pulse ranged from 6 to 10 μm.

Assessment of the terminal velocity of explosively-propelled metal liner using laser-induced breakdown spectroscopy

ABSTRACT Organic energetic compounds containing aluminum (OECAl) are hazardous materials, which have extensive applications in industries. For military and commercial high explosives, Gurney velocity is the terminal velocity of explosively-propelled metal liner on the bases of the ratio of the mass of metal to the mass of explosive. Due to the high cost of experimental determination of Gurney velocity, it is suitable to have a low-cost experimental method for reliable estimation of Gurney velocity of OECAl. A novel approach is introduced to use laser-induced breakdown spectroscopy (LIBS) as a highly energetic laser pulse to atomize and excite samples (a plasma) for assessment of the Gurney velocity of OECAl. Five compositions of 1,3,5-trinitro-1,3,5-triazine (RDX)-based aluminized explosives are studied through the LIBS technique to detect their atomic and molecular emissions in the air atmosphere. Plasma emissions of these compositions are recorded where the atomic line of Al as well as molecular bands of AlO and CN have the highest intensities at some wavelengths. Intensities of Al (λ = 394.38 and 396.16 nm), CN (λ = 388.29 and 422.70 nm), and AlO (λ = 467.19, 484.25, and 464.84 nm) peaks are correlated with their Gurney velocities. The intensity of Al at 396.16 nm gives the best linear relationship (r2 = 0.981) with the Gurney velocity of OECAl samples.

The quality monitoring of paracetamol medicament using a noninvasive microwave sensor

Environmental conditions, including temperature, humidity, and light, can impact the quality of drugs. Microwave-based approaches offer a fast and cost-effective way to detect quality variations, providing an alternative to traditional techniques in the pharmaceutical and cosmetic industries. This article proposes the use of a microwave sensor for monitoring the quality of pharmaceutical drugs at distinct temperature levels. A small planar sensor based on three hexagonal split ring resonators (TH-SRR) is fabricated. The design is manufactured on an FR-4 dielectric substrate. The sensor is tested on a 1000 mg paracetamol tablet, at temperatures ranging from 40 to 80 ^circC. The Variation in the permittivity that characterizes product degradation is translated into a shift in the frequency of the scattering matrix elements. To validate the microwave approach, drug quality is examined with the laser-induced breakdown spectroscopy (LIBS) technique, an optical emission laser used for both qualitative and quantitative investigations of elements contained in a sample. The existing elements are classified using the National Institute of Standards and Technology (NIST) database and categorized according to their spectral line wavelengths. The experiments show the presence of optimal wavelength values for carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) at 247.92 nm, 656.49 nm, 244.23 nm, and 777.48 nm, respectively. The microwave experimental results show a shift frequency of approximately 1 MHz on average when the tablet is heated at 80 ^circC for 15 min. Meanwhile, the LIBS measurement shows a remarkable shift in terms of intensity of approximately 8884 and 812 for carbon and hydrogen, respectively. Understanding how paracetamol dries under high temperatures and improving the process settings of the microwave sensor are investigated and assessed in this work.

Wind turbine contaminant classification using machine learning techniques

It has been well established in the literature that surface contamination can adversely affect the aerodynamic performance of aerofoils and hence the efficiency with which turbines can convert wind to electrical power. Hence it is critical to ensure that turbine blades are kept as free as possible of contaminants. In this manuscript, we discuss LIBS and machine learning techniques on contaminated wind turbine blades with a view to the possibility of integrating these methods into a standoff laser ablation setup in the future. A LIBS signal will be a key step in the decision process, i.e., to determine if a wind turbine blade has been fouled in the first place. Relatedly one must also determine the point at which the laser has adequately removed contaminants from the current Area of Irradiation (AoI) before moving to the adjacent AoI, i.e., interim end-point-detection. For both steps (presence / absence of fouling) we are investigating laser-induced breakdown spectroscopy (LIBS) to discriminate clean from fouled wind turbine blade samples. In particular we have performed LIBS in both the Vacuum Ultraviolet (VUV) and Ultraviolet Visible (UV–Vis) spectral ranges. Analysis of the spectra showed only slight variations in the constituent materials between clean and contaminated blade samples. In order to address this challenge, the efficacy of a number of machine learning and statistical methods for clean versus contaminated blade classification was investigated. Four methods (Partial Least Squares Discriminant Analysis (PLS-DA), Support Vector Machines (SVM), Competitive Learning (CL), and Convolutional Neural Networks (CNN)) were evaluated. The spectral regions where machine learning algorithms were applied was determined via a volumetric ellipsoid overlap test based on Principal Component Analysis (PCA). It was found that SVMs provided the most accurate methodology for binary classification of clean vs contaminated blades whilst also yielding the shortest run time.

EDX and LIBS Studies on Gallstones Using Partial Least Squares Discriminant Analysis (PLS-DA)

Gallstone formation inside the gallbladder is a serious disease and causes health problems. To create preventative measures, it is crucial to examine the composition of gallstones and identify the minerals that are responsible for their pathogenesis. In the present work, we have employed laser-induced breakdown spectroscopy (LIBS)-based elemental studies in combination with partial least squares discriminative analyses (PLS-DA). Energy dispersive X-ray spectroscopy (EDX) was also applied to quantify the elements in the different parts (core and surface) of the gallstones. Fourier transform infrared (FT-IR) spectroscopy was used to classify the gallstone samples. Spectral studies using the LIBS and EDX techniques revealed the presence of trace and toxic elements in the center part of gallstones in higher amounts than that from surface parts. The EDX study also revealed that the elemental distribution is quite heterogenous, and their distribution is random. The EDX method revealed that the center (core) part of the stone samples contained the presence of numerous heavy and toxic elements such as arsenic (As), cadmium (Cd), mercury (Hg), lead (Pb), and nickel (Ni).

UV femtosecond single-pulse and collinear double-pulse laser-induced breakdown spectroscopy (LIBS) for depth-resolved characterization of nano-scaled films

In the current work, we demonstrate the UV femtosecond (248 nm, 450 fs) single-pulse and double-pulse laser-induced breakdown spectroscopy (LIBS) as an effective method for depth profiling of nanometer-thick multi-layered structures, including photovoltaic thin films. Femtosecond LIBS enabled selective detection of both organic and inorganic materials at different depths within nanometer-scale (10–250 nm) multi-layered samples having thicknesses comparable to the etching depth produced by a single laser shot ablation. To enhance the analytical capabilities of the method, we applied the collinear double-pulse LIBS technique, using a Michelson interferometer to split the laser pulse into two equal-energy pulses. Results obtained with Indium Tin Oxide (ITO) nanofilms (115 nm layer thickness) present a clear increase of the intensity emission by a factor of 3 to 10, depending on laser fluence, when the double-pulse approach is used. Single-pulse LIBS achieved an ablation rate of around 60 nm, while the double-pulse configuration achieved 40 nm/pulse, in a sequence of seven laser shots. Furthermore, via double-pulse LIBS spectra were recorded even at fluences as low as 150 mJ/cm2, compared to 250 mJ/cm2 required for capturing spectra, when the same total energy per pulse was maintained.

Laser-Induced breakdown spectroscopy and Energy-Dispersive X-ray analyses for green mineral fluorite (CaF2)

Laser-induced breakdown spectroscopy (LIBS) technique was utilized to investigate the green mineral fluorite (CaF2) samples. The LIBS experiment was implemented by using Nd: YAG Laser system and a linear array CCD detector coupled with an Avantes spectrometer in an air atmosphere. The emission spectra of ten various fluorite samples were studied. The molecular bands correspond to the green B2Σ+-X2Σ+ and orange A2Π-X2Σ systems of diatomic CaF-molecule, specifically at Δν = -1, 0, +1 sequences and the CaO diatomic molecule between 618 nm and 630 nm were detected. It was observed that the CaF-diatomic molecular emission bands exhibited stronger optical emission compared to the fluorine (F) atomic lines. Chemical composition (wt.%) analysis was acquired using CF-LIBS methodology under optically thin and local thermodynamic equilibrium (LTE) conditions. Our CF-LIBS studies revealed that Ca (50–60%) and F (30–40%) were the major elements, while C (3–5%) and O (2–5%) were minor elements present in all samples. For comparison, we employed energy-dispersive X-ray (EDX) technique to study the essential elemental composition (wt.%). The results achieved from CF-LIBS were found to be in good agreement to that obtained from the EDX technique. To validate CF-LIBS results, the calibration curve method was employed using the validated samples (S3, S5, and S7). Furthermore, we utilized a principal component analysis (PCA) technique on the LIBS spectral data to classify the fluorite samples.