LIBS Core Scanner Review

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Literature[edit | edit source]

Laser-induced breakdown spectroscopy of silicate, vanadate and sulfide rocks [1][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) in air at atmospheric pressure has been used to study four geological samples belonging to different structural families. Atomic emission spectra of vanadinite, pyrite, garnet and a type of quartz (compostela's quartz) are shown. The 532 nm line of a Nd:YAG laser at an irradiance of 18 × 1011 W cm−2 was used. The precise focus of the beam allowed microanalysis of a 0.02 mm2 surface area working in single-laser shot mode. The use of an intensified gateable charge-coupled-device (CCD) detector permitted time-resolved studies. The spectral lines have been assigned to transitions in the neutral charge state of the corresponding atom of the material under investigation. The behavior of different transitions with time delay are shown. In experiments, minor components contained in several minerals have been detected. This fact has been used to demonstrate the applicability of the technique to characterize and identify similar minerals.

  • emission of neutrals dominate
  • even small differences can separate samples

Semi-quantitative Laser-Induced Breakdown Spectroscopy for Analysis of Mineral Drill Core [2][edit | edit source]

Abstract: An investigation is reported in the use of time-resolved laser-induced breakdown spectroscopy (LIBS) for mineral assaying applications. LIBS has potential for the rapid on-line determination of the major and minor constituents of mineral drill core samples. In this work a Q-switched Nd:YAG laser is used to test as-received lengths of drill core, with remote LIBS signal acquisition via a bare optical fiber bundle coupled to a spectrometer. A novel normalization scheme, based on integrating the total plasma emission, is demonstrated as a method for correction of signal variations due to the uneven surface geometry of rock. Averaged intensities of atomic emission for the elements Cr, Cu, Fe, Mn, and Ni show good linear correlations, with coefficients of R2 = 0.92-0.99, against laboratory assay values. Limitations in the comparison of the results of surface analysis to bulk compositions are discussed, with emphasis on mining applications of LIBS.

  • Factors that limit the quality are listed
  • Reasoning for using just the fiber
  • Surface vs. bulk measurements
  • Original source for whole spectrum normalization in LIBS

Determination of Mn and Si in iron ore by laser-induced plasma spectroscopy [3][edit | edit source]

Abstract: Laser-induced plasma spectroscopy (LIPS) has been evaluated for the analysis of manganese and silicon in iron ore using a Nd:YAG laser at 1064 nm. Optimal experimental conditions for analysis were evaluated, including repetition rate, number of laser sparks on sample, and laser energy. Gate delay and gate width time were also optimized to obtain the best signal to noise ratio (SNR) and precision. The manganese and silicon atomic emission lines at 403.45 and 251.6 nm were used. The results for samples applied to double-sided tape were compared to those obtained by pressing samples into pellets and no statistical differences between them were found. The precision of samples on tape for intra-measurements (precision of averages on one slide) and inter-measurements (precision of averages between slides) were studied.

  • Optimal measurement parameters for Mn and Si

Optimization of the spectral data processing in a LIBS simultaneous elemental analysis system [4][edit | edit source]

Abstract: An instrumentation variation on laser-induced breakdown spectroscopy (LIBS) is described that allows simultaneous determination of all detectable elements using a multiple spectrograph and synchronized, multiple CCD spectral acquisition system. The system is particularly suited to the rapid analysis of heterogeneous materials such as coal and mineral ores. For the analysis of a heterogeneous material the acquisition cycle typically stores 1000 spectra for subsequent filtering and analysis. The incorporation of an effective data analysis methodology has been critical in achieving both accurate and reproducible results in the analysis of powders with the technology. Using naturally occurring gypsum as the optimization matrix, various data analysis techniques have been investigated including: using pulse-to-pulse internal standardisation; data filtering; and spectral deconvolution. The incorporation of normalization of the elemental emission to the total plasma emission intensity has been found to yield the single biggest improvement in accuracy and precision. Spectral deconvolution has been found to yield further improvement and is particularly relevant to the analysis of complex materials such as black coal. The use of pulse-to-pulse intensity normalization has the further benefit of extending the period between instrument recalibration, thus enhancing the ease of use of the device. The benefit of the optimized data analysis methodology is revealed in the determination of eight elemental components of gypsum (Na, Ca, Mg, Fe, Al, Si, Ti and K) where a typical absolute analysis accuracy of ±10% is obtained. These results compare favourably to analysis by conventional techniques for these materials. The analysis accuracy and repeatability is further demonstrated by the determination of the concentrations of these elements in a black coal sample.

  • No technology is suitable for all elements
  • Reducing depence on analytical services
  • Worker healt and safety
  • Mostly used: acid extraction, XRF, arc-sparc, PGNAA
  • Beats XRF with light elements, PGNAA with trace elements
  • Little sample preparation
  • Samples: low-ash lignites
  • Simutanious elemental analysis to avoid errors (vs. multiple single elem. anal.)
  • Gypsum as primary test matrix
  • Difficulty in quantitative LIBS: Matrix effect, sample heterogeneity, instability of plasmas
  • Use multiple spectrometers
  • Samples on translation stage
  • Delay 1 µs, each CCD with fixed exposure
  • 1 pulse/spectra, 250 spectra collected, standard samples
  • Normalizing over the whole spectra (laser P fluctuations and matrix)
  • Spectral deconvolution (good for low res spectra)
  • RSD as figure of merit and calib. Curve
  • 10 fold enhancement to res. With spec. deconv.
  • For high concentration (Si), non-linear curve, use lower power or pick weaker line
  • BG-normalization works, deconvolution + Explanation for bg-correction: Laser E fluctuation compensated
  • Eliminating outliers +-40 median works (also explanation)
  • “pulse-to-pulse plasma instability is one of the key parameters effecting the accuracy in the LIBS measurement”

On-line iron-ore slurry monitoring for real-time process control of pellet making processes using laser-induced breakdown spectroscopy: graphitic vs. total carbon detection [5][edit | edit source]

Abstract: Chemical composition of iron-ore pellets has a significant impact on their quality and commercial value. Laser-induced breakdown spectroscopy (LIBS) technique has been extensively tested on line, at industrial pelletizing plants. It proved successful at measuring Si, Ca, Mg, Al and graphitic C contents of different iron-ore slurries prior to filtration and pelletizing. For this specific application, the sensitivity of the technique compares with the one obtained from dedicated chemical laboratories. But the real advantage of LIBS technique is that the results are delivered continuously and in real time compared to periodic sampling and standard analytical delays of more than 1 h. Consequently, LIBS gives a more representative reading of the state of the process — particularly when rapid perturbations occur — and allows process optimization and quality improvement. In this work, special attention was given to the fact that the detection system, with specific settings, gives direct measurement for either graphitic carbon (coke breeze) or total carbon (coke breeze, flux and natural carbonate). Graphitic carbon content is a key parameter for both the pellet production cost and its final commercial value. LIBS is a sensitive technique that can detect small variations. But matrix effects affect the spectral lines and it is sometimes difficult to establish universal calibration curve. This problem is partially overcome by the use of a multivariable calibration that corrects for matrix effects and evaluates a confidence level based on expertise for each measurement. Current research is aimed at the development of commercial equipment for continuous industrial use.

  • On-line ,measurement
  • Matrix correction
  • 3 different setups

Development of a method for automated quantitative analysis of ores using LIBS [6][edit | edit source]

Abstract: This paper reports the development of a method for real-time automated quantitative analysis of mineral ores using a commercial laser-induced breakdown spectroscopy instrument, TRACER™ 2100, fitted with a recently developed computer controlled auto-sampler. The auto-sampler permits the execution of methods for performing calibrations and analysis of multiple elements on multiple samples. Furthermore, the analysis is averaged over multiple locations on each sample, thus compensating for heterogeneous morphology. The results for phosphate ore are reported here, but similar methods are being developed for a range of ores and minerals. Methods were developed to automatically perform metallic element calibrations for supplied phosphate ore samples containing known concentrations of the following minerals: P2O5, CaO, MgO, SiO2 and Al2O3. A spectral line for each desired element was selected with respect to the best combination of peak intensity and minimum interferences from other lines. This is a key step, because of the observed matrix dependence of the technique. The optimum combination of the time interval between the laser firing (plasma formation), signal detection, and the duration of the optical detection was then determined for each element, to optimize spectral line intensity and resolution. The instrument was capable of analyzing the required elements in the phosphate ore samples supplied with 2–4% relative standard deviations for most elements. Calibrations were achieved for P, Ca, Mg, Al and Si with linear regression coefficients of 0.985, 0.980, 0.993, 0.987 and 0.985, respectively. Preparation and analysis time for each sample was less than 5 min.

  • Phosphate ore
  • Commercial equipment
  • Standard samples for calib.
  • ICP-AES for comparison
  • classification in the field possible

Sulfide mineral identification using laser-induced plasma spectroscopy [7][edit | edit source]

Abstract: Sulfide minerals in rock samples were identified with laser-induced plasma spectroscopy (LIPS) in the near vacuum ultraviolet spectral region. Reference spectra of pyrite, pyrrhotite, chalcopyrite, sphalerite, barite, calcite and dolomite were applied to classification of minerals in sulfur-bearing drill core samples. On the basis of the results mineral distributions in the sample were estimated. The potential of the LIPS method for in situ analysis is discussed.

  • Measuring sulphide minerals in VUV-region
  • Samples were drill cores, 3 samples, 5cm line, 0.2cm spatial res.
  • Ref. samples from GTK
  • Linear fitting with non.neg. const. highest fitting = right group
  • Purge gas needed
  • Grain size can be estimated
  • 6-8% not identified
  • Delay 170 nm, gate width 250 ns

New near-infrared LIBS detection technique for sulfur [8][edit | edit source]

Abstract: Sulfur has been detected in a spectral window (around 868 nm) previously unexplored by laser-induced breakdown spectrometry (LIBS), using an ablation laser with an ultraviolet wavelength, a gated detector, and inert ambient gas at a low, controlled pressure. This spectral window enables new-generation gated iCCD cameras to be used, which have adequate quantum efficiencies up to 900 nm. Application of our technique can substantially improve signal strength and thus extends the ability of LIBS to detect many nonmetallic elements.

  • 868 nm line for sulfur

Laser-Induced Breakdown Spectroscopy of Composite Samples:  Comparison of Advanced Chemometrics Methods [9][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy is used to measure chromium concentration in soil samples. A comparison is carried out between the calibration curve method and two chemometrics techniques:  partial least-squares regression and neural networks. The three quantitative techniques are evaluated in terms of prediction accuracy, prediction precision, and limit of detection. The influence of several parameters specific to each method is studied in detail, as well as the effect of different pretreatments of the spectra. Neural networks are shown to correctly model nonlinear effects due to self-absorption in the plasma and to provide the best results. Subsequently, principal components analysis is used for classifying spectra from two different soils. Then simultaneous prediction of chromium concentration in the two matrixes is successfully performed through partial least-squares regression and neural networks.

  • Standard calibration curve, PLS-regression and neural networks
  • NN gives best results
  • PCA for classification

Laser-induced breakdown spectroscopy – An emerging chemical sensor technology for real-time field-portable, geochemical, mineralogical, and environmental applications [10][edit | edit source]

Abstract: Laser induced breakdown spectroscopy (LIBS) is a simple spark spectrochemical sensor technology in which a laser beam is directed at a sample surface to create a high-temperature microplasma and a detector used to collect the spectrum of light emission and record its intensity at specific wavelengths. LIBS is an emerging chemical sensor technology undergoing rapid advancement in instrumentation capability and in areas of application. Attributes of a LIBS sensor system include: (i) small size and weight; (ii) technologically mature, inherently rugged, and affordable components; (iii) real-time response; (iv) in situ analysis with no sample preparation required; (v) a high sensitivity to low atomic weight elements which are difficult to determine by other field-portable sensor techniques, and (vi) point sensing or standoff detection. Recent developments in broadband LIBS provide the capability for detection at very high resolution (0.1 nm) of all elements in any unknown target material because all chemical elements emit in the 200–980 nm spectral region. This progress portends a unique potential for the development of a rugged and reliable field-portable chemical sensor that has the potential to be utilized in variety of geochemical, mineralogical, and environmental applications.

  • LIBS fundamentals and some applications

Phosphate ore beneficiation via determination of phosphorus-to-silica ratios by Laser Induced Breakdown Spectroscopy [11][edit | edit source]

Abstract: We report development and application of an in-situ applicable method to determine phosphate ore rock quality based on Laser-Induced Breakdown Spectroscopy (LIBS). This is an economically viable method for real-time evaluation of ore phosphate rocks in order to separate high-silica pebbles prior to deep beneficiation. This is achieved by monitoring relative emission line intensities from key probe elements via single laser ablation shots: the ratio of the phosphorous to silica line intensities (P/Si ratio) provides a simple and reliable indicator of ore rock quality. This is a unique LIBS application where no other current analytical spectroscopic method (ICP or XRF) can be applied. Method development is discussed, and results with actual ore samples are presented.

  • Nice application with LIBS that can't be done with other methods
  • phosphate rocks

Laser-induced breakdown spectroscopy analysis of complex silicate minerals—beryl [12][edit | edit source]

Abstract: Beryl (Be3Al2Si6O18) is a chemically complex and highly compositionally variable gem-forming mineral found in a variety of geologic settings worldwide. A methodology and analytical protocol were developed for the analysis of beryl by laser-induced breakdown spectroscopy (LIBS) that minimizes the coefficient of variance for multiple analyses of the same specimen. The parameters considered were laser energy/pulse, time delay and crystallographic orientation. Optimal analytical conditions are a laser energy/pulse of 102 mJ and a time delay of 2 μs. Beryl compositions measured parallel and perpendicular to the c axis were identical within analytical error. LIBS analysis of 96 beryls from 16 countries (Afghanistan, Brazil, Canada, China, Colombia, India, Ireland, Italy, Madagascar, Mexico, Mozambique, Namibia, Norway, Russia, Tanzania and United States), Antarctica, and ten US states (AZ, CA, CO, CT, ID, ME, NC, NH, NM and UT) were undertaken to determine whether or not LIBS analysis can be used to determine the provenance of gem beryl.

  • Three factors to contribute precicion
  • Min/fluid inclusions
  • Mineral zoning
  • position of plasma volume formation

Laser induced breakdown spectroscopy for bulk minerals online analyses [13][edit | edit source]

Abstract: The purpose of the work was to prove the ability of LIBS to provide on-line analyses for raw ores in field conditions. An industrial LIBS machine was developed and successfully tested for on-belt evaluation of phosphate measuring Mg, Fe, Al, Bone Phosphate Lime (BPL), Insoluble phase and Metal Impurity Ratio (MER) and of coal measuring its ash content. The comparison of LIBS on-line data with control analyses revealed good correlation, which corresponds to the required detection limits and accuracy. With frequent elemental data from a LIBS system, process engineers have the tools to best optimize the process. These processes could be minerals blending and separation to meet customer specifications, monitoring and controlling the efficiency of a minerals process, or a minerals accounting function.

  • Conveyor belt application
  • Can compeate with PGNAA
  • Surface represents the volume
  • Phosphates

Laser-induced breakdown spectroscopy analysis of minerals: Carbonates and silicates [14][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) provides an alternative chemical analytical technique that obviates the issues of sample preparation and sample destruction common to most laboratory-based analytical methods. This contribution explores the capability of LIBS analysis to identify carbonate and silicate minerals rapidly and accurately. Fifty-two mineral samples (18 carbonates, 9 pyroxenes and pyroxenoids, 6 amphiboles, 8 phyllosilicates, and 11 feldspars) were analyzed by LIBS. Two composite broadband spectra (averages of 10 shots each) were calculated for each sample to produce two databases each containing the composite LIBS spectra for the same 52 mineral samples. By using correlation coefficients resulting from the regression of the intensities of pairs of LIBS spectra, all 52 minerals were correctly identified in the database. If the LIBS spectra of each sample were compared to a database containing the other 51 minerals, 65% were identified as a mineral of similar composition from the same mineral family. The remaining minerals were misidentified for two reasons: 1) the mineral had high concentrations of an element not present in the database; and 2) the mineral was identified as a mineral with similar elemental composition from a different family. For instance, the Ca–Mg carbonate dolomite was misidentified as the Ca–Mg silicate diopside. This pilot study suggests that LIBS has promise in mineral identification and in situ analysis of minerals that record geological processes.

  • Nice set of samples
  • Classification with Correlation coefficients
  • 100% classification rate against spec. library

Multi-element and mineralogical analysis of mineral ores using laser induced breakdown spectroscopy and chemometric analysis [15][edit | edit source]

Abstract: In the mining industry the quality and extent of an ore body is determined on the basis of routine assays conducted on drill core and chip samples. Both the elemental composition and the mineralogical classification are important in the characterisation of an ore body for commercial exploitation. Mining industry laboratories typically analyse large numbers of samples from both exploration and mine production environments.

At CSIRO we have explored the application of chemometric methods of analysis in combination with laser induced breakdown spectroscopy (LIBS) in order to produce routine quantitative analysis of several ore types including iron, nickel and lead/zinc ores. In particular, principal components regression (PCR) has been applied to perform multi-element analysis of iron ore samples from Australia and West Africa. Calibration models for iron (4.8% Av. Relative Error), aluminium (2.2%), silicon (3.7%) and potassium (1.4%) were determined for the Australian ores. In addition phosphorous measurements were made at trace level for samples from West Africa (5.5% Av. Relative Error). LIBS measurements of segments of a nickel drill core were also analysed using PCR.

Mineralogical classification using a combination of LIBS and principal components analysis (PCA) has also been explored. Broad discrimination of ore mineralogy was demonstrated on the basis of the PCA of LIBS spectra in selected emission wavelength bands. The combination of PCA and PCR offers potential for both broad mineralogical and elemental analysis for the minerals industry in exploration and in mine production for the on-line monitoring of ore quality.

  • Good discussion about trace elements
  • PCA, PCR for ore mineralogy

LIBS analysis of geomaterials: Geochemical fingerprinting for the rapid analysis and discrimination of minerals [16][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) is a simple atomic emission spectroscopy technique capable of real-time, essentially non-destructive determination of the elemental composition of any substance (solid, liquid, or gas). LIBS, which is presently undergoing rapid research and development as a technology for geochemical analysis, has attractive potential as a field tool for rapid man-portable and/or stand-off chemical analysis. In LIBS, a pulsed laser beam is focused such that energy absorption produces a high-temperature microplasma at the sample surface resulting in the dissociation and ionization of small amounts of material, with both continuum and atomic/ionic emission generated by the plasma during cooling. A broadband spectrometer-detector is used to spectrally and temporally resolve the light from the plasma and record the intensity of elemental emission lines. Because the technique is simultaneously sensitive to all elements, a single laser shot can be used to track the spectral intensity of specific elements or record the broadband LIBS emission spectra, which are unique chemical ‘fingerprints’ of a material. In this study, a broad spectrum of geological materials was analyzed using a commercial bench-top LIBS system with broadband detection from ∼200 to 965 nm, with multiple single-shot spectra acquired. The subsequent use of statistical signal processing approaches to rapidly identify and classify samples highlights the potential of LIBS for ‘geochemical fingerprinting’ in a variety of geochemical, mineralogical, and environmental applications that would benefit from either real-time or in-field chemical analysis.

  • LIBS fundamentals
  • Matrix effect
  • Potential applications
  • Classification with CC

Laser-induced breakdown spectroscopy for on-line sulfur analyses of minerals in ambient conditions [17][edit | edit source]

Abstract: Different options of laser-induced breakdown spectroscopy arrangements for on-line analyses of sulfur in minerals in ambient conditions have been investigated. Depending on the sulfur concentration and the sample type, the following conditions appear as optimal: for concentration values of 20–30% (for example Cu and Ni ores, gypsum, anhydrite, and barite) it is the single-pulse option with emission in near infra-red; for concentration values of 5–10% it is the double-pulse option with emission in the green; for concentration values down to 0.2% (for example in coal) it is the single-pulse option in near VUV with a N2 filled spectrometer.

  • Double-pulse gives gain (2.5-10x)
  • Best solution: single pulse in VUV with purge gas

Multivariate analysis of laser-induced breakdown spectroscopy chemical signatures for geomaterial classification [18][edit | edit source]

Abstract: A large suite of natural carbonate, fluorite and silicate geological materials was studied using laser-induced breakdown spectroscopy (LIBS). Both single- and double-pulse LIBS spectra were acquired using close-contact benchtop and standoff (25 m) LIBS systems. Principal components analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were used to identify the distinguishing characteristics of the geological samples and to classify the materials. Excellent discrimination was achieved with all sample types using PLS-DA and several techniques for improving sample classification were identified. The laboratory double-pulse LIBS system did not provide any advantage for sample classification over the single-pulse LIBS system, except in the case of the soil samples. The standoff LIBS system provided comparable results to the laboratory systems. This work also demonstrates how PCA can be used to identify spectral differences between similar sample types based on minor impurities.

  • comparison of 3 different methods: Single pulse, double pulse, stand-off
  • PCA and PLS-DA
  • Soil samples were hard to classify

Quantitative analysis of arsenic in mine tailing soils using double pulse-laser induced breakdown spectroscopy [19] [edit | edit source]

Abstract: A double pulse-laser induced breakdown spectroscopy (DP-LIBS) was used to determine arsenic (As) concentration in 16 soil samples collected from 5 different mine tailing sites in Korea. We showed that the use of double pulse laser led to enhancements of signal intensity (by 13% on average) and signal-to-noise ratio of As emission lines (by 165% on average) with smaller relative standard deviation compared to single pulse laser approach. We believe this occurred because the second laser pulse in the rarefied atmosphere produced by the first pulse led to the increase of plasma temperature and populations of exited levels. An internal standardization method using a Fe emission line provided a better correlation and sensitivity between As concentration and the DP-LIBS signal than any other elements used. The Fe was known as one of the major components in current soil samples, and its concentration varied not substantially. The As concentration determined by the DP-LIBS was compared with that obtained by atomic absorption spectrometry (AAS) to evaluate the current LIBS system. They are correlated with a correlation coefficient of 0.94. The As concentration by the DP-LIBS was underestimated in the high concentration range (>1000 mg-As/kg). The loss of sensitivity that occurred at high concentrations could be explained by self-absorption in the generated plasma.

  • D-pulse system
  • Compared to AAS
  • D-LIBS underestimated high consentrations (self-abs.)

Laser-induced breakdown spectroscopy-based geochemical fingerprinting for the rapid analysis and discrimination of minerals: the example of garnet [20][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) is an analytical technique real-time geochemical analysis that is being developed for portable use outside of the laboratory. In this study, statistical signal processing and classification techniques were applied to single-shot, broadband LIBS spectra, comprising measured plasma light intensities between 200 and 960 nm, for a suite of 157 garnets of different composition from 92 locations worldwide. Partial least squares discriminant analysis was applied to sets of 25 LIBS spectra for each garnet sample and used to classify the garnet samples based on composition and geographic origin. Careful consideration was given to the cross-validation procedure to ensure that the classification algorithm is robust to unseen data. The results indicate that broadband LIBS analysis can be used to discriminate garnets of different composition and has the potential to discern geographic origin.

  • PLS-DA
  • PCA for visualize
  • 98% acc. for different groups

Optimization of laser-induced breakdown spectroscopy for rapid geochemical analysis [21][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) is demonstrated as a quantitative technique for geochemical analysis. This study demonstrates the applicability of LIBS to bulk elemental analysis of igneous rock powders. LIBS spectra of 100 igneous rocks with highly varying compositions were acquired at 9 m standoff distance under Mars atmospheric conditions. LIBS spectra were modeled using partial least squares regressions to predict major element compositions. A series of comparative tests determined the most effective methodologies for pre-processing of spectral and compositional data, and choice of calibration set. In the best cases, calculated 1−σ errors are 1.6 wt.% SiO2, 1.5 wt.% Al2O3, 0.4 wt.% TiO2, 1.2 wt.% Fe2O3T, 1.6 wt.% MgO, 0.02 wt.% MnO, 1.1 wt.% CaO, 0.5 wt.% Na2O, 0.2 wt.% P2O5, and 0.4 wt.% K2O, with totals near 100%. The largest improvement came as a result of scaling the elemental distributions to equalize the ranges of variability. Optimal predictions for this data set were produced with calibration set compositions input as weight % oxides and not atomic fractions. Predictions were also improved when calibration sets represented the smallest range of compositional variability possible, and completely encompassed the compositional range encountered. Multiple calibration sets relevant to different rock types are preferred over a single all-encompassing calibration set. Baseline removal and transforming spectral data by their first derivative do not improve predictions and can even have negative effects. These results are directly applicable to spectra that will be acquired by the ChemCam experiment on Mars Science Laboratory, but also apply more broadly to terrestrial LIBS applications.

  • Elem. distributions scaled
  • Quantification units as oxides
  • PLS

Analysis of Minerals and Rocks by Laser-Induced Breakdown Spectroscopy [22][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) technique was applied for rapid analysis of major and minor elements composing geological samples including minerals, rocks, and a soil sample. The plasma was produced in air at atmospheric pressure by focusing on the targets a pulsed infrared Nd:YAG laser in open-path configuration. The emitted light in the UV-Vis was analyzed by a compact LIBS system to measure spectral emission lines of Si, Al, Fe, Ca, Na, K, Mg, C, Cu, Mn, and Ti. The experimental issues relevant for the analysis of the different samples were investigated by taking into account their peculiar features: drilling through a weathered layer, roughness and grain-size considerations, statistical averaging, and accuracy of the measurements. In this approach, the characterization of the samples was achieved by studying the relative variations of the emission intensities of each element normalized with respect to an internal standard. The present study shows the usefulness of LIBS as a tool for reliable identification of field samples.

  • Non-gated
  • Errors due to: matrix, surf. roughness, grain size, inhomogenities, laser fluc. FL, regio of plasma plume
  • Internal standard norm. with N

Testing a portable laser-induced breakdown spectroscopy system on geological samples [23][edit | edit source]

Abstract: This paper illustrates the potentialities of a home-made portable LIBS (laser-induced breakdown spectroscopy) instrument in Earth sciences, more particularly in geochemically recognizing (i) tephra layers in lacustrine sediments and (ii) fossilization processes in ammonites. Abundances for selected lines of Al, Ca, Fe, Ti, Ba and Na were determined in lacustrine chalk sediments of the Jura, where the Laacher See Tephra (LST) layer is recorded. A statistical treatment of elemental maps produced from the section of a sedimentary column containing the LST event allows instrumental conditions to be optimized. Accumulating spectra from close shot positions gives better results than multiplying shots at the same location. A depth profile method was applied to study ammonite fossilization (pyritization, phosphatization) processes. Depth variations of Fe, Ca, Al intensities, and Fe/Ca and Al/Ca ratios provide indications about pyritization, but phosphatization processes cannot be determined with our device.

  • home-made portable LIBS

Cores and Core Logging for Geoscientists [24][edit | edit source]

Abstract: Cores and Core Logging for Geoscientists is essential reading for all geologists and environmental and engineering geoscientists who deal with core or results coming from core. This book is an update from the first-edition paperback version published almost 20 years earlier titled Cores and Core Logging for Geologists. As the title implies, the second edition broadens the scope to the larger “geoscience” audience, which is a reflection of the growing field of professionals using core data since the publication of the first edition.

  • Basic knowledge about cores and core sampling

Applications of laser-induced breakdown spectroscopy for geochemical and environmental analysis: A comprehensive review [25][edit | edit source]

Abstract: Applications of laser-induced breakdown spectroscopy (LIBS) have been growing rapidly and continue to be extended to a broad range of materials. This paper reviews recent application of LIBS for the analysis of geological and environmental materials, here termed "GEOLIBS" . Following a summary of fundamentals of the LIBS analytical technique and its potential for chemical analysis in real time, the history of the application of LIBS to the analysis of natural fluids, minerals, rocks, soils, sediments, and other natural materials is described.

  • List of LIBS attributes
  • Fundamentals
  • Different applications
  • Signal statistics

Laser-Induced Breakdown Spectroscopy for Rapid Elemental Analysis of Drillcore [26][edit | edit source]

Abstract: The elemental and mineralogical contents of rock drillcore can be analyzed using a variety of methods. For efficient exploration the characterization of the drillcore should be performed rapidly, so that the further drillings can be better planned and unnecessary costs can be reduced. In this paper, laser-induced breakdown spectroscopy (LIBS) is studied as a potential rapid on-line method for automated elemental analysis of drillcore. The method is based on a pulsed laser beam that transforms a small volume of the sample into plasma. Individual elements in the plasma have characteristic emission patterns detectable by a spectrometer. Based on the measured spectra the amount of different elements in the sample can be estimated. Drillcore samples from a gold mine in Finland are used as test cases in this study. The LIBS measurements are compared to laboratory analysis results as well as to hyperspectral imaging results obtained in the short-wave infrared region. It is shown that the LIBS method can produce similar elemental concentrations as the laboratory measurements. Moreover, based on the elemental contents, some minerals can be identified and the LIBS information can be used to confirm and complete the results of the hyperspectral analysis. However, the spot size of the LIBS measurement is very small, meaning that a large number of measurements must be taken to reach a representative sampling result for large drillcore volumes. On the other hand, high spatial resolution is easily achieved.

  • Drill core on conveyor
  • XRF and SWIR for comparison
  • Line scan
  • Suurikuusikko samples
  • PCA

Handbook of Laser-Induced Breakdown Spectroscopy [27][edit | edit source]

Abstract: Starting from fundamentals and moving through a thorough discussion of equipment, methods, and techniques, the Handbook of Laser-Induced Breakdown Spectroscopy provides a unique reference source that will be of value for many years to come for this important new analysis method. The authors, with a total of over 60 years of experience in the LIBS method, use a combination of tutorial discussions ranging from basic principles up to more advanced descriptions along with extensive figures and photographs to clearly explain topics addressed in the text. In this second edition, chapters on the use of statistical analysis and advances in detection of weapons of mass destruction have been added. Tables of data related to analysis with LIBS have been updated. The Handbook of Laser-Induced Breakdown Spectroscopy, Second Edition: provides a thorough but understandable discussion of the basic principles of the method based on atomic emission spectroscopy, including recently available data leading to better characterization of the LIBS plasma; presents a discussion of the many advantages of the method along with limitations, to provide the reader a balanced overview of capabilities of the method; describes LIBS instrumentation ranging from basic set-ups to more advanced configurations; presents a comprehensive discussion of the different types of components (laser, spectrometers, detectors) that can be used for LIBS apparatuses along with suggestions for their use, as well as an up-to-date treatment of the newest advances and capabilities of LIBS instruments; presents the analytical capabilities of the method in terms of detection limits, accuracy, and precision of measurements for a variety of different sample types; discusses methods of sampling different media such as gases, liquids, and solids; presents an overview of some real-world applications of the method, with new emphasis on sampling of biologically and physically dangerous materials; provides an up-to-date list of references to LIBS literature along with the latest detection limits and a unique list of element detection limits using a uniform analysis method; provides annotated examples of LIBS spectra which can serve as references for the general reader and will be especially useful for those starting out in the field.

  • Fundamentals of LIBS

Ore characterization, process mineralogy and lab automation a roadmap for future mining [28][edit | edit source]

Abstract: Mineralogical laboratory technology has undergone seismic shifts since the introduction of automated mineral analyzers and other quantitative tools such as XRD Rietveld analysis. During the last 25 years, these changes have positioned mineralogical data into the front line of ore characterization, process control and plant optimization. The continuous deterioration of ore quality in regard to grade, hardness, finer particle sizes and the increase of metallurgical complexities have made modern process mineralogy an integral part of new project development. In addition, it has supported improvement of existing plants and the better utilization of tailings or other residues. Automation in mineralogical (and chemical) laboratories from sample preparation to analysis has been the baseline for these improvements. This paper will highlight key benchmarks of mineralogical work from ore characterization to advanced process mineralogy including the increasing importance of mineralogical mine site laboratories. A roadmap for the future of operations-oriented process mineralogy will be provided.

  • Overall description of analytical needs in mining

Laser-induced breakdown spectroscopy expands into industrial applications [29][edit | edit source]

Abstract: This paper presents R&D activities in the field of laser-induced breakdown spectroscopy for industrial applications and shows novel LIBS systems running in routine operation for inline process control tasks. Starting with a comparison of the typical characteristics of LIBS with XRF and spark-discharge optical emission spectrometry, the principal structure of LIBS machines embedded for inline process monitoring will be presented. A systematic requirement analysis for LIBS systems following Ishikawa's scheme was worked out. Stability issues are studied for laser sources and Paschen-Runge spectrometers as key components for industrial LIBS systems. Examples of industrial applications range from handheld LIBS systems using a fiber laser source, via a set of LIBS machines for inline process control tasks, such as scrap analysis, coal analysis, liquid slag analysis and finally monitoring of drill dust.

  • Ishikawa diagram for a LIBS system
  • Different applications
  • imperatives for industrial LIBS applications

Good practices in LIBS analysis: Review and advices [30][edit | edit source]

Abstract: This paper presents a review on the analytical results obtained by laser-induced breakdown spectroscopy (LIBS). In the first part, results on identification and classification of samples are presented including the risk of misclassification, and in the second part, results on concentration measurement based on calibration are accompanied with significant figures of merit including the concept of accuracy. Both univariate and multivariate approaches are discussed with special emphasis on the methodology, the way of presenting the results and the assessment of the methods. Finally, good practices are proposed for both classification and concentration measurement.

  • Good article for selecting the classification and regression algorithms
  • Good talk about figures of merit

Laser-Induced Breakdown Spectroscopy (LIBS) applied to terrestrial and extraterrestrial analogue geomaterials with emphasis to minerals and rocks [31][edit | edit source]

Abstract: Thanks to its unique, unprecedented and very appealing analytical capabilities and performances, the Laser-Induced Breakdown Spectroscopy (LIBS) technique has expanded rapidly in the last two decades in several fields of academic and applicative research, including the study of geomaterials. This review mainly consists of two parts, the first one provides a general and brief summary and discussion of the basic theory and principles of LIBS, the experimental set-up of conventional laboratory bench-top and portable, remote and stand-off configurations, the main methodologies of qualitative and quantitative LIBS analysis with the support of chemometric approaches, and the advantages and disadvantages of the technique. The second part aims to provide a comprehensive, detailed and adjourned at-my-best overview of the huge work done on LIBS applications to the study of geomaterials with focus on minerals and rocks. In particular, results obtained on element detection and quantification, identification, discrimination, classification, provenance, weathering and alteration of minerals, igneous, sedimentary and metamorphic rocks, gemstones, mine ores, archeological artifacts and speleothems, are reviewed and briefly discussed. The enormous efforts and remarkable progresses made in the last decade by several research groups on the potential and viable use of LIBS on robotic vehicles for studying meteorites and planetary analogue terrestrial rocks in simulated planetary conditions, have also been reviewed.

  • Very usefull review article

A Review of Laser-Induced Breakdown Spectroscopy for Analysis of Geological Materials [32][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) as an analytical technique has been developing into a versatile tool in various fields because of its distinct abilities, especially the simple, rapid, in situ detection of any material (solid, liquid, or gas). Following a brief description of LIBS instrumentation, the recent development in the field of geology is reviewed, including the qualitative and quantitative analysis of geological materials, as well as the LIBS application in some specific fields to the analysis of ores, extraterrestrial materials, speleothems, marine sediments, and fluid inclusion.

  • Calib and calib-free LIBS
  • Ore analysis
  • Nice review

Fast mineral identification using elemental LIBS technique [33][edit | edit source]

Abstract: Rapid and on-line scanning of rock and drillcore samples gives fast results that can be used to ease the decision-making process during exploration and to guide the future drilling activities without delays. Recently, faster and more efficient ore characterization by combining various laser-based and contactless measurement techniques has drawn tremendous attention in research. However, complexity of different measurement setups and the difference between the sources of light make it non-economic and complicated for industry. Considering the wide range of the elements which can be detected by Laser-Induced Breakdown Spectroscopy and bearing in mind that LIBS is a very simple spectroscopic technique, the importance of applying LIBS for fast scanning purposes is certified. This study proposes a simple statistical analysis technique leading to mineral identification from the elemental results of LIBS. It is shown that LIBS can be used for calibrating and giving complementary information to other fast scanning techniques like Laser-Induced Fluorescence imaging. The application of the point-wise LIBS measurement technique for online and fast estimation of the minerals abundance from the surface of the rock and drillcore samples is discussed.

  • LIF + LIBS
  • Core samples
  • SVD

Application of Handheld Laser-Induced Breakdown Spectroscopy (LIBS) to Geochemical Analysis [34][edit | edit source]

Abstract: While laser-induced breakdown spectroscopy (LIBS) has been in use for decades, only within the last two years has technology progressed to the point of enabling true handheld, self-contained instruments. Several instruments are now commercially available with a range of capabilities and features. In this paper, the SciAps Z-500 handheld LIBS instrument functionality and sub-systems are reviewed. Several assayed geochemical sample sets, including igneous rocks and soils, are investigated. Calibration data are presented for multiple elements of interest along with examples of elemental mapping in heterogeneous samples. Sample preparation and the data collection method from multiple locations and data analysis are discussed.

  • Showcasing the ability of HH-LIBS

Chemical mapping of mine waste drill cores with laser-induced breakdown spectroscopy (LIBS) and energy dispersive X-ray fluorescence (EDXRF) for mineral resource exploration [35][edit | edit source]

Abstract: Resource estimation for metals in mine tailings and ore deposits requires many samples, usually in the form of drill cores. In order to detect zones of metal enrichment or depletion as well as different lithological zones in such cores, two different core scanning methods were tested on three drill core metres from tailings of a former Pb–Zn mine to obtain chemical information. The results provide an objective basis for further sub-sampling of the taken drill cores and help reduce the amount of samples and therefore the costs for further investigations. For the determination of element concentrations a prototype of a core scanner working with laser-induced breakdown spectroscopy (LIBS) was tested and the results were compared to data from a commercially available ITRAX core scanner, working with energy-dispersive X-ray fluorescence (EDXRF). Apart from a smooth surface, no complex sample preparation was necessary. Peak intensities of selected elements determined by the two scanners were calibrated by means of linear regression (LR) and partial least squares (PLS) regression with respect to bulk geochemical wavelength-dispersive XRF (WDXRF) analysis results of representative core samples. The application of PLS compensates for matrix effects in LIBS and EDXRF and improves prediction accuracy for most elements, compared to LR. In general, prediction ability of PLS models is slightly higher for EDXRF results than for LIBS. The advantage of the LIBS core scanner is the high spatial resolution and the ability to create two-dimensional (2D) element distribution images as well as phase or mineral distribution maps of the drill core at larger scales. Within the analysed tailing cores metal-rich layers with concentrations up to a maximum of 2.2% Pb + Zn + Cu, could be detected by both core scanning methods. Since these layers are not visible by the human eye, the used core scanning methods are appropriate methods for mineral exploration.

  • Two scanning methods tested (LIBS, EDXRF)
  • Pb-Zn mine (tailings)
  • Provides basis for sub-samling (less samples, lower costs)
  • Prototype of LIBS-scanner tested against ITRAX
  • Linear reg. and PLS (PLS compensates Matrix eff.)
  • LIBS adv. High spatial res. & 2d-images
  • List of current core logging methods
  • List of elemental mapping techniques
  • Gamma-ray (K ,U, Th), XRF(Al-U), EDXRF not available in 1m long
  • LIBS often used in material sci. but not geo, only few research groups
  • Results semi-quantitative
  • “Chemical matrix effects can occur in the LIBS plasma, when a species, present in the sample, inhibits the ionization of another species of much lower ionization potential”
  • Phycical M-eff. Also explained
  • “Therefore, the emission intensity of one element measured in two different matrixes does not necessarily represent the real element concentration, and a simple linear correlation of element intensity and real element concentration is not possible.”
  • Univariate cal. Not efficient
  • User mainly interested in distribution of minerals
  • The scanner is able to map 1m x 2.5 cm
  • Five shots accum.
  • Echelle spec. 285-964nm, Nd:YAG 1064, 11 ns, 55mJ
  • Delay 1.5-1.7µs
  • Pb, Zn, Cu, Ni, Co, Si, Al, K, Na, Ca, Mg, Fe, Mn, Ti, Ba, and S were investigated.
  • Elemental lines listed
  • Normalization with total energy, only listed peaks were used and areas integrated
  • Validation with WDXRF
  • Data was Checked for saturation or bg-noice
  • 2-3 lines per element
  • Outlier removal 2 std
  • Quartz giving matrix effect?

Rapid Analysis of Geological Drill‐Cores with LIBS [36][edit | edit source]

Abstract: Spectroscopy — the study of interaction between electromagnetic radiation and matter — is a continually developing branch of science that facilitates a number of research and industrial applications. As a state‐of‐the‐art technique, spectroscopy offers many experimental possibilities to acquire compositional information of inorganic materials, including core samples, minerals and geological specimens. Laser‐induced breakdown spectroscopy (LIBS), which provides fast, accurate and high‐resolution measurements, is one such spectroscopic technique. LIBS is primarily suited for phase‐independent, simultaneous, qualitative and quantitative analysis of samples, dovetailing the technique perfectly with geological standards.

  • EDXRF limitations
  • High res. 8-9h, low res. 30 min
  • 200*20 mm samples
  • Proto can accept whole casing
  • 100 Hz laser
  • Regions of interest

Development of seafloor mineral processing for Seafloor Massive Sulfides [37][edit | edit source]

Abstract: Seafloor Massive Sulfides (SMSs), which are formed from hydrothermal fluids vented from seafloor, have been expected as one of future mineral resources. The authors have proposed the concept of seafloor mineral processing, where valuable minerals contained in SMS ores are separated on seafloor. Experimental studies were carried out to apply conventional mineral processing technologies such as ball mill grinding and column flotation to seafloor mineral processing. Experimental studies suggest that these technologies would be applicable to seafloor mineral processing. In addition, application of Laser-Induced Breakdown Spectroscopy (LIBS) to in-situ measurement of metal grade of ore particles in the mineral processing system was investigated. By adapting seafloor mineral processing to the mining scheme of SMSs, the mining costs are expected to be reduced significantly.

Signal and noise in Laser Induced Breakdown Spectroscopy: An introductory review [38][edit | edit source]

Abstract: Laser Induced Breakdown Spectroscopy (LIBS) has become a very popular technique for elemental analysis thanks to its ease of use. However, LIBS users often report poor repeatability of the signal, due to shot-to-shot fluctuations, and consequent not satisfactory limits of detection. In many practical cases, these shortcomings are difficult to control because the signal is affected by several noise sources that cannot be reduced simultaneously. Hopefully, there is a large amount of knowledge, accumulated during several decades, that can provide guidelines to reduce the effect of the single sources of fluctuations. Experimental setup and measurement settings can be optimized on purpose. Spectral data can be processed in order to better exploit the information contained. In the current paper several approaches to improve the analytical figures-of-merit are reviewed and the respective advantages and drawbacks are discussed.

Sensor-based real-time resource model reconciliation for improved mine production control – a conceptual framework [39][edit | edit source]

Abstract: The flow of information and consequently the decision-making along the chain of mining from exploration to beneficiation typically occurs in a discontinuous fashion over long time spans. In addition, due to the uncertain nature of the knowledge about the deposit and its inherent spatial distribution of material characteristics, actual production performance in terms of produced ore grades and quantity and extraction process efficiency often deviate from expectations. Reconciliation exercises to adjust mineral resource models and planning assumptions are performed with timely lags of weeks, months or even years. With the development of modern Information and Communication Technology over the last decade, literally a flood of data about different aspects of the production process is available in a real-time manner. For example, sensor technology enables online characterisation of geochemical, mineralogical and physical material characteristics on conveyor belts or at working faces. The ability to utilise the value of this additional information and feed it back into resource block models and planning assumptions opens up new opportunities to continuously control the decisions made in production planning to increase resource recovery and process efficiency. This leads to a change in paradigm from a discontinuous to a near real-time reserve reconciliation and model updating, which calls for suitable modelling and optimisation methodologies to quantify prior knowledge in the resource model, to process and integrate information from different sensor-sources and accuracy, back propagate the gain in information into resource models and efficiently optimise operational decisions real time. This contribution introduces the concept of an integrated closed-loop framework for Real-Time Reserve management incorporating sensor-based material characterisation, geostatistical modelling under uncertainty, modern data assimilation methods for a sequential model updating and mining system simulation and optimisation. Selected aspects of the framework are demonstrated in an illustrative case study.

  • The need for sensor technologies in mining

Singular value decomposition approach to the yttrium occurrence in mineral maps of rare earth element ores using laser-induced breakdown spectroscopy [40][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) has been used in analysis of rare earth element (REE) ores from the geological formation of Norra Kärr Alkaline Complex in southern Sweden. Yttrium has been detected in eudialyte (Na15 Ca6(Fe,Mn)3 Zr3Si(Si25O73)(O,OH,H2O)3 (OH,Cl)2) and catapleiite (Ca/Na2ZrSi3O9·2H2O). Singular value decomposition (SVD) has been employed in classification of the minerals in the rock samples and maps representing the mineralogy in the sampled area have been constructed. Based on the SVD classification the percentage of the yttrium-bearing ore minerals can be calculated even in fine-grained rock samples.

  • Core samples
  • Samples with REEs
  • SVD with +- classification

Megapixel multi-elemental imaging by Laser-Induced Breakdown Spectroscopy, a technology with considerable potential for paleoclimate studies [41][edit | edit source]

Abstract: Paleoclimate studies play a crucial role in understanding past and future climates and their environmental impacts. Current methodologies for performing highly sensitive elemental analysis at micrometre spatial resolutions are restricted to the use of complex and/or not easily applied techniques, such as synchrotron radiation X-ray fluorescence micro-analysis (μ-SRXRF), nano secondary ion mass spectrometry (nano-SIMS) or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Moreover, the analysis of large samples (>few cm²) with any of these methods remains very challenging due to their relatively low acquisition speed (~1–10 Hz), and because they must be operated in vacuum or controlled atmosphere. In this work, we proposed an imaging methodology based on laser-induced breakdown spectroscopy, to perform fast multi-elemental scanning of large geological samples with high performance in terms of sensitivity (ppm-level), lateral resolution (up to 10 μm) and operating speed (100 Hz). This method was successfully applied to obtain the first megapixel images of large geological samples and yielded new information, not accessible using other techniques. These results open a new perspective into the use of laser spectroscopy in a variety of geochemical applications.

  • Amazing pictures
  • Autofocus

Analysis of gold in rock samples using laser-induced breakdown spectroscopy: Matrix and heterogeneity effects [42][edit | edit source]

Abstract: We used the laser-induced breakdown spectroscopy (LIBS) technique to determine the concentration of gold in rock samples. 44 reference materials (mostly compressed fine powders) of various chemical compositions, with a quasi-homogeneous concentration of gold varying from 0 to 1000 ppm, were used to establish the calibration curve for the Au I 267.59 nm line. A chemometric study based on the principal component analysis (PCA) showed that ~ 83% of the LIBS spectra variations are attributable to the presence of iron in the samples. Two distinct branches were obtained in the calibration curve: one for Si-rich samples (< 5% of iron) and one for Fe-rich samples (> 13% of iron) with limits of detection of 0.8 ppm and 1.5 ppm, respectively. Different normalization schemes of the gold signal were tested in order to reduce the matrix effects. The LIBS analysis was performed on various mineral samples of practical interest, namely two Si-rich uncompressed ore powders, fine and granular, and three bulk drill cores. The fluctuations in the gold concentration measurements appear to be about two times greater in the granular powder (5–10%) than in the fine one (2–5%). A detailed mapping of the gold concentration on a solid drill core was also performed, revealing multiscale heterogeneity of the gold distribution on the surface of the sample.

  • Nice 3D-map
  • Calib. curve from powders
  • Also core samples
  • Standard lab result can have huge error

Quantitative methods for compensation of matrix effects and self-absorption in Laser Induced Breakdown Spectroscopy signals of solids [43][edit | edit source]

Abstract: This paper reviews methods to compensate for matrix effects and self-absorption during quantitative analysis of compositions of solids measured using Laser Induced Breakdown Spectroscopy (LIBS) and their applications to in-situ analysis. Methods to reduce matrix and self-absorption effects on calibration curves are first introduced. The conditions where calibration curves are applicable to quantification of compositions of solid samples and their limitations are discussed. While calibration-free LIBS (CF-LIBS), which corrects matrix effects theoretically based on the Boltzmann distribution law and Saha equation, has been applied in a number of studies, requirements need to be satisfied for the calculation of chemical compositions to be valid. Also, peaks of all elements contained in the target need to be detected, which is a bottleneck for in-situ analysis of unknown materials. Multivariate analysis techniques are gaining momentum in LIBS analysis. Among the available techniques, principal component regression (PCR) analysis and partial least squares (PLS) regression analysis, which can extract related information to compositions from all spectral data, are widely established methods and have been applied to various fields including in-situ applications in air and for planetary explorations. Artificial neural networks (ANNs), where non-linear effects can be modelled, have also been investigated as a quantitative method and their applications are introduced. The ability to make quantitative estimates based on LIBS signals is seen as a key element for the technique to gain wider acceptance as an analytical method, especially in in-situ applications. In order to accelerate this process, it is recommended that the accuracy should be described using common figures of merit which express the overall normalised accuracy, such as the normalised root mean square errors (NRMSEs), when comparing the accuracy obtained from different setups and analytical methods

  • Figures of merit
  • Different normalizations
  • SA-corrections
  • PCR & PLS
  • ANN

Univariate and multivariate analyses of rare earth elements by laser-induced breakdown spectroscopy [44][edit | edit source]

Abstract: Univariate and multivariate analyses of six rare earth elements [cerium (Ce), europium (Eu), gadolinium (Gd), neodymium (Nd), samarium (Sm), and yttrium (Y)] have been performed using data from laser-induced breakdown spectroscopy (LIBS). Binary mixtures of oxide forms of each rare earth element in an Al2O3 matrix with their concentrations varying from 1% to 10% by weight in powder form were used as working samples for univariate analysis. For multivariate analysis, complex mixtures of oxides of all these six rare earth elements and Al2O3 in powder form, where the concentration of each element oxide was varied from 1% to 50% by weight one by one, were used to record LIBS spectra. Optimum values of gate delay, gate width, and laser energy were used to get spectra from these samples and spectra were used to develop calibration models. The limits of detection for Ce, Eu, Gd, Nd, Sm, and Y were calculated to be 0.098%, 0.052%, 0.077%, 0.047%, 0.250%, and 0.036%, respectively, from the calibration curves.

Detection of contaminants in ore samples using laser-induced breakdown spectroscopy [45][edit | edit source]

Abstract: Laser-induced breakdown spectroscopy (LIBS) has been applied for the determination of contaminants present in ore samples. The plasma was generated by focusing a pulsed Nd:YAG laser radiation at 1064 nm wavelength on the ore sample collected from one of the open-pit mines located in Saudi Arabia. The concentrations in this ore sample of different elements of environmental significance like Cu, Cr, Ca, Mg, Zn, Ti, Si, Fe and Al were determined by spectral analysis. Parametric dependence for improvement of LIBS sensitivity was carried out. The LIBS results were compared with the results obtained using other analytical techniques such as the inductively coupled plasma emission spectroscopy (ICP-AES). Limits of detection (LOD) of our LIBS system were also calculated for the elements under investigation.

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