2p 3s Research Articles

Improvement of CO Oxidation and CH4 Combustion by Pd and Pt Partial Substitution on LaMn0.5Cu0.5O3 Perovskite.

LaMn0.5Cu0.5O3 (LMC) as the parent perovskite and Pd- and Pt-doped LaMn0.5Cu0.5O3 catalysts (LMCPd and LMCPt) instead of Cu were synthesized in a new solid-state synthesis technique at a low temperature. Perovskite lattice formation of the LMC catalyst was successfully performed at 600 °C. All perovskites were investigated by X-ray diffraction, HRTEM, O2-TPD, H2-TPR, BET, and XPS analyses. The prepared perovskites were used as heterogeneous catalysts for CO oxidation and methane combustion reactions. The catalytic performance of the LMC catalyst was noticeably enhanced via Pd and Pt substitution instead of Cu. The enhancement in the mobility of lattice oxygen and specific surface area has triggered this catalytic performance improvement, which play an important role in CO oxidation and methane combustion. The Mn 2p and Mn 3s XPS spectra showed that by doping Pd and Pt in the LMC perovskite, Mn was affected in different states and the Mn 3s peaks were only observed in the LMCPt catalyst. XPS spectra of the LMCPd1 sample showed a high oxidation state of Pd3+ or Pd4+, from which it can be concluded that Pd was successfully incorporated into the LMC perovskite lattice. The H2-TPR profiles of the LMCPd and LMCPt perovskites revealed that the reduction peaks of Cu and Mn were shifted to lower temperatures by increasing Pd and Pt partial substitution due to the synergetic effect of the cation and the H2-spillover effect of palladium and platinum.

Electronic properties of MnO(110) film grown on Cu (111)

In this study, we investigated MnO thin films grown on Cu(111) using a soft x-ray and UV based spectroscopy, low energy electron diffraction (LEED), scanning tunneling (STM) and scanning transmission electron microscopy (STEM). MnO thin film assumes (110) preferential plane orientation organized in different spatial domains to better adapt to Cu(111) surface and an in-plane/out-of-plane lattice parameter variation up to 11% with respect to bulk counterpart originating a sizeable XLD signal at Mn L2,3 edges. The formation of oxidized Cu region during the MnO thin film growth is not avoidable due to the copper reactivity to oxygen and at the interface the coexistence of MnO islands alternated with Cu2O regions was observed by STM. Mn 2p and Mn 3s core level photoemission line shapes present a slight change in multiplet peak relative intensity with respect bulk MnO counterpart due to the role of Cu substrate in the core level relaxation process. The photon energy dependent photoemission spectra of valence band discriminate the MnO states and indicate a weak influence of the substrate once the film thickness is reduced to 1 nm. These findings open new route in the tuning oxide thin film properties.

Masses and thermal properties of a Charmonium and Bottomonium Mesons

In this research, we model Hulthén plus generalized inverse quadratic Yukawa potential to interact in a quark-antiquark system. The solutions of the Schrödinger equation are obtained using the Nikiforov-Uvarov method. The energy spectrum and normalized wave function were obtained. The masses of the heavy mesons for different quantum states such as 1S, 2S , 1P, 2P 3S, 4S, 1D, and 2D were predicted as 3.096 GeV, 3.686 GeV, 3.327 GeV, 3.774GeV, 4.040 GeV, 4.364GeV, 3.761 GeV, and 4.058 GeV respectively for charmonium (cc). Also, for bottomonium (bb) we obtained 9.460 GeV, 10.023 GeV, 9.841 GeV, 10.160 GeV, 10.345 GeV, 10.522 GeV, and 10.142GeV for different states of 1S , 2S , 1P , 2P , 3S , 4S , 1D respectively. The partition function was calculated from the energy spectrum, thereafter other thermal properties were obtained. The results obtained showed an improvement when compared with the work of other researchers and excellently agreed with experimental data with a percentage error of 1.60 % and 0.46 % for (cc) and (bb), respectively.

Atomic structure for carbon-like ions from Na vi to Ar xiii

ABSTRACT We have calculated the energy levels, oscillator strengths, and transition probabilities for eight carbon-like ions (Na vi, Mg vii, Al viii, Si ix, P x, S xi, Cl xii and Ar xiii) using the Hartree–Fock pseudo-relativistic (HFR) and Thomas–Fermi–Dirac–Amaldi (TFDA) approaches. We used configuration expansions containing eight configurations, namely 2s2 2p2, 2s 2p3, 2s2 2p 3s, 2s2 2p 3p, 2s2 2p 3d, 2s2 2p 4s, 2s2 2p 4p, and 2s2 2p 5s. For each of the considered ions we obtained 59 energy levels, a number of which are not in the National Institute of Standards and Technology (NIST) data base. We compared our results with critically selected experimental data from NIST and with calculations made using the multiconfiguration Hartree–Fock (MCHF) method. We calculated weighted oscillator strengths and transition probabilities using two methods (HFR and TFDA) for the 2s2 2p2 and 2s 2p3 configurations for the eight C-like ions considered here. We analysed the atomic structure parameter trends, which allowed us to find missing data belonging to an isoelectronic sequence. The energy levels, oscillator strengths, and transition probabilities calculated here are in good agreement with the data from the NIST data base. Because emission and absorption features from C-like ions are often used for density and temperature diagnostics of various plasmas in astrophysics, and in studies of the solar corona, including solar flares, and of the coronae of other stars and of ionized outflows in active galactic nuclei etc., the obtained data will be useful for improving plasma diagnostics and modelling, in particular for the X-ray Universe.

Fe xvii 2p–3s Line Ratio Diagnostic of Shock Formation Radius in O Stars

Abstract The 2p–3s lines of Fe xvii in the X-ray spectrum of the O-type star ζ Puppis exhibit an anomalous (3G + M2)/(3F) line ratio of ∼1.4, in comparison with ∼2.4 for almost all other collisionally excited astrophysical spectra. Based on the work of Mauche et al., we conjectured that the strong UV field of ζ Puppis produces the observed ratio by depopulation of metastable 3s excited states, and that the ratio can potentially be used as an independent diagnostic of plasma formation radius. We used the Flexible Atomic Code collisional-radiative model to model the effect of UV photoexcitation from O stars on the Fe xvii lines. We compared our model calculations to archival spectra of coronal and hot stars from the Chandra HETGS and XMM-Newton RGS to benchmark our calculations for various electron densities and UV field intensities. Our calculations show that UV photoexcitation does not produce a sufficiently large dynamic range in the 3F / (3F + 3G + M2) fraction to explain the difference in the observed ratio between coronal stars and ζ Pup. Thus, this effect likely cannot explain the observed line ratio of ζ Pup, and its origin is still unexplained.

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Operando leaching of pre-incorporated Al and mechanism in transition-metal hybrids on carbon substrates for enhanced charge storage

Photoelectron Spectroscopy and Ionic Fragmentation of OSeCl2 and Its Analogue OSCl2 under VUV Irradiation.

The electronic structure and the dissociative ionization of selenium oxychloride, OSeCl2, have been investigated in the valence region by using results from both photoelectron spectroscopy (PES) and synchrotron-based photoelectron photoion coincidence (PEPICO) spectra. The PES is assigned with the help of quantum chemical calculations at the outer-valence Green's function (OVGF) and symmetry adapted cluster/configuration interaction (SAC-CI) levels. The first energy ionization is observed at 11.47 eV assigned to the ionization of electrons formally delocalized over the Se, Cl, and O lone pair orbitals. Irradiation of OSeCl2 with photons in the valence region leads to the formation of OSeCl2(•+), OSeCl(+), SeCl2(•+), SeCl(+), and SeO(•+) ions. Furthermore, the inner shell Se 3p, Cl 2p, and Se 3s electronic regions of OSeCl2 together with S 2p, Cl 2p, and S 2s electronic regions of thionyl chloride, OSCl2, have been studied by using tunable synchrotron radiation. Thus, total ion yield spectra and the fragmentation patterns deduced from PEPICO spectra at the various excitation energies have been studied. Cl(+), O(•+), and Se(•+) ions appear as the most intense fragments in the OSeCl2 PEPICO spectra, like in the sulfur analogue OSCl2, whose photofragmentation is dominated by the Cl(+), O(•+), and S(•+) ions. Fragmentation processes in OSCl2 leading to the formation of the double coincidences involving atomic ions appear as the most intense in the PEPIPICO spectra.

Determination of tungsten and molybdenum concentrations from an x-ray range spectrum in JET with the ITER-like wall configuration

The and 3p–4d inner shell excitation lines in addition to 2p–3s lines have been identified from the spectrum taken by an upgraded high-resolution x-ray spectrometer. It is found from analysis of the absolute intensities of the and lines that W and Mo concentrations are in the range of and , respectively, with a ratio of ∼5% in JET with the ITER-like wall configuration for ELMy H-mode plasmas with a plasma current of 2.0–2.5 MA, a toroidal magnetic field of 2.7 T and a neutral beam injection power of 14–18 MW. For the purpose of checking self-consistency, it is confirmed that the W concentration determined from the line is in agreement with that from the line within 20% and that the plasma effective charge determined from the continuum of the first order reflection spectrum is also in agreement with that from the second order within 50%. Further, the determined plasma effective charge is in agreement with that determined from a visible spectroscopy, confirming that the sensitivity of the x-ray spectrometer is valid and that the W and the Mo concentrations are also likely to be valid.

Relativistic configuration-interaction calculations of electric dipole [formula omitted] transitions for medium-charge Li-like ions

In this work, the multi-configuration Dirac–Fock and relativistic configuration-interaction methods have been used to calculate the transition wavelengths, electric dipole transition probabilities, line strengths, and absorption oscillator strengths for the 2s–3p, 2p–3s, and 2p–3d transitions in Li-like ions with nuclear charge Z=7–30. Our calculated values are in good agreement with previous experimental and theoretical results. We took the contributions from Breit interaction, finite nuclear mass corrections, and quantum electrodynamics corrections to the initial and final levels into account, and also found that the contributions from Breit interaction, self-energy, and vacuum polarization grow fast with increasing nuclear charge for a fixed configuration. The ratio of the velocity to length form of the transition rate (Av/Al) was used to estimate the accuracy of our calculations.

Blue satellites on He lines due to He-He collisions

The shape and broadening of He lines affects radiative transport in dense, He-rich, stellar atmospheres. At wavelengths inaccessible for direct observation, we rely on theoretical calculations of self-broadening to support stellar structure and spectral modeling. In this work, we examine lines of He due to 1s–2p and 2p–3s transitions. The line profiles are analyzed in terms of a unified theory of spectral line broadening using ab initio potential energies that have been recently determined. For temperatures up to 20 000 K, the linear dependence of width and shift on gas density and the non-linear dependence on temperature of the Lorentzian core of the resonance line are described. Beyond the conventional symmetrical Lorentzian core, we show that they are asymmetrical and have significant additional contributions on the short wavelength side. This blue asymmetry is a consequence of maxima in the corresponding He2 potential energy difference curves at short and intermediate internuclear distance. Over a limited range of density and temperature, laboratory measurements in the visible and near infrared can be used to validate the potentials that underlie the spectral line profile theory, which is useful for modeling spectra over the extreme ranges of temperature and density encountered in stellar and planetary atmospheres.

Measurement and modeling of the n = 2–3 emission of O VIII near 102 Å

In observations of Capella, the x-ray ultraviolet (XUV) emission compared to the extreme ultraviolet (EUV) emission significantly exceeds expectation from collisional–radiative spectral modeling. This discrepancy is presently undergoing experimental verification at an electron beam ion trap. An important step of the procedure is the relative efficiency calibration of spectroscopic detection equipment for EUV and XUV observations, for which we use the branching ratio of 1s–3p and 2s–3p transitions in the H-like spectrum O VIII. We present high-resolution measurements and associated modeling of the O VIII emission near 102 Å, which consists not only of the two 2s–3p transitions, but also of two 2p–3s and three 2p–3d transitions.

Valence state of the manganese ions in mixed-valence La1−αBiβMn1+δO3±γ ceramics by Mn 2p and Mn 3s X-ray photoelectron spectra

Valence state of Mn in La1−αBiβMn1+δO3±γ (LBMO) ceramic samples and in orthorhombic manganates RMn2O5 (R=Y, Bi, Eu, Gd), is studied using Mn 2p- and Mn 3s-spectra. Both Mn3+ and Mn4+ ions are shown to be present in those compounds. Relative Mn3+/Mn4+ ions contents are determined by fitting experimental Mn 2p-spectra with weighted superpositions of theoretical spectra of Mn3+ and Mn4+ ions calculated in one-configuration Pauli–Fock approximation considering thermal excitations in initial state. Content of the Mn4+ ions correlates with the deviation δ in La1−αBiβMn1+δO3±γ from stoichiometry, La1−xBixMnO3. Separation of low-spin and high-spin components of Mn 3s-spectrum can be sensible to the relative content of Mn3+ and Mn4+ ions. Mn3+/Mn4+ ratios derived from Mn 2p- and from Mn 3s-spectra compare well in the case of the RMn2O5 manganates, while in the case of the LBMO ceramics the results obtained from the Mn 3s spectra are physically meaningless. Due to a complex interplay between 3d-electrons delocalization and strong many-electron effects the 3s spectra of 3d-elements may be misleading.

A complex scaled multiconfigurational time-dependent Hartree–Fock method for studying resonant states

A new complex scaled multiconfigurational time-dependent Hartree–Fock (CMCTDHF) method (also called the complex scaled multiconfigurational linear response (CMCLR)) has been developed. CMCTDHF uses complex multiconfigurational Hartree–Fock states as initial states, and in real space has been successfully used to study electronic excitation energies and linear response properties. With CMCTDHF, shape and Feshbach resonances of an N-electron system can be obtained by studying the excited states of an (N + 1)-electron system with the trajectory method. Our first application of CMCTDHF has been for the beryllium doubly excited state 1Po (1s2 2p 3s) with a 14s 14p 5d Gaussian basis and a 2s 2p 3s 3p 3d complete active space (CAS). We find the resonance position and width are (11.01, 0.434) eV, which agrees very well with the experimental result (10.89, 0.531) eV. This is the first time that the complex scaling method has been successfully used to study beryllium doubly excited states. Our calculations show that CMCTDHF is a practical and important tool for studying resonant states.

Synthesis of monodisperse nanocrystals of manganese oxides

The nanocrystals Mn3O4 powder have been prepared using [Bis(salicylidiminato)manganese(II) ] as precursor. Effect of oleylamine and triphenylphosphine on particle morphology has been investigated. Transmission electron microscopy (TEM) analysis demonstrated nanocrystals Mn3O4 with an average diameter of about 20 nm. The structural study by X-ray diffraction (XRD) indicates that these nanocrystals have pure tetragonal phase. The phase pure samples were characterised using X-ray photoelectron spectroscopy (XPS) for both Mn 2p and Mn 3s levels. The values of binding energies are consistent with the relative values reported in the literature.

Adhesion and Cu Diffusion Barrier Properties of a MnOx Barrier Layer Formed with Thermal MOCVD

AbstractA thin-amorphous MnOx layer using self-forming barrier process with a Cu-Mn alloy shows good adhesion and diffusion barrier properties between copper and dielectric layer, resulting in excellent reliability for stress and electromigration. Meanwhile, chemical vapor deposition (CVD) can be employed for conformal deposition of the barrier layer in narrow trenches and vias for future technology node. In our previous research, a thin and uniform amorphous MnOx layer could be formed on TEOS-oxide by thermal metal-organic CVD (MOCVD), showing a good diffusion barrier property. In addition, a good adhesion strength is necessary between a Cu line and a dielectric layer not only to ensure good SM and EM resistance but also to prevent film delamination under mechanical or thermal stress conditions during fabrication process such as chemical mechanical polishing or high temperature annealing. To date, no information is available with regard to the adhesion property of CVD-MnOx. In this work, we report diffusion barrier property in further detail and adhesion property in PVD-Cu/CVD-MnOx/SiO2/Si. The temperature dependence of the adhesion property is correlated with the chemical composition and valence state of Mn investigated with SIMS and Raman spectroscopy.Substrates were p-type Si wafers having a plasma-TEOS oxide of 100nm in thickness. CVD was carried out in a deposition chamber. A manganese precursor was vaporized and introduced into the deposition chamber with H2 carrier gas. After the CVD, a Cu overlayer was deposited on some samples using a sputtering system in load lock chamber of the CVD machine. The diffusion barrier property of the MnOx film was investigated in annealed samples at 400 oC for 100 hours in a vacuum of better than 1.0×10-5 Pa. The Adhesion property of Mn oxide was investigated by Scotch tape test in the as-deposited and in the annealed Cu/CVD-MnOx/TEOS samples. The obtained samples were analyzed for thickness and microstructure with TEM, chemical bonding states of the MnOx layer with XPS, and composition of each layer with SIMS.In the CVD deposition below 300 °C, no Cu delamination was observed both in the as-deposited and in the annealed Cu/CVD-MnOx/SiO2 samples. On the other hand, in the CVD deposition at 400 °C, the Cu films were delaminated from the CVD-MnOx/TEOS substrates. The XPS peak position of Mn 2p and Mn 3s spectra indicated that the valence state of Mn in the as-deposited barrier layer below 400 °C was 2+. Composition analysis with SIMS as well as Raman also indicated the presence of a larger amount of carbon at 400 °C than at less than 300 °C. The good adhesion between Cu and MnO could be attributed to an amount of carbon inclusion in the CVD barrier layer.

Synthesis of Mn 3O 4 nanoparticles by thermal decomposition of a [bis(salicylidiminato)manganese(II)] complex

The present investigation reports on the novel synthesis of Mn 3O 4 nanoparticles using thermal decomposition and their physicochemical characterization. The Mn 3O 4 nanoparticle powder has been prepared using [bis(salicylidiminato)manganese(II)] as a precursor. The effect of oleyl amine and triphenylphosphine on the particle morphology has been investigated. Transmission electron microscopy (TEM) analysis demonstrated Mn 3O 4 nanoparticles with an average diameter of about 25 nm. The structural study by X-ray diffraction (XRD) indicates that these nanoparticles have a pure tetragonal phase. The phase pure samples were characterized using X-ray photoelectron spectroscopy (XPS) for both Mn 2p and Mn 3s levels. The values of binding energies are consistent with related values reported in the literature.

Valence states of 3d ions in lanthanum manganites-cobaltites, determined by X-ray spectroscopy

The valence states of manganese and cobalt ions in lanthanum manganites-cobaltites La1 − xCaxMn0.5Co0.5O3 have been determined by 2p X-ray absorption and 3s X-ray photoelectron spectroscopies. The nanostructured P1 manganite-cobaltite phase with the concentration x = 0, obtained by the citrate method at a temperature of 700°C, is characterized by a valence state of cobalt ions close to 2+ and a valence state of Mn ions of about 3.5+. The P2 phase at the same calcium concentration, synthesized by the high-temperature solid-phase method at a temperature of 1300°C, is characterized by a manganese valence of 3.5+ and a cobalt valence of about 2.3+. An increase in the dopant concentration leads to an increase in the average valence of 3d ions.

Is MPI suitable for a generative design-pattern system?

Generative parallel design patterns can be used to improve the productivity of parallel program development. However many of the generative design-pattern systems are developed for target languages that are not widely used by the high-performance computing community. This paper describes an initial effort to develop a system that will hopefully answer the question in the title in the affirmative. This new system is ostensibly based on, and built upon the experience with, the successful CO 2P 3S system. Significant challenges must be overcome to implement the features of a system that generates frameworks conceived for an object-oriented programming language (Java) into a parallel-annotated procedural language (MPI/C).

On the structure and composition of the phosphosulfide overlayer on Ni 2P at hydrotreating conditions

Ni 2P has shown very promising catalytic activity as a hydrotreating catalyst, but the exact structure of the actual active phase is not understood. The present work has systematically studied the structures and energetics of possible surface compositions of the (001) surface of Ni 2P (i.e., the Ni 3P 2 plane) at hydrotreating conditions using density functional theory calculations. By comparing the energetics of surfaces with adsorbed H 2S, SH, and atomic sulfur and the surfaces with phosphorous replaced by sulfur as a function of concentration and atomic location on the (001) surface, we have identified a stable phosphosulfide surface consistent with a surface stoichiometry of Ni 3PS. This surface composition is energetically more stable than bulk Ni 2P or Ni 3S 2 at hydrotreating conditions. To provide additional confirmation of the proposed surface structure, we calculated CO absorbance frequencies on the Ni 3P 2 and Ni 3PS surfaces as a function of surface CO coverage, and found that they are in excellent agreement with previously published experimental infrared spectroscopy data. These calculations, combined with literature experimental observations, indicate that the surface with 50% phosphorus replaced by sulfur and some atomic sulfur deposited on the three-fold hollow sites is an accurate representation for the actual active phase, or the so-called “phosphosulfide” surface, of Ni 2P at typical hydrotreating conditions.

Nanosize Mn 3O 4 (Hausmannite) by microwave irradiation method

The present investigation reports, the novel synthesis of nanosize Mn 3O 4 powder with nanorods using microwaves and its physicochemical characterization. The nanosize Mn 3O 4 powder has been prepared using manganese nitrate as a precursor and effect of ethanolamine and ethylenediamine on particle morphology has been studied. The microwave irradiation has been carried out in the range 50–500 W and it was observed that formation of Mn 3O 4 takes place at 50 W. TEM analysis demonstrated nanosize Mn 3O 4 powder and nanorods with an average diameter of about 10 nm. The structural study by XRD indicates that these nano-powders have pure tetragonal phase. The phase pure samples were characterized using X-Ray Photoelectron Spectroscopy (XPS) for both Mn 2p and Mn 3s levels. The values of binding energies are consistent with the relative values reported in the literature. The metallic impurity levels have been characterized using Inductively Coupled Plasma-Optical Emission Spectrophotometer (ICP-OES).