Energy Auger Electron Research Articles

Energies, radiative and Auger transitions of the core-excited states for the boron atom

Energies, radiative and Auger transitions of the 1s vacancy resonances 1s2s22p2, 1s2s22p3p, 1s2s2p3, 1s2p4, and 1s2p33p, 4L (L=S, P, D) for the neutral boron atom are calculated using the saddle-point variation and saddle-point complex-rotation methods. Large-scale wave functions are used to obtain reliable results. Relativistic and mass polarization corrections are included by the first-order perturbation theory. The calculated term energies, x-ray wavelengths, and Auger electron energies for these core-excited states are compared with available theoretical and experimental results. Auger electron energies and branching ratios are used to identify high-resolution B Auger spectrum produced in 300keV B+ on CH4 collision experiment. It is found that the Auger decay of core-excited states of the boron atom gives significant contributions to Auger spectrum in the range of 165–210eV, and many previously unknown line identifications are presented.

Features of Auger-emission in channeling

Shown in this paper is the influence of channeling effect on formation of the signal for low- and high-energy Auger-electrons observed in monocrystalline silicon. It has been ascertained the anisotropic (wave-like) character of the yield value for low- energy Auger-electrons in silicon, when changing the angle of acting initial radiation during sample rotation.

Investigation of the electron structure ofZnOby the GGA and mBJ calculations associated with the characterization techniques AES and EELS

The semiconductor ZnO of large gap of 3,4 eV is of great interest for the technological applications as chemical sensors, UV light emission, optical memories, laser emission, solar cells, etc. These applications depend on the electron structure of material. We adopt the density functional theory (DFT) calculation by using the program Wien2K, within the Generalized Gradient Approximation (GGA) and modified Becke–Johnson (mBJ) for studying the electron behavior of ZnO . The features of the valence band derived from the hybridization of Zn -3d and O -2p states. The electron charge density calculated by these simulation methods indicates a charge transfer between zinc and oxygen inducing a difference in electronegativity between both species ( Zn and O ), responsible to ionic character of bonding in ZnO . The predictions based on the GGA and mBJ calculations are confirmed by the results of the experimental spectroscopic analysis Auger Electron Spectroscopy (AES) and Electron Energy Loss Spectroscopy (EELS).

The Low Energy Auger Electron Spectroscopy Lines as an Index of the Ba Overlayer Order on the Ni(110) Surface

We investigate the interaction of Ba with the Ni(110) surface at elevated temperatures by means of Auger electron spectroscopy and low energy electron diffraction. The results show that annealing of the substrate causes desorption and ordering of the initially amorphous overlayer, resulting in c(2×2) and (2×2) structures. It is observed that the induced ordering crucially affects the lineshape of the double Auger transition line Ba(73 eV)N45O23P1, establishing this line as an index of ordering of the Ba overlayer. The underlying physics of this effect is discussed.

Surface modified Ti based metallic glasses for bioactivation by electrochemical treatment technique

The aim of this study is surface modification of Ni-free type Ti based metallic glass (Ti42Hf11Cu11Pd36at.%) for increasing calcification by electrochemical treatment. Ni-free type Ti based metallic glass has excellent mechanical and chemical properties which are comparable with those of Ti based alloys. Surface of Ti based metallic glasses was prepared as follows; one is anodically-oxidized porous layer by potentiostatic control in 5M NaOH solution at 25°C for 2h, and the other is simple hydrothermal treated poros layer by immersion in 5M NaOH solution at 60°C for 24h. The synthesized surface structures were characterized by X-ray diffraction (XRD) identification, SEM observation, energy dispersive X-ray spectroscopy (EDS) analysis and Auger electron spectroscopy (AES) analysis. These surfaces on the modified specimens have nano-mesh laminated structures and are consist of sodium titanate and titanium oxide. In addition, the above two types surfaces with nano-mesh laminated layer were immersed in Hank’s balance salt solution (HBSS) at 37°C for 21days for evaluation of calcification. The apatite-forming ability on these surfaces is observed by SEM observation and EDS analysis. As stated above surface modifications are also discussed about calcification effect by different surface treatment and different formability of porosity in this study.

Characterization of the Protective Surface Films Formed on Molten AZ91D Magnesium Alloy in SO2/Air Atmospheres in a Sealed Furnace

Surface films that formed on molten AZ91D magnesium alloy in SO2/air cover gases at 680 °C in a sealed furnace were characterized by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and Auger electron spectroscopy. It is revealed that the film formed on molten AZ91D alloy surface in cover gas with high air content can prevent the molten AZ91D alloy from oxidation and ignition. The surface film contained three elements, namely magnesium, oxygen and sulfur, and was mainly composed of MgO and MgS. The properties of the film depended on air content in the cover gas and holding time. Thermodynamic calculation showed that MgSO4 was the stable phase, and it was concluded that the formation of MgSO4 was important for the formation of the protective surface film in SO2/air atmospheres.

3d photoionization and subsequent decay of atomic gallium

We present an experimental and theoretical study of 3d photoionization and subsequent Auger decay of atomic gallium. The synchrotron radiation-induced electron spectra have been compared and analysed using multiconfiguration Dirac–Fock calculations. It has been shown that the theoretically predicted photoelectron spectrum is in rather good agreement with the experiment allowing us to identify the main spectral features. However, prediction of the Auger decay intensities fails due to calculational difficulties for the continuum wavefunctions of very low kinetic energy Auger electrons.

Synthesis and characterization of novel elastomeric poly(D,L-lactide urethane) maleate composites for bone tissue engineering

Here, we report the synthesis and characterization of a novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its composites with nano-hydroxyapatite (nHA) as potential weight-bearing composite. The 4PLAUMA/nHA ratios of the composites were 1:3, 2:5, 1:2 and 1:1. FTIR and NMR characterization showed urethane and maleate units integrated into the PLA matrix. Energy dispersion and Auger electron spectroscopy confirmed homogeneous distribution of nHA in the polymer matrix. Maximum moduli and strength of the composites of 4PLAUMA/nHA, respectively, are 1973.31±298.53MPa and 78.10±3.82MPa for compression, 3630.46±528.32MPa and 6.23±1.44MPa for tension, 1810.42±86.10MPa and 13.00±0.72 for bending, and 282.46±24.91MPa and 5.20±0.85MPa for torsion. The maximum tensile strains of the polymer and composites are in the range of 5–93%, and their maximum torsional strains vary from 0.26 to 0.90. The composites exhibited very slow degradation rates in aqueous solution, from approximately 50% mass remaining for the pure polymer to 75% mass remaining for composites with high nHA contents, after a period of 8weeks. Increase in ceramic content increased mechanical properties, but decreased maximum strain, degradation rate, and swelling of the composites. Human bone marrow stem cells and human endothelial cells adhered and proliferated on 4PLAUMA films and degradation products of the composites showed little-to-no toxicity. These results demonstrate that novel 4-arm poly(lactic acid urethane)-maleate (4PLAUMA) elastomer and its nHA composites may have potential applications in regenerative medicine.

Observations of soft x-ray emission and wall ablation in a fast low-energy pulsed capillary discharge

We report on experimental observations of pulsed capillary discharges aimed at soft x-ray production within the water-window range. Through systematical studies of capillary tube characteristics and discharge conditions, radiation emission was analysed. Plasma properties were studied by means of spectrometry, wide-band PIN diode signals and plasma micro-channel plate imaging. Surface and bulk material analyses were performed using scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS) and Auger electron spectroscopy (AES) in order to characterize the capillary inner surface after discharges. We report on hollow cathode effect enhancement by modification of cathode electrode aperture, as well as pressure conditions along the capillary, which were found to have an important effect over plasma and x-ray yields due to the modification of local electrical field and gas density. Capillary tube material and inner diameter also modified the interaction of the plasma channel with the capillary surface, thus modifying the plasma source characteristics. It was found that emission of the NVI line at 28.8 Å can be enhanced within the conditions studied, from no significant emission to sources delivering an average brightness of over 70.0 mW mm−2 per 2π sr. This demonstrates that hollow cathode electrons and plasma–wall interaction and ablation have a direct impact on emission quality.

Radiative and Auger transitions of core-excited states for the boron isoelectronic sequence

Energy levels, radiative rates, Auger branching ratios of the 1s vacancy resonances 1s2s 22p 2 and 1s2s2p 3 2,4L (L = S, P, D) of the boron isoelectronic sequence including O3+, Ne5+, Mg7+, Si9+ ions are calculated by the saddle-point variation and saddle-point complex-rotation methods. Large-scale wavefunctions are used to obtain reliable results. Relativistic corrections and mass polarisation effects are taken into account to get precise energy levels. Calculated X-ray wavelengths, radiative rates, Auger electron energies, and Auger rates for these core-excited states are compared with available theoretical and experimental results. Furthermore, calculated reliable X-ray wavelengths are used to give possible identifications for satellite lines in the X-ray spectrum of foil-excited magnesium and silicon ions. Calculated Auger electron energies and Auger branching ratios are used to identify oxygen and neon Auger electron spectral lines in previous collision experiments. Three unidentified experimental spectral lines in neon KLL Auger electron spectrum are identified in the present work. The total radiative rates and the total Auger rates for the 1s2s 22p 2 and 1s2s2p 3 resonances of B-like ions are also discussed, as a function of atomic number Z. It is found that the total Auger rates of these resonances are several orders of magnitude larger than the total radiative rates for these low-Z (Z = 6–14) ions.

Energies and the radiative and Auger transition rates of1s2p4resonances of B-like ions

Energy levels and the radiative and Auger transition rates of the 1$s$2${p}^{4}$ ${}^{2,4}L$ ($L=S$, $P$, $D$) resonances in the boron isoelectronic sequence are calculated using the saddle-point variation and saddle-point complex-rotation methods. Large-scale wave functions are used to saturate the functional space. Relativistic and mass polarization corrections are included by the first-order perturbation theory. The Auger branching ratios of the important decay channels for these core-excited states are calculated. The reliable transition wavelengths and Auger electron energies are used to identify available x-ray spectra and Auger electron spectra. Identifications of several unknown experimental lines from 1$s$2${p}^{4}$ resonances are reported. The total radiative rates and total Auger rates of these 1$s$2${p}^{4}$ resonances are also reported and discussed along with the increase of atomic number $Z$. It is found that the total Auger rates are several orders of magnitude greater than the total radiative rates in these low-$Z$ ions.

Surface failure and wear of cemented carbide rock drill buttons—The importance of sample preparation and optimized microscopy settings

The combination of suitable mechanical properties and wear resistance makes cemented carbide one of the most interesting engineering composite materials for tribological applications, such as in rock drilling. Despite the fact that cemented carbide buttons have been used in rock drilling applications for a long time the detailed understanding of the prevailing wear mechanisms is far from complete and wear and breakage of rock drill buttons are still one of the lifetime-limiting factors for rock drill bits. Consequently, further research in this area, including detailed characterization of worn drill button surfaces and sub-surface regions, is needed in order to support the future development of new cemented carbide grades with improved failure and wear resistance. In the present paper, high resolution scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Auger electron spectroscopy (AES) have been used to characterize the wear and failure mechanisms of worn drill buttons and samples exposed to well controlled impact and scratch tests performed in the laboratory. The most important mechanisms of surface failure and wear were found to be severe plastic deformation, cracking, crushing of individual WC grains and mechanical/tribochemical degradation of the Co binder phase including Co depletion. Fracture cross-sectioning under tensile stress-state was found to be the best method for achieving large and reliable sub-surface cross-sections within a short time and to a low cost. The importance of optimized microscopy and spectroscopy settings for enhanced surface sensitivity for the examination of small-scale tribological phenomena is illuminated and discussed.

Chemical-state imaging of Li using scanning Auger electron microscopy

The demand for measurement tools to detect Li with high spatial resolution and precise chemical sensitivity is increasing with the spread of lithium-ion batteries (LIBs) for use in a wide range of applications. In this work, scanning Auger electron microscopy (SAM) is used to image chemical states of a partially oxidized Li surface on the basis of the Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) data obtained during an oxidation process of a metal Li. We show that distribution of metallic and oxidized states of Li is clearly imaged by mapping the intensity of the corresponding AES and EELS peaks. Furthermore, a tiny difference in the extent of oxidation can be distinguished by comparing the elemental map of an AES peak with that of an EELS peak owing to the different behaviors of those signals to the chemical states of Li.

Functionalised porous nanocomposites: a multidisciplinary approach to investigate designed structures for supercapacitor applications

The rational design of nanocomposite structures with specific functions in energy storage applications is a key requisite to increase energy and power density in electrical storage systems. Nanoscale characterisation tools are essential to achieve controlled syntheses of such well-defined interface structures in order to reveal structure–property relationships in functional nanocomposites. In the following, we report on the synthesis of iron (hydr)oxide nanoparticles homogeneously embedded into the walls of the three dimensional carbon network of mesoporous carbon CMK-3 via a mild one-step redox functionalisation. Depth profile Auger electron spectroscopy (DP-AES) and energy filtered transmission electron microscopy (EF-TEM) are applied to analyse elemental distribution profiles and location of the active components. The combination of the two analytical techniques provides a highly resolved spatial distribution of transition metal (hydr)oxide nanoparticles inside the carbon network. Functionalised porous carbon nanocomposites were tested for supercapacitor applications and the highest energy density of an iron oxide carbon composite is demonstrated. The iron (hydr)oxide contributes with a pseudocapacitance of 357 F g−1 to the porous nanocomposite in a 6 M KOH electrolyte. An overall doubling of the specific capacitance of the active electrode material compared to the pristine CMK-3 is achieved.

Interference of electron pairs in photoinduced N4,5 − O1O2,3 Auger decay in xenon

We observed an interference originating from coincidence detection of two indistinguishable electron pairs emitted upon photoionization of 4d electron in Xe. At 89.9 eV photon impact the energy of photoelectron ejected from 4d5/2 orbital equals energy of Auger electron emitted in decay of 4d3/2 hole into the [5s5p1P] state, and for the same final state the energy of the 4d3/2 photoelectron equals the Auger electron energy in decay of 4d5/2 hole. An angle-integrated coincidence yield as a function of photon energy is measured with the magnetic bottle time-of-flight spectrometer and shows a peak at the expected energy position.

Determination of 41Ca with LSC and AMS: method development, modifications and applications

Despite the emission of only low energy Auger electrons (ca. 3.6 keV) and the difficulty of obtaining a certified standard, Liquid scintillation counting (LSC) determinations are still reasonable options for a radioanalytical laboratory involved in nuclear installation decommission. Besides, accelerator mass spectrometry (AMS), being the most sensitive analytical technique not only for 41Ca, is gaining increasingly broader accessibility and applicability. Herein, we present a radiochemical separation procedure developed for 41Ca determination with LSC and AMS in varying materials (i.e. water, concrete, sediment, soil, and biota). The radioanalytical isolation consists of anion exchange and extraction chromatography as well as carbonate precipitation and recrystallization from organic solvents. Thereby, interfering radionuclides as 55Fe, 60Co, 152Eu, U or actinides are removed with decontamination factors of 102–104. Quench curves for determining the measurement efficiency is generated with a 41Ca solution gained from the 41Ca/40Ca certified reference material ERM-AE701. In routine application the procedure is characterized by chemical yields of 67–86 %, measurement efficiencies of 1–10 % and detection limits of 0.05 Bq g−1 and 0.3 Bq L−1. Aliquots of the digestion solutions of LSC can be easily converted into CaF2–AMS targets by successive oxsalate and fluoride precipitation. Pros and cons for both measurement techniques are addressed based on 41Ca results from LSC and AMS for the same material.

Properties of ultra‐thin SiGe‐on‐insulator materials prepared by Ge condensation method

AbstractUltra‐thin SiGe‐on‐insulator (SGOI and GOI)materials with various Ge concentrations were fabricated by oxidation of SiGe on SOI substrate, in which Si was oxidized and Ge was confined between the two oxide layers. The SGOI (GOI) materials were systematically characterized with double‐crystal X‐ray diffraction, Raman spectroscopy, Auger electron energy spectroscopy, and high‐resolution transmission electron microscopy. It is indicated that Ge profile in the SGOI is uniform with smooth surface and the strain relaxation process in the SGOI is still dominated by the critical thickness. An ultra‐thin GOI with 11 nm Ge layer was achieved, in which room temperature photoluminescence due to its direct band transition was observed. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The effect of underlayer-modified atomic monolayer on the mechanism of subsequent film growth

We have studied the influence of the upper Si monolayer (ML) in Fe-Si interlayers on the mechanism of subsequent growth of 7-ML-thick Cu films during molecular beam deposition. The Fe-Si interlayers and Cu films were studied in ultrahigh vacuum by the methods of electron energy loss spectroscopy (EELS) and Auger electron spectroscopy (AES). The final morphology of samples was examined in air by the atomic force microscopy. It is established that the growth of a Cu film on a Si(1 ML)/Fe2Si3(5 ML)/Si(001) structure has a pseudolayer character (with dissolution of the uppermost Si monolayer), while the growth of Cu on a Si(1 ML)/Fe(1 ML)/Si (1 ML)/Fe(1 ML)/Si(001) structure proceeds in the form of islands. This behavior is explained by different chemical states of the uppermost Si monolayer, which is modified by Fe-Si underlayers with different structures.

Spectroscopy of carbon: from diamond to nitride films

Every surface scientist knows about the importance of carbon spectroscopy: the signals of C 1 s and C KLL usually are indicating the surface cleanness, whereas C 1 s peak is often used as a reference for the calibration of energy scale. Carbon spectroscopy becomes even more important in the case of the studies dedicated to new carbon‐based materials, such as nanotubes, graphene, diamond‐like carbon (DLC), carbon nitride, carbides, etc. It is well‐known that the carbon atoms can be arranged in a great variety of crystalline and disordered structures, because their electrons can hybridize in sp3, sp2and even in linear sp configurations. Namely, the hybridization of carbon electrons defines the mechanical, electrical and optical properties of these materials. Indeed, between the pure diamond (sp3) and graphite (sp2), there are many phases of amorphous material characterized by different sp2/sp3ratios and generally named DLC. Electron spectroscopies (X‐ray photoelectron spectroscopy, Auger electron spectroscopy and electron energy loss spectroscopy) are widely recognized as analytical techniques, able to identify the bonds of diamond, graphite and amorphous phases of carbon. The binding energy of C 1 s spectrum together with its plasmon losses, the shape of Auger peak and valence band spectra can be used to characterize the structure of carbon‐based materials. In this study, an overview is reported on carbon spectroscopy, comparing different experimental methods. Their application for the characterization of DLC and carbon nitride films, including the determination of carbon's sp2/sp3ratio is discussed and illustrated by experimental results obtained for a series of thin films of these materials. Copyright © 2012 John Wiley & Sons, Ltd.

AES and EELS tools associated to TRIM simulation methods to study nanostructures on III-V semiconductor surfaces

At low energy (300 eV), the Ar+ ions bombardment lead to the formation of small nanodots on the InP and the InSb surface compounds. We used the Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) to detect the presence of these features. However, these techniques alone do not allow us to determine with accuracy their disturbed dimension related to the height and periodicity. For this reason, we combine these spectroscopy methods with the TRIM (transport and range of ions in matter), SRIM (Stopping and Range of Ion in Matter) and Sigmund simulation methods to show the mechanism of interaction between the argon ions and the III-V compounds cited above and determine the dimension of disturbed areas as a function of Ar+ energy during 30 min.