The Experts below are selected from a list of 13362 Experts worldwide ranked by ideXlab platform
L. Luo - One of the best experts on this subject based on the ideXlab platform.
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phosphorus speciation and transformation in long term fertilized soil evidence from chemical fractionation and p k edge XANES Spectroscopy
Nutrient Cycling in Agroecosystems, 2017Co-Authors: L. Luo, Rebecca L Sanders, Satish Chandra Babu MyneniAbstract:Knowledge of speciation and transformation of phosphorus (P) in soil following high application rates of chemical and organic fertilizers is essential for improving P management in Chinese agricultural ecosystems because P fertilizers have been increasingly overapplied in China. Phosphorus speciation of the soil in three long-term fertilization experiments established in 1990 was investigated jointly with a sequential fractionation scheme and P K-edge X-ray absorption near edge structure (XANES) Spectroscopy. Both chemical fractionation and XANES Spectroscopy confirmed that P species in the topsoils (0–20 cm) were mainly composed of iron phosphate, calcium phosphate and organic P, regardless of soil pH and mineralogy. The continuous application of nitrogen, phosphorus and potassium fertilizers (NPK) had little effect on the distribution of P species in the topsoils compared with that in the control and 1990 baseline topsoils. In contrast, the application of NPK plus organic manures (MNPK) changed significantly the speciation distribution of P by increasing distinctly available P in the soil. The transportation and transformation of P species depended on soil properties including P levels, organic carbon concentrations and mineral types. The long-term application of MNPK facilitated the transportation of P into lower horizons and the accumulation of organic P in the soil. The XANES results provided spectroscopic support for the P species identified by the fractionation scheme, and the combination of the two techniques provided complementary information on the speciation and transformation of P in soil.
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sulphur speciation and availability in long term fertilized soil evidence from chemical fractionation and s k edge XANES Spectroscopy
European Journal of Soil Science, 2016Co-Authors: Shaobin Wang, Z. J. Chen, L. LuoAbstract:Knowledge of sulphur (S) speciation in soil following applications of chemical and organic fertilizers is important for understanding the availability and fate of S in agricultural ecosystems. Sulphur speciation of the soil in three fields, which are part of the National Long-term Monitoring Network of Soil Fertility and Fertilizer Effects of China, was investigated with a combination of a wet-chemical fractionation scheme and S K-edge X-ray absorption near edge structure (XANES) Spectroscopy. Treatments of the soil included no fertilizers (control), regular applications of nitrogen, phosphorus and potassium fertilizers (NPK), or of NPK plus organic manures (MNPK) since 1990. Soil samples were taken from the topsoil (0–20 cm) and subsoil (20–40 cm) horizons in 2011. Chemical fractionation showed that available sulphate was the predominant inorganic S species in the Eutric Cambisol, whereas HCl-extractable sulphate was the main inorganic S species in the Haplic Phaeozem and Calcaric Cambisol. Organic S accounted for up to 77% of total S in all soil samples. Results from the fractionation (inorganic S plus ester-S) and XANES analysis (oxidized S) were correlated (r = 0.585, P < 0.01), which confirmed the presence of HCl-extractable sulphate and the speciation of residual S in soil. Long-term application of organic manures facilitated significantly the accumulation of intermediate and reduced S species and increased total and organic S in the soil (P < 0.01). In contrast, the application of chemical fertilizers (NPK) had little effect on the distribution of organic S species compared with the control. Atmospheric deposition was identified as an important source of S. The combination of chemical fractionation and XANES Spectroscopy provided complementary information on the availability and speciation of S in soil. Highlights Availability and species of S are characterized with chemical fractionation and XANES Spectroscopy. Insoluble sulphate is identified as an important form of S in the soil regardless of soil pH. Organic manure facilitates the accumulation of organic S in long-term fertilized soil. Atmospheric deposition contributes importantly to the input and cycling of S in soil.
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Sulphur speciation and availability in long‐term fertilized soil: evidence from chemical fractionation and S K‐edge XANES Spectroscopy
European Journal of Soil Science, 2016Co-Authors: Shouyang Wang, Z. J. Chen, L. LuoAbstract:Knowledge of sulphur (S) speciation in soil following applications of chemical and organic fertilizers is important for understanding the availability and fate of S in agricultural ecosystems. Sulphur speciation of the soil in three fields, which are part of the National Long-term Monitoring Network of Soil Fertility and Fertilizer Effects of China, was investigated with a combination of a wet-chemical fractionation scheme and S K-edge X-ray absorption near edge structure (XANES) Spectroscopy. Treatments of the soil included no fertilizers (control), regular applications of nitrogen, phosphorus and potassium fertilizers (NPK), or of NPK plus organic manures (MNPK) since 1990. Soil samples were taken from the topsoil (0–20 cm) and subsoil (20–40 cm) horizons in 2011. Chemical fractionation showed that available sulphate was the predominant inorganic S species in the Eutric Cambisol, whereas HCl-extractable sulphate was the main inorganic S species in the Haplic Phaeozem and Calcaric Cambisol. Organic S accounted for up to 77% of total S in all soil samples. Results from the fractionation (inorganic S plus ester-S) and XANES analysis (oxidized S) were correlated (r = 0.585, P < 0.01), which confirmed the presence of HCl-extractable sulphate and the speciation of residual S in soil. Long-term application of organic manures facilitated significantly the accumulation of intermediate and reduced S species and increased total and organic S in the soil (P < 0.01). In contrast, the application of chemical fertilizers (NPK) had little effect on the distribution of organic S species compared with the control. Atmospheric deposition was identified as an important source of S. The combination of chemical fractionation and XANES Spectroscopy provided complementary information on the availability and speciation of S in soil. Highlights Availability and species of S are characterized with chemical fractionation and XANES Spectroscopy. Insoluble sulphate is identified as an important form of S in the soil regardless of soil pH. Organic manure facilitates the accumulation of organic S in long-term fertilized soil. Atmospheric deposition contributes importantly to the input and cycling of S in soil.
Naomi Kawamura - One of the best experts on this subject based on the ideXlab platform.
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Quadrupole transition in the Dy L{sub 3} edge observed by lifetime-broadening-suppressed XANES Spectroscopy
Physical Review B, 2004Co-Authors: Hisashi Hayashi, Rumi Takeda, Masaki Kawata, Yasuo Udagawa, Naomi Kawamura, Yasuhiro Watanabe, Susumu NanaoAbstract:Lifetime-broadening-suppressed x-ray absorption near edge structure (LBS-XANES) Spectroscopy is applied to the Dy L{sub 3} edge, where multiplet nature of the final state as well as lifetime-broadening distorts the band shape. It was found that, by determining appropriate final state density function from observed the L{alpha} band shape, LBS-XANES spectra can be obtained and 2p{yields}4f quadrupole transition is unequivocally observed as a separate peak. It has been proved from the present results that LBS-XANES Spectroscopy is very versatile; transitions with multiplet final states can be studied by the use of hard x-rays and forbidden transitions obscured by intense dipole-allowed transitions can be revealed. Implications for resonant inelastic x-ray scattering (RIXS) spectra are also discussed in terms of RIXS contour plot and the Kramers-Heisenberg equation.
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Lifetime-broadening-suppressed/free XANES Spectroscopy by high-resolution resonant inelastic x-ray scattering
Physical Review B, 2003Co-Authors: Hisashi Hayashi, Rumi Takeda, Yasuo Udagawa, Susumu Nanao, Tetsuya Nakamura, Hayato Miyagawa, Hironobu Shoji, Naomi KawamuraAbstract:The resonant inelastic x-ray scattering (RIXS) spectrum is uniquely related to the x-ray absorption oscillator strength distribution by the Kramers-Heisenberg equation via lifetime widths of the states involved. In this work it is shown that x-ray absorption near-edge structure (XANES), where the lifetime broadening of 1s core holes is suppressed and that of the 2p hole determines the resolution, can be analytically deduced from RIXS spectra. Furthermore, it is demonstrated that numerical procedures can provide lifetime-broadening-free (LBF) XANES, where the remaining 2p broadening is also eliminated. As examples, lifetime-broadening-suppressed (LBS) XANES and LBF-XANES of CuO and CuCl 2 .2H 2 O are derived from RIXS spectra measured by the use of a third-generation synchrotron source SPring-8 and are compared with XANES obtained by other methods to discuss the significance of LBS and LBF XANES Spectroscopy.
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lifetime broadening suppressed free XANES Spectroscopy by high resolution resonant inelastic x ray scattering
Physical Review B, 2003Co-Authors: Hisashi Hayashi, Rumi Takeda, Yasuo Udagawa, Tetsuya Nakamura, Hayato Miyagawa, Hironobu Shoji, S Nanao, Naomi KawamuraAbstract:The resonant inelastic x-ray scattering (RIXS) spectrum is uniquely related to the x-ray absorption oscillator strength distribution by the Kramers-Heisenberg equation via lifetime widths of the states involved. In this work it is shown that x-ray absorption near-edge structure (XANES), where the lifetime broadening of 1s core holes is suppressed and that of the 2p hole determines the resolution, can be analytically deduced from RIXS spectra. Furthermore, it is demonstrated that numerical procedures can provide lifetime-broadening-free (LBF) XANES, where the remaining 2p broadening is also eliminated. As examples, lifetime-broadening-suppressed (LBS) XANES and LBF-XANES of CuO and CuCl 2 .2H 2 O are derived from RIXS spectra measured by the use of a third-generation synchrotron source SPring-8 and are compared with XANES obtained by other methods to discuss the significance of LBS and LBF XANES Spectroscopy.
N. V. Bausk - One of the best experts on this subject based on the ideXlab platform.
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XANES Spectroscopy Study of Pb(Ti, Zr)O3 Ferroelectric Thin Films
Integrated Ferroelectrics, 2004Co-Authors: Mira Mandeljc, S. B. Erenburg, Svyatoslav P. Gabuda, Svetlana G. Kozlova, Marija Kosec, N. V. BauskAbstract:Thin films of zirconium-rich perovskites Pb1 − 3x/2La x Ti0.35Zr0.65O3(PLZT; x = 0.095) and PbTi0.7Zr0.3O3 were studied using X-ray absorption near-edge structure (XANES) Spectroscopy. Is shown, that slow crystallization of the system is accompanied by essential change of PbL(3)-edge fine structure indicating that perovskite thin film band structure is sensitive of Ti/Zr ratio. The same results were found in the samples of the same composition with addition of 30% mol of PbO. The evidence for stereo active 6s2 lone-pair is discussed.
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XANES Spectroscopy study of Pb(Ti, Zr)O3 ferroelectric thin films
arXiv: Materials Science, 2003Co-Authors: Mira Mandeljc, S. B. Erenburg, Svyatoslav P. Gabuda, Svetlana G. Kozlova, Marija Kosec, N. V. BauskAbstract:Thin films of zirconium-rich perovskites Pb1-3x/2 Lax Zr0.65 Ti0.35O3 (PLZT; x=0.095) were studied using X-ray absorption near-edge structure (XANES) Spectroscopy. Is shown, that slow crystallization of the system is accompanied by partial reduction of lead oxides to a metal (Pb0) state. The same results were found in the samples of the same composition with addition of 30% mol of PbO. The evidence for stereo active 6s2 lone-pair is discussed.
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Tunneling of 6s 2 electrons in PbO and Bi2O3: XANES Spectroscopy and DFT calculations
Jetp Letters, 2002Co-Authors: Svyatoslav P. Gabuda, S. B. Erenburg, N. V. Bausk, R. L. Davidovich, V. V. Zyryanov, Svetlana G. Kozlova, Yu M YukhinAbstract:The results of XANES Spectroscopy and DFT calculations are evidence for the occurrence of anomalous 2p2/3→6s1/2 electronic transitions in lead(II) and bismuth(III) oxides. The observed transitions may be due to the tunneling of outer 6s2 electrons.
Hisashi Hayashi - One of the best experts on this subject based on the ideXlab platform.
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Quadrupole transition in the Dy L{sub 3} edge observed by lifetime-broadening-suppressed XANES Spectroscopy
Physical Review B, 2004Co-Authors: Hisashi Hayashi, Rumi Takeda, Masaki Kawata, Yasuo Udagawa, Naomi Kawamura, Yasuhiro Watanabe, Susumu NanaoAbstract:Lifetime-broadening-suppressed x-ray absorption near edge structure (LBS-XANES) Spectroscopy is applied to the Dy L{sub 3} edge, where multiplet nature of the final state as well as lifetime-broadening distorts the band shape. It was found that, by determining appropriate final state density function from observed the L{alpha} band shape, LBS-XANES spectra can be obtained and 2p{yields}4f quadrupole transition is unequivocally observed as a separate peak. It has been proved from the present results that LBS-XANES Spectroscopy is very versatile; transitions with multiplet final states can be studied by the use of hard x-rays and forbidden transitions obscured by intense dipole-allowed transitions can be revealed. Implications for resonant inelastic x-ray scattering (RIXS) spectra are also discussed in terms of RIXS contour plot and the Kramers-Heisenberg equation.
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Lifetime-broadening-suppressed/free XANES Spectroscopy by high-resolution resonant inelastic x-ray scattering
Physical Review B, 2003Co-Authors: Hisashi Hayashi, Rumi Takeda, Yasuo Udagawa, Susumu Nanao, Tetsuya Nakamura, Hayato Miyagawa, Hironobu Shoji, Naomi KawamuraAbstract:The resonant inelastic x-ray scattering (RIXS) spectrum is uniquely related to the x-ray absorption oscillator strength distribution by the Kramers-Heisenberg equation via lifetime widths of the states involved. In this work it is shown that x-ray absorption near-edge structure (XANES), where the lifetime broadening of 1s core holes is suppressed and that of the 2p hole determines the resolution, can be analytically deduced from RIXS spectra. Furthermore, it is demonstrated that numerical procedures can provide lifetime-broadening-free (LBF) XANES, where the remaining 2p broadening is also eliminated. As examples, lifetime-broadening-suppressed (LBS) XANES and LBF-XANES of CuO and CuCl 2 .2H 2 O are derived from RIXS spectra measured by the use of a third-generation synchrotron source SPring-8 and are compared with XANES obtained by other methods to discuss the significance of LBS and LBF XANES Spectroscopy.
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lifetime broadening suppressed free XANES Spectroscopy by high resolution resonant inelastic x ray scattering
Physical Review B, 2003Co-Authors: Hisashi Hayashi, Rumi Takeda, Yasuo Udagawa, Tetsuya Nakamura, Hayato Miyagawa, Hironobu Shoji, S Nanao, Naomi KawamuraAbstract:The resonant inelastic x-ray scattering (RIXS) spectrum is uniquely related to the x-ray absorption oscillator strength distribution by the Kramers-Heisenberg equation via lifetime widths of the states involved. In this work it is shown that x-ray absorption near-edge structure (XANES), where the lifetime broadening of 1s core holes is suppressed and that of the 2p hole determines the resolution, can be analytically deduced from RIXS spectra. Furthermore, it is demonstrated that numerical procedures can provide lifetime-broadening-free (LBF) XANES, where the remaining 2p broadening is also eliminated. As examples, lifetime-broadening-suppressed (LBS) XANES and LBF-XANES of CuO and CuCl 2 .2H 2 O are derived from RIXS spectra measured by the use of a third-generation synchrotron source SPring-8 and are compared with XANES obtained by other methods to discuss the significance of LBS and LBF XANES Spectroscopy.
Matthew Newville - One of the best experts on this subject based on the ideXlab platform.
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XANES Spectroscopy of sulfides stable under reducing conditions
American Mineralogist, 2020Co-Authors: Brendan A. Anzures, Antonio Lanzirotti, Stephen W. Parman, Ralph E. Milliken, Matthew NewvilleAbstract:Abstract X-ray absorption near-edge structure (XANES) Spectroscopy is a powerful technique to quantitatively investigate sulfur speciation in geologically complex materials such as minerals, glasses, soils, organic compounds, industrial slags, and extraterrestrial materials. This technique allows non-destructive investigation of the coordination chemistry and oxidation state of sulfur species ranging from sulfide (2–oxidation state) to sulfate (6+ oxidation state). Each sulfur species has a unique spectral shape with a characteristic K-edge representing the s → p and d hybridization photoelectron transitions. As such, sulfur speciation is used to measure the oxidation state of samples by comparing the overall XANES spectra to that of reference compounds. Although many S XANES spectral standards exist for terrestrial applications under oxidized conditions, new sulfide standards are needed to investigate reduced (oxygen fugacity, fO2, below IW) silicate systems relevant for studies of extraterrestrial materials and systems. Sulfides found in certain meteorites (e.g., enstatite chondrites and aubrites) and predicted to exist on Mercury, such as CaS (oldhamite), MgS (niningerite), and FeCr2S4 (daubréelite), are stable at fO2 below IW-3 but rapidly oxidize to sulfate and/or produce sulfurous gases under terrestrial surface conditions. XANES spectra of these compounds collected to date have been of variable quality, possibly due to the unstable nature of certain sulfides under typical (e.g., oxidizing) laboratory conditions. A new set of compounds was prepared for this study and their XANES spectra are analyzed for comparison with potential extraterrestrial analogs. S K-edge XANES spectra were collected at Argonne National Lab for FeS (troilite), MnS (alabandite), CaS (oldhamite), MgS (niningerite), Ni1–xS, NiS2, CaSO4 (anhydrite), MgSO4, FeSO4, Fe2(SO4)3, FeCr2S4 (daubréelite), Na2S, Al2S3, Ni7S6, and Ni3S2; the latter five were analyzed for the first time using XANES. These standards expand upon the existing S XANES end-member libraries at a higher spectral resolution (0.25 eV steps) near the S K-edge. Processed spectra, those that have been normalized and “flattened,” are compared to quantify uncertainties due to data processing methods. Future investigations that require well-characterized sulfide standards, such as the ones presented here, may have important implications for understanding sulfur speciation in reduced silicate glasses and minerals with applications for the early Earth, Moon, Mercury, and enstatite chondrites.
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the source of sulfate in brachiopod calcite insights from μ xrf imaging and XANES Spectroscopy
Chemical Geology, 2019Co-Authors: Jocelyn A Richardson, Matthew Newville, Antonio Lanzirotti, Samuel M Webb, Catherine V Rose, Jeffrey G Catalano, David A FikeAbstract:Abstract Geochemical signatures preserved in sedimentary carbonate strata are often used as archives for paleoenvironmental reconstructions. However, diagenetic overprinting and/or muting of primary geochemical signatures complicates the interpretation of these data. To avoid this issue, geochemical techniques strive to target unaltered (or minimally altered) carbonate components. The multi-layer low-Mg calcite shell composition of articulate brachiopods are often the target in such studies because they are commonly more robust to recrystallization than the shells of other biomineralizers. Here, we have combined S K-edge μ-XRF imaging, XANES Spectroscopy and petrography to determine the source of sulfate in the calcite lattice (carbonate-associated sulfate; CAS) of ancient and extant brachiopods, in order to establish their suitability for use in reconstructing seawater sulfate δ34S throughout the Phanerozoic. Both the extant brachiopod Terebratalia transversa and fossil brachiopods display intra-specimen variability in sulfate abundance parallel to the primary fabric, likely corresponding to variations in growth rate. XANES Spectroscopy identifies a majority of the sulfate as inorganic. Additionally, XANES Spectroscopy detected low abundances of both reduced and oxidized organic sulfur species (thiol, thioether, sulfoxide and sulfate esters) in all T. transversa samples and lesser abundances in a few of the fossil brachiopods. In T. transversa, inorganic sulfate and sulfate ester abundance increase towards the hinge of the valves. Bulk δ34SCAS of the samples containing the fossil brachiopods are consistently more positive than time-equivalent brachiopod-only values, likely reflecting a mixture of CAS signals from homogenization of carbonate components differentially affected by depositional environment and diagenesis. In contrast, bulk δ34SCAS of modern T. transversa is approximately 1‰ more positive than coeval seawater. Although organic sulfate esters are found within the brachiopod shells, they are only ever present as trace components. Our findings indicate that the vast majority of sulfate in brachiopod shells is inorganic, sourced from coeval seawater. This result supports the use of brachiopods as a potential archive for a faithful CAS record of seawater sulfate throughout the Phanerozoic. The characterization of in situ organic sulfur compounds in both extant and fossil brachiopods indicates the potential importance of various organic sulfur compounds in mineralogical determination (and therefore fossil preservation) and crystal orientation during brachiopod biomineralization throughout geologic time.
