Laser Induced Breakdown Spectroscopy

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Laser-induced breakdown spectroscopy (LIBS) and atomic absorption spectroscopy (AAS) techniques were applied for quantitative analysis of the remaining Pb content in water samples after treatment with a raw montmorillonite (MMT) and an organic derivative (MMO) clays for heavy metal removal, an issue of crucial importance for decontamination of water bodies. The Pb sorption capabilities of MMT and MMO clays were assessed by using solutions with known Pb concentrations, in the range 100-500 ppm. To carry out the LIBS analysis, the samples were prepared in the form of solid pellets with powdered calcium hydroxide addition. The measurement conditions were optimized to achieve reliable analytical results and the plasma parameters, i.e., temperature and electron density, were obtained. For quantification purpose, a calibration curve was constructed with the Pb I emission line at 4057.8 Å measured at the time window 30-45 s by using reference samples with Pb concentrations in the range 56-715 ppm. The Pb residual content in the liquid samples determined with LIBS showed a good agreement with those measured with AAS. The sorption efficiency of Pb from contaminated water was calculated through a sorption percentage SPb%. The calculated SPb% was higher for MMT (56%-100%) than for MMO (27%-47%). The results also demonstrated the usefulness of LIBS method for the determination of Pb concentrations in liquid samples.

A study on the identification of the work piece being laser machined is conducted with the goal of developing a strategy to automatically adjust the processing parameters. The identification technique is based on the spectroscopic analysis of the plasma emission generated during laser ablation. Radiation emitted by the plasma is characteristic of the ablated material and thus can be used as a spectral "fingerprint" for identification purposes. Linear correlation and artificial neural networks are implemented as classification algorithms. Both methods present efficient identification of samples with recognizably different emission spectra. Neural networks outperform linear correlation for the identification of work pieces with very similar spectra. Additionally, the influence of processing and acquisition conditions on the performance of both algorithms is investigated. Finally, a strategy for customized processing based on the identification of each studied work piece is proposed. Linear correlation is used for general identification. Meanwhile, artificial neural networks are solely employed to identify materials for which classification performance of linear correlation decreases. Subsequently, machining parameters are adjusted according to the identified work piece.

The interaction between atmospheric pollutants and architectural cultural heritage leads to several degradation processes, mainly the formation of black crusts. Numerous studies have highlighted that their elemental composition can be used to determine the main pollutant sources of the surrounding areas. Therefore, black crusts may represent actual "registries of pollution sources" and may help to understand the evolution of these sources and their impact throughout the years. In this study, Laser Induced Breakdown Spectroscopy was employed to study a series of black crusts from the Monumental Cemetery of Milan. Surface analysis was carried out in order to evaluate the feasibility of the technique, whereas stratigraphic analysis enabled to highlight the in-depth distribution of the detected elements. The elemental profile of the black crusts was used to identify the main pollution sources of the surrounding areas and the variation of their impact throughout the years.

This paper presents the results of an analysis of carbon (in the form of graphene oxide) deposited on the surface of threads made from stainless steel 316 and titanium alloy Ti6Al4V used in orthopedics using Laser Induced Breakdown Spectroscopy (LIBS). The aim of the article is to indicate the possibility of using the LIBS spectra for the study of thin layers, including graphene derivatives and other elements. Stratigraphic measurements allowed the detection of differences in the spectra peaks of individual elements, not only in the surface layer itself and in the native material, but also in the intermediate layer connecting the two layers. Due to the clear difference in the outline of the spectrum of graphene oxide and the spectrum of the native material of the samples analyzed, a clear incorporation of carbon atoms into the surface layer was observed. A factor analysis was performed, which confirmed the incorporation of graphene oxide into the surface layer of the native material...

Laser induced breakdown plasmas are ``dirty'' events yielding a mixture of ionized species, electrons, and non-ionized matter of various size. Molecular emissions have been detected in excited nanosecond plasmas microseconds after the ablation event. However, with these ...

Soil bacteria are sensitive to ecological change and can be assessed to gauge anthropogenic influences and ecosystem health. In recent years, there has been a significant increase in the focus on new technologies that can be applied to the evaluation of soil quality. Laserinduced breakdown spectroscopy (LIBS) is a promising technique that has been used for the investigation and characterization of explosives, solids, liquids, gases, biological and environmental samples. In this study, bacteria from un-mined and a chronosequence of reclaimed bauxite soils were isolated on Luria-Bertani agar media. Polymerase chain reaction amplification of the bacterial 16S rDNA, sequencing, and phylogenetic analysis were applied to each isolated soil bacteria from the sample sites resulting in the identification and classification of the organisms. Femtosecond LIBS performed on the isolated bacteria showed atomic and ionic emission lines in the spectrum containing inorganic elements such as sodium (Na), magnesium (Mg), potassium (K), zinc (Zn), and calcium (Ca). Principal component analysis and partial least squares regression analysis were performed on the acquired bacterial spectra demonstrating that LIBS has the potential to differentiate and discriminate among bacteria in the un-mined and reclaimed chronosequence of bauxite soils.

Soil bacteria are sensitive to ecological change and can be assessed to gauge anthropogenic influences and ecosystem health. In recent years, there has been a significant increase in the focus on new technologies that can be applied to the evaluation of soil quality. Laser-induced breakdown spectroscopy (LIBS) is a promising technique that has been used for the investigation and characterization of explosives, solids, liquids, gases, biological and environmental samples. In this study, bacteria from un-mined and a chronosequence of reclaimed bauxite soils were isolated on Luria–Bertani agar media. Polymerase chain reaction amplification of the bacterial 16S rDNA, sequencing, and phylogenetic analysis were applied to each isolated soil bacteria from the sample sites resulting in the identification and classification of the organisms. Femtosecond LIBS performed on the isolated bacteria showed atomic and ionic emission lines in the spectrum containing inorganic elements such as sodium ...

Polymers are required to use in radiation environments as insulation materials. However, they often suffer from tracking failure. There is an increasing demand to evaluate radiation effects on dielectric performance. This paper presents a recurrence plot (RP) approach to analyse surface discharge sequences of gamma-ray irradiated polymer materials based on tracking test. Studying the non-linear characteristics of discharge sequences can assist in understanding the underlying mechanism of the discharge process. Discharge sequences of the test are extended to m-dimensional phase space by using the phase space reconstructed method. As test samples, polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) were irradiated to 100 kGy and then up to 1 MGy with a dosage rate of 10 kGy h -1 by using a 60 Co gamma source. The tracking tests were carried out according to the test method described in IEC60112. It is found that the RPs can give visual recurrent patterns of discharge sequences for identification of the effects of gamma-ray radiation dosage on the resistance to tracking of the polymers. The detection of recurrent patterns together with comparative tracking index value results indicate that with the increase in the radiation dosage, the resistance to tracking of PBT decreases, but increases for PBN.

There is a need for an instrument that can be used for remote in situ identification of biogenic and a-biogenic minerals, various types of ices, and organic and inorganic materials on planetary surfaces. In this paper, we explore the use of remote pulsed laser Raman spectroscopy for mineral analysis at distances from 10 to 66 m on planetary surfaces. We have constructed a remote Raman system utilizing a small pulsed Nd:YAG laser and a 5-in. telescope coupled to a spectrograph with an optical fiber. The performance of our system is demonstrated by presenting spectra of benzene and marble (calcium carbonate) while varying the integration time (i.e., number of laser shots), as well as single laser shot spectra of marble while decreasing laser power. Finally, Raman spectra of representatives of several different mineral groups are presented, including hydrated substances, carbonates, silicates (e.g., olivine, pyroxene, feldspars, etc.), water, and ice.

In this paper, the four parameters of plasma (density of electron, temperature of electron, length Debye and frequency of plasma) are studied. Optical emission spectroscopy method is utilized to study Debye sphere (N D) . The spectrum of plasma with different values of energy, Zn with Nio at different percentage (X=0.1, 0.3, 0.5) were recorded. The spectroscopic study for these mixing under vacuum with pressure down to P=2.5×10 -2 mbar. The results of electron temperature for X=0.1 range (1.312-1.413) eV, for X=0.3 the Te range (1.315-1.399) eV and X=0.5 the Te is (1.137-1.226) eV. Optical properties of Zn: Nio pellets were determined through the optical transmission method using ultraviolet visible spectrophotometer within the range (190 -1100) nm.

Tato diplomová práce se zabývá způsoby měření útlumu ultrazvuku. V rámci práce jsou navrženy a proměřeny různé metody měření útlumu. Jako referenční látka pro toto měření je použit ricinový olej. Pro měření jsou využity různé ultrazvukové měniče, hydrofon a ultrazvukový zobrazovací systém GE Vingmed SystemFive. Naměřená data jsou zpracována pomocí skriptů navržených ve vývojovém prostředí Matlab.This diploma thesis deals with ultrasound attenuation measurement methods. Variety of methods are developed and tested . Castor oil was used as reference material. Different kinds of ultrasound transducers, hydrophone and ultrasound scanner GE Vingmed SystemFive were used for measurement. Data was processed by scripts developed in matlab.

Optical emission signal enhancement from palladium (Pd) plasma by magnetic field-assisted laser-induced breakdown spectroscopy (MF-LIBS) is reported. Plasma from Pd target was produced by second harmonic generation (532 nm, 5 ns) of Nd:YAG laser using fluence values in the range of 12.6-38.1 J/cm 2 . In the designed experiment, the magnetic field was parallel to the axis of plasma expansion direction with a maximum strength of 0.12 T at the target surface. Optical signals of the emission from the plasma were recorded in the spectral range of 200-700 nm with a LIBS2000+ spectrometer. A significant enhancement was noticed particularly at low fluence values for both atomic and singly ionized Pd lines. For the minimum fluence 12.6 J/cm 2 , an intensity enhancement of 3-4 fold was observed for Pd-I and Pd-II lines and dropped exponentially for the increased fluence values. At low fluence values, the trace elements viz., Ca and Mg were detected only in the presence of magnetic field. The optical signal enhancement effect of magnetic field was different for Pd, Ca, Mg, and H; suggesting that the field enhanced effect is strictly element dependent for plasma at the same conditions. The field influenced the plasma parameters; the electron number density (n e ), and temperature (T) which were increased considerably compared to without field. Expectedly, these attributes come from the plasma confinement by the external magnetic field and have been explained in the framework of magneto hydrodynamic (MHD) model.

In the work that is being presented here, the effect of sample thickness and laser irradiance on the reduction of the signal-to-background ratio SBG and the plasma parameters, specifically electron temperature and electron density, is being investigated using back-reflection-enhanced laserinduced breakdown spectroscopy (BRELIBS). Copper and silver discs that had been highly polished were attached to the back surface of the glass target, and the Nd-YAG laser beam that was focused on the front surface of the target was tuned to its fundamental wavelength. The thicknesses of the transparent glass samples that were analysed were 1 mm, 3 mm, and 6 mm. One is able to achieve a range of different laser irradiance levels by adjusting the working distance that exists between the target sample and the focusing lens. The end result of this is that the signal-to-background ratio in the BRELIBS spectra of thicker glass samples is significantly lower as compared to the ratio in the spectra of thinner glass samples. In addition, a significant influence of modifying the laser irradiance (by increasing the working distance on the SBG ratio) is seen at various glass thicknesses for both BRELIBS and LIBS, with BRELIBS having a better SBG. Nevertheless, the laser-induced plasma parameter known as the electron temperature has not been significantly impacted by the decrease in the glass thickness. Laser-Induced Breakdown Spectroscopy (LIBS) is a spectrochemical analytical technique used for the elemental analysis of any target material, whether gas, liquid, or solid 1-3 . Since the early emergence of LIBS in 1982, the technique has been applied in numerous fields, industrial 4-6 , biology 7 , medicine 8 , environmental 9,10 , forensic , archeological , geology , etc. Details of the fundamentals and applications of LIBS can be found in many published books and review papers . Focusing a nanosecond, picosecond, or femtosecond laser pulses of a few mJ energy per pulse onto the surface of a solid target leads to melting, boiling, and evaporation of a tiny amount of the target material. The rise of the vapor temperature due to heat absorption from the laser pulse dissociates the molecules into atoms. With further increase in the temperature (6000-60,000 K), atoms are ionized, and a plasma plume consisting of a collection of ions and swirling electrons is evolved at such elevated temperature . As the plasma plume cools down, it gets rid of the previously absorbed energy by emitting photons of light. The emitted plasma light is collected, dispersed, and displayed as an emission spectrum. Qualitatively, the spectral lines in the obtained spectrum characterize the elements in the plasma and, consequently, the target material. On the other hand, quantitatively, there is a proportionality relation between the spectral lines' intensity and the concentration of the corresponding elements, considering the self-absorption and the matrix effects. Two critical parameters that characterize the expanding laser-induced plasma plume are the plasma temperature and the electron density. The widespread of LIBS worldwide refers to its appealing pros, such as its simplicity, cost-effectiveness, no or minimal preparation of the target material, quasi-nondestructive, noninvasive, and can detect low and high atomic number elements simultaneously. However, LIBS has a significant limitation in its relatively inferior limit-of detection compared to other conventional analytical techniques, such as ICP, LA-ICP, and EDX. Promoting LIBS sensitivity has represented an important challenge for researchers during the last two

In the work that is being presented here, the effect of sample thickness and laser irradiance on the reduction of the signal-to-background ratio SBG and the plasma parameters, specifically electron temperature and electron density, is being investigated using back-reflection-enhanced laser-induced breakdown spectroscopy ( BRELIBS). Copper and silver discs that had been highly polished were attached to the back surface of the glass target, and the Nd-YAG laser beam that was focused on the front surface of the target was tuned to its fundamental wavelength. The thicknesses of the transparent glass samples that were analysed were one millimetre, three millimetres, and six millimetres. One is able to achieve a range of different laser irradiance levels by adjusting the working distance that exists between the target sample and the focusing lens. The end result of this is that the signal-to-background ratio in the BRELIBS spectra of thicker glass samples is significantly lower as compare...

Tato práce se zabývá podrobnou analýzou a modelováním vybraných sensorů a aktuátorů programovatelné robotické stavebnice LEGO Mindstorms NXT 2.0. Aktuátory jsou zastoupeny servomotory a mezi vybrané sensory patří barevný a ultrazvukový sensor, oba dostupné v základní verzi stavebnice, a také sensor gyroskopický od firmy HiTechnic. Obsahem práce je realizace a vyhodnocení experimentů pro jednotlivé prvky a výsledkem jsou grafická znázornění vlastností sensorů, modely v prostředí Simulink reprezentující dané prvky a přehledy parametrů a vlastností jednotlivých sensorů a aktuátorů. Detailní analýza sensorů a servomotorů stavebnice poskytuje přehled o možnostech, ale i omezeních jednotlivých prvků. Tyto znalosti mohou být poté využity pro široké spektrum možných aplikací stavebnice.

Dissertation for Doctoral Degree Development of advanced elemental detection methods in particles and gases using laser-induced breakdown spectroscopy and laser breakdown time-of-flight mass spectrometry for the application to thermal and nuclear power plants A dissertation submitted to The University of Tokushima in partial fulfillment of the requirements for the doctor degree

Laser induced breakdown spectroscopy (LIBS), as performed by the ChemCam instrument, provides a new tech nique to measure hydrogen at the surface of Mars. Using a laboratory replica of the LIBS instrument onboard the Curiosity rover, different types of hydrated samples (basalts, calcium and magnesium sulfates, opals and apatites) covering a range of targets observed on Mars have been characterized and analyzed. A number of factors related to laser parameters, atmospheric conditions and differences in targets properties can affect the standoff LIBS sig nal, and in particular the hydrogen emission peak. Dedicated laboratory tests were run to identify a normalization of the hydrogen signal which could best compensate for these effects and enable the application of the laboratory calibration to Mars data. We check that the hydrogen signal increases linearly with water content; and normal ization of the hydrogen emission peak using to oxygen and carbon emission peaks (related to the breakdown of atmospheric carbon dioxide) constitutes a robust approach. Moreover, the calibration curve obtained is relatively independent of the samples types.

W spółczesne metody analityczne pozwalają na identyfikację techniki, która została zastosowana do naniesienia warstwy złota na metalowe podłoże zabytku. To rozpoznanie może być przeprowadzone sposobami bazującymi na detekcji sygnałów pochodzących od wzbudzonych atomów, które spontanicznie emitują promieniowanie elektromagnetyczne 1 . Jest ono rejestrowane przez detektor i przetwarzane na widmo liniowe charakterystyczne dla danego pierwiastka. Obecnie stosowane detektory promieniowania pozwalają na analizę jakościową i ilościową pierwiastków w badanej próbce. Na materiale zabytkowym sprawdzono możliwości następujących technik analitycznych: fluorescencyjnej spektrometrii rentgenowskiej 2 -XRF

Quantitative chemical mapping of battery electrodes is a rather new post-mortem analytics method for identifying and describing chemical degradation processes in lithium-based battery systems. In consideration of future applications, the development of lithium-ion batteries is quite essential in order to meet requirements such as improved cell lifetime (>5000 cycles), high energy density at the cell level (>250 W h kg À1 ), reduced charging times (<15 min), high power density (>2500 W kg À1 ), and reduced manufacturing costs (<150 $ per kW h). One novel approach that can handle a contemporaneous enhancement of energy and power density is the development of a novel cell design, mandated in a threedimensional (3D) arrangement. This so-called "3D battery concept" enables electrode configurations with improved lithium-ion diffusion kinetics and provides reduced mechanical stresses which could arise during battery cycling. Within this study, laser-induced breakdown spectroscopy (LIBS) was applied quantitatively as a powerful analytical tool in order to study chemical degradation mechanisms and the impact of 3D electrode architectures on lithium distribution. It could be shown so far that free-standing electrode architectures can provide new lithium-insertion pathways which enhance the capability of the electrode material to operate under abuse conditions. Elemental mapping and elemental depth-profiling were applied for characterizing the electrode as a function of cell lifetime and architecture. For the first time, it was demonstrated that LIBS can be used to quantitatively describe lithium distribution in a 3D battery with specific design parameters. Finally, new scientific findings regarding electrochemically driven degradation and aging mechanisms of laser-structured, embossed, and unstructured NMC electrodes were explored.

In emissions originating from industrial processes, elemental concentration characteristically depends on particle size. Therefore, not only is the average chemical composition of the particles in the focus of interest but also their size-dependent composition. For industrial applications such as on-line process control, a system using laser-induced breakdown spectroscopy (LIBS) is developed providing the analysis of particulate matter directly in an air stream with a short response time to changes in elemental composition. By using a co-flow in addition to the aersosol flow the time resolution of the system can be enhanced. Investigations are undertaken concerning properties of the laser plasma, the analysis of monodisperse and polydisperse aerosols with regard to the relative elemental concentration and the mass concentration of the particles. The system can be calibrated to either total elemental concentrations or relative compositions. The signal response to a variation of elemental concentration as well as to the particle mass concentration show kinds of saturation effects. Temporal plasma evolution for CaCl 2 particles and pure argon are investigated. Different decay times for argon and the particle matter depending on the origin of lines within the plasma are observed. Electron density and temperature are determined using Ca emission lines to describe the temporal evolution of the plasma state for the particle analysis. It has been observed that the electron density increases rapidly for plasma temperatures above 10 000 K. Size-resolved analyses of particles in the size range from 20 nm up to 800 nm are carried out. It has been found that the signal response correlates with the mass distribution of the particles.

Material ablation driven by focused laser pulses is an important aspect of laser-induced breakdown spectroscopy (LIBS). It has frequently been used to ablate non-representative layers from the surface or to generate analytic depth profiles of samples. In this paper we discuss the crosstalk effects of the locally ablated surface on the LIBS measurement of the underlying bulk material. As a measuring object, a model artefact is chosen consisting of an iron-free brass bulk sample on which a steel plate with a thickness of 500 mm was brought in close contact. This steel sheet acts as a surrogate for a nonrepresentative surface layer. It is shown by LIBS measurements and cross polish methods that an indirect interaction between the expanding plasma originating from the substrate and the surface layer at the crater walls as well as a recasting of the ablated material from the steel plate have a notable influence on LIBS measurements of the underlying bulk sample. By a two-step ablation sequence crosstalk effects can be reduced to levels equivalent to those persisting for the model artefact without the steel sheet.

A significant parameter to monitor the status of concrete buildings like bridges or parking garages is the determination of the depth profile of the chlorine concentration below the exposed concrete surface. This information is required to define the needed volume of restoration for a construction. Conventional methods like wet chemical analysis are time-and cost-intensive so an alternative method is developed using laserinduced breakdown spectroscopy (LIBS). The idea is to deploy LIBS to analyze drill cores by scanning the sample surface with laser pulses. Chlorine spectral lines in the infrared (IR) and ultraviolet (UV)-range were studied for chlorine detection in hydrated cement samples. The excitation energies of these spectral lines are above 9.2 eV. Hence high plasma temperatures and pulse energies in the range of some hundred millijoules are needed to induce sufficient line intensity levels at the required working distance. To further increase the line intensity and to lower the detection limit (LOD) of chlorine a measuring chamber is used where different ambient pressures and gases can be chosen for the measurements. The influences on the line intensity for pressures between 5 mbar and 400 mbar using helium as process gas and the influence of different laser burst modi like single and collinear double pulses are investigated. For the first time a LOD according to DIN 32 645 of 0.1 mass% was achieved for chlorine in hydrated cement using the UV line 134.72 nm.

Laser-induced breakdown spectroscopy (LIBS) is applied for the inline analysis of liquid slag at a steel works. The slag in the ladle of a slag transporter is measured at a distance of several meters during a short stop of the transporter. The slag surface with temperatures from ≈600 to ≈1400 °C consists of liquid slag and solidified slag parts. Automatic measurements at varying filling levels of the ladle are realized, and the duration amounts to 2 min including data transmission to the host computer. Analytical results of the major components such as CaO, Fe, SiO2, MgO, Mn, and Al2O3 are compared with reference values from the steel works laboratory for solid pressed slag samples as well as for samples from the liquid slag. Stable 24/7 operation during the first three-month test run was achieved.

The miniaturization of analytical techniques is a general trend in speciation analytics. We have developed a new analytical technique combining high pressure liquid chromatography (HPLC) with laser-induced breakdown spectroscopy (LIBS). This enables a moleculespecific separation followed by an element-specific analysis of smallest amounts of complex samples. The liquid flow coming from a HPLC pump is transformed into a continuous stream of small droplets (diameter 50 -100 Am, volume 65 -500 pl) using a piezoelectric pulsed nozzle. After the detection of single droplets with a droplet detector, a Q-switched Nd:YAG Laser is triggered to emit a synchronized laser pulse that irradiates a single droplet. The droplets are evaporated and transformed to the plasma state. The spectrum emitted from the plasma is collected by a spherical mirror and directed through the entrance slit of a Paschen -Runge spectrometer equipped with channel photomultipliers. The spectrometer detects 31 elements simultaneously covering a spectral range from 120 to 589 nm. Purging the measurement chamber with argon enables the detection of vacuum -UV lines. Since the sample is transferred to the plasma state without dilution, very low flow rates in the sub-Al/min range can be realised.

In the last years laser-induced breakdown spectroscopy was introduced in various industrial applications. Automated inspection machines were developed capable to operate under harsh ambient conditions. As an example laser-induced breakdown spectroscopy-based inspection machines for the identification testing of fittings and tubes made of high-alloy steel will be presented. Within an inspection time of 2 seconds 100 spectra are gained yielding the signals of 12 elemental lines to identify more than 30 different high-alloy steel grades in order to prevent material mix-ups at the end of a production line prior to packaging and dispatch. More than 1.5 million products have been inspected within the last 5 years in routine operation. Requirements, concepts and design of such machines will be discussed considering the issues on analytical resolution and system monitoring. For the first time a data set of more than 10 8 laser-induced breakdown spectroscopy measurements has become available, giving insight into the long-term behavior of the system performance. First evaluations of this data demonstrate the influence of laser power, sample position and temperature on the spectroscopic signals and the system state. Future demands on next-generation inspection machines based on laser-induced breakdown spectroscopy will be defined.

Comparative measurements of Laser-Induced Breakdown Spectroscopy (LIBS) for ultraviolet (UV) and near infrared (NIR) excitation wavelengths on a wide range of plastics and one kind of explosive are presented. The focus of work is on the influence of laser wavelength on the Signal-to-peak to peak noise ratio (SPPNR) for selected emission lines as well as the plasma thresholds for NIR and UV excitation wavelengths. The merits of both excitation wavelengths are discussed with respect to the detection of explosives.

In emissions originating from industrial processes, elemental concentration characteristically depends on particle size. Therefore, not only is the average chemical composition of the particles in the focus of interest but also their size-dependent composition. For industrial applications such as on-line process control, a system using laser-induced breakdown spectroscopy (LIBS) is developed providing the analysis of particulate matter directly in an air stream with a short response time to changes in elemental composition. By using a co-flow in addition to the aersosol flow the time resolution of the system can be enhanced. Investigations are undertaken concerning properties of the laser plasma, the analysis of monodisperse and polydisperse aerosols with regard to the relative elemental concentration and the mass concentration of the particles. The system can be calibrated to either total elemental concentrations or relative compositions. The signal response to a variation of elemental concentration as well as to the particle mass concentration show kinds of saturation effects. Temporal plasma evolution for CaCl 2 particles and pure argon are investigated. Different decay times for argon and the particle matter depending on the origin of lines within the plasma are observed. Electron density and temperature are determined using Ca emission lines to describe the temporal evolution of the plasma state for the particle analysis. It has been observed that the electron density increases rapidly for plasma temperatures above 10 000 K. Size-resolved analyses of particles in the size range from 20 nm up to 800 nm are carried out. It has been found that the signal response correlates with the mass distribution of the particles.

The use of laser-induced breakdown spectrometry ͑LIBS͒ for the analysis of heavy metals and brominated flame retardants in end-of-life waste electric and electronic equipment ͑EOL-WEEE͒ pieces is investigated. Single-and double-pulse plasma excitation as well as the influence of detection parameters is studied to yield a parameter field with improved sensitivity and limits of detection. A LIBS analyzer was set up as an on-line measuring unit to detect heavy metals and brominated flame retardants in moving EOL-WEEE pieces in an automatic sorting line. An autofocusing unit with an adjustment range of 50 mm was incorporated to permit measurements of objects that pass by a LIBS analyzer with their surfaces at various distances from it. Tests with EOL-WEEE monitor housings on the conveyor belt of a pilot sorting system successfully demonstrated the capability of the LIBS analyzer to quantify the concentration of hazardous elements in real waste EOL-WEEE pieces.

Laser-induced breakdown spectro metry (LIBS) with m ultiple pulse excitation has been applied for the m ultielem ental analysis of steel samples in the vacuum ultraviolet. The em ission of the induced plasm a was coupled into a Paschen-Runge spectrom eter equipped with photomultipliers linked to high-speed multichannel signal electronics. Tim e-resolved signal evaluation yields a signi cantly improved signal-to-noise ratio for the plasma emission periods after a multipulse excitation. Reference m aterials for low-alloy steel grades were used to calibrate the measurem ents. The investigations concen trated on the light elem ents phosphorus, sulfur, and carbon using emission wavelengths in the range from 178.28 nm to 193.09 nm. For the rst tim e, limits of detection below 10 m g/g were achieved for the light elem ents phosphorus, sulfur, and carbon using LIBS. With these resu lts the basis is established for future on-line applications of LIBS in the steel industry.

LIBS can be used as an online method of characterizing galvanized coatings on sheet steel moving through a production line. The traversing sheet steel is irradiated with a series of single laser bursts, each at a different position on the sheet steel. An ablation depth in the same range as the coating thickness (about 10 μm) is achieved by using a Nd:YAG laser at 1064 nm in collinear double-pulse mode. The coating thickness is determined from the ratio of the intensities of an iron line and a zinc line measured at a burst energy high enough to penetrate the coating with a single burst. Experiments at different burst energies were carried out to optimize the thickness resolution, and a method of systematically selecting iron and zinc lines was deduced, which is based on multivariate data analysis (MVDA) of the intensity ratios calculated for a set of 6 zinc lines and 21 iron lines. A temperature correction was applied, because the parameters of the plasma change with burst energy, and the influence of this on the thickness resolution is discussed. The ambient atmosphere present (air, Ar, N 2 ) as well as self-absorption of spectral lines both have an influence on the thickness resolution. At optimum conditions, a thickness measurement accuracy of better than 150 nm was obtained for a set of electrolytic galvanized sheet steels with coating thicknesses in the range 4.1-11.2 μm.

The sensitivity of laser-induced breakdown spectroscopy of solid samples depends on the number of ablated and excited analytes. Laser ablation of solid samples can be enhanced by using collinear multiple laser pulses, for example double or triple pulses, rather than single laser pulses with the same total laser pulse energy. The ablation rates and the plasma conditions are affected by the ambient gas. In this study laser ablation was examined by varying the interpulse separation of the multiple pulses, within double and triple-pulse bursts, and the gas mass density at constant gas pressure. Different ambient gases and gas mixtures consisting of argon, oxygen, and nitrogen were used to study their effect on ablation rates. In a pure argon atmosphere (99.999% v/v Ar) the ablation burst number required to penetrate a steel plate of thickness 100 μm is reduced by a factor of approximately six by use of triple-pulse bursts with a symmetric interpulse separation of 15 μs rather than single pulses with the same total burst energy of 105 mJ. For double and single pulses the factors are 1.6 for Ar and 2.8 for synthetic air. Analyte lines are 4 to 8 times more intense if an argon atmosphere, rather than air, is used.

Los estudios químicos sobre restos zooarqueológicos se vienen desarrollando con mayor intensidad en las últimas décadas, especialmente aquellos dedicados a la identificación de huellas químicas o diversos tipos de isótopos y sus relaciones. El objetivo de este trabajo es el de presentar dos procedimientos utilizados para la caracterización química de huesos en base a datos espectrométricos obtenidos mediante la técnica LIBS (Laser Induced Breakdown Spectroscopy). El primero denominado Adición Estándar, consiste en un procedimiento destructivo, con un grado de error estimable, mientras que el segundo, Reemplazo de la Matriz Ósea, constituye un método no invasivo y con un grado de error relativamente bajo. Con esto se espera lograr el desarrollo de un corpus metodológico y analítico que permita caracterizar de un modo eficiente y económico las huellas químicas de diverso material arqueofaunístico. En este sentido se intenta lograr una caracterización química de huesos arqueológicos co...

Metal artworks are subjected to corrosion and oxidation processes due to reactive agents present in the air, water and in the ground that these objects have been in contact with for hundreds of years. This is the case for archaeological metals that are recovered from excavation sites, as well as artefacts exposed to polluted air. Stabilization of the conservation state of these objects needs precise diagnostics of the accrued surface layers and identification of original, historical materials before further protective treatments, including safe laser cleaning of unwanted layers. This paper presents analyses of the chemical composition and stratigraphy of corrosion products with the use of laser OPEN ACCESS induced breakdown spectroscopy (LIBS) and Raman spectroscopy. The discussion of the results is supported by material studies (SEM-EDS, XRF, ion-analyses). The tests were performed on several samples taken from original objects, including copper roofing from Wilanów Palace in Warsaw and Karol Poznański Palace in Łódź, bronze decorative figures from the Wilanów Palace gardens, and four archaeological examples of old jewellery (different copper alloys). Work has been performed as a part of the MATLAS project in the frames of EEA and Norway Grants (www.matlas.eu) and the results enable the comparison of the methodology and to elaborate the joint diagnostic procedures of the three project partner independent laboratories.

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Laser Induced Breakdown Spectroscopy (LIBS) and Laser Ablation Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) are used simultaneously for spatially resolved mapping of major and trace elements and isotopes within aBastnäsiterare earth ore sample.

A method based on laser induced breakdown spectroscopy (LIBS) and neural networks (NNs) has been developed and applied to the identification and discrimination of specific bacteria strains (Pseudomonas aeroginosa, Escherichia coli and Salmonella typhimurium). Instant identification of the samples is achieved using a spectral library, which was obtained by analysis using a single laser pulse of representative samples and treatment by neural networks. The samples used in this study were divided into three groups, which were prepared on three different days. The results obtained allow the identification of the bacteria tested with a certainty of over 95%, and show that only a difference between the bacteria can cause identification. Single-shot measurements were sufficient for clear identification of the bacterial strains studied. The method can be developed for automatic real time, fast, reliable and robust measurements and can be packaged in portable systems for non-specialist users.

Laser induced breakdown spectroscopy (LIBS) calibration curves for ZrSn alloys were obtained. Relationships between the atomic emission lines present in the spectra and the Sn concentration of the samples showed a linear behavior. Also Zy-2 standards were measured to contrast the behavior of the technique in different kind of alloys. The choice of proper Sn and Zr lines and the equipment´s parameters, such as "integration start delay" and the spectrometer height, were fundamental to enhance the measurements. All samples were analyzed with X-ray fluorescence for a precise determination of their Sn concentration.

Laser-induced breakdown spectroscopy (LIBS) has emerged as a powerful analytical method for the elemental mapping and depth profiling of many materials. This review offers insight into the contemporary applications of LIBS for the depth profiling of materials whose elemental composition changes either abruptly (multilayered materials) or continuously (functionally graded or corroded materials). The spectrum of materials is discussed, spanning from laboratory-synthesized model materials to real-world products including materials for fusion reactors, photovoltaic cells, ceramic and galvanic coatings, lithium batteries, historical and archaeological artifacts, and polymeric materials. The nuances of ablation conditions and the resulting crater morphologies, which are instrumental in depth-related studies, are discussed in detail. The challenges of calibration and quantitative profiling using LIBS are also addressed. Finally, the possible directions of the evolution of LIBS applications...

Pyroprocessing of used nuclear fuel (UNF) has many advantages-including that it is proliferation resistant. However, as part of the process, special nuclear materials accumulate in the electrolyte salt and present material accountability and safeguards concerns. The main motivation of this work was to explore a laser-induced breakdown spectroscopy (LIBS) approach as an online monitoring technique to enhance the material accountability of special nuclear materials in pyroprocessing. In this work, a vacuum extraction method was used to draw the molten salt (CeCl 3 -GdCl 3 -LiCl-KCl) up into 4 mm diameter Pyrex tubes where it froze. The salt was then removed and the solid salt was measured using LIBS and inductively coupled plasma mass spectroscopy (ICP-MS). A total of 36 samples were made that varied the CeCl 3 and GdCl 3 (surrogates for uranium and plutonium, respectively) concentrations from 0.5 wt% to 5 wt%. From these samples, univariate calibration curves for Ce and Gd were generated using peak area and peak intensity methods. For Ce, the Ce 551.1 nm line using the peak area provided the best calibration curve with a limit of detection (LOD) of 0.099 wt% and a root mean squared error of cross-validation (RMSECV) of 0.197 wt%. For Gd, the best curve was generated using the peak intensities of the Gd 564.2 nm line resulting in a LOD of 0.027 wt% and a RMSECV of 0.295 wt%. The RMSECV for the univariate cases were determined using leave-one-out cross-validation. In addition to the univariate calibration curves, partial least squares (PLS) regression was done to develop a calibration model. The PLS models yielded similar results with RMSECV (determined using Venetian blind cross-validation with 17% left out per split) values of 0.30 wt% and 0.29 wt% for Ce and Gd, respectively. This work has shown that solid pyroprocessing salt can be qualitatively and quantitatively monitored using LIBS. This work has the potential of significantly enhancing the material monitoring and safeguards of special nuclear materials in pyroprocessing.

Biochar has gained agricultural importance as a soil amendment because of its important agricultural properties such as water retention, plant nutrient supplier, promoter of microorganism growth, sequestration action of atmospheric CO 2 , etc. Further, it is a low cost material being produced by recycling. Due to its active sites, biochar can adsorb nutrients so acting as a soil fertilizer. Thus the rapid assessment of nutrients in these materials is essential to ensure quality control for agricultural purposes. This work aimed to develop a simple analytical method based on Laser-Induced Breakdown Spectroscopy (LIBS) to determine Ca in biochar-based fertilizers. In particular, biochar samples enriched with Ca were prepared from peanut shells, residues of eucalyptus and banana fibers. The calibration standards were prepared by matrix matching using a biochar from eucalyptus residues. Different spectral preprocessing were evaluated to enhance the precision and accuracy of the method. However, the matrix effects demanded the use of internal standardization as the appropriate methodology to obtain the best accuracy. A linear correlation coefficient of 0.989 and a linear work range of 1.51-11.23% Ca were obtained using the proposed method, which yielded limits of detection and quantification of 0.45% e 1.51%, respectively. Calcium contents determined by LIBS in biochar-based fertilizers were in good agreement (paired t-test at 95% confidence level) with those determined by using High-Resolution Continuous Source Atomic Absorption Spectrometry (HR-CS FAAS) as the reference technique. Thus, the importance of internal standardization was demonstrated to be successful for the quantitative analysis of Ca in complex matrices like biochar-based fertilizers.

Laser-induced breakdown spectroscopy (LIBS) is applied for the inline analysis of liquid slag at a steel works. The slag in the ladle of a slag transporter is measured at a distance of several meters during a short stop of the transporter. The slag surface with temperatures from ≈600 to ≈1400 °C consists of liquid slag and solidified slag parts. Automatic measurements at varying filling levels of the ladle are realized, and the duration amounts to 2 min including data transmission to the host computer. Analytical results of the major components such as CaO, Fe, SiO 2 , MgO, Mn, and Al 2 O 3 are compared with reference values from the steel works laboratory for solid pressed slag samples as well as for samples from the liquid slag. Stable 24/7 operation during the first three-month test run was achieved. A t the steel works of voestalpine Stahl GmbH, Linz, the Linz-Donawitz process (LD or basic oxygen process) is used for crude steel production. After steel tapping, approximately 15-20 tons of liquid LD (converter) slag is filled into ladles. Transporters carry the ladles to slag pits where the slag is poured out for cooling and further process ing. The slag temperature in the ladle is in the range of ≈600 to ≈1400 °C and sometimes even more. The amount of slag at this plant is about 600 × 10 3 tons per year. Because the slag composition varies from ladle to ladle, the analysis of each ladle is of interest for the further use of the slag, such as for bituminous road construction and others. Standard X-ray fluorescence (XRF) analysis 3 requires sampling, sample transport, and preparative actions prior to analysis. For a fast analysis of each ladle, this is considered as being too labor-intensive and time-consuming. Furthermore, a complete automation is hard to implement. In contrast, laserinduced breakdown spectroscopy (LIBS) allows measurement directly in the process at a distance of several meters and can be automated more easily while avoiding mechanical sampling, sample transport, and mechanical sample preparation. Several aspects and applications of LIBS are described in the literature. The LIBS analysis of liquid steel, 11-15 liquid aluminum alloys, and liquid glass are noted because of needs similar to that for liquid slag analysis. Recently, industrial applications of LIBS with 24/7 operation were published for sorting and analyzing materials (coal, minerals) on moving conveyor belts. Analysis of steel slags is reported for solid samples which are prepared by crushing, milling, homogenizing, and pressing to pellets prior to LIBS analysis, as well as measured directly at a steel works site next to a vacuum degasser unit.

A process optimization and control system called VAI-CON Chem has been developed that uses laser-induced breakdown spectroscopy (LIBS) to quasicontinuously chemically analyze liquid high-alloy steel under pressure. The beam from a Nd:YAG laser, located on safe ground and operating at its fundamental wavelength, is guided by a mirror system to a process tuyere below bath level. Passing through the ∼1.5 m long tuyere, the beam is then focused onto the steel bath. Light emitted from the induced plasma passes back through the tuyere, which is coupled to a fiber optic cable that carries the information over a distance of approximately 10 m back to an Echelle spectrometer located beside the laser. Calibrations were performed using the complete system, located in a laboratory, during system testing. An induction furnace was used to simulate the AOD converter, wherein the samples were molten and superheated to a temperature of ∼1600 °C and kept at a pressure of ∼1.7 bar under an argon atmosphere. Twelve different high alloyed reference samples taken from normal AOD production with Fe concentrations of >48 wt.% and non-Fe element concentrations of up to 25 wt.% were available for calibration. The mean residual deviations (defined as the square root of the variance of the concentration ratios determined by LIBS and the reference element concentration ratios) obtained were close to those reported for other comparable highalloy samples that were investigated at room temperature under normal atmospheric pressure.

Laser-induced breakdown spectroscopy (LIBS) is applied for the inline analysis of liquid slag at a steel works. The slag in the ladle of a slag transporter is measured at a distance of several meters during a short stop of the transporter. The slag surface with temperatures from ≈600 to ≈1400 °C consists of liquid slag and solidified slag parts. Automatic measurements at varying filling levels of the ladle are realized, and the duration amounts to 2 min including data transmission to the host computer. Analytical results of the major components such as CaO, Fe, SiO2, MgO, Mn, and Al2O3 are compared with reference values from the steel works laboratory for solid pressed slag samples as well as for samples from the liquid slag. Stable 24/7 operation during the first three-month test run was achieved.