Kα X-ray Research Articles

Antioxidative 2-(2-phenylethyl)chromones in Chinese eaglewood from Aquilaria sinensis

Two new compounds 6,7-dimethoxy-2-[2-(2′-hydroxyphenyl)ethyl]chromone (1) and 6,7-dimethoxy-2-[2-(4′-hydroxyphenyl)ethenyl]chromone (2), together with ten known 2-(2-phenylethyl)chromones (3–12) were isolated from the resinous wood of Aquilaria sinensis (Lour.) Gilg. Their structures were elucidated by detailed IR, MS, NMR spectroscopic analyses, and comparison with reported. The absolute configuration of 3 was confirmed by Cu Kα X-ray crystallographic experiment, and the X-ray crystallographic data of 3 were firstly reported. Compounds 2, 8, 10, and 11 exhibited strong ABTS•+ radical scavenging activity, with IC50 values of 12.3, 16.5, 12.1, and 34.7 μM, respectively.

Feasibility study of a new method to measure fast neutron flux by neutron-induced X-ray fluorescence method

A new method is proposed to detect fast neutron flux: the neutron-induced X-ray fluorescence method. In this method, the neutrons are firstly converted to charged particles, and then the charged particles interact with the target to generate the characteristic X-ray fluorescence. Finally, the Kα X-ray emission from the target is detected for measurement of the neutron flux. On the basis of this method, the structure of the detection device is designed: it is composed mainly of a layer of a fast neutron converter and a layer of the target. The Geant4 Monte Carlo simulation toolkit is used to optimize the detection device. According to the simulation results, the detection device is manufactured so as to perform the feasibility verification experiments. In the experiments, a D-T neutron generator is used as the neutron source, and the number of neutrons is changed in two ways: by change of the working voltage of the neutron generator or by change of the measurement time. The experimental results show that there is a good linear relationship between the number of neutrons and the Kα X-ray counts when the measurement time is changed. When the working voltage of the neutron generator is changed, a 3He proportional counter is used as a reference detector. The results show that the trend of the Kα X-ray counts is in good agreement with the trend for the 3He proportional counter. It is proved that this method is feasible for fast neutron flux measurement.

Vieloplains A-G, seven new guaiane-type sesquiterpenoid dimers from Xylopia vielana

Seven new guaiane-type sesquiterpene dimers vieloplains A-G, connecting patterns through three different direct CC bonds compounds 1–5 (C-3 to C-3′, C-4 to C-1′), compound 6 (C-2 to C-3′, C-4 to C-2′) and compound 7 (C-2 to C-1′, C-4 to C-2′) were isolated from the roots of Xylopia vielana. Their absolute configurations were established by NOESY analysis, the Cu Kα X-ray crystallographic the experiment circular dichroism (ECD) and the calculated ECD. Among them, only compound 6 showed a considerable cytotoxicity against DU145 cells with IC50 values of 9.5 μM. Flow cytometry analysis confirmed that 6 caused death of DU145 cells via apoptosis induction.

New acetylenic compounds and lignans from Dolomiaea berardioidea (Franch.) Shih

Two new acetylenic compounds (1 and 2), two new lignans (3 and 4) along with eight known lignans (5−12), ten known terpenoids (13−22) and one known aromatic compound (23) were isolated from the whole plants of Dolomiaea berardioidea (Franch.) Shih. Structures of new compounds were elucidated by combined use of HRESIMS, 1D and 2D NMR and CD spectroscopic methods. The absolute structures of 1 and 3 were further confirmed by Cu Kα X-ray crystallographic analyses. In addition, all isolated compounds were also tested for their inhibitory effects against LPS-induced NO production of RAW 264.7 macrophage. Compound 22 displayed potential anti-inflammatory activity with IC50 value of 7.4 μM.

Multiple ionization state of Arq+ ions during collisions near the Bohr velocity

In order to clarify the mechanism and the influence of the initial charge state and target atomic parameters for the formation of L-shell multiple ionization state of Arq+ ions produced by the collisions near the Bohr velocity, the k-shell x-ray emission of Ar is measured for 1.2 MeV Arq+(q=4, 6, 8, 9, 11, 12) ions impacting on V target and 3 MeV Ar11+ ions interacting with selected targets (Z2 = 23, 26, 27, 28, 29, 30). It is found that the measured Ar Kα and Kβ x-ray energies shift to the high energy side, and the relative intensity ratios of Kβ/Kα are enlarged than the atomic data, owing to the presence of out-shell multiple vacancies. The multiple ionization is almost independence of the projectile charge state, but is diminished with increasing target atomic number.

Angular and impact energy dependence of intensity ratio of Kα,β x-rays to underneath bremsstrahlung radiation emitted from 15 to 25 keV electrons incident on a pure thick Cu (Z=29) target

We present new results on angular and impact energy dependence of the relative intensity ratios of Kα and Kβ characteristic (CS) x-ray lines to their respective underneath bremsstrahlung (BS) radiation produced from 15-25 keV electrons incident on a thick polycrystalline pure target of Cu (Z = 29). The angular distributions of relative intensity ratios were carried out by measuring the radiations emitted at incidence angle θi that varied from 15° to 75° in reflection geometry mode of the target. The x-rays emerging from the target surface were detected by an energy dispersive Si PIN photodiode detector. The magnitude of relative intensity ratio of Kα/BS is found to be larger than that of Kβ/BS by a factor of about 5.11, 5.24 and 5.49 for 15 keV, 20 keV and 25 keV impact energy, respectively measured, for example, at θi = 15°. However, the intensity ratio of a given characteristic line to its underneath BS increases on average by a factor of about 2.2 in varying the impact energy from 15 keV to 25 keV measured at different angles. The experimental results on angular and impact energy dependence are compared with the corresponding results obtained from Monte-Carlo simulations using the PENELOPE code. The overall agreement between experiment and theory is found to be satisfactory within the uncertainty of measurements.

Phosphorous incorporation in olivine crystallized from potassium-rich magmas

Abstract Olivine phenocrysts in basaltic rocks carry valuable mineral-chemical information on early evolution processes in mafic magmatic systems. Fast intra-crystalline diffusion and re-equilibration weakens this potential for major cation constituents of olivine, but the relative immobility of phosphorous makes this element a promising tracer of early crystallization histories. Although phosphorous zoning patterns and underlying kinetic controls have been studied in recent years, little is known about compositional controls on phosphorous incorporation into igneous olivines. We have analysed olivine phenocrysts, hosting Mg-rich melt inclusions, from a range of mafic potassium-rich lavas from Quaternary volcanic centres in Italy for phosphorous and associated trace elements by laser ablation inductively coupled mass spectrometry (LA-ICP-MS), and intra-crystal zoning by electron probe micro-analysis (EPMA) using Kα X-ray elemental maps and quantitative traverses. The studied olivines are marked by low and variable phosphorous concentrations (generally ≤ 200 ppm, but up to 435 ppm in enriched zones). In most cases, phosphorous zoning is decoupled from zoning in any other element or forsterite content. From a comprehensive database of melt inclusions and host phenocrysts, we infer that the composition of the host melt (silica and phosphorous activities) and olivine crystallization dynamics (interplay between diffusion rate of cation constituents in the melt and crystal growth rate) largely regulate phosphorous incorporation in olivines. Melt composition is likely the most important control under near-equilibrium crystallization conditions, as apparent phosphorous partition coefficients tend to increase with increasing silica activity. A negative relationship between apparent partition coefficients and XPO2.5 indicates that phosphorous partitioning into olivine may deviate from Henry’s law behaviour. Melt inclusions are virtually always surrounded by phosphorous-poor zones that are also depleted in Cr and enriched in Al and Ti, suggesting that supply-limited slow growth and coupled-substitution mechanisms largely govern phosphorous uptake here. Our results demonstrate the potential versatility of phosphorous as sensitive indicator of crystal-growth histories and magmatic evolution processes in mafic systems.

PIXE-measurement of Kα X-ray production cross sections for 1-MeV C+-ions in thick samples of Si, Fe, Cu and Zn

Particle-Induced X-ray Emission (PIXE) using heavy ions proved to be an alternative with respect to PIXE using light protons due to relatively large cross sections. In this work we explored the capabilities of PIXE with using singly-charged carbon ions at relatively low energy of 1 MeV (or 83 keV/amu) to measure Kα X-ray production cross sections. The measurement was performed for thick samples of Si, Fe, Cu and Zn, using the standard 2-MeV proton-induced cross sections as the reference. For the measurement from thick samples, we adopted a special multi-slabs method in the calculation by considering the sample thickness effect. The effective ion range was divided into a number of thin slabs in which the energy dependent cross section and the thickness dependent X-ray transmission were varied. The paper describes details of the measurement principle and method and reports the result. The resulting data obtained from the present work were compared with those from the PWBA and ECPSSR theories, the simple thin-film method and the measurement of thin film samples and discussed for the validity of our result.

Binding effects in sulfur Kα and Kβ X-ray emission spectra

Sulfur samples in different oxidation states (+4, +6, 0 and −2) were irradiated in a commercial microscope, acquiring Kα and Kβ spectra in order to investigate the influence of the chemical bond on the occurrence of different sulfur decays to 1s vacancy states.

Assessing zinc from a nail clipping using mono-energetic portable X-ray fluorescence

A mono-energetic X-ray beam from a portable X-ray fluorescence device was used to excite characteristic X-rays from zinc in a series of nail clipping phantoms. Twenty nail clipping phantoms having equal zinc concentrations of ~40 µg/g, but with different physical characteristics, were measured individually for 300 s using a small diameter (~1 mm) X-ray beam. Energy spectra obtained from the measurements were analyzed using PyMca software. Zinc signal size varied widely between the different clippings, with a relative standard deviation of 41% observed in the combined signal from zinc Kα and Kβ characteristic X-rays. Three different normalization approaches were introduced to account for variation in the amounts of sample interrogated by the X-ray beam. All three approaches produced similar results, and successfully reduced the relative standard deviation to between 12% and 13%. A clear trend was still observed, however, between the normalized zinc signal and the thickness of clipping measured. To account for this effect, normalized signals were adjusted to calculate “thickness-corrected” values. The relative standard deviation of these thickness-corrected values was 6.2%. Reproducibility of measurement from individual clippings was excellent, with relative standard deviations on the order of 1%, with or without normalization. Overall, this new method of measuring zinc in nail shows promise for the assessment of zinc status in humans using a portable device. The method is sensitive, rapid, and requires only a single nail clipping.

Relativistic calculations on the x-ray satellites of platinum with multiply ionized L shell

The energies, electric dipole rates and oscillator strengths of Kα x-ray satellites from 1s–2p transitions in platinum with a single vacancy in the K shell and variously ionized L shell are calculated using multi-configuration Dirac Fock wavefunctions with the inclusion of Breit interaction and quantum electrodynamics effects. The computations have been performed for low ionized (Pt1+–Pt6+) and also for highly ionized (Pt69+–Pt77+) Pt. As Kα x-ray satellites with spectator vacancies only in the L shell, to the best of our knowledge, have been studied for the first time, to check the accuracy of the present work, calculations have also been performed for H-, He-, Li-, Be-, B- and F-like Pt for which theoretical data for comparison exist. The purpose of choosing a high Z element is that the detailed decay properties of heavy ions due to systematic 1s–2p transitions with spectator vacancies in the L shell using fully relativistic treatment are unexplored and the increasing need for reliable data from such ions in various applications that are under investigations in recent years. Also, for heavy ions like Pt, the contribution from the competing non-radiative transitions is less and hence the atomic properties are largely due to radiative transitions. The K X ray satellite energies, rates and resonance photo- ionization cross sections from H-, He-, Li-, Be-, B- and F-like Pt are compared with available data.

Modeling of Heat Transfer in an Aluminum X-Ray Anode Employing a Chemical Vapor Deposited Diamond Heat Spreader

X-ray sources are used for both scientific instrumentation and inspection applications. In X-ray photoelectron spectroscopy (XPS), aluminum Kα X-rays are generated through electron beam irradiation of a copper-based X-ray anode incorporating a thin surface layer of aluminum. The maximum power operation of the X-ray anode is limited by the relatively low melting point of the aluminum. Hence, optimization of the materials and design of the X-ray anode to transfer heat away from the aluminum thin film is key to maximizing performance. Finite element analysis (FEA) has been employed to model the heat transfer of a water-cooled copper-based X-ray anode with and without the use of a chemical vapor deposited (CVD) diamond heat spreader. The modeling approach was to construct a representative baseline model, and then to vary different parameters systematically, solving for a steady-state thermal condition, and observing the effect on the maximum temperature attained. The model indicates that a CVD diamond heat spreader (with isotropic thermal properties) brazed into the copper body reduces the maximum temperature in the 4 μm aluminum layer from 613 °C to 301 °C. Introducing realistic anisotropy and inhomogeneity in the thermal conductivity (TC) of the CVD diamond has no significant effect on heat transfer if the aluminum film is on the CVD diamond growth face (with the highest TC). However, if the aluminum layer is on the CVD diamond nucleation face (with the lowest TC), the maximum temperature is 575 °C. Implications for anode design are discussed.

High conversion efficiency and small spot size of Kα X-ray generated from nano-foam Cu targets irradiated by femtosecond laser pulses

Developing high-quality X-ray source to diagnose shock wave and changing the material and structure features of the target were presented to enhance its absorbability to ultra-intense laser energy. Experiments were carried out on the XingGuang-III Ti: sapphire laser facility (2.1– 6 J, 30 fs) at Laser Fusion Research Center, China Academy of Engineering Physics. The minimum intensity was 1.6 × 1018 W/cm2 on a nano-foam Cu target with the thickness of 100 µm, the porosity of 70% and the density ratio of 30% solids of Cu. The emission of Kα X-rays from the target was measured using a single-photon counting CCD device. This nano-foam target had generated a Kα peak photon rate of 2.9 × 108 photons sr−1 s−1 and the maximum conversion efficiency (CE) value was 0.0084%. The average CE of the nano-foam Cu was 1.8 times greater than that of foil Cu target. The minimum spot size of the X-ray source was measured to be about 40 µm at full width at half maximum, smaller than 47–86 µm of the foil Cu target using 0.1-mm thick knife-edge method. The nano-foam structure showed the potential of enhancing the CE of the femtosecond laser for X-ray conversion.

Vielopsides A-E, five new guaiane-type sesquiterpenoid dimers from Xylopia vielana

Five new guaiane-type sesquiterpenoid dimers vielopsides A-E, connecting patterns through two direct CC bonds (C-2 to C-2′, C-4 to C-1′), were isolated from the roots of Xylopia vielana. Their absolute configurations were established by NOE analysis, the Cu Kα X-ray crystallographic and circular dichroism (CD) experiment. Among them, compound 5 showed moderate activity IC50 values of 33.8 μM on NO production in RAW 264.7 macrophages.

Kα X-ray Emission Spectroscopy on the Photosynthetic Oxygen-Evolving Complex Supports Manganese Oxidation and Water Binding in the S3 State.

The unique manganese-calcium catalyst in photosystem II (PSII) is the natural paragon for efficient light-driven water oxidation to yield O2. The oxygen-evolving complex (OEC) in the dark-stable state (S1) comprises a Mn4CaO4 core with five metal-bound water species. Binding and modification of the water molecules that are substrates of the water-oxidation reaction is mechanistically crucial but controversially debated. Two recent crystal structures of the OEC in its highest oxidation state (S3) show either a vacant Mn coordination site or a bound peroxide species. For purified PSII at room temperature, we collected Mn Kα X-ray emission spectra of the S0, S1, S2, and S3 intermediates in the OEC cycle, which were analyzed by comparison to synthetic Mn compounds, spectral simulations, and OEC models from density functional theory. Our results contrast both crystallographic structures. They indicate Mn oxidation in three S-transitions and suggest additional water binding at a previously open Mn coordination site. These findings exclude Mn reduction and render peroxide formation in S3 unlikely.

Investigation of Tm2O3 As a Gate Dielectric for Ge MOS Devices

Germanium (Ge) has been intensively investigated as a high-mobility channel material alternative to silicon (Si). A high quality Ge/dielectric interface with interface state density Dit compared to Si is required for competitive device performance. GeO2 has been identified as potential candidate for an interfacial layer (IL) due to effective Ge surface passivation with Dit in the range of 1011 cm-2eV-1 [1]. However, in order to achieve scaled effective oxide thickness (EOT) a combination of GeO2 IL and a high-k dielectric is needed. Low interface state density in the range of 1011 cm-2eV-1 has been achieved while employing Al2O3 barrier [2] as well as rare earth oxides such as Y2O3 [3]. Rare-earth thulium oxide (Tm2O3) provides high dielectric constant k~16 [4] and sufficient valence (3.05 eV) and conduction (2.05 eV) band offsets [5] for a high-k dielectric layer on Ge. In this work Ge/GeOx/Tm2O3 interface quality and the impact of post deposition anneal ambient are investigated. Metal oxide semiconductor (MOS) capacitors were fabricated to evaluate Ge/GeOx/Tm2O3 gate stacks. After n-Ge substrate clean (acetone, propanol and O2 plasma) and native germanium oxide removal with aqueous HF and HCl solutions the samples were immediately loaded into the rapid thermal anneal (RTA) chamber where oxidation was carried out at 550 °C for 5 s to 5 min. The temperature in the chamber is controlled by a pyrometer which is calibrated to a Si wafer, and oxidation is performed by placing a Ge substrate piece on a Si carrier wafer. The temperature of the Ge sample is thus lower than that of the Si wafer. After oxidation the samples were loaded to atomic layer deposition (ALD) chamber where 40 cycles (~7 nm) of Tm2O3 were deposited using TmCp3 and H2O as precursors. Then Ge/GeO2/Tm2O3 gate stacks were annealed in different ambient (O2, O3, N2 and H2/N2) and temperatures (400 - 550 °C). Reference samples without Tm2O3 deposition or without post deposition anneal (PDA) were also fabricated. Al gate metal was deposited by physical vapor deposition and patterned. MOS capacitors were electrically characterized with capacitance-voltage (CV) measurements. Interface state density in the midgap was evaluated from CV curves using a method described in [6]. X-ray photoelectron spectroscopy (XPS) was performed on some samples using Al Kα X-ray (1486.6 eV) source and PSP Vacuum Technology electron energy analyser. Electrical properties of thermally grown Ge/GeO2 interfaces were evaluated and low interface state density Dit < 5·1011 cm-2eV-1 in the midgap was extracted from CV measurements. The influence of Tm2O3 deposition on high-quality Ge/GeO2 interfaces was then determined. A degradation of the interface quality after the deposition was observed as displayed in Fig. 1. Dit is higher for thinner underlying GeOx layer and seems to saturate to ~9·1011 cm-2eV-1 for thick layers. A series of post deposition anneals in different ambient and temperatures were performed on Ge/GeOx/Tm2O3 gate stacks in order to investigate the influence on the interface state density and capacitance equivalent thickness (CET). The results are shown in Fig. 2. It can be seen that a temperature of 500 °C or higher and O2 ambient is needed to sufficiently reduce Dit, when values as low as 2·1011 cm-2eV-1 can be reached. XPS measurement was performed on Ge/GeOx/Tm2O3 gate stack with O2 PDA at 500 °C and the obtained spectrum is shown in Fig. 3. The difference between the GeOx 3d5/2 peak and Ge0 3d5/2 peak is 2.7 eV which corresponds to Ge3+ oxidation state. This result is consistent with previously reported XPS results on Ge/GeOx/Al2O3 stacks [7] and suggests that Ge3+ oxidation state provides the low Dit values of Ge/GeOx/Tm2O3 gate stacks. Tm2O3 integrated with GeO2 and O2 PDA is a viable candidate for Ge MOS devices due to low interface state density of ~2·1011 cm-2eV-1 which is correlated to Ge3+ oxidation state. A further investigation of O2 PDA time in terms of the trade-off between Dit and CET will be reported.

High photon flux Kα Mo x-ray source driven by a multi-terawatt femtosecond laser at 100 Hz.

We develop a pulsed hard x-ray Kα source at 17.4keV produced by the interaction of a multi-terawatt peak power infrared femtosecond laser pulse with a thick molybdenum (Mo) target at a 100Hz repetition rate. We measure the highest Mo Kα photon production reported to date corresponding to a Kα photon flux of 1×1011 ph/(sr·s) and an estimated peak brightness of ∼2.5×1017 ph/(s·mm2·mrad2(0.1% bandwidth)) at ∼5×1018 W/cm2 driving laser intensity.

Temperature‐dependent local atomic structures in the traditional Fe65Ni35 Invar alloy by X‐ray fluorescence holography

Fe and Ni Kα X‐ray fluorescence holography measurements were conducted on a single crystal Fe65Ni35 Invar alloy at 100 and 300 K to investigate the temperature dependence of the 3‐dimensional local structures around the Fe and Ni atoms, respectively. Local structural information was obtained by detailed analyses using a L1‐regularized linear regression for the experimental data. At 100 K, the local atomic arrangements around both the elements show fcc structures. At 300 K, however, only the image around Fe shows a bcc‐like neighboring arrangement. From these X‐ray fluorescence holography data, we propose a model that with increasing temperature, an Fe atom with the low‐spin state enters at the central position of the fcc lattice and is stabilized. And then, large angular positional fluctuations are induced for the atoms at the face‐centered positions around the central Fe atom only.

X- and gamma-ray irradiation effects on vanadium pentoxide thin films

Thickness and composition of thin films can be measured with X- and gamma-rays. In this work, thickness and composition of vanadium pentoxide thin films are investigated by energy dispersive and wavelength dispersive X-ray fluorescence systems. Also, the surface analysis of vanadium pentoxide thin films irradiated with Rhodium Kα X-rays and 59.54 keV gamma-rays emitted from 100 mCi and 5 Ci Americium-241 radioactive sources is performed by scanning electron microscope. It is observed that X- and gamma-rays are destructive for vanadium pentoxide thin films. Also, the composition of vanadium pentoxide thin films changes by irradiation with X- and gamma-rays.

Core-level spectra of powdered tungsten disulfide, WS2

Core level spectra, generated by monochromatic Al Kα x-rays for a commercial, powdered tungsten disulfide (WS2) specimen, have been recorded and presented. The x-ray photoelectron spectra of WS2 obtained include a survey scan, high-resolution spectra of W 4f, S 2p, S 2s, W 4d, W 4p, O 1s, W 4s, S LMM, and the valence band. Quantitative analysis has been achieved using a two-parameter Tougaard background and line shapes indicated for fitting; using these methods a surface composition of WS2 is found.