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Analytical evaluation of nebulizers for the introduction of acetic acid extracts aiming at the determination of trace elements by inductively coupled plasma mass spectrometry
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Jefferson S. de Gois, Tatiane de A. Maranhão, Fernando J.S. de Oliveira, Vera L.A.F. Bascuñan, Adilson J. Curtius, Daniel L.G. Borges
Most of the official procedures aiming at classification of solid waste toxicity take into account metal solubility and bioavailability by means of extraction experiments using acetic acid solutions. Hence, the aim of this work was to investigate and optimize conditions to suppress the effect of acetic acid on the determination of trace elements using inductively coupled plasma mass spectrometry. The performance of four nebulizers (cross-flow (CFN), ultrasonic (USN), Meinhard (MN) and MicroMist (MMN)) were compared as to their efficiency in minimizing spectral and non-spectral effects on the determination of Ag, As, Ba, Cd, Cr, Hg, Pb and Se, with the ultimate goal to analyze acetic acid extracts obtained from solid waste residues. Operating conditions (desolvation temperatures for USN, RF power and nebulizer gas flow rates) were optimized individually for each nebulizer and for all analytes maintained in 0.14molL-1 HNO3 solutions and in solutions prepared with acetic acid and acetic acid+NaOH, adjusted to pH 2.88 and 4.93, respectively. Pronounced non-spectral interference for 75As and 82Se was observed in the presence of acetic acid for CF and MN, although to a less extent also for MMN and USN. Signal increase for blank solutions measured at m/z 208 (208Pb) for CFN and MN, 107 (107Ag) for USN and MN coupled to a cyclonic chamber and, m/z 82 (82Se) for USN was observed, indicating increased risk of spectral interference upon an increase in the concentration of acetic acid. Signal increase at specific m/z ratios, however, was not significant when the MMN was used, with the exception of m/z 52 (52Cr) in acetic acid solutions, arising from the formation of 40Ar12C+. This same effect was noticed for all nebulizers, although at noticeably different intensities. A signal stability study was performed, demonstrating that variations in the analytical signal were within a 20% range for all analytes, with the exception of Hg, after continuous aspiration for 70min. The nebulization efficiency ranged from 4.6% to 64% for CF and MM nebulizers, respectively. Leaching solution from a solid waste residue was analyzed using all the studied systems in three different calibration media. In general, the results indicate that calibration solutions should be prepared in the same medium as the leachate, although for USN and MMN reasonable agreement among the results was obtained regardless of the calibration solution used. Detection limits ranging from 0.01μgL-1 to 2μgL-1 were obtained, with little discrepancy amongst the different nebulizers used.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
Jefferson S. de Gois, Tatiane de A. Maranhão, Fernando J.S. de Oliveira, Vera L.A.F. Bascuñan, Adilson J. Curtius, Daniel L.G. Borges
Most of the official procedures aiming at classification of solid waste toxicity take into account metal solubility and bioavailability by means of extraction experiments using acetic acid solutions. Hence, the aim of this work was to investigate and optimize conditions to suppress the effect of acetic acid on the determination of trace elements using inductively coupled plasma mass spectrometry. The performance of four nebulizers (cross-flow (CFN), ultrasonic (USN), Meinhard (MN) and MicroMist (MMN)) were compared as to their efficiency in minimizing spectral and non-spectral effects on the determination of Ag, As, Ba, Cd, Cr, Hg, Pb and Se, with the ultimate goal to analyze acetic acid extracts obtained from solid waste residues. Operating conditions (desolvation temperatures for USN, RF power and nebulizer gas flow rates) were optimized individually for each nebulizer and for all analytes maintained in 0.14molL-1 HNO3 solutions and in solutions prepared with acetic acid and acetic acid+NaOH, adjusted to pH 2.88 and 4.93, respectively. Pronounced non-spectral interference for 75As and 82Se was observed in the presence of acetic acid for CF and MN, although to a less extent also for MMN and USN. Signal increase for blank solutions measured at m/z 208 (208Pb) for CFN and MN, 107 (107Ag) for USN and MN coupled to a cyclonic chamber and, m/z 82 (82Se) for USN was observed, indicating increased risk of spectral interference upon an increase in the concentration of acetic acid. Signal increase at specific m/z ratios, however, was not significant when the MMN was used, with the exception of m/z 52 (52Cr) in acetic acid solutions, arising from the formation of 40Ar12C+. This same effect was noticed for all nebulizers, although at noticeably different intensities. A signal stability study was performed, demonstrating that variations in the analytical signal were within a 20% range for all analytes, with the exception of Hg, after continuous aspiration for 70min. The nebulization efficiency ranged from 4.6% to 64% for CF and MM nebulizers, respectively. Leaching solution from a solid waste residue was analyzed using all the studied systems in three different calibration media. In general, the results indicate that calibration solutions should be prepared in the same medium as the leachate, although for USN and MMN reasonable agreement among the results was obtained regardless of the calibration solution used. Detection limits ranging from 0.01μgL-1 to 2μgL-1 were obtained, with little discrepancy amongst the different nebulizers used.
Highlights
► Four distinct nebulizers are evaluated for analysis of acetic acid extracts at two pH ► Tolerance to low concentrations of acetic acid was observed in all systems ► Trace elements determination in acetic acid requires specific calibration approachesProduction of the ideal sample shape for Total Reflection X-ray Fluorescence Analysis
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
C. Horntrich, P. Kregsamer, J. Prost, F. Stadlbauer, P. Wobrauschek, C. Streli
Total Reflection X-ray Fluorescence analysis (TXRF) is a well-established analytical method in the semiconductor industry for the analysis of silicon wafer surfaces. For the calibration of the spectrometer typically an external standard is used which is sensitive to quantification errors. In general TXRF is known to allow for linear calibration. For small sample amounts (pg to ng region) the thin film approximation is valid neglecting absorption effects of the exciting and the detected radiation. For higher total amounts of sample the relation between fluorescence intensity and sample amount diverges from linearity (saturation effect). These deviations lead to difficulties in quantification with external standard. Content of the presented work is the production of the ideal TXRF sample shape, which was theoretically determined to be ring-shaped. A possibility for the production of samples with ring shape is the use of a nanodispensing system combined with a positioning device. Therewith it is possible to produce ring shaped samples in a controlled way with the ring consisting of individual nanodroplets, so that the wanted diameter of the ring can be chosen. A comparison of the fluorescence intensities emitted by contracted and ring shaped samples shows that the ring shape is not only theoretically the best TXRF shape but also experimentally. It could be proven that for contracted samples the saturation effect occurs at a lower sample mass than for samples with ring shape.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy
C. Horntrich, P. Kregsamer, J. Prost, F. Stadlbauer, P. Wobrauschek, C. Streli
Total Reflection X-ray Fluorescence analysis (TXRF) is a well-established analytical method in the semiconductor industry for the analysis of silicon wafer surfaces. For the calibration of the spectrometer typically an external standard is used which is sensitive to quantification errors. In general TXRF is known to allow for linear calibration. For small sample amounts (pg to ng region) the thin film approximation is valid neglecting absorption effects of the exciting and the detected radiation. For higher total amounts of sample the relation between fluorescence intensity and sample amount diverges from linearity (saturation effect). These deviations lead to difficulties in quantification with external standard. Content of the presented work is the production of the ideal TXRF sample shape, which was theoretically determined to be ring-shaped. A possibility for the production of samples with ring shape is the use of a nanodispensing system combined with a positioning device. Therewith it is possible to produce ring shaped samples in a controlled way with the ring consisting of individual nanodroplets, so that the wanted diameter of the ring can be chosen. A comparison of the fluorescence intensities emitted by contracted and ring shaped samples shows that the ring shape is not only theoretically the best TXRF shape but also experimentally. It could be proven that for contracted samples the saturation effect occurs at a lower sample mass than for samples with ring shape.
Highlights
► The ring shape was found to theoretically be the ideal TXRF sample in a former study. ► A nanodispensing system enables the production of ring shaped samples. ► Contracted and ring shaped samples were compared. ► The ring shape was also experimentally proven to be the best TXRF shape.The mechanism for continuum polarization in laser induced breakdown spectroscopy of Si(111)
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
John S. Penczak, Yaoming Liu, Richard D. Schaller, Daniel H. Rich, Robert J. Gordon
Polarization of the plasma luminescence produced by both nanosecond and femtosecond laser ablation of Si(111) was analyzed under different conditions of fluence and detection geometry. It is shown that the luminescence is partially polarized and is directed in the plane of the crystal. The time evolution of the plasma emission signal was also investigated with the use of a streak camera. The mechanism for polarization is proposed to be preferential reflection of s-polarized light (i.e., light polarized normal to the plane of laser incidence) by the melted surface, in agreement with the Fresnel equations. Earlier reports of much stronger polarization are shown to be erroneous.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
John S. Penczak, Yaoming Liu, Richard D. Schaller, Daniel H. Rich, Robert J. Gordon
Polarization of the plasma luminescence produced by both nanosecond and femtosecond laser ablation of Si(111) was analyzed under different conditions of fluence and detection geometry. It is shown that the luminescence is partially polarized and is directed in the plane of the crystal. The time evolution of the plasma emission signal was also investigated with the use of a streak camera. The mechanism for polarization is proposed to be preferential reflection of s-polarized light (i.e., light polarized normal to the plane of laser incidence) by the melted surface, in agreement with the Fresnel equations. Earlier reports of much stronger polarization are shown to be erroneous.
Highlights
► The LIBS continuum for Si produced with fs and ns lasers is 15–20% s-polarized. ► The time dependence of the polarization was measured with a streak camera. ► The polarization mechanism is reflection of plasma emission by the molten surface. ► Earlier observations of greater polarization were due to scattered laser light.Dual-wavelength differential spectroscopic imaging for diagnostics of laser-induced plasma
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
V. Motto-Ros, Q.L. Ma, S. Grégoire, W.Q. Lei, X.C. Wang, F. Pelascini, F. Surma, V. Detalle, J. Yu
A specific configuration for plasma fast spectroscopic imaging was developed, where a pair of narrowband filters, one fitting an emission line of a species to be studied and the other out of its emission line, allowed double images to be taken for a laser-induced plasma. A dedicated software was developed for the subtraction between the double images. The result represents therefore the monochromatic emission image of the species in the plasma. We have shown in this work that such configuration is especially efficient for the monitoring of a plasma generated under the atmospheric pressure at very short delays after the impact of the laser pulse on the target, when a strong continuum emission is observed. The efficiency of the technique has been particularly demonstrated in the study of laser-induced plasma on a polymer target. Molecular species, such as C2 and CN, as well as atomic species, such as C and N, were imaged starting from 50ns after the laser impact. Moreover space segregation of different species, atomic or molecular, inside of the plasma was clearly observed.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
V. Motto-Ros, Q.L. Ma, S. Grégoire, W.Q. Lei, X.C. Wang, F. Pelascini, F. Surma, V. Detalle, J. Yu
A specific configuration for plasma fast spectroscopic imaging was developed, where a pair of narrowband filters, one fitting an emission line of a species to be studied and the other out of its emission line, allowed double images to be taken for a laser-induced plasma. A dedicated software was developed for the subtraction between the double images. The result represents therefore the monochromatic emission image of the species in the plasma. We have shown in this work that such configuration is especially efficient for the monitoring of a plasma generated under the atmospheric pressure at very short delays after the impact of the laser pulse on the target, when a strong continuum emission is observed. The efficiency of the technique has been particularly demonstrated in the study of laser-induced plasma on a polymer target. Molecular species, such as C2 and CN, as well as atomic species, such as C and N, were imaged starting from 50ns after the laser impact. Moreover space segregation of different species, atomic or molecular, inside of the plasma was clearly observed.
Highlights
► Imaging to study species with time and space resolution in laser induced plasma. ► Image display of multiple species is proposed based on RGB color model. ► Molecular emission (CN and C2) is observed at very short delays (50ns). ► Segregation of different species inside the plasma is clearly established.Effect of ambient conditions on ultraviolet femtosecond pulse laser induced breakdown spectra
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
M.P. Mateo, V. Piñon, D. Anglos, G. Nicolas
In this work, the results of a study on the influence of buffer gas and pressure on the LIBS spectrum characteristics are reported. Ultraviolet femtosecond pulses were employed in the analysis of several solid samples including brass, copper, aluminum and silicon under different buffer gasses: air, argon and helium. Given a buffer gas, ambient pressure was varied and its effect on the intensity and broadening of the spectral emission lines and on the background of the spectra was evaluated. A maximum emission intensity of the lines was observed at 500hPa in helium or argon and at 30hPa in air. Line broadening, attributed to the Stark effect, was found to be negligible in spectra acquired with helium as a buffer gas compared to spectra recorded under air or argon atmosphere, which showed noticeable line broadening particularly at high ambient pressure.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
M.P. Mateo, V. Piñon, D. Anglos, G. Nicolas
In this work, the results of a study on the influence of buffer gas and pressure on the LIBS spectrum characteristics are reported. Ultraviolet femtosecond pulses were employed in the analysis of several solid samples including brass, copper, aluminum and silicon under different buffer gasses: air, argon and helium. Given a buffer gas, ambient pressure was varied and its effect on the intensity and broadening of the spectral emission lines and on the background of the spectra was evaluated. A maximum emission intensity of the lines was observed at 500hPa in helium or argon and at 30hPa in air. Line broadening, attributed to the Stark effect, was found to be negligible in spectra acquired with helium as a buffer gas compared to spectra recorded under air or argon atmosphere, which showed noticeable line broadening particularly at high ambient pressure.
Highlights
► Influence of buffer gas (air, helium and argon) on the LIBS signal ► Influence of pressure gas (under and over atmospheric pressure) on the LIBS signal ► LIBS analysis of solid materials using ultraviolet femtosecond pulsesLaser light scattering in a laser-induced argon plasma: Investigations of the shock wave
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
B. Pokrzywka, A. Mendys, K. Dzierżęga, M. Grabiec, S. Pellerin
Shock wave produced by a laser induced spark in argon at atmospheric pressure was examined using Rayleigh and Thomson scattering. The spark was generated by focusing a laser pulse from the second harmonic (λ =532nm) of a nanosecond Nd:YAG laser using an 80mm focal length lens, with a fluence of 2kJ·cm−2. Images of the spark emission were recorded for times between 30ns and 100μs after the laser pulse in order to characterize its spatial evolution. The position of the shock wave at several instants of its evolution and for several plasma regions was determined from the Rayleigh-scattered light of another nanosecond Nd:YAG laser (532nm, 40J·cm−2 fluence). Simultaneously, Thomson scattering technique was applied to determine the electron density and temperature in the hot plasma core. Attempts were made to describe the temporal evolution of the shock wave within a self-similar model, both by the simple Sedov–Taylor formula as well as its extension deduced by de Izarra. The temporal radial evolution of the shock position is similar to that obtained within theory taking into account the counter pressure of the ambient gas. Density profiles just behind the shock front are in qualitative agreement with those obtained by numerically solving the Euler equations for instantaneous explosion at a point with counter pressure.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
B. Pokrzywka, A. Mendys, K. Dzierżęga, M. Grabiec, S. Pellerin
Shock wave produced by a laser induced spark in argon at atmospheric pressure was examined using Rayleigh and Thomson scattering. The spark was generated by focusing a laser pulse from the second harmonic (λ =532nm) of a nanosecond Nd:YAG laser using an 80mm focal length lens, with a fluence of 2kJ·cm−2. Images of the spark emission were recorded for times between 30ns and 100μs after the laser pulse in order to characterize its spatial evolution. The position of the shock wave at several instants of its evolution and for several plasma regions was determined from the Rayleigh-scattered light of another nanosecond Nd:YAG laser (532nm, 40J·cm−2 fluence). Simultaneously, Thomson scattering technique was applied to determine the electron density and temperature in the hot plasma core. Attempts were made to describe the temporal evolution of the shock wave within a self-similar model, both by the simple Sedov–Taylor formula as well as its extension deduced by de Izarra. The temporal radial evolution of the shock position is similar to that obtained within theory taking into account the counter pressure of the ambient gas. Density profiles just behind the shock front are in qualitative agreement with those obtained by numerically solving the Euler equations for instantaneous explosion at a point with counter pressure.
Highlights
► We investigated shock wave evolution by Rayleigh scattering method. ► 2D map of shockwave position for several times after plasma generation is presented. ► Shock wave evolution is not satisfactorily described within self-similar models. ► Evolution of shock position similar to theory taking into account counter pressure. ► Density profile behind the shock similar to numerical solution of Euler equations.Correlation between native bonds in a polymeric material and molecular emissions from the laser-induced plasma observed with space and time resolved imaging
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
S. Grégoire, V. Motto-Ros, Q.L. Ma, W.Q. Lei, X.C. Wang, F. Pelascini, F. Surma, V. Detalle, J. Yu
Emissions from C2 molecules and CN radicals in laser-induced plasmas on polymeric materials were observed with time-resolved spectroscopic imaging. More precisely, differential imaging with a pair of narrowband filters (one centered on the emission line and another out of the line) was used to extract emission images of interested molecules or radicals. The correlation between the molecular emission image of the plasma and the molecular structure of the polymer to be analyzed was studied for four different types of materials: polyamide (PA) with native CN bonds, polyethylene (PE) with simple CC bonds, polystyrene (PS) with delocalized double CC bonds, and polyoxymethylene (POM) which neither contains CC nor CN bonds. A clear correlation is demonstrated between emission and molecular structure of the material, allowing the identification of several organic compounds by differential spectroscopic imaging.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
S. Grégoire, V. Motto-Ros, Q.L. Ma, W.Q. Lei, X.C. Wang, F. Pelascini, F. Surma, V. Detalle, J. Yu
Emissions from C2 molecules and CN radicals in laser-induced plasmas on polymeric materials were observed with time-resolved spectroscopic imaging. More precisely, differential imaging with a pair of narrowband filters (one centered on the emission line and another out of the line) was used to extract emission images of interested molecules or radicals. The correlation between the molecular emission image of the plasma and the molecular structure of the polymer to be analyzed was studied for four different types of materials: polyamide (PA) with native CN bonds, polyethylene (PE) with simple CC bonds, polystyrene (PS) with delocalized double CC bonds, and polyoxymethylene (POM) which neither contains CC nor CN bonds. A clear correlation is demonstrated between emission and molecular structure of the material, allowing the identification of several organic compounds by differential spectroscopic imaging.
Highlights
► Plasma imaging method to discriminate different type of polymers. ► Molecular emissions (CN and C2) are spatially and temporally correlated to native bonds. ► Several formation processes of molecular fragments are observed.Laser-induced plasma analysis of copper alloys based on Local Thermodynamic Equilibrium: An alternative approach to plasma temperature determination and archeometric applications
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
R. Gaudiuso, M. Dell'Aglio, O. De Pascale, A. Santagata, A. De Giacomo
The excitation temperature of Laser Induced Plasmas (LIPs) of copper-based alloys was determined with an alternative approach, which reverses the procedure of calibration-free methods for quantitative analysis through Laser Induced Breakdown Spectroscopy (LIBS). The inverse method here proposed is based on the Local Thermodynamic Equilibrium (LTE) equations, which were applied to simulate the elemental composition of certified samples at different temperatures, assuming that the actual plasma temperature was the one providing the best agreement with certified data. This procedure was validated for a set of bronze and brass standard samples and in different experimental conditions, by changing laser pulse width (7ns and 250fs) and laser wavelength (1064nm, 532nm and 355nm). The temperature determined with the inverse method was then employed to determine the elemental composition of archeological findings of different copper-based alloys from Southern Italy sites (from VII century B.C. to VII A.D.), in order to test its validity for the analysis of actual unknown samples. The obtained weight percentages showed a good correlation with those obtained with the calibration line method, which provided a further confirmation of the assumptions made.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
R. Gaudiuso, M. Dell'Aglio, O. De Pascale, A. Santagata, A. De Giacomo
The excitation temperature of Laser Induced Plasmas (LIPs) of copper-based alloys was determined with an alternative approach, which reverses the procedure of calibration-free methods for quantitative analysis through Laser Induced Breakdown Spectroscopy (LIBS). The inverse method here proposed is based on the Local Thermodynamic Equilibrium (LTE) equations, which were applied to simulate the elemental composition of certified samples at different temperatures, assuming that the actual plasma temperature was the one providing the best agreement with certified data. This procedure was validated for a set of bronze and brass standard samples and in different experimental conditions, by changing laser pulse width (7ns and 250fs) and laser wavelength (1064nm, 532nm and 355nm). The temperature determined with the inverse method was then employed to determine the elemental composition of archeological findings of different copper-based alloys from Southern Italy sites (from VII century B.C. to VII A.D.), in order to test its validity for the analysis of actual unknown samples. The obtained weight percentages showed a good correlation with those obtained with the calibration line method, which provided a further confirmation of the assumptions made.
Highlights
► A novel method based on LTE was developed for plasma temperature determination. ► Calibration-free quantitative analyses were optimized with the proposed inverse method. ► The inverse method was tested and validated for standard copper-based alloys. ► Archeological finds were analyzed with the inverse method and with calibration lines. ► The inverse method was proved reliable also for the analysis of unknown samples.Laser induced breakdown spectroscopy for fast elemental analysis and sorting of metallic scrap pieces using certified reference materials
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
J. Gurell, A. Bengtson, M. Falkenström, B.A.M. Hansson
A setup utilizing laser induced breakdown spectroscopy (LIBS) for performing elemental analysis in order to classify metallic samples is currently under construction. The setup uses short laser pulses to locally ablate the sample and create luminous plasmas. The emitted light is analyzed spectroscopically for instantaneous determination of the elemental composition. A table-top system based on a compact CCD spectrometer has been constructed and combined with fast software in order to test the concept of remote, single shot material classification with LIBS. Certified reference materials with known elemental compositions were used in the laboratory tests. We report on successful laboratory tests in which samples were classified using an analysis based on optical emission following a single laser pulse and with an operating distance of approximately 1m. Details regarding field tests of this versatile and promising technique are discussed.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
J. Gurell, A. Bengtson, M. Falkenström, B.A.M. Hansson
A setup utilizing laser induced breakdown spectroscopy (LIBS) for performing elemental analysis in order to classify metallic samples is currently under construction. The setup uses short laser pulses to locally ablate the sample and create luminous plasmas. The emitted light is analyzed spectroscopically for instantaneous determination of the elemental composition. A table-top system based on a compact CCD spectrometer has been constructed and combined with fast software in order to test the concept of remote, single shot material classification with LIBS. Certified reference materials with known elemental compositions were used in the laboratory tests. We report on successful laboratory tests in which samples were classified using an analysis based on optical emission following a single laser pulse and with an operating distance of approximately 1m. Details regarding field tests of this versatile and promising technique are discussed.
Highlights
► We give a short background to the area of metallic scrap recycling. ► We present the development of an automatic LIBS-based system for material analysis. ► We present experimental data from laboratory results. ► We discuss the possibility of surface cleaning through laser ablation with this setup.Comparison of gated and non-gated detectors for double-pulse laser induced plasma analysis of trace elements in iron oxide
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
H. Heilbrunner, N. Huber, H. Wolfmeir, E. Arenholz, J.D. Pedarnig, J. Heitz
Double-pulse laser-induced breakdown spectroscopy (LIBS) is an emerging technique for accurate compositional analysis of many different materials. We present results of collinear double-pulse LIBS for analysis of the trace elements aluminum, phosphorus and boron in sintered iron oxide targets. The samples were ablated in air by double-pulse Nd:YAG laser radiation (6ns pulse duration, laser wavelength of 532nm) and spectra were recorded with an Echelle spectrometer equipped either with a CCD (charge coupled device) or an ICCD (intensified charge coupled device) camera. For the trace elements aluminum and phosphorus, the use of the CCD detector system resulted in considerable higher signal-to-noise ratios and/or better limits of detection compared to the results achieved with the ICCD detector. The use of CCD double-pulse LIBS enables to detect low concentrations of phosphorus with a limit of detection of 10ppm by evaluating the UV line at 214.91nm, which overlaps with a Fe I line. Compared to the ICCD system, the CCD system requires the accumulation of a higher number of laser double-pulses to achieve acceptable signal quality. This can be disadvantageous for elements showing pronounced depletion effects as for the trace element boron in sintered iron oxide targets.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
H. Heilbrunner, N. Huber, H. Wolfmeir, E. Arenholz, J.D. Pedarnig, J. Heitz
Double-pulse laser-induced breakdown spectroscopy (LIBS) is an emerging technique for accurate compositional analysis of many different materials. We present results of collinear double-pulse LIBS for analysis of the trace elements aluminum, phosphorus and boron in sintered iron oxide targets. The samples were ablated in air by double-pulse Nd:YAG laser radiation (6ns pulse duration, laser wavelength of 532nm) and spectra were recorded with an Echelle spectrometer equipped either with a CCD (charge coupled device) or an ICCD (intensified charge coupled device) camera. For the trace elements aluminum and phosphorus, the use of the CCD detector system resulted in considerable higher signal-to-noise ratios and/or better limits of detection compared to the results achieved with the ICCD detector. The use of CCD double-pulse LIBS enables to detect low concentrations of phosphorus with a limit of detection of 10ppm by evaluating the UV line at 214.91nm, which overlaps with a Fe I line. Compared to the ICCD system, the CCD system requires the accumulation of a higher number of laser double-pulses to achieve acceptable signal quality. This can be disadvantageous for elements showing pronounced depletion effects as for the trace element boron in sintered iron oxide targets.
Highlights
► Direct comparison of double-pulse LIBS analysis using CCD and ICCD detectors ► Double-pulse LIBS technique for monitoring of trace elements in iron oxide ► CCD detector can result in better signal-to-noise ratios and limits of detection. ► Low P concentrations detectable by CCD double-pulse LIBS of the line at 214.91nm ► CCD system disadvantageous for elements showing pronounced depletion effectsTesting a portable laser-induced breakdown spectroscopy system on geological samples
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
Jozef Rakovský, Olivier Musset, JeanFrançois Buoncristiani, Vincent Bichet, Fabrice Monna, Pascal Neige, Pavel Veis
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.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
Jozef Rakovský, Olivier Musset, JeanFrançois Buoncristiani, Vincent Bichet, Fabrice Monna, Pascal Neige, Pavel Veis
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.
Highlights
► Element cartography maps for sediment which contains tephra layer have been created. ► The maps have been used for on-site conditions determination by statistical treatment. ► Pyritization process on ammonite surface was identified successfully.Development of a laser-induced plasma probe to measure gas phase plasma signals at high pressures and temperatures
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
J.D. Gounder, P. Kutne, W. Meier
The ability of laser induced breakdown spectroscopy (LIBS) technique for on line simultaneous measurement of elemental concentrations has led to its application in a wide number of processes. The simplicity of the technique allows its application to harsh environments such as present in boilers, furnaces and gasifiers. This paper presents the design of a probe using a custom optic which transforms a round beam into a ring (Donut) beam, which is used for forming a plasma in an atmosphere of nitrogen at high pressure (20bar) and temperature (200°C). The LIBS experiments were performed using a high pressure cell to characterize and test the effectiveness of the donut beam transmitted through the LIBS probe and collect plasma signal in back scatter mode. The first tests used the second harmonic of a Nd:YAG laser, pulse width 7ns, to form a plasma in nitrogen gas at five different pressures (1, 5, 10, 15 and 20bar) and three different gas temperatures (25, 100 and 200°C). The uniqueness of this probe is the custom made optic used for reshaping the round laser beam into a ring (Donut) shaped laser beam, which is fed into the probe and focused to form a plasma at the measurement point. The plasma signal is collected and collimated using the laser focusing lens and is reflected from the laser beam axis onto an achromatic lens by a high reflection mirror mounted in the center section of the donut laser beam. The effect of gas pressure and temperature on N(I) lines in the high pressure cell experiment shows that the line intensity decreases with pressure and increases with temperature. Mean plasma temperature was calculated using the ratios of N(I) line intensities ranging from 7400K to 8900K at 1bar and 2400K to 3200K at 20bar for the three different gas temperatures. The results show that as a proof of principle the donut beam optics in combination with the LIBS probe can be used for performing extensive LIBS measurements in well controlled laboratory environment as well as harsh and demanding environments of practical devices at both high pressures and temperatures.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
J.D. Gounder, P. Kutne, W. Meier
The ability of laser induced breakdown spectroscopy (LIBS) technique for on line simultaneous measurement of elemental concentrations has led to its application in a wide number of processes. The simplicity of the technique allows its application to harsh environments such as present in boilers, furnaces and gasifiers. This paper presents the design of a probe using a custom optic which transforms a round beam into a ring (Donut) beam, which is used for forming a plasma in an atmosphere of nitrogen at high pressure (20bar) and temperature (200°C). The LIBS experiments were performed using a high pressure cell to characterize and test the effectiveness of the donut beam transmitted through the LIBS probe and collect plasma signal in back scatter mode. The first tests used the second harmonic of a Nd:YAG laser, pulse width 7ns, to form a plasma in nitrogen gas at five different pressures (1, 5, 10, 15 and 20bar) and three different gas temperatures (25, 100 and 200°C). The uniqueness of this probe is the custom made optic used for reshaping the round laser beam into a ring (Donut) shaped laser beam, which is fed into the probe and focused to form a plasma at the measurement point. The plasma signal is collected and collimated using the laser focusing lens and is reflected from the laser beam axis onto an achromatic lens by a high reflection mirror mounted in the center section of the donut laser beam. The effect of gas pressure and temperature on N(I) lines in the high pressure cell experiment shows that the line intensity decreases with pressure and increases with temperature. Mean plasma temperature was calculated using the ratios of N(I) line intensities ranging from 7400K to 8900K at 1bar and 2400K to 3200K at 20bar for the three different gas temperatures. The results show that as a proof of principle the donut beam optics in combination with the LIBS probe can be used for performing extensive LIBS measurements in well controlled laboratory environment as well as harsh and demanding environments of practical devices at both high pressures and temperatures.
Highlights
► High pressure LIBS measurements ► LIBS probe for measurement in gasifiers ► Plasma temperature calculated from N(I) signal measured at 20bars.Investigation of materials of different crystal structure under various time delays using double pulse laser induced breakdown spectroscopy
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
E. Yurdanur-Tasel, H. Berberoglu, S. Bilikmen
The performance of a commercial, compact and portable laser induced breakdown spectroscopy (LIBS) system and a constructed laboratory LIBS system with different experimental approaches were investigated in order to make improvements in the qualitative results. One of the experimental studies pertained to the investigation of the different crystal surfaces of silicon. The second experimental study involved the polarization effects by which the polarization dependency was demonstrated. The third and final experimental study was an unconventional orthogonal double pulse configuration with a 45° angle of incidence for both lasers in opposite directions. By means of these experimental approaches reliable, reproducible results were obtained, relative intensities of the emission lines were enhanced and better signal to noise ratios were observed. Furthermore, the qualitative analysis performance of the commercial system software was compared with the code developed. The code yielded more accurate and precise analysis capability.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
E. Yurdanur-Tasel, H. Berberoglu, S. Bilikmen
The performance of a commercial, compact and portable laser induced breakdown spectroscopy (LIBS) system and a constructed laboratory LIBS system with different experimental approaches were investigated in order to make improvements in the qualitative results. One of the experimental studies pertained to the investigation of the different crystal surfaces of silicon. The second experimental study involved the polarization effects by which the polarization dependency was demonstrated. The third and final experimental study was an unconventional orthogonal double pulse configuration with a 45° angle of incidence for both lasers in opposite directions. By means of these experimental approaches reliable, reproducible results were obtained, relative intensities of the emission lines were enhanced and better signal to noise ratios were observed. Furthermore, the qualitative analysis performance of the commercial system software was compared with the code developed. The code yielded more accurate and precise analysis capability.
Highlights
► Double pulse LIBS with lasers at 45° angle to the sample is investigated. ► Si (100) emission intensities are higher than (111) due to dangling bond density. ► Plasma polarization behavior is strong at the peaks of the smaller wavelengths. ► A basic and more accurate code for the analysis of spectral lines is developed.Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
José Carlos Diaz Rosado, Daniel L'hermite, Yves Levi
The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension. We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2μm to 90μm) of Al2O3 in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum. In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100μm as ablated water column depth.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
José Carlos Diaz Rosado, Daniel L'hermite, Yves Levi
The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension. We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2μm to 90μm) of Al2O3 in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum. In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100μm as ablated water column depth.
Highlights
► We have identified a decrease of calibration curve when particle size increases. ► Partial particle ablation has been identified as the origin of this effect. ► The ablation rate on Al2O3 particles in suspension in water has been estimated. ► We can determine the deepness of the interaction volume into the liquid.Ultrasonic nebulization-sample introduction system for quantitative analysis of liquid samples by laser-induced breakdown spectroscopy
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
Nadir Aras, Semira Ünal Yeşiller, Dilek Arıca Ateş, Şerife Yalçın
In this study, design and optimization studies of a sample introduction system based on ultrasonic nebulization of metal salts in aqueous environment for laser-induced breakdown spectroscopic detection were presented. The system consisted of an ultrasonic nebulizer connected to a tandem heater–condenser–membrane dryer unit that produces sub-micron size aerosols. Results indicate improvements in detection limits for some elements with the use of membrane dryer. Optimization studies were performed by systematical investigation of LIBS emission signal with respect to laser energy, carrier gas flow rate and detector timing parameters. Under optimized conditions, calibration graphs for Na, K, Mg, Ca, Cu, Al, Cr, Cd, Pb and Zn were constructed and detection limits were calculated. The applicability of the ultrasonic nebulization-LIBS system was tested on real water samples. This system establishes LIBS as an effective analytical tool for both qualitative and quantitative determination of metal aerosols in aqueous environments. This technique is sufficiently rapid to provide real-time monitoring of toxic metals.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
Nadir Aras, Semira Ünal Yeşiller, Dilek Arıca Ateş, Şerife Yalçın
In this study, design and optimization studies of a sample introduction system based on ultrasonic nebulization of metal salts in aqueous environment for laser-induced breakdown spectroscopic detection were presented. The system consisted of an ultrasonic nebulizer connected to a tandem heater–condenser–membrane dryer unit that produces sub-micron size aerosols. Results indicate improvements in detection limits for some elements with the use of membrane dryer. Optimization studies were performed by systematical investigation of LIBS emission signal with respect to laser energy, carrier gas flow rate and detector timing parameters. Under optimized conditions, calibration graphs for Na, K, Mg, Ca, Cu, Al, Cr, Cd, Pb and Zn were constructed and detection limits were calculated. The applicability of the ultrasonic nebulization-LIBS system was tested on real water samples. This system establishes LIBS as an effective analytical tool for both qualitative and quantitative determination of metal aerosols in aqueous environments. This technique is sufficiently rapid to provide real-time monitoring of toxic metals.
Highlights
► An USN Sample Introduction System for LIBS detection of liquids has been realized. ► Use of membrane dryer has provided some enhancements in signal intensities. ► Enhancements of up to 3 times in LOD values of some toxic metals were obtained. ► Technique is sufficiently rapid for monitoring toxic metals in water samples.Laser‐induced breakdown spectroscopy of metals covered by water droplets
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
L.M. Cabalín, A. González, V. Lazic, J.J. Laserna
LIBS analyses of deep metallic layers were performed by dual-pulse excitation, where the first laser pulse efficiently ablates material covered by poly-dispersed water aerosol and water droplets, and the second laser pulse generates the analytical plasma on the crater's bottom. Enhancement of ablation rate in presence of water confinement was studied on various pure metals, namely Sn, Pb, Zn, Al, Cu, Fe, W, Ti and Mo. Crater depths and shapes were measured comparatively for dry surfaces and the same covered with water aerosol and water droplets of various volumes, and at different laser energies. With wet ablation using water droplet the mass removal efficiency was increased up to 20 times with respect to a dry process. The correlation between ablated mass and the thermal and mechanical properties of the examined metals was also studied.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
L.M. Cabalín, A. González, V. Lazic, J.J. Laserna
LIBS analyses of deep metallic layers were performed by dual-pulse excitation, where the first laser pulse efficiently ablates material covered by poly-dispersed water aerosol and water droplets, and the second laser pulse generates the analytical plasma on the crater's bottom. Enhancement of ablation rate in presence of water confinement was studied on various pure metals, namely Sn, Pb, Zn, Al, Cu, Fe, W, Ti and Mo. Crater depths and shapes were measured comparatively for dry surfaces and the same covered with water aerosol and water droplets of various volumes, and at different laser energies. With wet ablation using water droplet the mass removal efficiency was increased up to 20 times with respect to a dry process. The correlation between ablated mass and the thermal and mechanical properties of the examined metals was also studied.
Highlights
► The deposition of water droplets on metallic samples increases the ablation rate. ► Enhancement of the ablation rate by a factor 20× has been found for Al target. ► This result opens the possibility to analyze deep sample layers with this arrangement. ► The photothermal and mechanical effects play a significant role.Laser-induced breakdown spectroscopy for lambda quantification in a direct-injection engine
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
M. Buschbeck, F. Büchler, T. Halfmann, S. Arndt
We apply laser-induced breakdown spectroscopy (LIBS) to determine local lambda values (i.e. the normalized air-fuel mass ratio) at the ignition location λ ip in a direct-injection single-cylinder optical research engine. The technique enables us to determine variations of λ ip for different fuel injection strategies, as well as correlations between variations in λ ip and the combustion dynamics. In particular we observe, that fluctuations in λ ip are not the major cause of cycle-to-cycle variations in the combustion process. Moreover, our experiments identify insufficient lean λ ip values as a source of misfires in lean combustions. In a combination of LIBS with laser-induced fluorescence (LIF), we obtain additionally information about the two-dimensional λ distribution. These results demonstrate the potential of LIBS to monitor λ values during mixture formation in gasoline engines.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
M. Buschbeck, F. Büchler, T. Halfmann, S. Arndt
We apply laser-induced breakdown spectroscopy (LIBS) to determine local lambda values (i.e. the normalized air-fuel mass ratio) at the ignition location λ ip in a direct-injection single-cylinder optical research engine. The technique enables us to determine variations of λ ip for different fuel injection strategies, as well as correlations between variations in λ ip and the combustion dynamics. In particular we observe, that fluctuations in λ ip are not the major cause of cycle-to-cycle variations in the combustion process. Moreover, our experiments identify insufficient lean λ ip values as a source of misfires in lean combustions. In a combination of LIBS with laser-induced fluorescence (LIF), we obtain additionally information about the two-dimensional λ distribution. These results demonstrate the potential of LIBS to monitor λ values during mixture formation in gasoline engines.
Highlights
► Determination of λ values by means of LIBS in an optical gasoline engine. ► Evaluation of λ fluctuations for different fuel injection strategies. ► Investigation of the effect of λ upon combustion dynamics. ► Combination of LIBS and LIF to obtain two-dimensional λ distributions.Mapping of mechanical specimens by laser induced breakdown spectroscopy method: Application to an engine valve
17 August 2012,
10:39:04
Publication year:
2012
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
I. Lopez-Quintas, M.P. Mateo, V. Piñon, A. Yañez, G. Nicolas
In this work, an engine valve composed of different alloys has been analyzed by laser- induced breakdown spectroscopy to prove the capability of this technique to characterize mechanical parts which are complex in terms of shape and composition. With the acquired spectral data, 3D chemical maps have been plotted using a computer application for four representative elements: Fe, Cr, Ni and Mn. In addition, information about the in-depth distribution of Cr and Fe in different parts of the valve is shown. Results prove the potential of this technique to be implemented as an evaluation tool for quality control.
Source:Spectrochimica Acta Part B: Atomic Spectroscopy, Volumes 74–75
I. Lopez-Quintas, M.P. Mateo, V. Piñon, A. Yañez, G. Nicolas
In this work, an engine valve composed of different alloys has been analyzed by laser- induced breakdown spectroscopy to prove the capability of this technique to characterize mechanical parts which are complex in terms of shape and composition. With the acquired spectral data, 3D chemical maps have been plotted using a computer application for four representative elements: Fe, Cr, Ni and Mn. In addition, information about the in-depth distribution of Cr and Fe in different parts of the valve is shown. Results prove the potential of this technique to be implemented as an evaluation tool for quality control.
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