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Ptychographic coherent diffraction imaging (CDI) allows the visualization of both the structure and chemical state of materials on the nanoscale, and has been developed for use in the soft and hard X-ray regions. In this study, a ptychographic CDI system with pinhole or Fresnel zone-plate optics for use in the tender X-ray region (2–5 keV) was developed on beamline BL27SU at SPring-8, in which high-precision pinholes optimized for the tender energy range were used to obtain diffraction intensity patterns with a low background, and a temperature stabilization system was developed to reduce the drift of the sample position. A ptychography measurement of a 200 nm thick tantalum test chart was performed at an incident X-ray energy of 2.500 keV, and the phase image of the test chart was successfully reconstructed with approximately 50 nm resolution. As an application to practical materials, a sulfur polymer material was measured in the range of 2.465 to 2.500 keV including the sulfur K absorption edge, and the phase and absorption images were successfully reconstructed and the nanoscale absorption/phase spectra were derived from images at multiple energies. In 3 GeV synchrotron radiation facilities with a low-emittance storage ring, the use of the present system will allow the visualization on the nanoscale of the chemical states of various light elements that play important roles in materials science, biology and environmental science.

Context. The current period is conducive to exploring our Solar System's origins with recent and future space sample return missions, which provide invaluable information from known Solar System asteroids and comets The Hayabusa2 mission of the Japan Aerospace Exploration Agency (JAXA) recently brought back samples from the surface of the Ryugu carbonaceous asteroid. Aims. We aim to identify the different forms of chemical composition of organic matter and minerals that constitute these Solar System primitive objects, to shed light on the Solar System's origins. Methods. In this work, we recorded infrared (IR) hyper-spectral maps of whole-rock Ryugu asteroid samples at the highest achievable spatial resolution with a synchrotron in the mid-IR (MIR). Additional global far-IR (FIR) spectra of each sample were also acquired. Results. The hyper-spectral maps reveal the variability of the functional groups at small scales and the intimate association of phyl-losilicates with the aliphatic components of the organic matter present in Ryugu. The relative proportion of column densities of the identified IR functional groups (aliphatics, hydroxyl + interlayer and/or physisorbed water, carbonyl, carbonates, and silicates) giving access to the composition of the Ryugu samples is estimated from these IR hyper-spectral maps. Phyllosilicate spectra reveal the presence of mixtures of serpentine and saponite. We do not detect anhydrous silicates in the samples analysed, at the scales probed. The carbonates are dominated by dolomite. Aliphatics organics are distributed over the whole samples at the micron scale probed with the synchrotron, and intimately mixed with the phyllosilicates. The aromatic C=C contribution could not be safely deconvolved from OH in most spectra, due to the ubiquitous presence of hydrated minerals. The peak intensity ratios of the organics methylene to methyl (CH2/CH3) of the Ryugu samples vary between about 1.5 and 2.5, and are compared to the ratios in chondrites from types 1 to 3. Overall, the mineralogical and organic characteristics of the Ryugu samples show similarities with those of CI chondrites, although with a noticeably higher CH2/CH3 in Ryugu than generally measured in C1 chondrites collected on Earth, and possibly a higher carbonate content.

Wurtzite AlN films with high Fe concentrations were deposited on Si(100) substrates using radio-frequency sputtering, and the growth process was investigated. X-Ray diffraction (XRD) analysis with parallel incident X-rays showed that a thick film (∼2.5 μm) had a non-polar a-axis orientation, similar to the films deposited on SiO2 glass substrates. Through powder XRD analysis, it was found that non-wurtzite fine crystals and/or amorphous materials formed during the initial stage of deposition, followed by wurtzite nucleation with various orientations of the axes, such as a, m, and r orientations. The XRD results also implied that the a-axis-oriented regions drastically increased with increasing film thickness. Scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy analyses suggested that one of the candidates for the non-wurtzite fine crystalline material was γ-Al2O3. STEM analysis also demonstrated that a-axis-oriented single-crystal grains grew from randomly oriented small wurtzite grains that increased in diameter with increasing deposition time. Al K-edge X-ray absorption near-edge structure results suggested that the electronic structure in the polar c-axis direction of wurtzite lying in the film plane developed with deposition time, thereby further supporting the findings of the XRD and STEM analyses.

Atmospheric deposition is one of the main sources of dissolved iron (Fe) in the ocean surfaces. Atmospheric processes are recognized as controlling fractional Fe solubility (Fesol%) in marine aerosol particles. However, the impact of these processes on Fesol% remains unclear. One of the reasons for this is the lack of field observations focusing on the relationship between Fesol% and Fe species in marine aerosol particles. In particular, the effects of organic ligands on Fesol% have not been thoroughly investigated in observational studies. In this study, Fe species in size-fractionated aerosol particles in the Pacific Ocean were determined using X-ray absorption fine structure (XAFS) spectroscopy. The internal mixing states of Fe and organic carbon were investigated using scanning transmission X-ray microscopy (STXM). The effects of atmospheric processes on Fesol% in marine aerosol particles were investigated based on the speciation results. Iron in size-fractionated aerosol particles was mainly derived from mineral dust, regardless of aerosol diameter, because the enrichment factor of Fe was almost 1 in both coarse (PM>1.3) and fine aerosol particles (PM1.3). Approximately 80 % of the total Fe (insoluble + labile Fe) was present in PM>1.3, whereas labile Fe was mainly present in PM1.3. The Fesol% in PM>1.3 was not significantly increased (2.56±2.53 %, 0.00 %–8.50 %, n=20) by the atmospheric processes because mineral dust was not acidified beyond the buffer capacity of calcite. In contrast, mineral dust in PM1.3 was acidified beyond the buffer capacity of calcite. As a result, Fesol% in PM1.3 (0.202 %–64.7 %, n=10) was an order of magnitude higher than that in PM>1.3. The PM1.3 contained ferric organic complexes with humic-like substances (Fe(III)-HULIS, but not Fe-oxalate complexes), and the abundance correlated with Fesol%. Iron(III)-HULIS was formed during transport in the Pacific Ocean because Fe(III)-HULIS was not found in aerosol particles in Beijing and Japan. The pH estimations of mineral dust in PM1.3 established that Fe was solubilized by proton-promoted dissolution under highly acidic conditions (pH < 3.0), whereas Fe(III)-HULIS was stabilized under moderately acidic conditions (pH 3.0–6.0). Since the observed labile Fe concentration could not be reproduced by proton-promoted dissolution under moderately acidic conditions, the pH of mineral dust increased after proton-promoted dissolution. The cloud process in the marine atmosphere increases the mineral dust pH because the dust particles are covered with organic carbon and Na. The precipitation of ferrihydrite was suppressed by Fe(III)-HULIS owing to its high water solubility. Thus, the organic complexation of Fe with HULIS plays a significant role in the stabilization of Fe that was initially solubilized by proton-promoted dissolution.

Absolute measurements of small-angle X-ray scattering (SAXS) intensities at the K absorption edge of Mg have been performed using glassy carbon as an intensity standard. Glassy carbon samples polished down to give appropriate transmission have been prepared as a secondary standard to be used at 1.3 keV. Al–Mg binary alloys were used to assess the metastable phase boundary for the Al3Mg metastable precipitation from the absolute scattering intensity. The assessed phase boundary agreed with the previous reports. Glassy carbon was concluded to be an appropriate candidate for an intensity standard sample for transmission measurements of SAXS in the tender X-ray regions.

Understanding the origin of organic material on Mars is a major issue in modern planetary science. Recent robotic exploration of Martian sedimentary rocks and laboratory analyses of Martian meteorites have both reported plausible indigenous organic components. However, little is known about their origin, evolution, and preservation. Here we report that 4-billion-year-old (Ga) carbonates in Martian meteorite, Allan Hills 84001, preserve indigenous nitrogen(N)-bearing organics by developing a new technique for high-spatial resolution in situ N-chemical speciation. The organic materials were synthesized locally and/or delivered meteoritically on Mars during Noachian age. The carbonates, alteration minerals from the Martian near-surface aqueous fluid, trapped and kept the organic materials intact over long geological times. This presence of N-bearing compounds requires abiotic or possibly biotic N-fixation and ammonia storage, suggesting that early Mars had a less oxidizing environment than today., Mars has long been thought to contain organic compounds, but the origins and plausibility are debated. Here the authors employ a new technique to assess organic nitrogen compounds in a Martian meteorite, concluding that these compounds are indeed likely to originate from the Red Planet.

Using N K-edge XANES studies, we demonstrate a noticeable difference in local structure around the nitrogen atoms in as-deposited amorphous and annealed N-doped GeTe-based phase change alloys. The pronounced changes appear as a ≈ 2 eV shift in the absorption edge to higher photon energies and the overall shape of the XANES spectrum. Comparison of the experimental XANES spectrum of the as-deposited amorphous phase with ab-initio XANES simulations discloses that the as-deposited phase mainly consists of the NGe3 and the NTe3 pyramidal units in approximately equal concentration. When annealed, NTe3 units gradually rebond to the NGe3 units and at the same time N atoms diffuse through the amorphous phase to form the GexNy aggregates. Upon long-standing annealing at 400 ∘ C a compact interlayer of Ge3N4 is formed in the crystalline phase.

The evaporites of the Realmonte salt mine (Sicily, Italy) are important archives recording the most extreme conditions of the Messinian Salinity Crisis (MSC). However, geochemical approach on these evaporitic sequences is scarce and little is known on the response of the biological community to drastically elevating salinity. In the present work, we investigated the depositional environments and the biological community of the shale¿anhydrite¿halite triplets and the K¿Mg salt layer deposited during the peak of the MSC. Both hopanes and steranes are detected in the shale¿anhydrite¿halite triplets, suggesting the presence of eukaryotes and bacteria throughout their deposition. The K¿Mg salt layer is composed of primary halites, diagenetic leonite, and primary and/or secondary kainite, which are interpreted to have precipitated from density-stratified water column with the halite-precipitating brine at the surface and the brine-precipitating K¿Mg salts at the bottom. The presence of hopanes and a trace amount of steranes implicates that eukaryotes and bacteria were able to survive in the surface halite-precipitating brine even during the most extreme condition of the MSC. Graphical abstract: [Figure not available: see fulltext.]. © 2019, The Author(s)., This work was performed with the support of Japan Society for the Promotion of Science (JSPS) Research Fellowship (16 J07844) to YI and JAMSTEC President Fund to NO.

The molecular-frame photoelectron angular distributions (MFPADs) in O 1s photoemission from CO2 molecule were measured. Patterns due to photoelectron diffractions were observed in the MFPADs. The polarization-averaged MFPADs were compared with theoretical calculation and were found to be useful in determining the molecular bond-length, which is a component to determine molecular structures.

Because reef-dwelling large benthic foraminifera (LBF) tests, which is composed of high-magnesium calcite, are the common components of modern reef sediments, and ancient reef carbonate rocks, they can provide a continuous record of the paleoenvironment of reef sediments. Evaluation of the responses of the minor element concentrations (Mg, Sr, Na, P, and S) of individual tests to ambient temperature and LBF growth modes was conducted with two cultured species, Calcarina gaudichaudii and Amphisorus kudakajimensis. The elements were assessed as tracers of temperature, salinity, nutrient concentration, and calcification rate. The Mg content of C. gaudichaudii and the Sr content of both species were controlled by temperature. It can be confirmed that the Mg of individual tests of C. gaudichaudii is a useful paleothermometer. There was a large biological modulation of Na, P, and S incorporation. In-situ XANES analysis revealed that both inorganic and organic species contributed to the P and S content of LBF tests. We observed five sulfur components with variable oxidation states.

To understand the formation mechanism of carbon clusters in low-carbon steel, the dynamic behavior of carbon in solid solutions subjected to aging at low temperatures was investigated by X-ray absorption spectroscopy. While it is hypothesized that the C-Fe bond distance and lattice strain induced by the carbon in solid solution affect the formation and strengthening mechanism of carbon clusters in low-carbon steels, currently, there is no information on the local structure of carbon in ferritic steels. Therefore, in this study, the relationship between the correlation coefficient derived from C K near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and mechanical properties, in terms of Vickers hardness, was elucidated. The changes occurring in the spectral shape in the initial stages of aging were found to be clearly associated with the diffusion of carbon in the solid solution. The presence of the carbon-cluster precursor state suggested that the correlation coefficient calculated from the C K NEXAFS spectra experienced variations in spite of a constant Vickers hardness. Furthermore, we proposed a method to analyze the local structure of carbon in solid solution in steels using C K NEXAFS. Finally, our observations illustrate that the local structure of carbon is dependent on age-hardening during low-temperature aging.

We have developed a conceptually and methodologically novel self-assembled multilayer nickel nanoparticle (NP) catalyst – sulfur-modified gold-supported Ni NPs (SANi) – for organic synthesis. The SANi catalyst was easily prepared through a three-step procedure involving simultaneous in situ metal NP and nanospace organization. This unique method does not require any conventional preformed template for immobilizing and stabilizing NPs. SANi catalyzes carbon-carbon bond-forming cross-coupling, Kumada coupling, and Negishi coupling reactions under ligand-free conditions and can be used repeatedly for these reactions. Physical analysis of SANi showed that the active species in these reactions are self-assembled multilayer zerovalent Ni NPs with a size of ∼3 nm.

The Messinian salinity crisis is a dramatic hydrological and biological crisis that occurred in the Mediterranean basin at 5.97–5.33 Ma. The interpretation of the facies and stratigraphic associations of the Messinian salt deposits is still the object of active research because of the absence of modern depositional analogues of comparable scale. In this study, the spatial distributions of Na, Mg, S, O, Si, and Al in a potassic-magnesian salt and a halite layers of Messinian evaporites from the Realmonte mine on Sicily were determined using synchrotron based micro-X-ray fluorescence. The dominant molecular host site of Mg and S obtained by X-ray absorption near edge structure (XANES) is applied to specify the hydrochemistry of hypersaline brines and the presence of diagenetic minerals, thus shedding light on evaporative concentration processes in the Caltanissetta Basin of Sicily. Mg and S K-edge XANES spectra revealed the presence of highly soluble Mg-bearing sulfates. The massive halite layer “unit C,” contains less soluble minerals, thus did not exceed the stage of halite crystallization. We infer that as evaporative concentration increased, the density of the brine at the shallow margin of the basin increased as salinity increased to concentrations over 70 times the starting values, creating brines that were oversaturated with Mg-sulfate. Density stratification of the deep basin caused heavy brines to sink to the bottom and become overlain by more dilute brines. We propose lateral advection of dense Mg-sulfate brines that certainly affected marine biota.

The P dopant site control in diamond is critical to achieve high mobility n type channels and high concentration n+ layers for power device applications. In this study, the P doped diamond films grown by three institutes with varying hydrogen and dopant concentrations were analyzed by X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). By XANES, the film with high H concentration (4.0 × 1019 cm−3) was estimated to show a higher peak intensity of 2147.7 eV than that of a low H concentration film. H was likely to be incorporated in the diamond as P-H at the substitutional sites under H rich growth condition. Another film showed considerably low peak intensities at 2147.7 and 2148.6 eV because of the “substitutional with H” and “substitutional” sites, respectively. The EXAFS result revealed that the first nearest neighbor distance is slightly shifted from the “substitutional” to “interstitial” site. The low P concentration film showed different types of energy profiles, particularly in the high energy region, indicating that dopant sites change with dopant concentration. Overall, the P dopant site is likely to be influenced by the machine system, H and P concentrations.

The structure of a recently developed Pd catalyst, named sulfur-modified gold-supported palladium (SAPd), has been determined to be composed of multi-layered Pd nanoparticles. SAPd is easily prepared by self-assembly on a sulfur-modified gold surface, and near-edge X-ray absorption fine structure (NEXAFS) analysis at the Pd K-edge determined that the Pd in SAPd is zero-valence analogous to metallic Pd. However, transmission electron microscopy (TEM) analyses and extended X-ray absorption fine structure (EXAFS) analysis clarified that SAPd has approximately 10 layers and consists of nanoparticles with a diameter less than 5 nm. High-density Pd nanoparticles were embedded without condensation. NEXAFS analysis at the S and C K-edge revealed that the organic matter containing sulfate and xylene as a major ingredient is distributed between Pd nanoparticles, and it seems to prevent condensation. These findings suggest that a highly efficient cross-coupling reaction, which was reported in earlier works, has been achieved by the high-density Pd nanoparticles.

Two dimensional anomalous small-angle scattering measurement at K absorption edge of Mg has been successfully demonstrated for concentrated Al-Mg binary alloys and MgO nanoparticles. Enhancing the contrast between Mg-rich precipitates and Al matrix was explained by the anomalous dispersion of Mg, and anisotropic SAXS pattern was in good agreement with the microstructure observed by transmission electron microscopy. Agreement of atomic scattering factor obtained from Al-Mg and MgO nanoparticles indicates that the origin of SAXS in the present Al-Mg alloys are Guinier-Preston zones, not the voids that grew from supersaturated vacancies.

MagnesiumK-edge X-ray absorption near-edge structure (XANES) spectra have been investigated to develop a systematic understanding of a suite of Mg-bearing geological materials such as silicate and carbonate minerals, sediments, rocks and chemical reagents. For the model compounds the Mg XANES was found to vary widely between compounds and to provide a fingerprint for the form of Mg involved in geologic materials. The energy positions and resonance features obtained from these spectra can be used to specify the dominant molecular host site of Mg, thus shedding light on Mg partitioning and isotope fractionation in geologic materials and providing a valuable complement to existing knowledge of Mg geochemistry.

In an aim to create a "sharp" molecular knife, we have studied site-specific fragmentation caused by Si:2p core photoionization of bridged trihalosilyltrimethylsilyl molecules in the vapor phase. Highly site-specific bond dissociation has been found to occur around the core-ionized Si site in some of the molecules studied. The site specificity in fragmentation and the 2p binding energy difference between the two Si sites depend in similar ways on the intersite bridge and the electronegativities of the included halogen atoms. The present experimental and computational results show that for efficient "cutting" the following conditions for the two atomic sites to be separated by the knife should be satisfied. First, the sites should be located far from each other and connected by a chain of saturated bonds so that intersite electron migration can be reduced. Second, the chemical environments of the atomic sites should be as different as possible.

In this study, in situ soft X-ray absorption spectroscopy (soft XAS) technique, which enables us to analyze electronic structures of oxides at elevated temperatures while controlling atmospheric conditions, was developed. The technique was applied to investigate the electronic structures of La0.6Sr0.4CoO3 − δ. X-ray absorption spectra at the Co L-edges and the O K-edge were measured in the temperature range from room temperature to 873 K and the p(O2) range from 10− 4 to 10− 2 bar. The developed in situ soft XAS technique is found to be effective for evaluating electronic structures of oxides under controlled temperature and p(O2).

The electronic structures of forsterite and its amorphous state were investigated using soft X-ray absorption near-edge structure (XANES) analysis at the Mg, Si, and O K-edges. The experimental spectra were reproduced theoretically using density functional theory calculations. Surface-sensitive XANES spectra for the (001), (010), and (100) surfaces were also observed. This study reports the first observation at the O K-edge using synchrotron radiation, and, in addition, reveals that the spectra is surface-sensitive at the Mg and Si K-edges. These findings demonstrate that XANES is a powerful technique to study silicate compounds.

Ionization energies for valence electrons of CF 3 SF 5 were measured in the 12–35 eV region by means of angle-resolved photoelectron spectroscopy. The observed ionization energies were basically consistent with previous ones measured by threshold photoelectron and HeI photoelectron spectroscopy, and the ionization levels at 22.60, 26.92 and 27.86 eV were newly observed. Asymmetry parameter derived at hν = 684.7 eV was a constant of β = 1.02 ± 0.04 in the ionization energy lower than 20 eV, suggesting that lone pair electron of F atom is probably released through 2p → ɛ d like electron emission. Characters of the 22 valence bands were elucidated with the help of ab initio calculations and of the nature of valence orbitals for CF 4 and SF 6 .

After inner shell excitation the ultrafast fragmentation of small molecules can proceed on a time scale similar to that of the Auger decay. In this case the nuclear motion affects the observed electron spectrum in various ways. The best known example is the Doppler splitting of atomiclike Auger lines, but non-parallel potential surfaces are equally important. Using an electron energy - ion momentum coincidence experiment and an ab initio calculation of potential curves, we discuss the main features seen in the non-coincident and coincident resonant Auger spectrum by decay of the F(1s)->6a1* core excited state of CH3F.

The chemical states of sulfur in 11 tires were analyzed using X-ray absorption near-edge structure (XANES) in order to discriminate between various tire rubbers. All tires had peaks around 2471.5 and 2480.5 eV, and the shapes and heights of these peaks differed among tires, suggesting that the sulfur chemical state could be used for discrimination between tire rubbers. Based on t-tests on the results of XANES, 43 of 55 combinations were different at a significance level of 5%.

Ionic fragmentation caused by Si:1s photoexcitation of 1-trifluorosilyl-2-trimethylsilylethane [F 3 SiCH 2 CH 2 Si(CH 3 ) 3 ] vapor was studied using monochromatized synchrotron radiation and a reflectron-type mass spectrometer. The total ion-yield spectrum in the Si:1s excitation region was found to be very similar to the superposition of the ion-yield spectra of Si(CH 3 ) 4 and SiF 4 , showing that site-specific excitation occurred in this molecule. When the photon energy was scanned from low to high, the 1s → σ * excitation at the Si atom bonded to three CH 3 groups suppressed the production of CH 3 + and SiCH 3 + . The 1s → σ * excitation at the Si atom bonded to three F atoms, on the other hand, enhanced the production of F + and SiF + and suppressed the production of SiF 3 + . These results suggest that Si:1s site-specific excitation causes site-specific fragmentation. The fragmentation caused by Si:1s → σ * photoexcitation was also found to be more violent than that caused by Si:2p → σ * photoexcitation.

Resonant Auger transitions into 1G4•nl states following Kr 2p3/2 electron excitation have been measured using monochromatized undulator radiation and a hemispherical electron energy analyzer. A clear identification of electron peaks was made for the 1G4•5s, 1G4•4d, 1G4•5d and so forth when the photon energy approached to the ionization threshold. The formation of the 1G4•4d state was found over a relatively wide energy range across the threshold, because of the short lifetime of the 2p hole and of shake effects in electron emission processes. The angular dependence of these decays showed little effect on the polarization direction of the incident photon, which suggests that little anisotropy is related to that of the normal Auger transition into the 1G4 state.

Out-of-plane nuclear motion stimulated in the core-excited state and symmetry breaking due to this nuclear motion have been investigated for B Is excitation in the BF3 molecule by a combination of three different experimental methods: angle-resolved ion-yield spectroscopy, vibrationally resolved resonant Auger electron spectroscopy and quadruple-ion coincidence momentum-imaging technique. (C) 2002 Elsevier Science B.V. All rights reserved.

This study investigated the distribution of magnesium (Mg), phosphorus (P), sulfur (S) and strontium (Sr) using micro X-ray fluorescence (µ-XRF) along the annual growth rings in the skeleton of Japanese red coral Paracorallium japonicum. The Mg, P and S distribution in µ-XRF mapping images correspond to the dark and light bands along the annual growth rings observed in microscopic images of the coral skeleton. The µ-XRF mapping data showed a positive correlation (r = 0.6) between P and S distribution in the coral skeleton. A contrasting distribution pattern of S and Mg along the axial skeleton of P. japonicum indicates a weak negative correlation (r = -0.2) between these two trace elements. The distribution pattern of S, P and Mg reveals linkage between their distributions and the formation of dark/light bands along the annual growth rings in the axial skeleton of P. japonicum. Sulfur and P were distributed in the organic matrix rich dark bands, while Mg was distributed in the light bands of the annual growth rings.

We used micro-X-ray fluorescence combined with X-ray photoabsorption spectroscopy to investigate speciation-specific sulfur profiles in the inner shell layer of a giant clam (Hippopus hippopus). The sulfate, S-bearing amino acids, and total sulfur profiles indicated that inorganic sulfate was the dominant component in the shell of this bivalve. Sulfur profiles in the inner shell layer showed clear annual fluctuations that varied by more than one order of magnitude, from < 50 to 1420 ppm, and sulfate and total sulfur maxima became higher with age, whereas no ontogenetic trend was noticeable in the profile of S-bearing amino acids. A change in the carbonate ion concentration in the calcifying fluid would suggest that an ontogenetic increase in the relative activity of sulfate ions to carbonate ions in the calcifying fluid affects sulfate concentrations in the shells. These results suggest that trace sulfur profiles in the shell of the giant clam may reflect both cyclic shell growth related to environmental factors such as insolation and temperature and ontogenetic changes of the calcifying fluid chemistry mediated by physiological processes. The observed S profile implies a clear change in calcifying fluid chemistry towards less alkaline condition with age. Magnesium fluctuations suggested that Mg was incorporated into the shells at high growth rates during warm seasons. The spectrum of Mg K-edge X-ray absorption near edge structure (XANES) and comparison of Mg and S-bearing amino acids profiles indicated that a pronounced effect of the organic fraction or disordered phases were observed in aragonitic shell of H. hippopus rather than regulated substitution into the aragonite crystal lattice.

A gradual uncontrollable increase in the resistivity of the amorphous phase of phase-change alloys, such as Ge2Sb2Te5, known as drift, is a serious technological issue for application of phase-change memory. While it has been proposed that drift is related to structural relaxation, no direct structural results have been reported so far. Here, we report the results of Ge L3-edge x-ray absorption measurements that suggest that the drift in electrical conductivity is associated with the gradual conversion of tetrahedrally coordinated Ge sites into pyramidal sites, while the system still remains in the amorphous phase. Based on electronic configuration arguments, we propose that during this process, which is governed by the existence of lone-pair electrons, the concentration of free carriers in the system decreases resulting in an increase in resistance despite the structural relaxation towards the crystalline phase.

Silicon dioxide has eight stable crystalline phases at conditions of the Earth's rocky parts. Many metastable phases including amorphous phases have been known, which indicates the presence of large kinetic barriers. As a consequence, some crystalline silica phases transform to amorphous phases by bypassing the liquid via two different pathways. Here we show a new pathway, a fracture-induced amorphization of stishovite that is a high-pressure polymorph. The amorphization accompanies a huge volume expansion of ~100% and occurs in a thin layer whose thickness from the fracture surface is several tens of nanometers. Amorphous silica materials that look like strings or worms were observed on the fracture surfaces. The amount of amorphous silica near the fracture surfaces is positively correlated with indentation fracture toughness. This result indicates that the fracture-induced amorphization causes toughening of stishovite polycrystals. The fracture-induced solid-state amorphization may provide a potential platform for toughening in ceramics.

Dissociative photoionization processes of iron pentacarbonyl are investigated in the inner-valence region by use of the photoelectron−photoion coincidence (PEPICO) and photoion−photoion coincidence (PIPICO) technique combined with synchrotron radiation. Photon energy dependence of the yield is examined in detail for all observed ions and ion pairs in the range 38−120 eV. Ions observed in the PEPICO measurements include not only the fragment ions resulting from simple CO elimination but also those resulting from additional cleavage of the C−O covalent bond(s) in the ligand. In the PIPICO measurements, several novel ion pairs that unambiguously indicate the cleavage of the covalent C−O bond in the ligated state are detected. From the analysis of these PEPICO and PIPICO efficiency curves, dissociation mechanisms leading to all ions and ion pairs are discussed, placing special emphasis on the cleavage of one or more covalent C−O bonds. It is concluded that the increased extent of the back-donation of dπ elect...

Photoabsorption cross-sections of CF2CH2 were measured in the carbon K-edge region and linear time-of-flight mass spectra were acquired at some photon energies across the two π* peaks. The kinetic energy distributions of CH2+ and CF2+ with two components were deduced from the analysis of the mass spectra. The CH2+ ion with high kinetic energies increases with the extent of vibrational excitation of the CF 1s → π* state, indicating that molecular vibrations play an important role in the photofragmentation of the inner-shell excited molecule.

An improved process for the preparation of sulfur-modified gold-supported palladium material [SAPd, second generation] is presented. The developed preparation method is safer and generates less heat (aqueous Na2S2O8 and H2SO4) for sulfur fixation on a gold surface, and it is superior to the previous method of preparing SAPd (first generation), which requires the use of the more heat-generating and dangerous piranha solution (concentrated H2SO4 and 35% H2O2) in the sulfur fixation step. This safer and improved preparation method is particularly important for the mass production of SAPd (second generation) for which the catalytic activity was examined in ligand-free Buchwald–Hartwig cross-coupling reactions. The catalytic activities were the same between the first and second generation SAPds in aromatic aminations, but the lower palladium leaching properties and safer preparative method of second generation SAPd are a significant improvement over the first generation SAPd.