The Experts below are selected from a list of 210 Experts worldwide ranked by ideXlab platform
Mitsuo Maeda - One of the best experts on this subject based on the ideXlab platform.
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nanometer scale depth resolution and sensitive surface analysis using laser ablation Atomic Fluorescence Spectroscopy
Japanese Journal of Applied Physics, 2006Co-Authors: Daisuke Nakamura, Yuji Oki, Takayuki Takao, Takashi Higotani, Mitsuo MaedaAbstract:An extremely high-resolution, nanometer-resolution, solid-surface trace element detection has been demonstrated. Nanometer-thinned pulsed laser ablation was combined with extremely sensitive laser-induced Fluorescence Spectroscopy, and depth resolution of 3.6 nm was experimentally demonstrated for the first time on sodium detection in polymeric samples. An extremely high absolute detection limit of 25.2 fg was also obtained, and a theoretical calculation program was also generated to analyze the results.
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Active control of the ablation plume for laser ablation Atomic Fluorescence Spectroscopy
Photon Processing in Microelectronics and Photonics V, 2006Co-Authors: Dasisuke Nakamura, Takayuki Takao, Yuji Oki, Mitsuo MaedaAbstract:We have developed an extreme sensitive trace element detection technique that has been labeled Laser ablation Atomic Fluorescence (LAAF) Spectroscopy, and applied to a nanometer-scale solid surface analysis. The absolute weight of the detection limit of 870 ag (10 -18 g) and high depth resolution of 3.6 nm had been demonstrated in trace sodium detection of polymethylmethacrylate. As a laser ablation was used in the LAAF Spectroscopy, the behavior of the ablation plume is a very important factor for high sensitivity. So, we tried to control the plume by a buffer gas and an assist mask for more sensitive analysis. The diffusion velocity of the ablated particles was modified in collision with the gas molecules. Furthermore, it was found that the form of the plume was changed by the mask. Thus, improvement of the detection sensitivity of the LAAF is expected using this approach.
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trace element analysis of nanometer scaled solid state surface by laser ablation Atomic Fluorescence Spectroscopy
Conference on Lasers and Electro-Optics, 2003Co-Authors: Daisuke Nakamura, Yuji Oki, Takayuki Takao, Mitsuo MaedaAbstract:A nanometer-scaled layer removal of a surface of poly-methylmethacrylate was attained by a single laser shot from a pulsed excimer laser ablation. The combination of the removal and laser Fluorescence Spectroscopy demonstrated a nanometer-scaled element analysis on a solid surface.
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nanometer scale surface element analysis in polymers using laser ablation Atomic Fluorescence Spectroscopy
Journal of Applied Physics, 2000Co-Authors: Min Kyu Kim, Yuji Oki, Hiroyuki Ishii, Kazuyoshi Taoka, Mitsuo MaedaAbstract:In this paper, laser ablation Atomic Fluorescence (LAAF) Spectroscopy has been applied for a nanometer-scale solid surface analysis of Na-doped polymethyl methacrylate (PMMA). LAAF Spectroscopy is a new sensitive element detection technique which involves atomizing of a sample by the laser ablation and detection of the ablated plume by laser-induced Fluorescence (LIF) Spectroscopy. Using this technique in the detection of Na atoms with a sample of Na-doped PMMA, an ablation rate of 4.4 nm/shot is attained and a detection limit is estimated to be 36 fg for a single laser shot. Further, a two-layer PMMA sample is ablated and by observing the shot-by-shot LIF intensity from Na atoms, the depth distribution in the sample is measured with a very high spatial resolution.
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removal of thin layer for trace element analysis of solid surface in subnanometer scale using laser ablation Atomic Fluorescence Spectroscopy
Applied Physics Letters, 1997Co-Authors: Yuji Oki, Kenji Matsunaga, Takumi Nomura, Mitsuo MaedaAbstract:Laser-ablation Atomic Fluorescence (LAAF) Spectroscopy has extremely high sensitivity in the analysis of trace elements. Using the ArF laser-ablation technique at a wavelength of 193 nm, removal of thin surface layer of the order of 1.1 nm/shot for the first 50 shots and 0.4 nm/shot after that is demonstrated for a solid glass sample. A constant Fluorescence signal from Na atoms is obtained for each shot. There is a possibility of determining the depth distribution of an element with subnanometer resolution by applying LAAF Spectroscopy.
Yuji Oki - One of the best experts on this subject based on the ideXlab platform.
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nanometer scale depth resolution and sensitive surface analysis using laser ablation Atomic Fluorescence Spectroscopy
Japanese Journal of Applied Physics, 2006Co-Authors: Daisuke Nakamura, Yuji Oki, Takayuki Takao, Takashi Higotani, Mitsuo MaedaAbstract:An extremely high-resolution, nanometer-resolution, solid-surface trace element detection has been demonstrated. Nanometer-thinned pulsed laser ablation was combined with extremely sensitive laser-induced Fluorescence Spectroscopy, and depth resolution of 3.6 nm was experimentally demonstrated for the first time on sodium detection in polymeric samples. An extremely high absolute detection limit of 25.2 fg was also obtained, and a theoretical calculation program was also generated to analyze the results.
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Active control of the ablation plume for laser ablation Atomic Fluorescence Spectroscopy
Photon Processing in Microelectronics and Photonics V, 2006Co-Authors: Dasisuke Nakamura, Takayuki Takao, Yuji Oki, Mitsuo MaedaAbstract:We have developed an extreme sensitive trace element detection technique that has been labeled Laser ablation Atomic Fluorescence (LAAF) Spectroscopy, and applied to a nanometer-scale solid surface analysis. The absolute weight of the detection limit of 870 ag (10 -18 g) and high depth resolution of 3.6 nm had been demonstrated in trace sodium detection of polymethylmethacrylate. As a laser ablation was used in the LAAF Spectroscopy, the behavior of the ablation plume is a very important factor for high sensitivity. So, we tried to control the plume by a buffer gas and an assist mask for more sensitive analysis. The diffusion velocity of the ablated particles was modified in collision with the gas molecules. Furthermore, it was found that the form of the plume was changed by the mask. Thus, improvement of the detection sensitivity of the LAAF is expected using this approach.
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atogram and nanometer trace element detection from solid surface by soft laser ablation Atomic Fluorescence Spectroscopy
Quantum Electronics and Laser Science Conference, 2005Co-Authors: Daisuke Nakamura, Takayuki Takao, Yuji Oki, Mizuo MaedaAbstract:Ultimate high sensitivity of trace element detection was proposed and demonstrated by solid surface analysis with laser ablation Spectroscopy. Numerical calculation predicts LOD of atogram and 290ag was obtained experimentally about sodium in PMMA.
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trace element analysis of nanometer scaled solid state surface by laser ablation Atomic Fluorescence Spectroscopy
Conference on Lasers and Electro-Optics, 2003Co-Authors: Daisuke Nakamura, Yuji Oki, Takayuki Takao, Mitsuo MaedaAbstract:A nanometer-scaled layer removal of a surface of poly-methylmethacrylate was attained by a single laser shot from a pulsed excimer laser ablation. The combination of the removal and laser Fluorescence Spectroscopy demonstrated a nanometer-scaled element analysis on a solid surface.
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analysis of trace element in solids by using laser ablation Atomic Fluorescence Spectroscopy
Conference on Lasers and Electro-Optics, 2000Co-Authors: Min Kyu Kim, Takayuki Takao, Yuji Oki, Hiroyuki Ishii, Mizuo MaedaAbstract:Summary form only given. We have proposed a very sensitive detection technique of trace element in samples such as polymers, metals and semiconductors. It is called laser ablation Atomic Fluorescence (LAAF) Spectroscopy, which combines laser ablation process to atomize the sample surface and laser-induced Fluorescence (LIF) Spectroscopy to make a quantitative analysis of the atoms in the ablated plume. LIF provides selective excitation of the trace element to avoid interference due to the resonant excitation with the probe laser. In this study, we demonstrated the availability of LAAF Spectroscopy for the nano-meter scale analysis of the sample surface.
J L Gomezariza - One of the best experts on this subject based on the ideXlab platform.
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first approach of a methodological set up for selenomethionine chiral speciation in breast and formula milk using high performance liquid chromatography coupled to Atomic Fluorescence Spectroscopy
Applied Organometallic Chemistry, 2007Co-Authors: J L Gomezariza, V Bernaldaza, M J VillegasporteroAbstract:The chiral speciation of selenomethionine in breast and formula milk based on species separation by high-performance liquid chromatography followed by online microwave-assisted digestion and detection with hydride generation Atomic Fluorescence spectrometry (HPLC-MAD-HG-AFS) requires severe sample manipulation to avoid matrix influence. Sample clean-up for fat and protein elimination using centrifugation and ultrafiltration was optimized, and selenomethionine preconcentration based on cation exchange solid-phase extraction was studied and optimized. The resulting procedure is suitable for chiral selenium speciation in infant milk with detection limits of 3.1 and 3.5 ng ml−1 as Se for L-selenomethionine and D-selenomethionine, respectively. The time necessary for the analysis, about 90 min, including sample clean-up, analyte preconcentration and chromatographic separation, makes the approach suitable for routine analysis. Copyright © 2007 John Wiley & Sons, Ltd.
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sample treatment selection for routine mercury speciation in seafood by gas chromatography Atomic Fluorescence Spectroscopy
Applied Organometallic Chemistry, 2005Co-Authors: J L Gomezariza, F Lorenzo, Tamara GarciabarreraAbstract:A general analytical strategy for mercury speciation in seafood samples has been proposed to increase sample throughput. This consists of the initial determination of total mercury content, and then mercury speciation using gas chromatography coupled to Atomic Fluorescence Spectroscopy. The appropriate sample treatment for mercury speciation is selected between a method based on aqueous ethylation with sodium tetraethylborate (Approach A: a rapid methodology for samples with methylmercury concentrations between 150 and 2000 ng g−1) and another one based on the determination of organomercury chlorides (Approach B: a much more time-consuming methodology, applicable to samples with methylmercury at 1.2–200 ng g−1). Both procedures have been used together for the analysis of bivalves and fish samples. Copyright © 2005 John Wiley & Sons, Ltd.
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comparative study of Atomic Fluorescence Spectroscopy and inductively coupled plasma mass spectrometry for mercury and arsenic multispeciation
Analytical and Bioanalytical Chemistry, 2005Co-Authors: J L Gomezariza, F Lorenzo, T GarciabarreraAbstract:Mercury and arsenic are two elements of undoubted importance owing to their toxic character. Although speciation of these elements has been developed separately, in this work for the first time the speciation of As and Hg using two Atomic Fluorescence detectors in a sequential ensemble is presented. A coupling based on the combination of high-performance liquid chromatography (where mercury and arsenic species are separated) and two Atomic Fluorescence detectors in series, with several online treatments, including photooxidation (UV) and hydride generation, has allowed the determination of mercury and arsenic compounds simultaneously. The detection limits for this device were 16, 3, 17, 12 and 8 ng mL−1 for AsIII, monomethylarsinic acid, AsV, Hg2+ and methylmercury, respectively. This coupling was compared with an analogous one based on inductively coupled plasma–mass spectrometry (ICP-MS) detection, with detection limits of 0.7, 0.5, 0.8, 0.9 and 1.1 ng mL−1, respectively. Multispeciation based on ICP-MS exhibits better sensitivity than the coupling based on tandem Atomic Fluorescence, but this second device is a very robust system and exhibits obvious advantages related to the low cost of acquisition and maintenance, as well as easy handling, which makes it a suitable system for routine laboratories.
Gerald J. Keeler - One of the best experts on this subject based on the ideXlab platform.
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using thermal analysis coupled to isotope dilution cold vapor icp ms in the quantification of atmospheric particulate phase mercury
Journal of Analytical Atomic Spectrometry, 2013Co-Authors: Mary M Lynam, Gerald J. Keeler, Bjoern Klaue, Joel D BlumAbstract:An analytical method combining thermal analysis with isotope dilution cold vapor inductively coupled plasma mass spectrometry, ID-CV-ICP-MS, was developed to study mercury in particulate matter samples collected in urban Detroit, MI. We used this method to quantify mercury in NIST 1633b “mercury in fly ash standard” and determined an average concentration of 0.139 ± 0.009 μg g−1 (RSD 6%), which was within the certified range of 0.141 ± 0.019 μg g−1 determined by the National Institute of Standards and Technology using cold vapor Atomic absorption spectrometry. The method detection limit for each 3 second integration window was approximately 20 fg of mercury. When we compared results from thermal analysis coupled to ID-CV-ICP-MS to a well-established analysis method that combines microwave assisted nitric acid digestion with cold vapor Atomic Fluorescence Spectroscopy, mercury concentrations were found to be in good agreement with each other indicating that the former is a suitable technique for quantitative release and analysis of mercury from aerosol matrices. Using this method mercury concentrations in denuded and undenuded fine particulate samples collected in Detroit, MI were quantified. Undenuded filters collected more particulate mercury compared to filters that were denuded using a KCl-coated denuder in 60% of samples. Thermal profiles for samples revealed complex patterns and differences in amounts and release patterns of mercury likely due to temporal differences in meteorology and air shed properties that were evident during sampling. Night time samples that were undenuded revealed the most complexity and may be a reflection of increased partitioning of reactive gaseous mercury to the particle phase with decreasing overnight temperatures and reduced height of the boundary layer. These profiles suggest that binding sites of varying physical and chemical characteristics in particulate matter are available for sorption and/or condensation of reactive gaseous mercury.
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Microwave digestion and analysis of foliage for total mercury by cold vapor Atomic Fluorescence Spectroscopy
Biogeochemistry, 1998Co-Authors: Anne W. Rea, Gerald J. KeelerAbstract:A microwave technique for digesting foliage samples was developed and evaluated for quantifying low levels of Hg by cold vapor Atomic Fluorescence Spectroscopy, CVAFS. The method meets three criteria: (1) to digest all sample material completely and consistently, (2) to reduce sample digestion time to less than one hour, and (3) to maintain a low analytical blank. Mean recovery of NIST standards was 90±6%. Samples that were analyzed by this technique and by Instrumental Neutron Activation Analysis compared within 15%. This method also compared within 15% of hot acid digestion methods on samples prepared and analyzed by CVAFS at different laboratories in the First International Mercury in Foliage Intercomparison of Methods (FIM)^2. The largest source of variability in all of the interlaboratory comparisons was sample inhomogeneity rather than analytical error.
N Omenetto - One of the best experts on this subject based on the ideXlab platform.
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on line and in situ detection of lead aerosols by plasma Spectroscopy and laser excited Atomic Fluorescence Spectroscopy
Analytica Chimica Acta, 1997Co-Authors: R E Neuhauser, Ulrich Panne, Reinhard Niessner, G A Petrucci, P Cavalli, N OmenettoAbstract:Abstract A set-up for on-line and size-segregated detection of lead in ultrafine aerosols was developed. Lead nitrate aerosols with particle diameters between 10 and 300 nm were generated by ultrasonic nebulization of aqueous Pb(NO3)2-solutions. A differential mobility particle sizer (DMPS) was used for size-resolved mass calibration. Either a miniaturized acetylene-air-flame or a laser-induced plasma (LIP) was employed for atomization. Lead was detected with a spectrograph and a gateable, intensified CCD-camera by Atomic emission Spectroscopy (AES) and laser excited Atomic Fluorescence (LEAF). Due to the lower sensitivity, for LIP-AES no size-resolved calibration was possible and for calibration with polydisperse aerosols a detection limit of 155 μg m−3 was found for lead. With LEAF and flame atomization, a linear calibration curve was obtained with on-line detection limits of 47 ng m−3 for lead. No dependence of the detection limit on the particle diameter was observed. For LEAF with a laser-induced plasma as atom source, a correlation between the detection limit and the particle diameter was found. The detection limit increased from 55 ng m−3 for a particle diameter of 48 nm to 130 ng m−3 for a particle diameter of 300 nm. The increasing detection limit with increasing particle diameter was probably due to the incomplete atomization of larger particles in the colder periphery of the plasma.
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on line and in situ detection of lead in ultrafine aerosols by laser excited Atomic Fluorescence Spectroscopy
Sensors and Actuators B-chemical, 1997Co-Authors: R E Neuhauser, Ulrich Panne, Reinhard Niessner, G A Petrucci, P Cavalli, N OmenettoAbstract:Abstract A set-up for on-line and size-segregated detection of lead in ultrafine aerosols has been developed. Lead nitrate aerosols with particle diameters between 10 and 300 nm are generated by ultrasonic nebulization of aqueous Pb(NO 3 ) 2 solutions. A differential mobility particle sizer (DMPS) is used for size-resolved mass calibration. Either a miniaturized acetylene-air flame or a laser-induced plasma is employed for atomization. Lead is detected with a spectrograph and a gateable intensified CCD camera by laser-excited Atomic Fluorescence (LEAF). With LEAF and flame atomization, a linear calibration curve is obtained with on-line detection limits of 47 ng m −3 for lead. No dependence of the detection limit on the particle diameter is observed. For LEAF with a laser-induced plasma as atom source, a correlation between the detection limit and the particle diameter is found. The detection limit increases from 55 ng m −3 for a particle diameter of 48 nm to 130 ng m −3 for a particle diameter of 300 nm. The increasing detection limit with increasing particle diameter is probably due to the incomplete atomization of larger particles in the colder periphery of the plasma.