bluuebunny/crossref_metadata_2025_split huggingface dataset:
Novel spectroscopic evidence on the nature of the depassivation of iron by halide ion
Authors: Cocke D. L. , Nilsson P. , Murphy O. J. , Bockris J. O'M. 
Published: December 2004

AbstractXPS spectra of electrochemically formed passive films on Fe electrodes exposed to chloride ions, revealed chemical and physical changes in the films as a result of coming in contact with these ions. An enhanced C species signal with increasing exposure time to chloride ions was accounted for by increased chemical reactivity of the passive films toward hydrocarbons, due to the loss of hydroxyl groups and water, as well as to the creation of surface defect sites. An increasingly high binding energy O signal with increasing chloride ion exposure time was found to be due to physisorbed O species on an enlarged area, caused by a depolymerization or a pore breakdown mechanism in the passive layers. Chloride ion was not observed in the XPS spectra of the passive layers.
X‐ray photoelectron spectroscopic studies of carbon fibre surfaces. III—Industrially treated fibres and the effect of heat and exposure to oxygen
Authors: Proctor Andrew , Sherwood Peter M. A. 
Published: December 2004

AbstractCarbon fibres, surface treated by an industrial process, were analysed by x‐ray photoelectron spectroscopy (XPS). The results allow the surface chemistry to be compared with that achieved by controlled laboratory methods. It is found that industrial treatment has less control over individual fibre surface treatment than in the laboratory treated fibres, and that the reproducibity of treatment varies with the treatment method. As the level of treatment is increased the spectra show an increase in the C/O and C/N surface functional groups. In contrast to the laboratory treated fibres there is no identifiable difference in the types or proportions of C/O groups with the amount of surface treatment, and the overall changes in the spectra are much less. The type and proportion of surface groups between treated and untreated fibres are different. C=O type groups appear to dominate in the treated fibre samples over O—O— type groups. Mass spectroscopic analysis associated with heat treatment can be very usefully combined with XPS analysis in the same apparatus as an aid to the understanding of complex industrially treated samples. Thus the effect of surface treatment can be effectively reversed by heat treatment to very high temperatures, with the regeneration of a fibre surface which resembles that of the untreated fibre surface. Exposure of the heated fibre after cooling to gaseous oxygen causes little change in the surface chemistry.
X‐ray photoelectron spectroscopy study of the surface composition of CoO‐MgO solid solutions
Authors: Cimino A. , Minelli G. , De Angelis B. A. 
Published: December 2004

AbstractThe surface composition of CoO–MgO solid solutions has been investigated by XPS. The samples (prepared at 1200°C in air) were checked to be homogeneous by X‐ray diffraction analysis and by lattice parameter measurements. The study utilized peaks at different kinetic energies: Co 2p, O 1s, Co 3s, Mg 2s, Co 3p, Mg 2p and the Auger transition Mg KLL. It was shown that the specimens have a surface composition slightly different from the bulk, because of the formation of surface magnesium hydroxide. No segregation of cobalt was found. The results have a bearing on the catalytic activity of oxide solid solutions.
Surface preparation for quantitative auger electron spectroscopy: Mechanical polishing and inert gas ion sputtering
Authors: Burke M. A. , Schreurs J. J. 
Published: December 2004

AbstractThis paper discusses the effect of surface preparation on surface composition as measured by Auger electron spectroscopy (AES). The problems of producing atomistically clean surfaces for calibration standards in quantitative AES analysis are illustrated by comparing the analyses of a series of copper–nickel binary alloys prepared by mechanical polishing and sputter cleaning with the compositions measured immediately after in situ fracture. Mechanical polishing results in surface enrichment by nickel for alloys of less than about 0.6 atomic fraction nickel, while alloys of greater than about 0.7 atomic fraction nickel exhibit surface enrichment by copper after mechanical polishing. Sputter cleaning results in a surface enrichment by nickel for all the alloy compositions considered (Xcu < 0.5). Additionally sputtering of the mechanically polished surfaces produces maxima in the surface nickel concentration, after short time sputtering, which coincide with the removal of the oxygen signals from the spectra. The results are discussed using a preferential sputtering model.
The effect of the grain structure of Al2O3 substrate on the solid state reaction with a layer of NiO: A comparative backscattering spectrometry study 1
Authors: De Roos G. , Fluit J. M. , De Wit J. H. W. , Geus J. W. 
Published: December 2004

AbstractThe solid state reaction of Al2O3NiO reaction couples was investigated by means of Rutherford backscattering spectrometry. NiO films on the alumina substrates were obtained by vapour–deposition of Ni and subsequent oxidation at 800°C in air. Substrates of about the same surface roughness, thus providing equal contact areas for the reaction couples, were used. The materials were characterized by scanning electron microscopy. In spite of the different structure and a grain size that varied within a factor of 10, of the Al2O3 materials, no obvious difference in the spectra based on the used reaction couples could be detected. Suggested substantial contribution to the reaction from surface diffusion and grain boundary diffusion along the substrate grain boundaries could therefore be rejected.
Quantitative evaluation of AES‐depth profiles of thin anodic oxide films (Ta2O5/Ta, Nb2O5/Nb)
Authors: Sanz J. M. , Hofmann S. 
Published: December 2004

AbstractThin films of anodically formed Ta2O5 and Nb2O5 on polycristalline Ta and Nb, respectively, are analysed with AES during sputtering with Ar+ ions at energies between 0.5 keV and 5 keV. A sputtering induced depletion of oxygen at the surface is observed in both oxides. The kinetics of this depletion and the steady‐state composition at the surface of the samples are studied as a function of the primary ion energy. The results are interpreted using a modification of the model of Ho et al. (1976) for the preferential sputtering of alloys. The thickness of the transient layer increases non‐linearly from 1.6 to 3.4 nm with increasing ion energy. Below 2 keV, the surface depletion of oxygen increases with decreasing ion energy and is constant above 2 keV up to 5 keV. The results are similar for both oxides. At 2 keV, the minimum measured width of the oxide/metal interface is 2 nm for Ta2O5/Ta and is about two times larger for Nb2O5/Nb. In both cases it increases with the square root of the ion energy and it is independent on the oxide layer thickness between 10 nm and 150 nm.
Small area x‐ray photoelectron spectroscopy
Authors: Yates K. , West R. H. 
Published: December 2004

AbstractSmall area XPS can be easily performed on spectrometers with hemispherical analysers, in which electron transfer from sample to analyser precedes retardation. Spatial resolutions of 250 μm diameter have been achieved on a commercial spectrometer and applied to the study of a mixed phase sulphide mineral. Determination of the position and size of the analysis area has been made by a combined SEM/SAM technique.
The spatial distribution of minority elements in carbon black
Authors: Fabish T. J. 
Published: December 2004

AbstractX‐ray photoemission, elemental, and base neutralization measurements of minority element contents in carbon blacks are analysed self‐consistently within a model description of the powder to arrive at an estimation of the surface density of elements comprising the acidic surface groups for these materials. Element surface densities are found that are significantly smaller than those corresponding to concentrations of the minority elements wholly at the geometric surface of the carbon particle, but are generally greater than for a uniform bulk distribution. The intermediate values arise as a result of the concentration of oxygen into a shell occupying 60 to 90% of the total particle volume for the three carbon blacks considered.
Sulfur segregation to the metal oxide interface during the early stages in the oxidation of iron
Authors: Jennings Wayne D. , Chottiner Gary S. , Michal Gary M. 
Published: December 2004

AbstractIron (110) single crystals have been studied during the early stages of their oxidation at 800°C at an oxygen flux equivalent to a pressure of 2 × 10−5 Torr. Depth profiles using Auger electron spectroscopy (AES) determined that if sulfur was present on the metal surface before the oxidation then sulfur was present at the internal metal/oxide interface after a 20 minute oxidation. Oxidation of a clean surface resulted in very little sulfur at the internal metal/oxide interface after the same oxidation exposure even though sufficient time was available for sulfur to accumulate at that interface. The interpretation of the AES data was complicated by the non‐uniformity of the oxide growth. The oxide morphology was found to depend on the amount of sulfur on the free surface just prior to oxidation. A model for this growth was developed that was consistant with both the AES depth profiles and scanning electron microsopy (SEM) observations of the oxide surface morphology.
Analysis of semiconductors and insulators by high‐resolution electron energy loss spectroscopy—prospects for quantification
Authors: Pireaux J. J. , Thiry P. A. , Sporken R. , Caudano R. 
Published: December 2004

AbstractHigh‐resolution electron energy loss spectroscopy (HREELS) is now widely known and recognized for its very significant contributions to the characterization of molecules adsorbed on well‐defined surfaces: many chemical surface reactions were understood successfully (adsorption sites, reaction scheme, time‐resolved experiments) through the analysis of electron‐induced vibrational spectra. Semiconductors and insulators form other classes of materials that contribute to vibrational spectra by intrinsic vibrations: compound semiconductors, and insulators present acoustic and optical phonons, i.e. collective lattice vibrations, whereas organic insulators (like polymers) offer numerous molecular groups to the vibrational excitation by the electron beam (extrinsic vibrations). Quantitative analysis of the surface of those materials rests on the understanding of the interaction mechanisms between monochromatized electrons and intrinsic or extrinsic vibrations.Three scattering processes have been recognized to contribute to HREEL spectra: dipole interaction, impact scattering and resonance scattering. They have been characterized theoretically and experimentally through their dependence versus variation of the electron beam energy and/or of the scattering angular geometry.Recent experiments have shown that the analysis of intrinsic phonons is very well understood for insulators. As a consequence, quantitative analysis of compound semiconductors is possible and brings additional information on the surface stoichiometry (of AlxGa1−xAs, for example) and on the doping level. For organic polymers, however, the excitation of molecular vibrations does not—up to now—appear to follow a simple scheme: all the scattering mechanisms (dipolar, impact and resonance) appear to play a significant role; a true quantification will be possible only through a systematic study of model compounds, and will require further theoretical treatments.
Depth profiling studies of oxidized alloy surfaces by glow discharge emission spectroscopy
Authors: Tsuji K. , Hirokawa K. 
Published: December 2004

AbstractDepth profile analyses of elemental composition of Cu–Ni and Fe–Cr binary alloys oxidized in air and O2 gas mixtures were performed by glow discharge emission spectroscopy (GDS), adopting the cathode sputtering technique with a Grimm‐type glow lamp. The emission intensity ratio of Cu I 327.4/Ni I 352.5 for the oxidized Cu–Ni alloys is much larger than that for the non‐oxidized alloy at the beginning of the discharge, because of copper segregation on the surface of the oxidized Cu–Ni alloys. The composition depth profile analysis for oxidized Fe–Cr binary alloys indicates the presence of a stable chromium oxide formed on the surface, particularly a thinner oxide film for alloys having higher chromium concentration. The discharge current for the non‐oxidized alloy is almost constant during sputtering, but grows smaller for the oxidized alloys. This discharge behaviour must be considered in quantification.
An empirical electron spectrometer transmission function for applications in quantitative XPS
Authors: Hemminger Carol S. , Land Terry A. , Christie Alex , Hemminger John C. 
Published: December 2004

AbstractThe use of XPS data for accurate elemental quantitation requires that the transmission function of the electron spectrometer be known. Often, the dependence on electron kinetic energy (Ek) and spectrometer pass energy (Ea) are treated as separable functions. This is inadequate for the comparison of data taken with different pass energies. We have measured the variation of signal intensity as a function of Ea and Ek using the VG Escalab MK II spectrometer under constant analyzer energy conditions. Results from three independent laboratories on a variety of samples are in good agreement. The combined data have been used to develop an empirical formula that relates the signal intensity to the electron kinetic energy and spectrometer pass energy. The non‐separable relationship that we obtain is of the form

Relative sensitivity factors used for XPS quantitation depend on the instrument transmission function. It is not adequate to use an invariant table of factors for all analyser conditions, as is assumed by many XPS data systems. The above empirical formula leads to simple calculations of elemental sensitivity factors at different spectrometer pass energies. It will be demonstrated that this can facilitate comparison of small‐area and large‐area XPS data and quantitative analysis of complex materials where it is desirable to measure minor components at high pass energy.
A surface spectroscopic study of nitrogen ion‐implanted Ti and Ti–6Al–4V wear against UHMWPE
Authors: Lausmaa Jukka , Röstlund Tord , McKellop Harry 
Published: December 2004

AbstractNitrogen ion‐implanted pure Ti and Ti–6Al–4V alloy femoral heads that had been subjected to wear tests in a joint simulator were analysed by AES and XPS, in order to identify their surface composition and to estimate the amount of wear. XPS and AES survey spectra show that the surface of the ion‐implanted specimens consist of mainly a thin (∼10 nm) TiO2 surface oxide. Significant amounts of nitrogen in the form of Ti nitride are detected in spectra from the surface, both prior and after the wear tests. On some of the wear‐tested specimens, areas covered by a Ca‐dominated surface film of unidentified origin are observed. It is demonstrated how the overlapping Ti and N Auger peaks can be separated so that the nitrogen depth distribution can be obtained in depth profile measurements. The nitrogen depth profiles show that the thickness of the implantation layer varies considerably at different points on the samples. For the commercially pure Ti samples, the total amount of wear is significantly higher than for the Ti–6Al–4V samples. In none of the analysed samples had the ion‐implanted layer been worn off completely after the simulation.
Characterization of CuInSe2 thin films by XPS
Authors: Niemi E. , Stolt L. 
Published: December 2004

AbstractThe surface composition of CuInSe2 thin films, made by co‐evaporation of the elements, has been shown to be strongly dependent on the bulk composition of the films. This is explained by the presence of a secondary phase, most likely Cu2Se, on the surface of Cu‐rich films. The fast variation of the surface concentration is also found for films that, according to the equilibrium pseudobinary phase diagram (Cu2SeIn2Se3), should be single‐phase chalcopyrite. An explanation, suggesting the presence of a Cu‐rich compound also on the surface of films with a composition in the single phase regions, is proposed.Surface atomic concentrations have been shown to be modified in CuInSe2 films by a 4.5 keV Ar+ sputter etch. Heating in vacuum at the film deposition temperature restores the surface atomic concentrations to an as‐deposited condition, with the exception of the selenium concentration. The missing selenium atoms are substituted by oxygen atoms still remaining in the film after sputtering and heating.
Back‐side SIMS profiles of dopant redistribution under silicide films
Authors: Jackman J. A. , Kular A. , Weaver L. , Mayer D. , Jackman T. E. , MacPherson C. 
Published: December 2004

AbstractSamples suitable for sputter depth profiling of surface films from the substrate into the film have been produced by selective removal of most of the underlying silicon substrate. This procedure, which reduces problems due to collisional mixing and redeposition of sputtered material, was accomplished by the controlled growth of a boron‐rich etch‐stop layer using molecular beam epitaxy followed by selective chemical etching. The usefulness of this approach has been demonstrated by studying the redistribution of As during the growth of platinum and cobalt silicides with secondary ion mass spectrometry (SIMS).
Surface characterization of butyl methacrylate polymers by XPS and static SIMS
Authors: Castner David G. , Ratner Buddy D. 
Published: December 2004

AbstractX‐ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS) were used to identify and quantify different isomeric butyl methacrylate polymers. The samples examined were normal‐, iso‐ and tert‐ butyl methacrylate (n‐, i‐ and t‐BuMA) homopolymers and two n/t‐BuMA random copolymers. XPS could differentiate the various BuMA polymers based on their valence band (VB) lineshapes. Resolution of the C1s spectra into four Gaussian peaks (hydrocarbon, β‐shifted hydrocarbon, ether and ester) produced similar peak widths and good agreement between the resolved peak areas and the polymer structure. Because of the C4 carbonium ions formed, static SIMS can distinguish the BuMA homopolymers by the increase in the m/z = 57+ signal (C4H9+) from n‐BuMA to i‐BuMA to t‐BuMA. For the n/t‐BuMA random copolymers, the amount of dehydrogenated C4 groups produced by static SIMS experiments (positive 55 and negative 71 ions) increased with increasing n‐Bu concentrations. Any one of several peak intensity ratios (positive 55/57 and 57/69 and negative 57/85 and 71/85) can be used to determine the percentage of n‐BuMA and t‐BuMA components present in an n/t‐BuMA copolymer. A combination of two different peak intensity ratios is required to distinguish the i‐BuMA polymer from an n/t‐BuMA copolymer. The clearest differentiation of the BuMAs was obtained by combining XPS VB and static SIMS results.
XPS analysis of silane coupling agents and silane‐treated E‐glass fibers
Authors: Pantano Carlo G. , Wittberg T. N. 
Published: December 2004

AbstractThe photelectron spectra of five different liquid silanes were measured. Their C 1s spectra and measured compositions were all consistent with the theoretical formula of these compounds. Subsequently, E‐glass fibers were exposed to dilute aqueous solutions of these silanes, and their adsorption on the fiber surfaces was observed. The high‐resolution C 1s spectra revealed the extent of hydrolysis. The thicknesses of the adsorbed layers were determined and were found to scale with the length of the organic functional group.
Analysis of zirconium–niobium pressure tube surfaces for hydrogen using secondary ion mass spectrometry (SIMS)
Authors: McIntyre N. S. , Weisener C. G. , Davidson R. D. , Lennard W. N. , Massoumi G. R. , Mitchell I. V. , Brennenstuhl A. , Warr B. 
Published: December 2004

AbstractUnderstanding the mechanisms of hydrogen ingress into pressure tubes fabricated from zirconium–2.5% (w/w) niobium alloy requires knowledge of the hydrogen concentration in the surface oxides, of the oxide/metal interface and in the alloy phase beneath the interface. Secondary ion mass spectrometry (SIMS) has attractive capabilities for detecting hydrogen isotopes in such surface films, but its quantitative response and spatial resolution are controversial for hydrogen because of the strong tendency for the element to migrate, owing to thermal and sputtering effects. High sputter rate conditions have been used here, which result in an improved capability to detect hydrogen in ZrNb alloy and ZrO2 down to concentrations of <2 × 1017 atoms cm−3 (<0.1 ppm, w/w). Quantitation of deuterium concentrations has been accomplished by SIMS calibrated using ion implants and, in some cases, verified by nuclear reaction analysis (NRA).
A high energy resolution, high spatial resolution photoemission microscope
Authors: Knapp G. S. , Keenylside M. , Griffin C. 
Published: December 2004

AbstractThis paper will discuss a microscope that allows high energy resolution spectroscopy to be performed at high spatial resolution. This instrument uses a high magnetic field to contain and focus electrons emitted from the sample surface and has a two‐dimensional detector that records a photoelectron image. It is also equipped with a hemispherical analyzer, which allows state‐of‐the‐art spectroscopic performance to be obtained from very small areas. The instrument is unique in that it collects a much larger solid angle than any other instrument in use today, and spatial resolutions of 2 μm and energy resolutions of 0.25 eV have been achieved.
XPS analysis of thin chromium films
Authors: Petkov K. , Krastev V. , Marinova Ts. 
Published: December 2004

AbstractThe surface and mechanical properties of thin Cr films play an essential role in microphotolithographic processes in which an inorganic photoresist based on vacuum‐evaporated As2S3 is used as a light‐sensitive system. The present paper reports some XPS data about thin chromium layers obtained by thermal evaporation, high‐frequency sputtering, electron beam evaporation and de magnetron sputtering. A correlation is found between the surface elemental composition of the metal coating and the metal coating and the possibilities of obtaining good adhesion between the Cr and As2S3 used as the inorganic photoresist. It is shown that the presence of pure Cr on the surface of the samples is a defining condition for photolithography in the submicron region.
Photoemission applied to the in situ study of epitaxial growth: Theoretical modelling
Authors: Laamouri A. , Rouhani M. Djafari , Gue A. M. , Fazouan N. , Esteve D. 
Published: December 2004

AbstractReflection high‐energy electron diffraction oscillations are commonly used to monitor the growth of materials and to control the thickness as well as the roughness of the deposited layer.A new technique based on the photoemission current has been employed by Eckstein et al.1 to study the dynamics of the epitaxial growth of GaAs by molecular beam epitaxy. In particular, they have observed oscillations in the energy‐integrated near‐threshold photo emission current that they attribute to periodic changes in the nature of the surface.Our work deals with the physical origin of the observed photoemission oscillations during growth of GaAs. We assume that the photoemission properties depend on the chemical nature of the adsorbed atoms and on their local configurations. In this way, we have developed a theoretical model that associate a simple growth model with an atomic photoemission mechanism.The photoemitted current calculated with this model exhibits the features observed experimentally which seem to be strongly dependent on the molecular As2 adsorption mechanisms and on the roughness of the growing layer.