Free Laser Induced Breakdown Spectroscopy Research Articles

Elemental study of Devarda’s alloy using calibration free-laser induced breakdown spectroscopy (CF‒LIBS)

In the present study, we present the compositional analysis of a Devarda’s alloy using the calibration–free laser-induced breakdown spectroscopy (CF-LIBS) technique. A nanosecond pulsed Q-switched Nd:YAG laser was focused on the target-sample under investigation to ablate its surface and the measured emission spectrum was registered by using a spectrometer (LIBS2000+) having the optical spectral within a range from 200–720 nm. The analysis of the measured optical spectra confirms the presence of three major elements Aluminum (Al), Copper (Cu), and Zinc (Zn) in the target sample. The emission intensity line profiles of Zn, Cu, and Al were utilized to estimate the plasma-parameters consisting of excitation temperature, and the plasma number density. The plasma excitation temperature was investigated using the Boltzmann-plot technique, which yields the temperature for Cu and Zn as 8547 ± 5% K and 8100 ± 5%, respectively, while the electron plasma density was calculated from the Stark-broadening of individual neutral emission lines of Al, Cu, and Zn. For the quantitative analysis of the elements that exist in the target sample, a CF-LIBS technique was employed by assuming the condition of optically thin plasma as well as local thermodynamics equilibrium. Using the CF-LIBS technique, the relative composition in the form of weight percentage was estimated to be Zn: 57%, Al: 39%, and Cu: 4%, whereas, the certified concentration of Devarda’s alloy was 50% for Zn, 45% for Al, and 5% for Cu. These measured results reveal that the elemental concentration utilizing CF-LIBS shows a reasonable agreement with standard estimates illustrated by the manufacturer. This study further suggests that the CF-LIBS technique opens up an opportunity for engineering and industrial usage of LIBS where a quantifiable study of the substance is exceedingly advantageous.

Radiative transition probabilities of neutral and singly ionized rare earth elements (La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) estimated by laser-induced breakdown spectroscopy

Rare earth elements (REEs) are essential to society given their prevalence in many modern technologies. Quantitative elemental analysis of REEs is therefore a critical capability. Calibration free–laser-induced breakdown spectroscopy (CF-LIBS) is a rapidly maturing and promising approach to quantitative elemental analysis with many attractive qualities. The application of CF-LIBS to analyzing samples containing the REEs is hindered by a lack of fundamental data, specifically transition probabilities (TPs). This study seeks to help address this knowledge deficiency by reporting 967 previously unreported TPs for 13 REEs (lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). The method developed in this study to estimate the TPs requires small amounts of material (a few nanograms) compared with other approaches (∼ milligrams), uses non-specialized equipment, and does not involve complicated sample preparations.

Determination of Micronutrients and Toxic Elements in Moringa Oleifera Leaves by Calibration Free Laser-Induced Breakdown Spectroscopy (LIBS)

The Moringa oleifera tree, including the leaves, flowers, pods, and seeds, is highly nutritious and useful for the prevention and control of various diseases. Here we have probed the micronutrients in Moringa oleifera leaves using laser-induced breakdown spectroscopy (LIBS). The time-resolved and time-integrated LIBS data reveal the presence of Ca, Mg, K, C, Si, Fe, Al, Ti, Sr, Na, H, O, and Li. The plasma temperature and electron number density required for the elemental composition analysis were estimated to be (6375 ± 500) K from the Saha-Boltzmann plot and (1.0 ± 0.2) 1017 cm−3 from the Stark broadened Hα line, respectively. Elemental analysis of the samples was performed using one-line calibration free LIBS (CF-LIBS). The results reveal that C is the major element together with Ca, Mg, K, Fe Na, Al, Ti, Sr, and Li as micronutrients. The concentrations of the micronutrients determined by CF-LIBS were validated by inductively coupled plasma – optical emission spectrometry (ICP-OES). LIBS has been demonstrated to be a practical candidate for the detection of potentially toxic elements (Li, Al, Si, and Sr) as well as for the compositional analysis.

Development of laser induced breakdown spectroscopy technique to study irrigation water quality impact on nutrients and toxic elements distribution in cultivated soil.

This study is focused mainly on impact of irrigation water quality in cultivated soil on distribution of essentials nutrients (Al, Mg, Ca, Fe, S, Si, Na, P, and K) and relatively toxic metals (As, Ba, Cr, Cu, Ti, Sn, Mn, Ni, and Zn) using an elegant Laser induced breakdown spectroscopy (LIBS) technique. A pulsed Nd:YAG laser operating at 1064 nm in conjunction with suitable detector was applied to record soil emission spectra. The abundance of these elements were evaluated via standard calibration curve Laser Induced Breakdown Spectroscopy (CC-LIBS) and calibration free Laser Induced Breakdown Spectroscopy (CF-LIBS) approaches. Quantitative analyses were accomplished under conjecture of local thermodynamic equilibrium (L.T.E) and optically thin plasma. The average electron temperatures were estimated by Boltzmann plot method for cultivated soil samples in 7800 to 9300 K range. The electron number density was ~ 1.11 × 1017 cm − 3 to 1.60 × 1017 cm − 3. Prior to application on soil samples, the experimental setup was optimized at the following parameters: pulsed energy = 60 mJpulse-1, sample to lens distance of 9.0 cm, and the gate delay of 3.5 μs. It is noteworthy that nutritional elements content of cultivated soils were found strongly dependent upon the irrigation water quality. The cultivated soil from industrial area was found rich of toxins while the cultivated land using tube well water contains toxins in least amount. Our LIBS findings were also validated by comparing its results with contents measured using a standard inductively coupled plasma optical emission spectroscopy (ICP-OES) method and both were found in excellent agreement. The present study could be highly beneficial for agricultural applications and for farmers to produce safe food products and higher crops yield.

Branching Ratio Method for Assessing Optically Thin Conditions in Laser-Induced Plasmas.

The branching ratio method is usually used to evaluate the optical thinness conditions in laser-generated plasmas, which are important for the application of analytical methods such calibration free laser induced breakdown spectroscopy (CF-LIBS). In this communication, we warn on the possibility that in some circumstances, the branching-ratio method might give results close to the one characterizing optically thin plasma conditions, even in the presence of a substantial self-absorption for the transitions considered.

Analysis of Lakhra Coal by Calibration Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) and Comparison of Self-Absorption Correction Procedures

The analysis of Lakhra Coal to determine its total carbon content and ash content is reported by calibration-free laser-induced breakdown spectroscopy (CF-LIBS). The total carbon content and ash content in coal are key parameters for efficient energy u in sepower plants. The optical emission spectrum of coal contains spectral lines of Ca, Si, Fe, Ti, Mg, Na, K, Li, Al, and C together with traces of Ba and Sr. The excitation temperature and electron number density of the laser-produced plasma were estimated using a Boltzmann plot and Stark broadened Hα line, respectively. The self-absorption correction in the emission intensities of the spectral lines were performed using the internal reference self-absorption correction (IRSAC) and the density correction. The analysis of the coal was performed by CF-LIBS, CF-LIBS with IRSAC, and CF-LIBS with density correction which were then compared with the certified composition reported by the Lakhra Coal Development Company. The results revealed that IRSAC with a fixed slope is more easily applicable and reliable than the number density correction for analyzing the total carbon content, ash content, and trace elements.

Elemental Compositions of Earthquake-Stricken Soil from the Vicinity of the Epicenter at Eurasian and Indian Tectonic Plates Using Calibration Free Laser Induced Breakdown Spectroscopy

Laser induced breakdown spectroscopy (LIBS) was applied for analyzing the impact of earthquake on the elemental distribution of the soil, collected from the earthquake-stricken locations near Eurasian and Indian Tectonic Plates in the Kashmir Valley. The quantitative elemental analysis was carried out using an advanced calibration-free LIBS technique, assuming the establishment of optically thin plasma under the local thermodynamic equilibrium conditions. The results exhibited that the soil has nearly random concentration distribution of metallic elements such as Al, Na, and K, nonmetallic element P, micronutrients such as Fe and Si and secondary macronutrients such as Ca, S, and Mg, in and around the radius of 9 km from the epicenter of the earthquake. It is exhibited that the concentration of carbon in particular is the highest near the epicenter and declines systematically with the outward radial distance. The quantitative analysis by LIBS was confirmed and counter verified through the inductively coupled plasma atomic emission spectroscopy (ICP–OES), and results achieved by both the techniques (LIBS and ICP–OES) are in good agreement.

CF-LIBS analysis in depth profile of lithium corrosion resistance of Er2O3 coatings prepared by sol-gel method

Erbium oxide (Er2O3) coating has gained much attention as an effective measure to assist in solving some destructive problems in Tokamak blanket system. In this paper, Er2O3 coatings were deposited by sol-gel method on the SUS 304 stainless steel substrate, and then immersed the coating specimens in liquid lithium at 500℃ lasting for 600 h for corrosion resistance study. The coatings prepared at different temperatures before and after corrosion were characterized by XRD and SEM for crystal structure, surface and internal stress analysis. The grain size of Er2O3 layer varied with the annealing temperature, and the bigger size can be obtained by higher temperature. Lithium corrosion resistance of coating was analyzed by Calibration free laser-induced breakdown spectroscopy (CF-LIBS) with the content ratio of erbium to lithium to analyze the depth distribution of lithium. It is conservatively estimated that when the ratio is greater than 20, lithium disappeared in the coating, and the penetration depth is less than 0.5 μm. Analysis result support the hypothesis of the mechanism of corrosion product formation and confirm the reliable resistance of coating to lithium corrosion.

Exploiting calibration free laser-induced breakdown spectroscopy (CF-LIBS) for the analysis of food colors

The present study report the elemental concentration of different brands of food colors using calibration free laser induced breakdown spectroscopy (CF-LIBS). The laser induced plasma was produced on the surface of pelletized food colors using single and double pulse laser ablation and the plasma emissions were recorded with LIBS 2500+ spectrometer. The validity of local thermodynamic equilibrium LTE was confirmed using Mc. Whirter’s criteria. The emission spectra were qualitatively analyzed which detected seventeen elements in food color samples. The quantitative analysis was performed using plasma parameters and line emission intensities in CF-LIBS algorithm. The analysis shows that H, C, N, O, and Na are present as major elements, whereas Mg, Al, Si, K, Ca, Cr, Mn, Fe, Zn, Sr etc. are detected in trace amount in food colors.

Calibration-free analysis of a tungsten-based target for diagnostics of relevant fusion materials comparing picosecond and nanosecond LIBS

The elemental analysis of plasma-facing components (PFCs) with deposits is vital for the study of the material erosion, deposition, and fuel retention. For ITER-like divertor, first wall is formed by W-based deposit containing Be, O, D, H and other impurities. The quantification of fuel retention in these materials, including the depth dependence of the fuel retention and the elemental composition, is important. Calibration free laser-induced breakdown spectroscopy (CF-LIBS) is the only technique possible for online remote diagnostics with recognition of the hydrogen isotopes. But the most commonly used ns-LIBS leads to material's overheating; thus, larger non-realistic retention of hydrogen isotopes is generally obtained. In this work, we report the quantitative ps- and ns-CF LIBS analysis of W-based model material (WCu). A WCu alloy has been selected to permit the analysis of tungsten spectral lines in a binary alloy with an element with not too many weak lines. Surface experiments are performed by LIBS using ~30 ps and 5 ns, 1064 nm laser pulses at atmospheric pressure. One of the advantages of ps laser is that it ablates the surface more efficiently, without overheating the ablated material. The laser ablation threshold for the plasma creation in the ps regime is situated at lower energy, thus less material is needed and better depth resolution can be obtained. Suitable Cu and W spectral lines have been selected for the precise evaluation of the electron temperature using the Saha-Boltzmman plots. The electron density values were found from the Saha-Boltzmann plots and the Stark broadening of the Hα spectral line. The results demonstrate the successful detection of W and Cu spectral lines using ps- and ns-LIBS and its quantification.

Quantitative analysis of major components of mineral particulate matter by calibration free laser-induced breakdown spectroscopy

The composition of atmospheric aerosols (particulate matter - PM) has been studied through the quantification of major elements in filter samples by laser induced breakdown spectroscopy (LIBS). After the collection of PM on over quartz filters, the samples were directly analyzed without the need of wet chemistry. The spectral analysis was performed by calibration free method (CF-LIBS), which also avoids using calibration standards. The major mineral elements found in PM10 and PM2.5 samples were Al, Ca, Fe, Mg, K, Na and Si. Furthermore, elements such as C, O and H, which form part of the organic matter and/or water, were also identified and quantified. In addition to CF-LIBS fastness and feasibility, it has been demonstrated that CF-LIBS is a complementary technique for the characterization of PM.

Analysis of alloy and solar cells with double-pulse calibration-free laser-induced breakdown spectroscopy

We applied variant of calibration free laser induced Breakdown Spectroscopy (CF-LIBS) approach for the compositional analysis of standard Gd/Ge/Si alloy and solar cells. The double pulse laser induced plasma was produced on the sample surface and the emission spectra were recorded at optimized interpulse delay and energy ratio. The Plasma temperature, determined using Boltzmann plot, was used to determine the concentration of all species present in a sample. The results are compared with reference values as well as conventional CF-LIBS results, which show that conventional and variant CF-LIBS results are similar and in close agreement to reference values. It is worth mention that the variant CF-LIBS results, but the approach is simpler and faster. Therefore, this approach was applied to three unknown polycrystalline silicon solar cells, which yield Al, C, Ca, Fe, In, Ti, Sb and Sn in the parts per million (ppm). This approach can potentially be applied for real-time trace monitoring in manufacturing processes of photovoltaic devices where conversion efficiency depends strongly on impurities’ concentration.

Detection of toxicity in some oral antidiabetic drugs using LIBS and LA-TOF-MS

Majority of the pharmaceutical tablets and capsules available at the medical stores are film-coated for taste masking and for protection against moisture and light. The elemental concentration of the film-coated content should be carefully monitored otherwise it can be toxic. In the present work, the toxicity of some commercial antidiabetic tablets available in Pakistan has been checked by precise quantitative analyses of their elemental content using a novel method. The proposed technique combines calibration free laser induced breakdown spectroscopy (CF-LIBS) and laser ablation time of flight mass spectrometer (LA-TOF-MS) without using aggressive chemicals. The thickness and chemical composition of coating films are analyzed using cross-sectional scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). It is observed that the film-coating on the German sugar cure cores (GSCC) tablets consist of aluminum (50–100) μm and titanium (500–800) μm. In addition, the thicknesses of Glucophage and Zolid Plus tablets’ coatings are found to range from 20–30 μm and composed of titanium, carbon, oxygen, sodium and magnesium. It has been found that a daily dose of three times a day of GSCC tablets contains about 600 mg/day of titanium and 150 mg/day of aluminum may considered toxic according to the United States food and drug administration (FDA). The results demonstrated that the core of the GSCC tablets mainly composed of calcium (60.7%), magnesium (24.2%), sodium (4.3%), potassium (2.5%), barium (2.4%) and silicon (5.8%) whereas, the core material in the Zolid Plus 850 mg and Glucophage 1000 mg tablets contain metformin (C4H11N5•HCl) with hydrogen (7.3%), carbon (29.1%), nitrogen (42.4%) and chlorine (21.2%). Inclusive analysis based on the innovated non-destructive methodology that combines CF-LIBS and LA-TOF-MS reveals that it can be used for direct monitoring the toxicity for quality assurance in the pharmaceutical industry of antidiabetic drugs in future.

Quantification of elemental composition of Granite Gneiss collected from Neelum Valley using calibration free laser-induced breakdown and energy-dispersive X-ray spectroscopy

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, Pakist...

Химический анализ зоопланктона методом лазерно-искровой эмиссионной спектроскопии без использования образцов сравнения

This study deals with the determination of ratios of light metals (Li, Na, K, Mg, and Ca) in zooplankton (Calanus spp.) by calibration free laser-induced breakdown spectroscopy, assuming local thermodynamic equilibrium. The temperature of laser-induced plasma of zooplankton was derived from rotation-vibration bands of CN, and the electron density was calculated by Stark broadening of Mg I 383.23 nm, Li I 610.37 nm, and Ca II 396.85 nm lines. The synthetic spectra calculated with a radiation transport model for the experimental values of T and Ne were used for a selection of analytical atomic lines free from self-absorption. We compared the obtained data with the results of atomic emission and mass spectrometry with inductively coupled plasma. We also discussed the influence of ionization equilibrium on the accuracy of the results. We propose the presented method for direct semi-quantitative determination of Li, Mg, and Ca ratios in zooplankton.

On the compositional analysis of Coal using calibration free laser induced breakdown spectroscopy

In this contribution, we present analysis of the total carbon contents and the major constituents in the Reference Coal sample of known concentration (SARM 20) and the Pakistani Thar Coal samples using laser induced breakdown spectroscopy (LIBS). A high-power Q-switched Nd:YAG Laser, (532nm, 5ns pulse width and 10 Hz repletion rate) was used to produce the Coal plasma in air and the optical emission spectra were registered using a HR 4000 spectrometer covering the wavelength region from 200 nm to 1100 nm. The emission spectrum of the laser produced plume contains the atomic lines of Ca, Si, Fe, Ti, Mg, Na, K, Li, Al and C along with the traces of Ba, Sr and Mn. The intensities of the observed spectral lines were corrected for self-absorption using the internal reference line self absorption correction method. The excitation temperature was calculated using the Boltzmann plot method and the Stark broadened Hα line profile was used to determine the electron number density. The calibration free LIBS (CF-LIBS) technique with a fixed slope method was utilized for the quantification of the carbon and other elements whereas, a laser-ablation time of flight mass spectrometer (LA-TOF-MS) was used to obtain the mass spectra of the same samples. All the elements identified in the optical emission spectrum have been also observed in the LA-TOF-MS mass spectrum. The results reveal that the Thar Coal samples collected from Sindh, Pakistan are comparable to the Reference Coal samples. It is further demonstrated that CF-LIBS and the LA-TOF-MS are efficient, reliable and complementary techniques for analyzing the Coal samples for the total carbon content, elements forming the ash and even for the detection of the trace elements at the ppm level.

Elemental composition of rice using calibration free laser induced breakdown spectroscopy

In this paper, we apply laser induce breakdown spectroscopy (LIBS) to determine the elemental composition of different parts (root, stem and seed) of the rice plant and determine their weighted concentration using calibration free laser induced breakdown spectroscopy (CF-LIBS) technique. Ca, Fe and K are identified as major elements, while C, Ti, Mg, Si, Li, Ba, Sr, Cr, Na and Al as minor elements. We also detect the H-alpha line of hydrogen in the spectrum and determine the electron number density. The electron number density and its behavior as a function of laser energy, laser wavelength and the detector position are investigated. The plasma temperatures of samples are determined, and the validity of the assumption of the local thermodynamic equilibrium (LTE) is discussed.

Calibration Free Laser Induced Breakdown Spectroscopy (CF-LIBS) as a tool for Quantitative Elemental Analysis of Iraqi Cement

Calibration Free Laser Induced Breakdown Spectroscopy (CF-LIBS) as a tool for Quantitative Elemental Analysis of Iraqi Cement

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Laser-induced breakdown spectroscopy (LIBS) is a promising atomic emission based elemental analysis technique that has many potential applications for various samples. This paper presents the implementation of calibration free laser induced breakdown spectroscopy (CF-LIBS) approach to identify and determine the concentration of elements in Iraqi cement samples collected from local market. Q-switched Nd: YAG laser with energy laser pulse of 100 mJ and pulse duration of 9 ns is focused on cement pellet surface to generate a plasma spark in air. The plasma emission spectrum was recorded by the spectrometer connected to the fiber optic and resolved spectra were used for identification and quantification of detected elements. The produced plasma temperature was obtained from the Boltzmann plot method while their electron density was determined by Saha-Boltzmann equation. The major elements such as Ca, Si, Al, Fe, Mg and minor Mn, Ti, K and Na elements have been identified and their concentrations calculated based on analysis of the spectrum that contain all information needed to derive the elemental composition of the cement matrix.

Quantitative analysis of Al-Si alloy using calibration free laser induced breakdown spectroscopy (CF-LIBS)

The quantitative analysis of the standard aluminum-silicon alloy has been performed using calibration free laser induced breakdown spectroscopy (CF-LIBS). The plasma was produced using the fundamental harmonic (1064 nm) of the Nd: YAG laser and the emission spectra were recorded at 3.5 μs detector gate delay. The qualitative analysis of the emission spectra confirms the presence of Mg, Al, Si, Ti, Mn, Fe, Ni, Cu, Zn, Sn, and Pb in the alloy. The background subtracted and self-absorption corrected emission spectra were used for the estimation of plasma temperature as 10 100 ± 300 K. The plasma temperature and self-absorption corrected emission lines of each element have been used for the determination of concentration of each species present in the alloy. The use of corrected emission intensities and accurate evaluation of plasma temperature yield reliable quantitative analysis up to a maximum 2.2% deviation from reference sample concentration.