bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observation of ion nitriding on FeCr, FeNi and NiCr alloy surfaces in a glow discharge plasma
Authors: Wagatsuma Kazuaki , Hirokawa Kichinosuke 
Published: December 2004

AbstractFor FeCr, FeNi and NiCr alloys, iron nitriding in a glow discharge plasma was investigated by optical emission spectroscopy and Auger electron spectroscopy. The composition change in depth was provided by both techniques and, in addition, Auger nitrogen‐metal interatomic transitions give information about chemical environments surrounding N atoms. Chromium‐enrichment in the nitrided layers was observed from the variation both in the nitrogen‐KLL Auger lineshapes and in the depth profiles. The chemical composition in the layers was strongly affected by the alloyed chromium having a strong affinity with N in the chromium‐containing alloys.
RBS and SIMS characterization of tungsten silicide deposited by using dichlorosilane and tungsten hexafluoride
Authors: Gregory Richard B. , Lamartine Bruce C. , Wu T. H. Tom , Tompkins Harland G. 
Published: December 2004

AbstractRutherford back‐scattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) were used to characterize tungsten silicide (WSix) which had been chemical vapor deposited using higher‐than‐normal temperatures and a new reactant. Silicon wafers were subjected to a flowing mixture of dichlorosilane (SiH2Cl2) and tungsten hexafluoride (WF6) with temperatures ranging from 450°C to 650°C. The conventional process uses SiH4 and WF6 with temperatures from 250°C to 400°C.RBS analysis was performed on a matrix of samples produced to show silicon‐to‐tungsten ratios as functions of various deposition temperatures and reactant gas flow ratios. The Si/W ratios obtained ranged from 2.0 to 2.8 over the 450–650°C temperature range.SIMS analysis provided the chlorine and fluorine distributions in the WSix films, again as functions of various deposition temperatures and flow ratios. This data showed fluorine concentrations on the order of 1 × 1016− 4 × 1018 cm−3, which are far lower than those concentrations observed for the conventional WF6/SiH4 chemistry (about 1 × 1020 cm−3).
Hydrogen detection at thin film—silicon interfaces
Authors: Jaworowski A. E. 
Published: December 2004

AbstractThe resonance depth profiling with 15N beams was used to measure the hydrogen content and diffusion at the aluminum/silicon interface and the near‐interface region of silicon. The formation of a subsurface hydrogen barrier in silicon has been directly observed. The hydrogen barrier formation appears to be a general effect and a property of the near‐surface of silicon, and probably other semiconductors. The observed hydrogen profiles indicate that hydrogen can be easily and inadvertently introduced into the aluminum/silicon interface region and produces a large build‐up of hydrogen concentration in the near‐interface region of silicon.
Auger parameter measurements of zinc compounds relevant to zinc transport in the environment
Authors: Dake L. S. , Baer D. R. , Zachara J. M. 
Published: December 2004

AbstractThis paper reports x‐ray generated photoelectron and Auger transition data for Zn compounds that have not been previously examined by XPS, with the objective of establishing a self‐consistent data base for Zn compounds of environmental and geochemical importance. Additional Zn compounds were analyzed to allow comparison with existing Zn data. Specimens analyzed include: hydrozincite (Zn5(OH)6(CO3)2), sphalerite (ZnS), smithsonite (ZnCO3), willemite (ZnSiO4), franklinite (ZnFe2O4), ZnO, Zn(OH)2, ZnCl2 and Zn metal. Where possible, this data has been related to previously reported values using Wagner chemical‐state (modified Auger parameter) plots. This self‐consistent data base has been used to identify the Zn solids that form on CaCO3 in Zn2+ –CaCO3 suspension.
Chemical and electronic properties of Pd/SnO2(110) model gas sensors
Authors: Fryberger T. B. , Erickson J. W. , Semancik S. 
Published: December 2004

AbstractA model gas sensor system, Pd/SnO2(110), has been investigated using XPS, UPS, ISS and 4‐point conductivity measurements. The growth of Pd and its chemical interaction with the SnO2 surface were studied in the 0.1–10.0 monolayer equivalent (ML) regime. It was found that the Pd overlayer grows by clustering at 300 K and that the deposited Pd is primarily metallic by 3 ML. Heating Pd‐covered surfaces up to 800 K causes a decrease in the XPS Pd/Sn 3d intensity ratio, possibly due to further clustering of the overlayer above room temperature. Annealing did not, however, change the local metallic nature of the deposited Pd. The gas sensing behavior of these model interfaces was investigated by measuring the sheet conductance at different hydrogen pressures. The increase in conductance for a 3 ML Pd/SnO2(110) surface was 16 times greater than that for the Pd‐free surface at 10−5 Torr H2. This enhancement by Pd is duscussed in terms of a ‘spillover’ effect.
Cf‐252 particle desorption mass spectrometry of photo‐oxidized polystyrene
Authors: Quiñones Leticia , Schweikert Emile A. 
Published: December 2004

AbstractCf‐252 particle (plasma) desorption mass spectra are presented for polystyrene surfaces before and after exposure in air to UV light. The photo‐oxidation produces changes observed in both positive and negative ion spectra. Oxygen incorporation produces a slight increase in intensity of m/z+ 18 and 19 (H2O+ and H3O+) and m/z− 16 and 17 (O− and OH−). Also, the relative intensity of m/z+ 91 decreases after photo‐oxidation and is interpreted as the formation of a bond alpha to the benzene ring. New peaks are detected at m/z+ 226, 227 and 331, and are tentatively assigned to hydroperoxide‐containing structures. Other changes in the spectrum include the increase in intensity of m/z+ 77 and 105 arising from easily ionized fragments of the oxidation products of polystyrene.
Performance and application of the scienta ESCA300 spectrometer
Authors: Beamson G. , Briggs D. , Davies S. F. , Fletcher I. W. , Clark D. T. , Howard J. , Gelius U. , Wannberg B. , Balzer P. 
Published: December 2004

AbstractThe Scienta ESCA300 is a state‐of‐the‐art x‐ray photoelectron spectrometer with high intensity, and high energy and spatial resolution. This unique combination of features is made possible by the use of a high‐power rotating anode x‐ray source with monochromatization, high transmission and imaging electron optics and a multichannel detector. The first ESCA300 has been installed recently at ICI Wilton. We report on the performance of this instrument for conducting samples and as a microanalytical device. Also described are its performance for insulating samples (polymer films) and studies of charge compensation using the Bremsstrahlung‐induced electrons from an unmonochromated dual anode x‐ray source.
Ultrahigh lateral resolution spectromicroscopy beam line at ELETTRA (trieste)
Authors: Nataletti P. , Contarini S. , Gariazzo C. , Minnaja N. , Musicanti M. , Jark W. , Kiskinova M. , Melpignano P. , Morris D. , Rosei R. 
Published: December 2004

AbstractThis report presents the project for the development of a combined facility consisting of a high spatial resolution soft x‐ray scanning photoelectron microscope (SPEM) and a scanning tunnelling microscope (STM) that is going to be built in an ultrahigh vacuum (UHV) station on one of the undulator beam lines at ELETTRA, Trieste. The photon microprobe for SPEM will be generated using a zone plate diffraction optic. A special design of a spherical grating monochromator will provide the source for illuminating the zone plate. The emitted photoelectrons will be detected and analysed using a high‐energy resolution hemispherical analyser with a large acceptance angle. The performance of the SPEM is projected to be as follows:

(1) a photon spot size on the sample of ∼50 × 50 nm2;
(2) a tunable photon energy range of 200–800 eV, with an energy resolving power of 3000 at the carbon K‐edge;
(3) a photon flux in the spot that is > 109 photons s−1 (0.1% body wt.)−1.
The projected performance of the STM instrument ensures a lateral resolution better than 2 Å. The combination of SPEM and STM techniques will enable chemical and structural mapping within the same microscopic areas of the sample surface. Descriptions of the main beam line components together with some examples of possible applications of this unique tool are included in the paper.
A comparison of experimental and theoretically derived sensitivity factors for XPS
Authors: Ward R. J. , Wood B. J. 
Published: December 2004

AbstractX‐ray photoelectron spectroscopy sensitivity factors for elements from lithium to zinc have been determined experimentally using standard compounds. These are found to differ quite considerably from those theoretically calculated using Scofield's photoelectric cross‐sections, but are in good agreement with other experimentally derived databases in the literature. It is concluded that Scofield's cross‐sections are in error and that a correction factor must be employed if they are to be used for the calculation of XPS sensitivity factors.
XPS study of the interface reactions between buffer layers for HTSC thin films and silicon
Authors: Behner H. , Wecker J. , Matthée Th. , Samwer K. 
Published: December 2004

AbstractIn this work we have studied the interface reactions during e‐beam evaporation of yttria‐stabilized zirconia (YSZ), yttria (Y2O3) and Y on Si(100) substrates by means of x‐ray photoelectron spectroscopy (XPS). A deposition process was developed for the heteroepitaxial growth of YSZ and Y2O3. A high amount of metallic Zr in the YSZ vapour results in an in situ reduction of the native silicon oxide layer, allowing the growth of high‐quality YSZ films even on uncleaned Si substrates. A similar in situ reduction process was achieved for the Y2O3 film growth on uncleaned substrates by a predeposition of metallic Y. The deposition of YBa2Cu3O7−δ (YBCO) films on YSZ/Y2O3/Si multilayers by dc magnetron sputtering resulted in critical current densities of the YBCO layer in excess of 2 × 106 A cm−2.
Joint use of XPS and Auger techniques for the identification of chemical state of copper in spent catalysts
Authors: Guerrero‐Ruiz A. , Rodríguez‐Ramos I. , Siri G. J. , Fierro J. L. G. 
Published: December 2004

AbstractX‐ray photoelectron and x‐ray‐induced Auger spectroscopic analyses of various copper‐containing catalysts have been used to reveal the chemical state of copper during on‐stream in the dehydrogenation of methanol to methyl formate. Three catalyst systems have been selected for this purpose: (1) supported preparations (Cu/S, where S = ZrO2, SiO2, ZnO, MgO or graphite); (2) mixed oxides of the type LaMn1‐xCuxO3 (x = 0.4–0.6); (3) copper‐containing bentonite and sepiolite. The binding energies of the Cu 2p levels in all catalysts after reaction correspond to reduced Cu species, i.e. Cuo and/or Cu+. However, the precise differentiation between these reduced species is only feasible by measuring the Cu L3VV x‐ray‐induced Auger parameter. Acocordingly, the energies of the modified Auger parameter for type (1) and (2) catalysts were close to that of Cuo, while they correspond to Cu+ species for type (3) preparations.
Novel method for studying the kinetics of surface reactions at submonolayer exposures: Decomposition of acetic acid on palladium foil
Authors: Kelleter J. , Schüll G. , Kohl C. D. , Grüner U. , Kraft A. , Wollnik H. 
Published: December 2004

AbstractThe experimental set‐up for relaxation spectroscopy with a newly constructed time‐of‐flight mass spectrometer (ToF‐MS) is described. The response to single gas pulses is measured with the ToF‐MS, which is equipped with a special storing ion source and an electrostatic ion reflector. The gas pulses, with rise and fall times of less than 2 ms, are generated by a solenoid valve in a differentially pumped system. Conventional ToF instruments with ionization by electron pulses detect only a small fraction of the incoming molecules. Therefore our instrument with the storing (integrating) ion source is more sensitive, typically by a factor of 1000. Pulses of deuterated acetic acid (AcOD) with a length of 20 ms are used to produce exposures of 1/1000 monolayer (ML) per pulse on a polycrystalline Pd foil. On clean Pd the formation of CO2 is observed. An activation energy of 0.78 eV and a preexponential factor of 3 × 108 s−1 are derived from the transients in the temperature range between 550 and 650 K. After a total dose of 1 ML of AcOD the CO2 signal ceases and the AcOD signal emerges, yielding an activation energy of 0.44 eV and a pre‐exponential factor of 9 × 108 s−1. It is shown that even exposure to small doses of AcOD decreases the efficiency of CO2 formation. After a dose of 2 ML the CO2 formation is completely suppressed. To determine the energy and the pre‐exponential factor for the investigated surface reaction, an exposure dose of less than 1/100 ML is sufficient.
Surface studies of powder metallurgical stainless steel
Authors: Nyborg L. , Norell M. , Olefjord I. 
Published: December 2004

AbstractThe reaction products formed on the surfaces of gas‐atomized 12Cr steel powder are determined using ESCA and AES. It is shown that Cr and Mn oxide particles larger than about 10 nm are formed at high temperatures during atomization. At lower temperatures and during subsequent handling, the remainder of the powder surface is covered by a thin (<5 nm) layer of mainly Fe oxide. For particles larger than about 40 μm the average oxide thickness is about 5.5 nm, while smaller particles are less oxidized and also frequently covered by a thin (1 nm) S‐rich layer. On lowering the O2 availability, much less Mn, Cr and Fe oxides are formed and Si is oxidized instead. During hot isostatic pressing (HIPing), first Fe oxide and then Cr and Mn oxides are reduced as the temperature increases, while Si oxide particles are formed on the powder surfaces. Consequently, heating the powder in a temperature gradient causes reduction and oxidation at higher and lower temperatures respectively. The surface oxides on the particle boundaries provide sites for carbonitride precipitation. Local growth of manganese sulphide at 1200°C is noticed. The HIPing temperature should therefore be limited but high enough for reducing surface oxides and the pore system should be closed early during consolidation.
A surface study of the chemical pretreatment before coil coating of hot dip zinc‐coated steel
Authors: Hörnström S. E. , Hedlund E. G. , Klang H. , Nilsson J.‐O. , Backlund M. , Tegehall P.‐E. 
Published: December 2004

AbstractZinc‐coated steel strip is painted in coil‐coating plants in order to improve corrosion resistance and to provide a decorative surface. We have used Auger and x‐ray photoelectron spectroscopy to characterize the conversion coating formed during pretreatment of hot dip zinc‐coated steel prior to coil coating. The pretreatment process includes alkaline cleaning of the strip, alkaline oxidation and a chromic acid after‐rinse treatment. The composition and the chemical state of the surface have been examined after the different pretreatment steps.
A possible solution to the problem of compositional change with ion‐bombarded oxides
Authors: Bertóti Imre , Kelly Roger , Mohai Miklós , Tóth András 
Published: December 2004

AbstractWe have explored a new type of experiment in which the beam‐induced surface changes of MgO, SiO2, Al2O3, TiO2, V2O5 and MgAl2O4 are determined by XPS after ion bombardment at 2.5 keV with Ar+ or N2+. The initial bombardment, typically with Ar+, led to a combined surface cleaning and loss of O. Although the relative extents of these were difficult to establish, the result was in every case to define the composition in an N‐free situation. After a subsequent bombardment with N2+ the O content was distinctly lower than that after Ar+ impact, with the extra O deficiency in each case made up almost exactly by the N addition. For example, Al2O3 evolved from a nominal Al2O2.74 to a nominal Al2O2.20N0.48. The chemical state of this N was predominantly nitride‐type, indicative of MN bonds (M, metal). The observed replacement of MO bonds with MN bonds is disfavoured by thermodynamics and this, combined with the already mentioned tendency for the extra O loss to be closely matched by the N addition, together constitute a strong indication that the disturbed lattice is to some extent relaxing randomly. Interestingly, however, the extent by which N replaces O increases as the energy change calculated for this replacement decreases. This confirms, in agreement with a large body of earlier work, that the changes in the oxides are to some extent also chemically guided. The similarity to ion beam mixing and to ion‐beam‐induced grain growth is worth noting, where again one finds a mixture of ballistic (i.e. random) and chemically guided behaviour.
Auger analysis of Ni/Au/Te and Au/Te Ohmic Contacts on n‐GaAs
Authors: Bender H. , Wuyts K. , Watté J. , Silverans R. E. 
Published: December 2004

AbstractThe characterization of Ni/Au/Te and Au/Te contacts on n‐GaAs by Auger electron spectroscopy is studied by surface element mapping and depth profiling. Owing to the high lateral resolution of AES, important characteristics of these metallization schemes, which could not be detected by any other technique, are revealed. Comparison with other analysis technique is performed, yielding important insight into the mechanism of ohmic conductivity.
Spectroscopic ellipsometry characterization of anodic films on aluminium correlated with transmission electron microscopy and Auger electron spectroscopy
Authors: De Laet J. , Terryn H. , Vereecken J. , Vanhellemont J. 
Published: December 2004

AbstractThis paper reports the characterization of barrier‐type anodic oxide films on aluminium by means of spectroscopic ellipsometry. In order to show the capabilities of the technique for quantitative determination of the layer characteristics such as thickness, composition and interface structure, results based on ellipsometric data are correlated with results from transmission electron microscopy and Auger electron spectroscopy. Especially if measures are performed at multiple angles of incidence, ellipsometry allows an accurate determination of the thickness and the interfacial properties of the barrier layer.
X‐ray photoelectron spectroscopy of low‐temperature anodic silicon oxides
Authors: Galán L. , Montero I. , Rueda F. , Albella J. M. 
Published: December 2004

AbstractElectron spectroscopy investigations of anodic silicon oxides grown over monocrystalline silicon and obtained at room temperature under different oxidation conditions are discussed and compared with thermal silicon oxide. In the first place, XPS shows that these oxides are essentially similar to thermal oxides with the same band gap, valence band spectra, plasma frequency, charge transfer and bulk mass density. However, there are also some important differences with respect to thermal oxides, related to the large density of structural defects, mainly OH and H2O, incorporated in the lattice during the growth process. In spite of the SiO2/Si interface appearing to be locally abrupt, this interface seems to be very rough. The anodic oxides have some oxygen excess and consequently the electronic polarizability of such materials is slightly smaller than that of thermal oxides. However, the most striking difference is the build‐up of a surface potential of 1.4–3.3 V upon x‐irradiation, even for thin, low‐resistivity anodic oxide films.
Multiple‐angle ellipsometric study of the interfacial layer in SiSiO2 structures
Authors: Paneva A. , Szekeres A. 
Published: December 2004

AbstractThe optical parameters of the interface layer formed during low‐temperature oxidation of Si substrates were studied by means of multiple‐angle ellipsometry at a fixed wavelength λ = 632.8 nm. By numerical modelling of single‐ and two‐layer systems, it was observed that the maximum of the ellipsometric angle sensitivity to the presence of the interfacial layer is achieved at oxide thicknesses less than 30 nm. It was found that the thickness of the interface layer is tint = 0.93 ± 0.2 nm and its refractive index is nint = 2.45 ± 0.2. A difference between the substrate refractive indices obtained for bare and oxidized silicon wafers was also observed and is attributed to the internal stresses induced in the SiSiO2 structures during oxidation.
On the interaction of silica xerogel thin films with oxidized aluminium or phosphate coatings on steel
Authors: Stoch A. , Stoch J. 
Published: December 2004

AbstractXPS has been used to study the interaction between very thin layers of silica deposited by the sol–gel technique and coatings on metals of the simple oxide or the phosphate type. Samples were measured as‐received and after vacuum heating at 150–350°C. It has been found that silica xerogel below 500°C reacts with alumina and nickel oxide to form silicates. Compared with simple iron or zinc phosphates, mixed zinc‐iron phosphate coatings are more stable against heating and contain much more phosphorus. In this case silica surface deposits (1) reduced mass transfer and the ability for phosphate coating reconstruction, (2) limited phosphorus and/or water removal from the surface and (3) enhanced zinc segregation towards the surface.
Use of XPS and Ar+ depth profiling to determine the dispersion degree of Ni in Ni/TiO2 and Ni/SiO2 catalysts
Authors: Espinós J. P. , González‐Elipe A. R. , Fernández A. , Munuera G. 
Published: December 2004

AbstractTwo series of Ni/TiO2 and Ni/SiO2 catalysts prepared by different methods have been characterized by XPS and Ar+ sputtering. Depth profiles have been obtained from the intensity of the Ni 2p photoelectron peaks as a function of the sputtering time. The analysis has been carried out for samples in their precursor, calcined and reduced states, in order to obtain information on the changes in dispersion of the active phase through the whole activation process. In the case of reduced Ni/SiO2 catalysts, comparison with results by other techniques (i.e. H2 chemisorption, x‐ray diffraction and transmission electron microscopy) has shown that the sputtering method may give a semi‐quantitative assessment on the dispersion degree of nickel. However, for Ni/TiO2 catalysts in the SMSI state after reduction in H2 at 773 K only the Ar+ sputtering method was able to provide information on the distribution of nickel. In this case the depth profiles were consistent with partial solution of the nickel in the TiO2 matrix.
XPS study on barium‐promoted copper chromite catalysts
Authors: Bianchi C. L. , Cattania M. G. , Ragaini V. 
Published: December 2004

AbstractCopper chromite catalysts are used nowadays in catalytic reactions during the incineration of organic air pollutants, which is a subject of growing interest in environmental safety. The aim of this work was to investigate by XPS the surface species, on a sample prepared by ourselves and to study the modifications of these species after various heat treatments. This study confirmed the deep surface transformation on the sample. We observed a complete reduction of the copper atoms from oxidation state II to I. In contrast, this behaviour is not followed by the chromium atoms, which are reduced to oxidation state III only to a small degree. This fact could be explained by the presence of barium which was introduced as a promoter in the catalyst.
Effects of elastic scattering on energy spectra of emitted and backscattered electrons
Authors: Borodyansky S. 
Published: December 2004

AbstractThe problem of elastic and inelastic scattering of Auger electrons, photoelectrons and backscattered electrons is investigated. The path length distribution functions for emitted and backscattered electrons are calculated analytically in different approximations for elastic scattering. The calculations are carried out on the basis of an invariant‐embedding approach. A procedure of background subtraction in AES/XPS in the presence of elastic scattering and a procedure of reflection electron energy‐loss spectra processing are also discussed.