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Junichi Kimura - One of the best experts on this subject based on the ideXlab platform.
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high precision in situ analysis of pb isotopes in glasses using 1013 ω resistor high gain amplifiers with ultraviolet Femtosecond Laser Ablation multiple faraday collector inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2016Co-Authors: Junichi Kimura, Qing Chang, Nobuyuki Kanazawa, Satoshi Sasaki, Bogdan Stefanov VaglarovAbstract:We report high-precision in situ determination of Pb isotope ratios in glass samples, using 200 nm ultraviolet Femtosecond Laser Ablation coupled with a multiple Faraday collector-inductively coupled plasma mass spectrometer (MFC-ICPMS), equipped with 1013 Ω resistor high gain Faraday amplifiers. The use of the highly sensitive ion interface of MFC-ICPMS together with the state-of-the-art amplifiers enabled determination of 208Pb/206Pb and 207Pb/206Pb isotope ratios at the highest precision ever achieved from a Laser crater with 30 μm diameter and 30 μm depth dug on glass samples containing 1.7–39 ppm Pb. The signal responses of the 1013 Ω amplifiers were slower than those of the 1011 and 1012 Ω amplifiers. We confirmed a strong linear correlation between the rates of signal intensity change for D208Pbi/dt and the measured isotope ratios [20XPb/206Pb]/dt for the same time intervals. The D208Pbi/dt values deviated around zero, and the [20XPb/204Pb]/dt value at the zero intercept of the linear regression line represents the Pb isotope ratio of the sample. The slope of the linear regression line was either positive or negative because of different combinations of the amplifiers, indicating that the response of the amplifiers differed individually. The slope also changed with the signal intensity for 208Pbi or D208Pbi/dt, i.e., it was flatter at low levels and steeper at high levels. By using these relationships, corrections were made on the time resolved data measured from a single crater. Furthermore, using the proposed analytical method, 208Pb/206Pb and 207Pb/206Pb isotope ratios in BHVO-2G (1.7 ppm Pb) and BCR-2G (11 ppm Pb) basalt glass samples were analysed by using the National Institute of Standards and Technology (NIST) standard reference material (SRM) 612 (38.57 ppm Pb) synthetic glass as an external standard. The laboratory bias of the basalt glass samples was ±0.05–0.15‰ RD (per mille relative difference) and intermediate precisions were ±3–7‰ 2 SD (per mille 2 standard deviation) for BHVO-2G and ±0.6–3.7‰ 2 SD for BCR-2G. These intermediate precisions, along with repeatability, were approximately 2–3 times better than those obtained by using either multiple ion counter ICPMS or MFC-ICPMS with 1012 Ω resistor amplifiers.
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an improved u pb age dating method for zircon and monazite using 200 266 nm Femtosecond Laser Ablation and enhanced sensitivity multiple faraday collector inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2015Co-Authors: Junichi Kimura, Qing Chang, Keita Itano, Tsuyoshi Iizuka, Bogdan Stefanov Vaglarov, Kenichiro TaniAbstract:We present an improved U–Pb age dating method for zircon and monazite crystals using 193 nm excimer Laser Ablation and 200/266 nm Femtosecond Laser Ablation (200/266FsLA) multiple-Faraday collector inductively coupled plasma-mass spectrometry (MFC-ICP-MS). Optimization of a 266 fs Laser beam enabled an analysis of 207Pb/206Pb and 206Pb/238U ratios with an in-run precision of 1–2% from a crater of dimensions 50 μm × 10 μm (diameter × depth) at a repetition rate of 2 Hz for 30 s. The same in-run precision was obtained from a 30 μm × 20 μm crater using a 200 fs Laser beam of 20 μm in diameter rastered along the circumference of a circle with a 7 μm radius at 25 Hz for 15 s. With an enhanced sensitivity ion interface, the sensitivity for the total amount of Pb was ∼2 mV ppm−1 or ∼125 000 cps ppm−1 using the above crater setup. The use of high gain amplifiers equipped with a 1012 Ω register enabled the determination of the U–Pb age of zircon and monazite crystals with an internal and intermediate precision comparable to that obtained from sensitive high resolution ion microprobe (SHRMP) techniques. We analysed standard zircon crystals using a 91500 zircon crystal (1065.4 ± 0.6 Ma determined by isotope dilution thermal ionization mass spectrometry (ID-TIMS)) as a bracketing standard. Ages determined from TEMORA2, Presovice, and OD-3 zircons compared very well with their reference ages determined by ID-TIMS and/or SHRIMP. Thompson Mine and Monangotory standard monazites, dated using a 44069 monazite crystal (424.9 ± 0.4 by ID-TIMS) as a standard, also reproduced the U–Pb ages determined by ID-TIMS/LA-MFC-ICP-MS, but at a sample volume four times smaller than that required for zircons. Zircon and monazite ages are accurate given the small offsets from ID-TIMS ages, 0.15–0.7% for zircons and 0.2–0.7% for monazite well within internal precision from the primary standard in the analytical session and competitive with an internal precision of 0.43–0.6% for zircon and 0.2–0.8% for monazite. More easily obtaining high resolution age data is useful for the precise determination of the U–Pb age.
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origin of the suppressed matrix effect for improved analytical performance in determination of major and trace elements in anhydrous silicate samples using 200 nm Femtosecond Laser Ablation sector field inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2012Co-Authors: Junichi Kimura, Qing ChangAbstract:We have tested an ultraviolet (200 nm) Femtosecond Laser Ablation (200FsLA) sector-field inductively coupled plasma mass spectrometry (SF-ICPMS) system for major and trace element analyses in anhydrous silicate glasses and minerals. Use of the 200FsLA minimized the matrix effect by 50% compared to that of a 193 nm nanosecond excimer LA. The origin of this improvement was identified as the suppression of ‘melting point (MP)-induced’ element fractionation at the LA site due to a decreased thermal effect of the 200FsLA. Sensitivity enhancement in elements with high first ionization energy remained for the basalt aerosols relative to silica-rich aerosols. This is interpreted as being due to the higher thermal conductivity of the basalt aerosols in the inductively coupled plasma enhanced ionization, which is essentially controlled by the first ionization energy of an element. This was confirmed by simulation using Saha's equation and by the analytical data after reduction of the MP-induced fractionation at the LA site. Accurate determination of trace elements (within 5% of accepted values) was achieved for MPI-DING glasses ranging from komatiite to rhyolite, using a single basalt glass BHVO-2G as the calibration standard. This method is also applicable to anhydrous silicate minerals such as plagioclase, pyroxenes, and garnet. However, SRM610 glass, which has a very different matrix compared to BHVO-2G, is preferred for zircon. Apart from this exception, the proposed method requires no external analytical techniques when the amounts of unmeasured elements in the materials, such as halogens or water, are negligibly low, which is the case for many geological materials.
Detlef Gunther - One of the best experts on this subject based on the ideXlab platform.
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depth profile analyses with sub 100 nm depth resolution of a metal thin film by Femtosecond Laser Ablation inductively coupled plasma time of flight mass spectrometry
Spectrochimica Acta Part B: Atomic Spectroscopy, 2018Co-Authors: Debora Kaser, Joachim Koch, Lyndsey Hendriks, Detlef GuntherAbstract:Abstract Herein we investigate the capabilities of near ultraviolet Femtosecond Laser Ablation - inductively coupled plasma – time-of-flight mass spectrometry (NUV-fs-LA-ICP-TOFMS) for sub-100 nm depth profile analysis of a Cr/Ni metal thin film. For this purpose, the Laser beam is guided through a homogenization scheme, which is based on aperture-assisted diffraction and reassembly of the beam by an optical lens. Using this set up, craters with well-defined cylindrical shapes are formed. Fluences between 0.6 and 1 J/cm2 were applied, resulting in mean LA up-take rate of 27 nm/pulse. Discrepancies between LA up-take rates and depth resolutions were examined by a Gaussian depth resolution function, commonly used in SIMS or AES. In this study, depth resolutions ranging from 47 nm up to 80 nm were determined.
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Femtosecond Laser Ablation visualization of the aerosol formation process by light scattering and shadowgraphic imaging
Spectrochimica Acta Part B: Atomic Spectroscopy, 2010Co-Authors: Joachim Koch, S Heiroth, Thomas Lippert, Detlef GuntherAbstract:The shockwave propagation and aerosol formation during Femtosecond Laser Ablation (fs-LA) of dielectric materials (Li2B4O7, Y:ZrO2) in ambient air were monitored using shadowgraphy and light scattering. Three independent shockwave fronts were observed originating from (i) the instantaneous compression of ambient gas during the initial stage of fs-LA, (ii) a secondary compression caused by material ejection, and (iii) an air breakdown well above the target surface. In addition, particle size distributions were found to be multimodal implying the co-existence of condensational growth and supplementary particle production pathways such as phase explosion or critical point phase separation (CPPS). As a consequence, fs-LA of Li2B4O7 resulted in the formation of primary aggregates reaching diameters of > 10 μm. In contrast, aggregates formed during fs-LA of Y:ZrO2 covered a size range < 1 μm. Our data, furthermore, indicate the existence of a breakdown channel in the ambient atmosphere being capable to carry plasmatic, i.e. non-condensed matter beyond the primary shockwave barrier which may occasionally causes a spatial separation of material released. Assuming the Taylor-Sedov model of explosion to be valid the over-all energy dissipated in acoustic transients was found to exceed values of 50%.
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capabilities of Femtosecond Laser Ablation inductively coupled plasma mass spectrometry for depth profiling of thin metal coatings
Analytical Chemistry, 2007Co-Authors: Jorge Pisonero, Joachim Koch, Markus Walle, Whitney Hartung, Nicholas D Spencer, Detlef GuntherAbstract:The capabilities of ultraviolet Femtosecond Laser Ablation inductively coupled plasma mass spectrometry (UV-fs-LA-ICPMS) for depth profile analysis of thin metal coatings were evaluated. A standard sample consisting of a single Cr thin layer of 500 nm ± 5% on a Ni substrate was used. A fast washout was obtained by a high-efficiency aerosol dispersion Ablation cell (V ∼1 cm3), which allowed single-shot analysis with increased depth resolution. Laser Ablation was performed in helium at atmospheric pressure conditions. A Laser repetition rate of 1 Hz and low Laser fluence (<0.5 J/cm2) were used. Very low Ablation rates (<10 nm/pulse) were determined by atomic force microscopy (AFM). Information about the crater geometry and morphology was investigated using scanning electron microscopy and AFM. The depth resolution, calculated via the maximum slope of the tangent in the layer interface region, was smaller than 300 nm. Our data indicate that UV-fs-LA-ICPMS represents a powerful combination of high lateral and...
Friedhelm Von Blanckenburg - One of the best experts on this subject based on the ideXlab platform.
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deciphering formation processes of banded iron formations from the transvaal and the hamersley successions by combined si and fe isotope analysis using uv Femtosecond Laser Ablation
Geochimica et Cosmochimica Acta, 2010Co-Authors: Grit Steinhoefel, Ingo Horn, Friedhelm Von Blanckenburg, Kurt O Konhauser, Nicolas J Beukes, Jens GutzmerAbstract:Abstract To investigate the genesis of BIFs, we have determined the Fe and Si isotope composition of coexisting mineral phases in samples from the ∼2.5 billion year old Kuruman Iron Formation (Transvaal Supergroup, South Africa) and Dales Gorges Member of the Brockman Iron Formation (Hamersley Group, Australia) by UV Femtosecond Laser Ablation coupled to a MC-ICP-MS. Chert yields a total range of δ30Si between −1.3‰ and −0.8‰, but the Si isotope compositions are uniform in each core section examined. This uniformity suggests that Si precipitated from well-mixed seawater far removed from its sources such as hydrothermal vents or continental drainage. The Fe isotope composition of Fe-bearing mineral phases is much more heterogeneous compared to Si with δ56Fe values of −2.2‰ to 0‰. This heterogeneity is likely due to variable degrees of partial Fe(II) oxidation in surface waters, precipitation of different mineral phases and post-depositional Fe redistribution. Magnetite exhibits negative δ56Fe values, which can be attributed to a variety of diagenetic pathways: the light Fe isotope composition was inherited from the Fe(III) precursor, heavy Fe(II) was lost by abiotic reduction of the Fe(III) precursor or light Fe(II) was gained from external fluids. Micrometer-scale heterogeneities of δ56Fe in Fe oxides are attributed to variable degrees of Fe(II) oxidation or to isotope exchange upon Fe(II) adsorption within the water column and to Fe redistribution during diagenesis. Diagenetic Fe(III) reduction caused by oxidation of organic matter and Fe redistribution is supported by the C isotope composition of a carbonate-rich sample containing primary siderite. These carbonates yield δ13C values of ∼−10‰, which hints at a mixed carbon source in the seawater of both organic and inorganic carbon. The ancient seawater composition is estimated to have a minimum range in δ56Fe of −0.8‰ to 0‰, assuming that hematite and siderite have preserved their primary Fe isotope signature. The long-term near-zero Fe isotope composition of the Hamersley and Transvaal BIFs is in balance with the assumed composition of the Fe sources. The negative Fe isotope composition of the investigated BIF samples, however, indicates either a perturbation of the steady state, or they have to be balanced spatially by deposition of isotopically heavy Fe. In the case of Si, the negative Si isotope signature of these BIFs stands in marked contrast to the assumed source composition. The deviation from potential source composition requires a complementary sink of isotopically heavy Si in order to maintain steady state in the basin. Perturbing the steady state by extraordinary hydrothermal activity or continental weathering in contrast would have led to precipitation of light Si isotopes from seawater. Combining an explanation for both elements, a likely scenario is a steady state ocean basin with two sinks. When all published Fe isotope records including BIFs, microbial carbonates, shales and sedimentary pyrites, are considered, a complementary sink for heavy Fe isotopes must have existed in Precambrian ocean basins. This Fe sink could have been pelagic sediments, which however are not preserved. For Si, such a complementary sink for heavy Si isotopes might have been provided by other chert deposits within the basin.
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micro scale tracing of fe and si isotope signatures in banded iron formation using Femtosecond Laser Ablation
Geochimica et Cosmochimica Acta, 2009Co-Authors: Grit Steinhoefel, Ingo Horn, Friedhelm Von BlanckenburgAbstract:We have detected micrometre-scale differences in Fe and Si stable isotope ratios between coexisting minerals and between layers of banded iron formation (BIF) using an UV Femtosecond Laser Ablation system connected to a MC-ICP-MS. In the magnetite–carbonate–chert BIF from the Archean Old Wanderer Formation in the Shurugwi Greenstone Belt (Zimbabwe), magnetite shows neither intra- nor inter-layer trends giving overall uniform d 56 Fe values of � 0.9&, but exhibits intra-crystal zonation. Bulk iron carbonates are also relatively uniform at near-zero values, however, their individual d 56 Fe value is highly composition-dependent: both siderite and ankerite and mixtures between both are present, and d 56 Fe end member values are 0.4& for siderite and � 0.7& for ankerite. The data suggest either an early diagenetic origin of magnetite and iron carbonates by the reaction of organic matter with ferric oxyhydroxides catalysed by Fe(III)-reducing bacteria; or more likely an abiotic reaction of organic carbon and Fe(III) during low-grade metamorphism. Si isotope composition of the Old Wanderer BIF also shows significant variations with d 30 Si values that range between � 1.0& and � 2.6& for bulk layers. These isotope compositions suggest rapid precipitation of the silicate phases from hydrothermal-rich waters. Interestingly, Fe and Si isotope compositions of bulk layers are covariant and are interpreted as largely primary signatures. Moreover, the changes of Fe and Si isotope signatures between bulk layers directly reflect the upwelling dynamics of hydrothermal-rich water which govern the rates of Fe and Si precipitation and therefore also the development of layering. During periods of low hydrothermal activity, precipitation of only small amounts of ferric oxyhydroxide was followed by complete reduction with organic carbon during diagenesis resulting in carbonate–chert layers. During periods of intensive hydrothermal activity, precipitation rates of ferric oxyhydroxide were high, and subsequent diagenesis triggered only partial reduction, forming magnetite–carbonate– chert layers. We are confident that our micro-analytical technique is able to detect both the solute flux history into the sedimentary BIF precursor, and the BIF’s diagenetic history from the comparison between coexisting minerals and their predicted fractionation factors.
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investigation on elemental and isotopic fractionation during 196 nm Femtosecond Laser Ablation multiple collector inductively coupled plasma mass spectrometry
Spectrochimica Acta Part B: Atomic Spectroscopy, 2007Co-Authors: Ingo Horn, Friedhelm Von BlanckenburgAbstract:Abstract Despite the large number of successful applications of Laser Ablation, elemental and isotopic fractionation coupled to inductively coupled plasma mass spectrometry (ICP-MS) remain as the main limitations for many applications of this technique in the fields of analytical chemistry and Earth Sciences. A substantial effort has been made to control such fractionations, which are well-established features of nanosecond Laser Ablation systems. Technological advancements made over the past decade now allow the Ablation of solids by Femtosecond Laser pulses in the deep ultraviolet (UV) region at wavelengths less than 200 nm. Here the use of Femtosecond Laser Ablation and its effects on elemental and isotopic fractionation is investigated. The Pb/U system is used to illustrate elemental fractionation and stable Fe isotopes are used to illustrate isotopic fractionation. No elemental fractionation is observed beyond the precision of the multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) measurements. Without a matrix match between standard and sample, elemental fractionation is absent even when using different Laser Ablation protocols for standardization and samples (spot versus raster). Furthermore, we found that Laser Ablation-induced isotope ratio drifts, commonly observed during nanosecond Laser Ablation, are undetectable during ultraviolet Femtosecond Laser Ablation. So far the precision obtained for Fe isotope ratio determinations is 0.1‰ (2 standard deviation) for the 56 Fe/ 54 Fe ratio. This is close to that obtainable by solution multiple-collector inductively coupled plasma mass spectrometry. The accuracy of the results appears to be independent of the matrix used for standardization. The resulting smaller particle sizes reduce fractionation processes. Femtosecond Laser Ablation carries the potential to solve some of the difficulties encountered during the two prior decades since the introduction of Laser Ablation.
Qing Chang - One of the best experts on this subject based on the ideXlab platform.
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high precision in situ analysis of pb isotopes in glasses using 1013 ω resistor high gain amplifiers with ultraviolet Femtosecond Laser Ablation multiple faraday collector inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2016Co-Authors: Junichi Kimura, Qing Chang, Nobuyuki Kanazawa, Satoshi Sasaki, Bogdan Stefanov VaglarovAbstract:We report high-precision in situ determination of Pb isotope ratios in glass samples, using 200 nm ultraviolet Femtosecond Laser Ablation coupled with a multiple Faraday collector-inductively coupled plasma mass spectrometer (MFC-ICPMS), equipped with 1013 Ω resistor high gain Faraday amplifiers. The use of the highly sensitive ion interface of MFC-ICPMS together with the state-of-the-art amplifiers enabled determination of 208Pb/206Pb and 207Pb/206Pb isotope ratios at the highest precision ever achieved from a Laser crater with 30 μm diameter and 30 μm depth dug on glass samples containing 1.7–39 ppm Pb. The signal responses of the 1013 Ω amplifiers were slower than those of the 1011 and 1012 Ω amplifiers. We confirmed a strong linear correlation between the rates of signal intensity change for D208Pbi/dt and the measured isotope ratios [20XPb/206Pb]/dt for the same time intervals. The D208Pbi/dt values deviated around zero, and the [20XPb/204Pb]/dt value at the zero intercept of the linear regression line represents the Pb isotope ratio of the sample. The slope of the linear regression line was either positive or negative because of different combinations of the amplifiers, indicating that the response of the amplifiers differed individually. The slope also changed with the signal intensity for 208Pbi or D208Pbi/dt, i.e., it was flatter at low levels and steeper at high levels. By using these relationships, corrections were made on the time resolved data measured from a single crater. Furthermore, using the proposed analytical method, 208Pb/206Pb and 207Pb/206Pb isotope ratios in BHVO-2G (1.7 ppm Pb) and BCR-2G (11 ppm Pb) basalt glass samples were analysed by using the National Institute of Standards and Technology (NIST) standard reference material (SRM) 612 (38.57 ppm Pb) synthetic glass as an external standard. The laboratory bias of the basalt glass samples was ±0.05–0.15‰ RD (per mille relative difference) and intermediate precisions were ±3–7‰ 2 SD (per mille 2 standard deviation) for BHVO-2G and ±0.6–3.7‰ 2 SD for BCR-2G. These intermediate precisions, along with repeatability, were approximately 2–3 times better than those obtained by using either multiple ion counter ICPMS or MFC-ICPMS with 1012 Ω resistor amplifiers.
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an improved u pb age dating method for zircon and monazite using 200 266 nm Femtosecond Laser Ablation and enhanced sensitivity multiple faraday collector inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2015Co-Authors: Junichi Kimura, Qing Chang, Keita Itano, Tsuyoshi Iizuka, Bogdan Stefanov Vaglarov, Kenichiro TaniAbstract:We present an improved U–Pb age dating method for zircon and monazite crystals using 193 nm excimer Laser Ablation and 200/266 nm Femtosecond Laser Ablation (200/266FsLA) multiple-Faraday collector inductively coupled plasma-mass spectrometry (MFC-ICP-MS). Optimization of a 266 fs Laser beam enabled an analysis of 207Pb/206Pb and 206Pb/238U ratios with an in-run precision of 1–2% from a crater of dimensions 50 μm × 10 μm (diameter × depth) at a repetition rate of 2 Hz for 30 s. The same in-run precision was obtained from a 30 μm × 20 μm crater using a 200 fs Laser beam of 20 μm in diameter rastered along the circumference of a circle with a 7 μm radius at 25 Hz for 15 s. With an enhanced sensitivity ion interface, the sensitivity for the total amount of Pb was ∼2 mV ppm−1 or ∼125 000 cps ppm−1 using the above crater setup. The use of high gain amplifiers equipped with a 1012 Ω register enabled the determination of the U–Pb age of zircon and monazite crystals with an internal and intermediate precision comparable to that obtained from sensitive high resolution ion microprobe (SHRMP) techniques. We analysed standard zircon crystals using a 91500 zircon crystal (1065.4 ± 0.6 Ma determined by isotope dilution thermal ionization mass spectrometry (ID-TIMS)) as a bracketing standard. Ages determined from TEMORA2, Presovice, and OD-3 zircons compared very well with their reference ages determined by ID-TIMS and/or SHRIMP. Thompson Mine and Monangotory standard monazites, dated using a 44069 monazite crystal (424.9 ± 0.4 by ID-TIMS) as a standard, also reproduced the U–Pb ages determined by ID-TIMS/LA-MFC-ICP-MS, but at a sample volume four times smaller than that required for zircons. Zircon and monazite ages are accurate given the small offsets from ID-TIMS ages, 0.15–0.7% for zircons and 0.2–0.7% for monazite well within internal precision from the primary standard in the analytical session and competitive with an internal precision of 0.43–0.6% for zircon and 0.2–0.8% for monazite. More easily obtaining high resolution age data is useful for the precise determination of the U–Pb age.
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origin of the suppressed matrix effect for improved analytical performance in determination of major and trace elements in anhydrous silicate samples using 200 nm Femtosecond Laser Ablation sector field inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2012Co-Authors: Junichi Kimura, Qing ChangAbstract:We have tested an ultraviolet (200 nm) Femtosecond Laser Ablation (200FsLA) sector-field inductively coupled plasma mass spectrometry (SF-ICPMS) system for major and trace element analyses in anhydrous silicate glasses and minerals. Use of the 200FsLA minimized the matrix effect by 50% compared to that of a 193 nm nanosecond excimer LA. The origin of this improvement was identified as the suppression of ‘melting point (MP)-induced’ element fractionation at the LA site due to a decreased thermal effect of the 200FsLA. Sensitivity enhancement in elements with high first ionization energy remained for the basalt aerosols relative to silica-rich aerosols. This is interpreted as being due to the higher thermal conductivity of the basalt aerosols in the inductively coupled plasma enhanced ionization, which is essentially controlled by the first ionization energy of an element. This was confirmed by simulation using Saha's equation and by the analytical data after reduction of the MP-induced fractionation at the LA site. Accurate determination of trace elements (within 5% of accepted values) was achieved for MPI-DING glasses ranging from komatiite to rhyolite, using a single basalt glass BHVO-2G as the calibration standard. This method is also applicable to anhydrous silicate minerals such as plagioclase, pyroxenes, and garnet. However, SRM610 glass, which has a very different matrix compared to BHVO-2G, is preferred for zircon. Apart from this exception, the proposed method requires no external analytical techniques when the amounts of unmeasured elements in the materials, such as halogens or water, are negligibly low, which is the case for many geological materials.
Joachim Koch - One of the best experts on this subject based on the ideXlab platform.
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depth profile analyses with sub 100 nm depth resolution of a metal thin film by Femtosecond Laser Ablation inductively coupled plasma time of flight mass spectrometry
Spectrochimica Acta Part B: Atomic Spectroscopy, 2018Co-Authors: Debora Kaser, Joachim Koch, Lyndsey Hendriks, Detlef GuntherAbstract:Abstract Herein we investigate the capabilities of near ultraviolet Femtosecond Laser Ablation - inductively coupled plasma – time-of-flight mass spectrometry (NUV-fs-LA-ICP-TOFMS) for sub-100 nm depth profile analysis of a Cr/Ni metal thin film. For this purpose, the Laser beam is guided through a homogenization scheme, which is based on aperture-assisted diffraction and reassembly of the beam by an optical lens. Using this set up, craters with well-defined cylindrical shapes are formed. Fluences between 0.6 and 1 J/cm2 were applied, resulting in mean LA up-take rate of 27 nm/pulse. Discrepancies between LA up-take rates and depth resolutions were examined by a Gaussian depth resolution function, commonly used in SIMS or AES. In this study, depth resolutions ranging from 47 nm up to 80 nm were determined.
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Femtosecond Laser Ablation visualization of the aerosol formation process by light scattering and shadowgraphic imaging
Spectrochimica Acta Part B: Atomic Spectroscopy, 2010Co-Authors: Joachim Koch, S Heiroth, Thomas Lippert, Detlef GuntherAbstract:The shockwave propagation and aerosol formation during Femtosecond Laser Ablation (fs-LA) of dielectric materials (Li2B4O7, Y:ZrO2) in ambient air were monitored using shadowgraphy and light scattering. Three independent shockwave fronts were observed originating from (i) the instantaneous compression of ambient gas during the initial stage of fs-LA, (ii) a secondary compression caused by material ejection, and (iii) an air breakdown well above the target surface. In addition, particle size distributions were found to be multimodal implying the co-existence of condensational growth and supplementary particle production pathways such as phase explosion or critical point phase separation (CPPS). As a consequence, fs-LA of Li2B4O7 resulted in the formation of primary aggregates reaching diameters of > 10 μm. In contrast, aggregates formed during fs-LA of Y:ZrO2 covered a size range < 1 μm. Our data, furthermore, indicate the existence of a breakdown channel in the ambient atmosphere being capable to carry plasmatic, i.e. non-condensed matter beyond the primary shockwave barrier which may occasionally causes a spatial separation of material released. Assuming the Taylor-Sedov model of explosion to be valid the over-all energy dissipated in acoustic transients was found to exceed values of 50%.
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capabilities of Femtosecond Laser Ablation inductively coupled plasma mass spectrometry for depth profiling of thin metal coatings
Analytical Chemistry, 2007Co-Authors: Jorge Pisonero, Joachim Koch, Markus Walle, Whitney Hartung, Nicholas D Spencer, Detlef GuntherAbstract:The capabilities of ultraviolet Femtosecond Laser Ablation inductively coupled plasma mass spectrometry (UV-fs-LA-ICPMS) for depth profile analysis of thin metal coatings were evaluated. A standard sample consisting of a single Cr thin layer of 500 nm ± 5% on a Ni substrate was used. A fast washout was obtained by a high-efficiency aerosol dispersion Ablation cell (V ∼1 cm3), which allowed single-shot analysis with increased depth resolution. Laser Ablation was performed in helium at atmospheric pressure conditions. A Laser repetition rate of 1 Hz and low Laser fluence (<0.5 J/cm2) were used. Very low Ablation rates (<10 nm/pulse) were determined by atomic force microscopy (AFM). Information about the crater geometry and morphology was investigated using scanning electron microscopy and AFM. The depth resolution, calculated via the maximum slope of the tangent in the layer interface region, was smaller than 300 nm. Our data indicate that UV-fs-LA-ICPMS represents a powerful combination of high lateral and...
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non matrix matched calibration of major and minor concentrations of zn and cu in brass aluminium and silicate glass using nir Femtosecond Laser Ablation inductively coupled plasma mass spectrometry
Journal of Analytical Atomic Spectrometry, 2006Co-Authors: Qunzhou Bian, Carmen C Garcia, Joachim Koch, Kay NiemaxAbstract:The feasibility of using near-infrared (NIR) Femtosecond Laser Ablation (fs-LA) inductively coupled plasma mass spectrometry (ICP-MS) for the analysis of solid samples with non-matrix matched standard reference materials was studied. Major and minor concentrations of Zn and Cu (433 μg g−1–0.95 g g−1) were measured in three sets of metallic and dielectric standards (brass, aluminium, silicate glass) using He as the Ablation cell gas and, with admixed Ar, for aerosol transportation from the cell into an Ar-ICP-MS instrument. Not surprisingly for ICP-MS detection, the experimental Zn/Cu ion ratios were found to be dependent on the sampler cone position in the plasma. However, at a fixed sampler position the experimental Zn/Cu ratios of the brass and Al samples were found to be proportional to the certified ratios independent of the Laser fluence applied (range: 2–42 J cm−2). In contrast, the Zn/Cu ratio of an optical transparent glass sample (NIST 610) was found to be strongly fluence dependent. However, with increasing fluence the measured ratio asymptotically approached the experimentally expected ratio taking into account the results obtained from the brass and aluminium measurements.