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The 3d core level photoemission of metallic Ag and In was measured over a wide energy range including the 2p ionization thresholds. The intensities (photoionization cross sections) of the 3d5/2 and 3d3/2 lines were observed to modulate significantly with photon energy, both absolute and relative, and this is most pronounced in the vicinity of the 2p thresholds, i.e., at photon energies about an order of magnitude above the 3d thresholds. Calculations based on the relativistic-random-phase approximation show that this effect is due to interchannel coupling of the 3d photoionization channels with the 2p channels affecting the cross section over a wide range of energies. It is argued that this is a general phenomenon in high-energy photoionization throughout the periodic table. [ABSTRACT FROM AUTHOR]

Abstract: PdAg(1 0 0) ordered surface alloys have been prepared by e-beam evaporation technique in situ in UHV and were investigated using high energy photoemission and normal incidence X-ray standing wave (NIXSW) techniques with wiggler radiation. The line shapes of 3d core levels of Ag and Pd exhibited interesting changes with the increase of Pd concentration in the alloys. The Ag 3d core level exhibited a disorder induced broadening that gradually increased with Pd concentration. On the other hand Pd 3d core level exhibited an asymmetry on the high binding energy side of the peak which gradually increased with Pd concentration. Interestingly, Pd core level did not exhibit a broadening with increase of Pd content in the alloy. [Copyright &y& Elsevier]

Abstract: High energy resolution KL23L23 Auger spectra of polycrystalline Cu and Ni were measured using photon energies up to about 50eV above the K-absorption edge and down to 5eV (Cu KLL) and 4eV (Ni KLL) below threshold. The spectra show strong satellite structures varying considerably as a function of the photon energy. In the sub-threshold region the linear dispersion of the diagram line energy positions and a distortion of the line shape as a function of photon energy, attributable to the Auger resonant Raman process, is clearly observed, indicating the one-step nature of the Auger emission. These changes in the resonant spectra are interpreted using a simple model based on resonant scattering theory in combination with partial density of states obtained from cluster molecular orbital (DV-Xα) calculations. [Copyright &y& Elsevier]

Abstract: The use of hard X-ray synchrotron radiation as the primary excitation for photoelectron spectroscopy has recently attracted great interest. At HASYLAB, a dedicated instrument for experiments in the photon energy range 2.3–10keV (electron energies up to 7.5keV) has been in operation for several years. The overall energy resolution is source limited to about 0.4eV, which is well suited for most core level studies. Scientific work using this instrument has so far focused on the near-threshold excitation of inner-shell Auger transitions and the electronic properties of buried structures and interfaces. Here, general aspects of photoelectron spectroscopy using X-rays in the keV energy regime are discussed and some applications are presented. [Copyright &y& Elsevier]

A versatile experimental setup is presented for both x-ray standing waves (XSW) and x-ray photoemission spectroscopy (XPS) studies in an energy range up to 7 keV. The compact apparatus operates under ultrahigh vacuum and includes in situ sample preparation and characterization techniques. For the XSW scans the incident photon energy is tuned through the Bragg reflection from the sample for Θ[sub B] ≈ 90° while measuring the intensity and energy distributions of both the emitted electrons and fluorescence radiation simultaneously. Alternatively, desorbing positive ions can be analyzed as a function of the standing wave phase shift using a time-of-flight spectrometer. In addition, energy dependent high-energy XPS measurements with medium overall energy resolution (δE = 1.5 eV at 3 keV) can be performed. Selected results obtained at the focused EXAFS II beamline of HASYLAB are shown. [ABSTRACT FROM AUTHOR]

Discusses the design and performance of the high-flux/high-brightness x-ray wiggler beamline BW2 at HASYLAB in Hamburg, Germany. Insertion device; Beamline layout and optical components; Monochromator; Beamline operation and control.

We report an in situ thermochemical treatment that significantly increases the macroscopic electrical conductivity of insulating yttria-stabilized zirconia (YSZ) (001) single-crystalline substrates. We demonstrate the high-quality surface crystalline structure of the resulting "conductive" cYSZ (001) by low- and high-energy electron diffraction. Soft- and hard X-ray photoemission spectroscopy measurements reveal a sizable reduction of Zr cations to a metallic state and their homogeneous distribution within the cYSZ. We discuss the correlation between the microscopic chemical processes leading to the increased macroscopic metallicity. Finally, the heteroepitaxial growth of a functional magnetic oxide model system, ultrathin EuO on cYSZ (001), was demonstrated. cYSZ (001) thereby enables both high quality oxide heteroepitaxy and the advanced sample characterization by high electron-fluence characterization techniques. [ABSTRACT FROM AUTHOR]

We report on a significant improvement of a simple, but effective bandpass photon detector specially suited for inverse photoemission studies. It consists of a commercial open CuBe multiplier with a CaF[sub 2] entrance window. The latter acts as a low pass, the high pass and the quantum efficiency in the new version are determined by the photoyield of KBr evaporated onto the first dynode, resulting in a bandpass with maximum efficiency at ℏω = 9.8 eV and ΔE = 0.6 eV (FWHM). This detector is easy to operate and up to one order of magnitude more efficient than other systems currently used. Further improvement concerning combined efficiency and resolution seems possible by suitable variation of the cathode material and entrance window. [ABSTRACT FROM AUTHOR]

Presents an abstract of a paper focusing on nonradiative x-ray resonant Raman scattering from solids. Utility of high-intensity synchrotron radiation in the study of photon-electron-scattering phenomena; Characteristics of the emission spectrum.

Abstract: We used hard X-ray photoelectron spectroscopy (HAXPES) with 8keV X-rays to investigate the 1s emission of carbon. We recorded spectra extending from the peak of the C 1s electrons (“elastic” line) to electrons with up to 110eV energy-loss. Using two samples side by side, we could compare the inelastic mean free paths (IMFPs) of the electrons of almost 8keV in diamond and graphite and find them to be practically identical despite about 50% difference in densities. Published extrapolations of their IMFP calculations at lower energies are in good agreement with this result. We show that information from the almost structureless region of overlapping multiple extrinsic energy-losses can be used to quantify the fraction of photoelectrons experiencing intrinsic energy-losses (those due to the sudden creation of the hole). We find that this fraction is 58% of the primary excited C 1s electrons for diamond and is practically the same for graphite. This is at first sight an unexpected result since hole-screening should differ in a semimetal from that in an insulator. The observation can be accounted for by dynamic screening in contrast to static screening. [Copyright &y& Elsevier]

Abstract: KLM Auger spectra of Ni metal were measured with high energy resolution and high statistical accuracy using monochromatic synchrotron radiation. The spectra were corrected for the background from inelastically scattered electrons using partial intensity analysis where the electron trajectories were calculated by Monte Carlo simulation. Following background correction, the corrected spectra were fitted to model peaks taking into account intrinsic excitations. The measured transition energy of the most intense KL2M3 (1D2) Auger line is 7388.1eV (0.4). The obtained relative intensities and energies of the Auger diagram lines are compared to published calculations as well as to experimental data for other 3d transition metals. In addition, the presence of Ni 3s, 3p photoelectron peaks in the spectra excited internally by Ni Kα X-rays is shown. [Copyright &y& Elsevier]

Abstract: We compare experimental measurements of the loss structure appearing in the Si2p and Si1s photoemission lines for a large range of emission angles (between 0° and 82°) and kinetic energies (125–3660eV) with calculations derived within a semiclassical dielectric–response formalism [A. Cohen Simonsen, F. Yubero, S. Tougaard, Phys. Rev. B 56 (1997) 1612]. It is found that this semi-classical dielectric description of the energy-loss processes reproduces the relative intensity of surface to bulk energy losses appearing in the lower kinetic energy side of the main photoelectron peaks as well as the relative intensity of the losses with respect to the zero-loss peak. The absolute ratio of intensity of the loss structure to the zero-loss is ∼25–35% lower compared to experiment using self-consistent inelastic mean free paths in the analysis. [Copyright &y& Elsevier]

The Si 1s and 2p photoemission and the Si KL2,3L2,3 Auger emission from SiO2/Si(1 0 0) surfaces were measured for oxide thicknesses from 0.4 to 3.8 nm using high-energy photoemission (hν=3000 eV). The energy of the SiO2 emission depends on the layer thickness. The Si4+–Si0 energy differences ΔE1s, ΔE2p and ΔEKLL were combined to separate the initial and final state contribution to the energy shift of the Si4+ 2p line. Within the experimental error, the 2p initial state is constant up to about 2 nm oxide thickness, where differential charging gradually sets in. The observed variation of ΔE2p is entirely due to final state relaxation. It is found that ΔE1s-ΔE2p=0.62 eV, independent of the oxide thickness. [Copyright &y& Elsevier]

The experimental determination of valence band offsets (VBOs) at interfaces in complex-oxide heterostructures using conventional soft x-ray photoelectron spectroscopy (SXPS, hν ≤ 1500 eV) and reference core-level binding energies can present challenges because of surface charging when photoelectrons are emitted and insufficient probing depth to clearly resolve the interfaces. In this paper, we compare VBOs measured with SXPS and its multi-keV hard x-ray analogue (HXPS, hν > 2000 eV). We demonstrate that the use of HXPS allows one to minimize charging effects and to probe more deeply buried interfaces in heterostructures such as SrTiO3/LaNiO3 and SrTiO3/GdTiO3. The VBO values obtained by HXPS for these interfaces are furthermore found to be close to those determined by first-principles calculations. [ABSTRACT FROM AUTHOR]

Hard x-ray photoelectron diffraction (hXPD) patterns recorded with a momentum microscope with high k-resolution (0.025 Ĺ−1 equivalent to an angular resolution of 0.034° at 7 keV) reveal unprecedented rich fine structure. We have studied hXPD of the C 1s core level in the prototypical low-Z material Graphite at 20 photon energies between 2.8 and 7.3 keV. Sharp bright and dark lines shift with energy; regions of Kikuchi band crossings near zone axis exhibit a filigree structure which varies rapidly with energy. Calculations based on the Bloch wave approach to electron diffraction from lattice planes show excellent agreement with the experimental results throughout the entire energy range. The main Kikuchi bands in the [001] zone axis appear fixed on the momentum scale with a width of the corresponding reciprocal lattice vector, allowing to reconstruct the size of the projected Brillouin zone. The newly developed high-energy k-microscope allows full-field imaging of (kx, ky)-distributions in large k-fields (up to >22 Ĺ−1 dia.) and time-of-flight energy recording. [ABSTRACT FROM AUTHOR]

An alternative approach to hard‐X‐ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high‐energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k‐resolution of 0.025 Å−1, equivalent to an angular resolution of 0.034°. A special objective lens with k‐space acceptance up to 25 Å−1 allows for simultaneous full‐field imaging of many Brillouin zones. Combined with time‐of‐flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s−1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core‐level signals and one million for d‐bands of transition metals. The concept of tomographic k‐space mapping established using soft X‐rays works equally well in the hard X‐ray range. Sharp valence band k‐patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF‐resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X‐ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) 'amplifies' phase differences, making full‐field hXPD a sensitive structural tool. [ABSTRACT FROM AUTHOR]

Tellurium based phase change materials are unique 3D-solids proposed to undergo Anderson type metal-insulator transition. However, the origin of this transition is not unambiguously understood. Here, we report combined high energy resolution photoemission spectroscopy and high k-resolution X-ray diffraction measurements on a reversibly phase switched Ge2Sb2Te5 film. The results resolve the ambiguity between previous spectroscopic data and the proposed theoretical model for the origin of Anderson localization in these materials. Furthermore, by switching between the metallic state to insulating and back to metallic, we probe the electronic structure evolution in the phase change material. [ABSTRACT FROM AUTHOR]

Total ion yield spectra of a supersonic beam of Ar clusters have been recorded in the Ar K-shell (1s) spectral region using synchrotron radiation. The spectrum of the cluster component of beams containing argon clusters of mean size N≊400 atoms is similar to that of the x-ray absorption spectrum of solid Ar. Analysis of the Ar 1s extended x-ray absorption fine structure (EXAFS) indicates an average first shell Ar–Ar distance in the cluster similar to that of the solid, but there is an increased Debye–Waller (disorder/thermal motion) term as well as changes in the higher coordination shell signals.Time-of-flight mass spectra and photoion–photoion coincidence (PIPICO) spectra of argon cluster beams are reported and the charge separation mechanisms of multiply charged argon clusters are discussed. The results are compared to those from recent studies of the Ar 2p spectra of Ar clusters. [ABSTRACT FROM AUTHOR]

Ni and Cu KLL Auger spectra excited by X-rays from polycrystalline metal foils were measured with good energy resolution and intensity earlier. Auger spectra of 3d transition metals contain satellite peaks due to the atomic excitation processes. Because of the complexity of the measured spectral shape a complete explanation of the spectra was not given in the previous works. A new analysis of the measured spectra is presented here, with improved description of effects of inelastic electron scattering of the electrons in the solid sample and using complex peak shapes to model the satellite structure that follows each diagram line. The energy loss part of measured spectra due to the bulk plasmon excitations, surface plasmon excitations and intrinsic loss processes was removed using the Partial Intensity Analysis method based on energy loss distributions obtained from experimental reflection electron energy loss spectra of the same Cu and Ni metal foils. Relative Auger-transition energies derived from measured spectra of copper are in good agreement with previous experimental works and the results of cluster molecular orbital multielectron (DV-ME) calculations. The intensity ratio I( 3 P 2 / 3 P 0 ) shows better agreement with the result of relativistic calculations than in previous works. In the case of nickel the relative Auger-transition energies are in good agreement with the previous results. According to the new evaluation four satellite peaks were identified on the low energy side of each diagram line in the Auger spectra of Ni. [ABSTRACT FROM AUTHOR]

The paper presents photoemission study of core level binding energy shifts caused by local crystalline structure collapse in cubic Pb 1− x Cd x Te crystal. Photoemission spectra of two kinds of semiconductor samples are compared. The first one is ternary crystal of Pb 0.94 Cd 0.06 Te with the frozen rock salt structure where the crystalline local structure collapse is expected due to the difference of ion radii of Cd and Pb cations. The second sample was the CdTe(22 nm)/PbTe(6 nm)/CdTe(4 μm)/GaAs(1 1 1)B nanostructure grown by molecular beam epitaxy (MBE) method, where crystalline local structure is not expected to be created. The photoemission spectra show that for the crystal with local structure the electron binding energies of cations are higher (e.g. +0.2 eV) whereas for anions they are lower (e.g. −0.08 eV) than in the multilayer structure. A model is proposed to explain obtained results by the local crystalline structure collapse in Pb 0.94 Cd 0.06 Te crystal. [ABSTRACT FROM AUTHOR]

Hard x-ray photoelectron spectroscopy (HAXPES) has now matured into a well-established technique as a bulk sensitive probe of the electronic structure due to the larger escape depth of the highly energetic electrons. In order to enable HAXPES studies with high lateral resolution, we have set up a dedicated energy-filtered hard x-ray photoemission electron microscope (HAXPEEM) working with electron kinetic energies up to 10 keV. It is based on the NanoESCA design and also preserves the performance of the instrument in the low and medium energy range. In this way, spectromicroscopy can be performed from threshold to hard x-ray photoemission. The high potential of the HAXPEEM approach for the investigation of buried layers and structures has been shown already on a layered and structured SrTiO3 sample. Here, we present results of experiments with test structures to elaborate the imaging and spectroscopic performance of the instrument and show the capabilities of the method to image bulk properties. Additionally, we introduce a method to determine the effective attenuation length of photoelectrons in a direct photoemission experiment. [ABSTRACT FROM AUTHOR]

Abstract: The multilevel resistive switching effect in Pt/HfxAl1−xOy/TiN stacks has been studied by hard X-ray photoelectron spectroscopy (HAXPES). Atomic layer deposition was used to grow HfxAl1−xOy films with graded Al depth profile, where the engineered Al concentration across the film facilitates the desired oxygen vacancies' profile. The method to derive the electrical potential profile across dielectric from the HAXPES spectra is proposed. By combining the information on the chemical state at both interfaces with the extracted potential distribution, a qualitative model for the resistive switching effect in the Pt/HfxAl1−xOy/TiN metal–insulator–metal stack is proposed. According to this model, the conductive filaments controlling the resistivity are formed by the electric field driven condensation of the charged oxygen vacancies in the oxide. [Copyright &y& Elsevier]

Highlights: [•] Electronic conditions at interfaces of functional multilayers probed by HAXPES. [•] In situ monitoring of chemical changes in MIM stacks undergoing resistance switching. [•] Potential barrier profile in functional FTJ experimentally determined by HAXPES. [•] VO present in ultrathin BaTiO3 layer affects band line-up at the interface. [ABSTRACT FROM AUTHOR]

Highlights: [•] Heteroepitaxial BTO(001)/Pt(001) films are grown on MgO(001) by PLD. [•] As grown BTO films are in a single-domain state and polarized downward. [•] The band gap of ultrathin heteroepitaxial BTO layer strongly depends on thickness. [•] Cr/BTO(3nm)/Pt based FTJ: tunneling electroresistance Rup/Rdown up to 30. [Copyright &y& Elsevier]

Abstract: Cu2ZnSnS4 (CZTS) thin films have been grown by reactive pulsed laser deposition in H2S atmosphere, combining the alternate ablation from the metallic (Cu) and alloyed (ZnxSn) targets at room temperature. The morphological, structural and optical properties of as grown CZTS thin films with varying compositions as well as upon annealing in N2 atmosphere are investigated by Rutherford backscattering spectrometry, X-ray diffraction, Raman spectroscopy and optical spectrophotometry. The chemical bonding in the “bulk” of the CZTS films is elucidated via hard X-ray photoemission spectroscopy measurements. The formation of the good quality stoichiometric polycrystalline CZTS films is demonstrated upon optimization of the growth parameters. [Copyright &y& Elsevier]

Electroresistance in ferroelectric tunnel junctions is controlled by changes in the electrostatic potential profile across the junction upon polarization reversal of the ultrathin ferroelectric barrier layer. Here, hard X-ray photoemission spectroscopy is used to reconstruct the electric potential barrier profile in as-grown Cr/BaTiO3(001)/Pt(001) heterostructures. Transport properties of Cr/BaTiO3/Pt junctions with a sub-μm Cr top electrode are interpreted in terms of tunneling electroresistance with resistance changes of a factor of ∼30 upon polarization reversal. By fitting the I-V characteristics with the model employing an experimentally determined electric potential barrier we derive the step height changes at the BaTiO3/Pt (Cr/BaTiO3) interface +0.42(-0.03) eV following downward to upward polarization reversal. [ABSTRACT FROM AUTHOR]

We have employed hard x-ray photoemission (HAXPES) to study a delta-doped SrTiO3 layer that consisted of a 3-nm thickness of La-doped SrTiO3 with 6% La embedded in a SrTiO3 film. Results are compared to a thick, uniformily doped La:SrTiO3 layer. We find no indication of a band offset for the delta-doped layer, but evidence of the presence of Ti3+ in both the thick sample and the delta-layer, and indications of a density of states increase near the Fermi energy in the delta-doped layer. These results further demonstrate that HAXPES is a powerful tool for the non-destructive investigation of deeply buried doped layers. [ABSTRACT FROM AUTHOR]

Stoichiometric FeRh undergoes a temperature-induced antiferromagnetic (AFM) to ferromagnetic (FM) transition at --350 K. In this Letter, changes in the electronic structure accompanying this transition are investigated in epitaxial FeRh thin films via bulk-sensitive valence-band and core-level hard x-ray photoelectron spectroscopy with a photon energy of 5.95 keV. Clear differences between the AFM and FM states are observed across the entire valence-band spectrum and these are well reproduced using density-functional theory. Changes in the 2p core levels of Fe are also observed and interpreted using Anderson impurity model calculations. These results indicate that significant electronic structure changes over the entire valence-band region are involved in this AFM-FM transition. [ABSTRACT FROM AUTHOR]

The chemical and electronic modifications induced by the electroforming process on the Ti/HfO2/TiN-based resistive switching devices were investigated by non-destructive hard x-ray photoelectron spectroscopy (HAXPES). The results indicate an increase of the titanium top electrode oxidation at the interface with HfO2 after the electroforming process. Additionally, the binding energy values of the HAXPES peaks of the electroformed sample increased as compared to the as-prepared sample. The observed changes between both samples are attributed to the creation of n-type defects, such as oxygen vacancies, in the HfO2 layer near the Ti interface during the electroforming process. [ABSTRACT FROM AUTHOR]

We present a detailed study of the electronic structure and chemical state of high-quality stoichiometric EuO and O-rich Eu1 O1+x thin films grown directly on silicon without any buffer layer using hard x-ray photoemission spectroscopy (HAXPES). We determine the EuO oxidation state from a consistent quantitative peak analysis of 4f valence band and 3d core-level spectra. The results prove that nearly ideal, stoichiometric, and homogeneous EuO thin films can be grown on silicon, with a uniform depth distribution of divalent Eu cations. Furthermore, we identify the chemical stability of the EuO/silicon interface from Si 2p core-level photoemission. This work clearly demonstrates the successful integration of high-quality EuO thin films directly on silicon, opening up the pathway for the future incorporation of this functional magnetic oxide into silicon-based spintronic devices. [ABSTRACT FROM AUTHOR]

Abstract: The spatial distribution of charges in a Pt/HfO2/Si stack has been manipulated by applying a cyclic bias voltage ±2.5V in combination with moderate (T ∼630K) heating. The modifications were monitored in situ by room temperature capacitance–voltage (C–V) and current–voltage (I–V) measurements and analyzed ex situ by hard X-ray photoelectron spectroscopy which additionally provides information on possible chemical changes at the interfaces. The experimental data on the charge/potential distributions resulting from the different steps of bias-temperature stress (BTS) are consistent with the model that additional oxygen vacancies, which are generated in HfO2 and positively charged by charge transfer across the interface with a high work function metal (Pt), are driven across the HfO2 layer. These vacancies ultimately control the observed growth/dissolution of SiO x at the bottom interface upon negative/positive BTS, respectively. [Copyright &y& Elsevier]

Abstract: The bulk single crystals of Pb1−x Cd x Te were obtained by self-selecting vapor growth (SSVG) method with proper quenching. Tunable high energy X-ray photoemission spectroscopy (THE-XPS) and ultraviolet photoemission spectroscopy (UPS) were applied to study the crystals electronic structure of valence band and core level regions. The valence band density of states distribution spectra remarkably changes with the crystal composition. In most cases obtained valence band spectra of ternary crystal with dominating of ionic bonding can be in first approximation treated as a sum of the components spectra. In the case of measured Pb1−x Cd x Te ternary crystal this first order approximation does not follow the rule and inclination of ternary crystal spectra possesses some differences from the sum of spectra measured for crystal PbTe and CdTe. The increase of Cd contents in the crystals leads to appearance of an additional density of states in the large part of the valence band, for binding energy range up to 10eV. [Copyright &y& Elsevier]

Hard x-ray photoelectron spectroscopy (HAXPES) is a new variant of the well-established photoemission technique, which extends its range to much higher photoelectron energies up to 10 keV and thus to enhanced probing depths of the order of 10 nm and beyond. This not only facilitates direct access to the intrinsic bulk electronic structure of solids, but also allows extended depth profiling and the study of buried interfaces not possible by conventional photoemission. Here, we present two HAXPES case studies on transition metal hybrid and heterostructures demonstrating the potential of the method. We also discuss a new HAXPES setup at the high-brilliance hard x-ray synchrotron radiation source PETRA III at DESY (Hamburg) currently under construction. [ABSTRACT FROM AUTHOR]

Abstract: The interaction between evaporated gold and pristine or oxygen plasma treated multi-walled carbon nanotubes (MWCNTs) is investigated. Experimental and theoretical results indicate that gold nucleation occurs at defect sites, whether initially present or introduced by oxygen plasma treatment. Uniform gold cluster dispersion is observed on plasma treated carbon nanotubes (CNTs) and associated with the presence of uniformly dispersed oxidized vacancy centres on the CNT surface. [Copyright &y& Elsevier]

Abstract: The chemical structure and possible hydro-oxidation of LaNiO3−δ films were studied by means of tuneable high-energy X-ray photoelectron spectroscopy using synchrotron radiation. It was shown that the hydroxyl-containing phase, located near the film surface, may be attributed to the lanthanum and nickel hydroxide species. The thickness of a hydroxide-enriched layer was estimated from the oxide/hydroxide ratio measured at normal and grazing conditions. The hydroxide layer thickness was about 2nm for step and/or exponential hydroxide spatial distribution. [Copyright &y& Elsevier]

Abstract: The effect of the oxygen plasma treatment on the electronic states of multi-wall carbon nanotubes (MWCNTs) is analyzed by X-ray photoemission measurements (XPS) and UPS, both using synchrotron radiation. It is found that the plasma treatment effectively grafts oxygen at the CNT-surface. Thereafter, the interaction between evaporated Pd and pristine or oxygen plasma-treated MWCNTs is investigated. Pd is found to nucleate at defective sites, whether initially present or introduced by oxygen plasma treatment. The plasma treatment induced a uniform dispersion of Pd clusters at the CNT-surface. The absence of additional features in the Pd 3d and C 1s core levels spectra testifies that no Pd–C bond is formed. The shift of the Pd 3d core level towards high-binding energy for the smallest clusters is attributed to the Coulomb energy of the charged final state. [Copyright &y& Elsevier]

Abstract: The interaction between evaporated Pt and pristine or oxygen-plasma-treated multiwall carbon nanotubes (CNTs) is investigated. Pt is found to nucleate at defect sites, whether initially present or introduced by oxygen plasma treatment. The plasma treatment induces a uniform dispersion of Pt nanoparticles at the CNT surface. The absence of additional features in the C 1s core level spectrum indicates that no mixed Pt–C phase is formed. The formation of C–O–Pt bonds at the cluster-CNT interface is suggested to reduce the electronic interaction between Pt nanoparticles and the CNT surface. [Copyright &y& Elsevier]

Abstract: A method is presented for analysing the energy loss part (dominated by contributions from extrinsic, intrinsic and surface plasmon excitations) of electron spectra excited from free-electron-like solids by X-rays. It is an improved version of the model originally proposed by Steiner, Höchst and Hüfner and it accounts for contributions of electrons suffering multiple energy losses of different origin. Applied for analysing a Ge 2s photoelectron spectrum excited from a thin Ge layer, the applicability of the method to separate contributions to the inelastic background of the spectra due to intrinsic, extrinsic and surface plasmons is demonstrated. The aim of this work to give a detailed description of the simple statistical model applied in ref. [M. Novák, S. Egri, L. Kövér, I. Cserny, W. Drube, W.S.M. Werner, Surf. Sci. 601 (2007) 2344] for practical analysis of photoelectron spectra. The effects of the application of energy loss distributions (for single bulk and single surface excitations) derived by using different methods are also investigated. [Copyright &y& Elsevier]

Abstract: Multi-wall carbon nanotubes (MWCNTs) were decorated with metal clusters by thermal evaporation. Transmission electron microscopy (TEM) shows that the nature and extent of metal coverage can be varied by plasma treating the MWCNT surface. The metal clusters on oxygen plasma treated arc-discharge MWCNTs have a more dense distribution than the clusters evaporated on as-synthesized arc-discharge MWCNTs. In contrast, the plasma treatment did not affect the cluster distribution on CVD MWCNTs. Analyses of the valence band and the core levels by X-ray photoelectron spectroscopy suggest poor charge transfer between gold clusters and MWCNTs; on the contrary suggest good charge transfer between Ni clusters and MWCNTs. [Copyright &y& Elsevier]

Abstract: Deep core Ge 2s photoelectron spectra from polycrystalline Ge films induced by monochromatic synchrotron radiation, of 4, 6 and 8keV were measured and analysed using two different methods, the partial intensity analysis and the extended Hüfner method to determine the spectral contributions from different electron energy loss processes due to bulk extrinsic, intrinsic and surface excitations. The obtained photon energy dependence of the ratio of these contributions was compared as a function of the photoelectron kinetic energy. It was found that the relative contribution of intrinsic excitations increase with the photon energy. [Copyright &y& Elsevier]

Abstract: Substitution of Gd3+ for Eu2+ ions in EuTe leads to the introduction of Gd 5d electrons to the conduction band and antiferromagnetic order of EuTe (Heisenberg magnetic semiconductor) can be replaced by ferromagnetic state due to RKKY interaction. The layers were grown by MBE method on BaF2 (111) substrate. Layer of Te deposited on top of (EuGd)Te protects surface of oxidation. Heating in 320°C leads to Te atoms desorption and to improvement of the layer electronic structure. Additional Gd atoms were sequentially deposited on the layer of (PbGd)Te and set of Fano resonance curves were observed for ions of Gd. The Fano type photoemission resonance corresponding to the 4d–4f transitions were studied for Eu and Gd. [Copyright &y& Elsevier]

Abstract: Carbon nanotubes (CNTs) were decorated with Ni clusters by thermal evaporation. It is shown that the CNT decoration with Ni varies from well-organized clusters to the complete coverage of the surface resulting in electronic charge transfer and formation of Ni–C bonds at the interface between these two materials, depending on the evaporated amount of Ni. The Ni–CNTs interaction induces an increase in the metallicity of the system suggesting that CNTs decorated with metal atoms can be a good candidate as template for production of metal nanowires. [Copyright &y& Elsevier]