Auger Energy Research Articles

Acceleration of Pd-V intermetallic diffusion by hydrogen

Vanadium-based membranes have great potential for hydrogen purification due to their perfect selectivity, high permeability, and relatively low cost. With appropriate surface cleaning, V efficiently permeates hydrogen at elevated temperature, but performance declines due to its affinity to absorb impurities. The application of palladium thin films maintains a clean surface that catalyzes hydrogen dissociation and recombination. Hydrogen permeation in Pd-V-Pd membranes initially reach theoretical permeability, but declines due to Pd-V interdiffusion. The objective of this work was to quantify the intermetallic diffusion process as a function of temperature and ambient. Pd-V composites were subjected to various annealing treatments and characterized using Auger electron spectroscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy, as well as correlated to measurements of membrane permeability. In an inert environment Pd-V interdiffusion was observable as low as 300 °C, and the diffusion coefficient had an activation energy of 44 kJ/mol. Furthermore, the presence of hydrogen at partial pressures > 10 kPa accelerated interdiffusion six-fold at T = 400 °C. Membrane performance degraded with an activation energy 75 kJ/mol, suggesting that intermetallic diffusion leads to both a loss of catalytic activity and as well as degradation of bulk permeability. These findings provide a baseline for evaluating hydrogen permeable interdiffusion barriers to overcome these challenges.

Resonant Auger spectromicroscopy in ultrathin Fe films on W(110)

L3MM Auger transition is measured near the L3 resonance of ferromagnetic Fe films on W(110). The kinetic energies of the Auger peaks display the typical Raman behaviour for photon energies well below the absorption threshold, where the Auger energy follows the changes in the photon energy. Classical Auger behaviour with constant kinetic energy sets in at about 1.5 eV below the L3 resonance independently from the number of Fe layers down to the monolayer thickness. Strong x-ray circular magnetic dichroism is observed at the L3 edge in the entire L3MM Auger spectrum. Different Auger features originating from the final state with two 3p core holes show slight variations in the dichroic signal, which is attributed to the exchange interaction between the core holes and the valence band. Finally, XMCD-PEEM magnetic domain imaging using Auger electrons is demonstrated with a high level of contrast and lateral resolution approaching that of imaging with secondary photoelectrons.

Predicting Auger Energy Consumption for Olive Orchards Using the Artificial Neural Networks

The present work aims to study the development and application of Radial Basis Function (RBF) networks for predicting auger energy consumption based on input energy. The study utilized RBF networks and explored the input energy with treatments 2 (Soil moisture content), 2 (Rotary speeds), 2 (Hole depths) and 4 (Replication) based on field operations. As indicated by the results, energy input differed between the treatments but was not significant. The highest input value in transaction soil moisture content was 14.75 %, rotary speeds of 235 rpm, and hole depths of 40 cm. In comparison, the lower input energy at transaction soil moisture content was 7.9%, rotary speeds of 235 rpm, and hole depths of 20 cm. Input energy in treatment (14.75 %, 235 rpm, and 40 cm) and treatment (7.9 %,235 rpm, and 20 cm) were 100.204 and 57.135 MJ. ha-1, respectively. The highest input energy shares were recorded for diesel fuel at all treatments. Furthermore, the RBF network with one hidden layer had good convergence. The output results showed 10 and five hidden neurons in a hidden layer with high accuracy for treatment (14.75 %, 235 rpm, and 40 cm) and treatment (7.9%, 235 rpm, and 20 cm). In the treatment (14.75 %, 235 rpm, and 40 cm), the MSE for the training and testing sets was 0.0001 % and 0.01 % for data points with Ordinary RBF (ORBF type). The performance of the 3-10-1 architecture was better than other architectures. Finally, this research concluded that the RBF network method can forecast the input energy and energy expenditures related to the types of treatments.

In-field performance of continuous flight auger (CFA) energy piles with different configurations

In order to face the national energy crisis in Brazil, the use of geothermal energy piles (GEP) integrated with heat pumps is an attractive and cost-effective solution for the building cooling demand. On the other hand, there are very few field studies on the thermal performance of GEP systems in Brazilian soils and climate conditions, and for this reason, the implementation of this technology is still a challenge. Motivated by this need, continuous flight auger (CFA) energy piles were constructed to support a building in São Paulo city, and an experimental study, described in this paper, was carried out to provide useful data for the design of these GEPs. This work examined two key aspects of the design of GEP systems: (1) the influence of the heat exchange pipe configuration, and (2) the thermal response of GEPs and their effect on nearby piles installed in multi-layered ground. For this study, thermal response tests (TRTs) were conducted on four GEPs constructed with different pipe configurations, installed in a saturated sandy deposit intercalated by soft organic clay layers. The results obtained showed that: (i) the influence of pipe configuration on the GEP heat transfer is more significant during the first hours of pile heating process, and decreases with time due to the thermal interference between the pipe loops; (ii) the GEP temperature profile is impacted by the presence of soil layers of highly different thermal conductivities and groundwater flow velocities; and (iii) the temperature variation of nearby piles was also affected by the thermal characteristics of the soil layers, and therefore it should be considered for the structural design of GEPs.

K-LL Auger electron angular distribution and absolute cross section measurement upon keV energy electron impact ionization of CH[formula omitted], N[formula omitted] and Ne

We report on the measurement of absolute cross sections and angular distribution of electron emission in the K-LL Auger region, upon electron impact ionization of molecular (CH4 and N2) and atomic (Ne) targets. Differential cross sections in the K-LL Auger energy range were measured at 6 keV and 8 keV impact energies. The angular distribution of the K-LL Auger yield is shown to be isotropic for all the three targets. Total K-LL Auger emission cross sections were estimated by integrating the measured differential cross sections over the entire energy and angular range. The estimated cross sections are in good agreement with the theoretical estimates.

Surface white spot and pitting corrosion of 316 L stainless steel

PurposeThe purpose of this paper is to address the concern of some stainless steel users. To understand the effect of surface white spots on corrosion performance of stainless steel.Design/methodology/approachWhite spots appeared on some component surfaces made of 316 L stainless steel in some industrial applications. To address the concern about the pitting performance in the spot areas, the pitting corrosion potential and corrosion resistance were measured in the spot and non-spot areas by means of potentiodynamic polarization and electrochemical impedance spectroscopy and the two different surface characteristics were analytically compared by using optical microscopy, laser confocal microscopy, scanning electron microscopy, x-ray diffraction, energy dispersive spectroscopy and auger energy spectroscopy. The results indicated that the pitting performance of the 316 L stainless steel was not negatively influenced by the spots and the white spots simply resulted from the slightly different surface morphology in the spot areas.FindingsThe white spots are actually the slightly rougher surface areas with some carbon-containing species. They do not reduce the pitting resistance. Interestingly, the white spot areas even have slightly improved general corrosion resistance.Research limitations/implicationsNot all surface contamination or roughening can adversely affect the corrosion resistance of stainless steel.Practical implicationsStainless steel components with such surface white spots are still qualified products in terms of corrosion performance.Originality/valueThe surface spot of stainless steel was systematically investigated for the first time for its effect on corrosion resistance and the conclusion was new to the common knowledge.

Elemental arsenic in the natural oxide on the MBE GaAs surface

The thickness, elemental and chemical compositions of the native oxide naturally formed on a perfect GaAs(1 0 0) crystal grown by MBE have been studied by Auger electron spectroscopy (AES) and electron energy-loss spectroscopy (EELS) to specify the oxidation mechanism and to confirm or reject the questionable presence of elemental arsenic in the natural oxide. Elemental arsenic (Aso) arising in the oxidation process due to reduction of As2O3 by the GaAs substrate was revealed at the Auger energy of 1225.8 eV and shown to reach ~16 at% of the oxide whose thickness was determined to be ~4 nm. Aso was shown by EELS to form a segregate with the plasmon energy of 18.1 eV. Room temperature oxygen diffusivity through the finally formed oxide layer was estimated to be low enough (D < 10−21 m2/s) to explain retention of the Aso in the deepest oxide layers where it cannot oxidize again or diffuse away. The studied natural oxide was shown to have a layered nanostructure consisting of a cap As2O3 layer (~1 nm), a core oxide layer containing a Ga2O3/As2O3 mixture (~2 nm) enriched in Ga by a factor of 1.5, and a deep interface layer of elemental arsenic (~1 nm).

Real-time dynamics of Auger wave packets and decays in ultrafast charge migration processes

The Auger decay is a relevant recombination channel during the first few femtoseconds of molecular targets impinged by attosecond XUV or soft X-ray pulses. Including this mechanism in time--dependent simulations of charge--migration processes is a difficult task, and Auger scatterings are often ignored altogether. In this work we present an advance of the current state-of-the-art by putting forward a real--time approach based on nonequilibrium Green's functions suitable for first-principles calculations of molecules with tens of active electrons. To demonstrate the accuracy of the method we report comparisons against accurate grid simulations of one-dimensional systems. We also predict a highly asymmetric profile of the Auger wavepacket, with a long tail exhibiting ripples temporally spaced by the inverse of the Auger energy.

Determination of the Lifetime Influence Upon the Conversion Efficiency of the Photovoltaic Silicon Solar Cells

AbstractIf the electrons and holes in excess are created in a semiconductor, either by means of light absorption, or using other methods, the thermic balance is disturbed, therefore these electrons and holes should be nullified after the source had been stopped. This process is named recombination. There are three main recombination types: radioactive, Auger and deep energy level recombination. All three are based on the doping concentration to a certain point. The life time is determined using the three recombination processes in semiconductor.

Compositional analysis of silicon oxide/silicon nitride thin films

AbstractHydrogen, amorphous silicon nitride (SiNx:H abbreviated SiNx) films were grown on multicrystalline silicon (mc-Si) substrate by plasma enhanced chemical vapour deposition (PECVD) in parallel configuration using NH3/SiH4gas mixtures. The mc-Si wafers were taken from the same column of Si cast ingot. After the deposition process, the layers were oxidized (thermal oxidation) in dry oxygen ambient environment at 950 °C to get oxide/nitride (ON) structure. Secondary ion mass spectroscopy (SIMS), Rutherford backscattering spectroscopy (RBS), Auger electron spectroscopy (AES) and energy dispersive X-ray analysis (EDX) were employed for analyzing quantitatively the chemical composition and stoichiometry in the oxide-nitride stacked films. The effect of annealing temperature on the chemical composition of ON structure has been investigated. Some species, O, N, Si were redistributed in this structure during the thermal oxidation of SiNx. Indeed, oxygen diffused to the nitride layer into Si2O2N during dry oxidation.

Triethanolamine-facilitated one-step electrodeposition of CuAlSe2 thin films and the mechanistic studies utilizing cyclic voltammetry

Abstract The electrochemical behavior of the compositional ingredients CuCl 2 , AlCl 3 and SeO 2 individually or collectively in acidic aqueous solution was investigated on a glassy carbon electrode using the technique of cyclic voltammetry. Co-electrodeposition mechanism of CuAlSe 2 was attempted to be unraveled through cyclic voltammetric study of the electroactive species. The formation of CuAlSe 2 was found to be achieved by the generation of the compounds Al 2 Se 3 and Cu 2 Se via reductions and/or chemical reactions of the precursors. Triethanolamine as the complexing agent was introduced in the electrodeposition of CuAlSe 2 on indium doped tin oxide glass substrates in order to assist the deposition and the stoichiometric composition of CuAlSe 2 thin films was fabricated. The deposited thin films were characterized by X-ray diffraction, scanning electron microscopy, UV–Vis spectrometry, Auger electron spectroscopy and energy dispersive X-ray spectrometry analysis.

Dosimetry at the sub-cellular scale of Auger-electron emitter 99mTc in a mouse single thyroid follicle

The Auger-electrons emitted by 99mTc have been recently associated with the induction of thyroid stunning in in vivo experiments in mice, making the dosimetry at the sub-cellular level of 99mTc a pertinent and pressing subject. The S-values for 99mTc were calculated using MCNP6, which was first validated for studies at the sub-cellular scale and for low energies electrons. The calculation was then performed for 99mTc within different cellular compartments in a single mouse thyroid follicle model, considering the radiative and non-radiative transitions of the 99mTc radiation spectrum. It was shown that the contribution of the 99mTc Auger and low energy electrons to the absorbed dose to the follicular cells' nucleus is important, being at least of the same order of magnitude compared to the emitted photons' contribution and cannot be neglected. The results suggest that Auger-electrons emitted by 99mTc play a significant role in the occurrence of the thyroid stunning effect in mice.

Electroless Ni alloy plating as a diffusion barrier for through silicon vias in three-dimensional packaging

Ni- and Co-based amorphous films are alternative diffusion barrier materials for Cu interconnection in three-dimensional (3D) packaging applications. In this paper, electroless Ni–P and Ni–W–P films deposited in through-silicon vias (TSVs) were prepared as a diffusion barrier and seed layer of Cu filling by using Sn–Pd activation pretreatment. The thermal stability of the electroless Ni alloy films subjected to rapid thermal annealing (RTA) in H2 atmosphere was investigated. The barrier properties of the electroless Ni alloy films were evaluated over a range of temperatures using auger electron spectroscopy (AES) and energy dispersive X-ray spectroscopy (EDS) line-scan. The microstructures, crystal structures and electrical resistivity were also examined. It was found that Ni alloy films are amorphous as deposited, that the films retain amorphous or amorphous-like structures after undergoing annealing at 400 °C for 1 h, and that they are feasible for the diffusion barrier layer for 3D Cu interconnect technology.

Alloying of austenitic steel surface with zirconium using nitrogen compression plasma flow

In this study, the effect of a nitrogen compression plasma flow on the microstructural and mechanical properties, as well as on the elemental and phase compositions of a Zr/chromium–nickel steel system has been investigated. The Zr/steel system was exposed to a single pulse of the compression plasma flow or to a series of pulses. The samples were characterized by scanning electron microscopy, Auger electron spectroscopy, X-ray diffraction, and energy dispersive X-ray analyses, and subjected to a Vickers microhardness test. The findings showed the formation of a surface modified layer alloyed by Zr with the thickness of up to ∼12 μm. The modified layer contains α- and γ-iron-based solid solutions, the Fe23Zr6 intermetallic compound, and ZrN and Cr2N nitrides due to nitrogen diffusion. The microhardness of the modified layer increased by a factor of ∼2.

Auger-mediated electron relaxation is robust to deep hole traps: time-domain ab initio study of CdSe quantum dots.

By slowing down electron-phonon relaxation in nanoscale materials, one can increase efficiencies of solar energy conversion via hot electron extraction, multiple exciton generation, and elimination of exciton trapping. The elusive phonon bottleneck is hard to achieve, in particular, due to Auger-type energy exchange between electrons and holes. The Auger channel can be suppressed by hole trapping. Using time-domain ab initio simulation, we show that deep hole traps cannot fully eliminate the Auger channel. The simulations show that the hole-mediated electron relaxation is slowed down only by about 30%, which is in agreement with the recent experiments. The Auger energy exchange and hole relaxation to the trap state occur on similar time scales. Hole trapping is slow, because holes themselves experience a weak bottleneck effect. The study establishes the fundamental mechanisms of the electron and hole relaxation processes with and without hole traps. It shows that more sophisticated hole trapping strategies, for example, involving shell layers, are required in order to achieve the phonon bottleneck and to reduce electronic energy losses.

Investigation of Sn surface segregation during GeSn epitaxial growth by Auger electron spectroscopy and energy dispersive x-ray spectroscopy

The mechanism of Sn surface segregation during the epitaxial growth of GeSn on Si (001) substrates was investigated by Auger electron spectroscopy and energy dispersive X-ray spectroscopy. Sn surface segregation depends on the growth temperature and Sn content of GeSn layers. During Sn surface segregation, Sn-rich nanoparticles form and move on the surface during the deposition, which results in a rough surface owing to facet formation. The Sn-rich nanoparticles moving on the surface during the deposition absorb Sn from the periphery and yield a lower Sn content, not on the surface but within the layer, because the Sn surface segregation and the GeSn deposition occur simultaneously. Sn surface segregation can occur at a lower temperature during the deposition compared with that during postannealing. This suggests that the Sn surface segregation during the deposition is strongly promoted by the migration of deposited Ge and Sn adatoms on the surface originating from the thermal effect of substrate temperature, which also suggests that limiting the migration of deposited Ge and Sn adatoms can reduce the Sn surface segregation and improve the crystallinity of GeSn layers.

Experimental Investigations on the Influence of Adhesive Oxides on the Metal-Ceramic Bond

The objective of this study was to test the influence of selected base metals, which act as oxide formers, on the metal-ceramic bond of dental veneer systems. Using ion implantation techniques, ions of Al, In and Cu were introduced into near-surface layers of a noble metal alloy containing no base metals. A noble metal alloy with base metals added for oxide formation was used as a reference. Both alloys were coated with a low-temperature fusing dental ceramic. Specimens without ion implantation or with Al2O3 air abrasion were used as controls. The test procedures comprised the Schwickerath shear bond strength test (ISO 9693-1), profile height (surface roughness) measurements (ISO 4287; ISO 4288; ISO 25178), scanning electron microscopy (SEM) imaging, auger electron spectroscopy (AES) and energy dispersive X-ray analysis (EDX). Ion implantation resulted in no increase in bond strength. The highest shear bond strengths were achieved after oxidation in air and air abrasion with Al2O3 (41.5 MPa and 47.8 MPa respectively). There was a positive correlation between shear bond strength and profile height. After air abrasion, a pronounced structuring of the surface occurred compared to ion implantation. The established concentration shifts in alloy and ceramic could be reproduced. However, their positive effects on shear bond strength were not confirmed. The mechanical bond appears to be of greater importance for metal-ceramic bonding.

Measurement of Atomic Fractions in Cu(In,Ga)Se2 Films by Auger Electron Spectroscopy (AES) and Energy Dispersive Electron Probe Microanalysis (ED-EPMA)

Measurement of Atomic Fractions in Cu(In,Ga)Se2 Films by Auger Electron Spectroscopy (AES) and Energy Dispersive Electron Probe Microanalysis (ED-EPMA)

Periodic variations of Auger energy maximum distribution following He2+ + H2 collisions: A complete analogy with photon interferences

In this article, we present experimental evidence of a particular electron-interference phenomenon. The electrons are provided by autoionization of 2l2l′ doubly excited He atoms following the capture of H2 electrons by a slow He2+ incoming ion. We observe that the position of the energy maximum of the Auger structures oscillates with the detection angle. Calculation based on a simple model that includes interferences clearly shows that the present oscillations are due to Young-type interferences caused by electrons scattering on both H+ centers.

Auger energies, branching ratios, widths and x-ray rates of double K-vacancy states of Ne2 +: a close-coupling calculation

A close-coupling calculation is performed for the photoionization cross section of the high-lying core-excited state 1s2s22p5 1Po of Ne2 + in the energy region of the double K-vacancy resonance 1s02s22p6 1S. The calculation is carried out by using the R-matrix method in the LS-coupling scheme, which includes 27 target states and extensive configuration interaction. The KK-KL x-ray energy, rate and autoionization width of the double K-vacancy state, together with KK-KLL Auger energies and branching ratios of the main channels, are obtained from the cross sections and the contributions of these channels. The calculated resonance energy and x-ray rate are in good agreement with the existing experimental and theoretical results. For the Auger width, our result agrees well with the available experimental result and it is very close to the average of other theoretical data, which shows considerable differences with each other. The Auger energy of the predominate channel KK-KL23L23 2D is in rather good agreement with recent experiments on the Auger spectra. Our branching ratios for the channels KK-KL23L23 2D and KK-KL23L23 2S are larger than the results obtained by the multi-configuration Dirac–Fock method by ∼20% on average, which may be due to the coupling of the continuum channels.