bluuebunny/crossref_metadata_2025_split huggingface dataset:
Growth and dissolution of a surface graphitic carbon monolayer on nickel and low‐chromium NiCr alloys
Authors: Hörz G. , Angermann H.‐H. 
Published: December 2004

AbstractOn Ni and low‐chromium NiCr alloys a surface graphitic carbon monolayer is formed when during carburization of the materials in carbon‐containing atmospheres, e.g. in C2H2 or CH4‐H2, at constant temperature the carbon activity aC exceeds a critical value aC,cr. On surface planes other than (111) and probably (110) and (311), carbon monolayer formation is accompanied by surface restructuring. The onset of formation and the growth of the carbon monolayer (two C atoms per one metal atom) on Ni and NiCr alloys have been studied at 1150–1400 K directly by in situ AES analysis of the surface composition during carburization or indirectly by using the specific kinetic features of a subsequent decarburization of the materials in H2 as a sensitive probe. The fractional area f of the material surface which becomes covered with the carbon monolayer during carburization in CH4H2 at carbon activities aC > aC,cr has been determined as a function of the time ta of exposure of the samples to the carburizing atmosphere for various carbon activities aC, temperatures and alloy compositions. For carbon monolayer formation a growth law according to f = 1 − exp [ − ½δt] with δ = δ(aC, T) has been established, indicating two‐dimensional growth of the monolayer. The dissolution of the carbon monolayer during decarburization was found to be controlled by the separation of carbon atoms from the monolayer along the perimeter of the monolayer domains.
Segregation in some Nickel‐based hard‐facing alloys prepared by melt‐spinning
Authors: Hamar‐Thibault Sylvaine , Ajao John , Lebaili Soltane 
Published: December 2004

AbstractThe segregation of a series of nickel‐based alloys rapidly quenched by melt‐spinning has been investigated in order to understand the distribution of the elements. These alloys have complex composition with metallic (Ni, Cr, W) and non‐metallic elements (C, B, Si). The microstructure of the ribbons obtained by melt‐spinning are examined by transmission electron microscopy and Auger spectometry. Even though the Auger spectra obtained on the two surfaces of the ribbon are generally identical, they differ from each other on the structure in the energy domain covering the Auger peaks of boron, tungsten and carbon. After sputtering the carbon appears with a fine well‐resolved structure towards the low‐energy region with low‐intensity peaks at 260, 252 and 244 eV, as in stable or unstable carbides.
Improved depth resolution of AES in‐depth profiling
Authors: Barna A. , Sulyok A. , Menyhard M. 
Published: December 2004

AbstractIn the case of conventional Auger in‐depth profiling, the depth resolution increases with the thickness of the removed layer. It was demonstrated that by rotating the specimen, the depth resolution improves drastically in certain cases. Independently from this, A. Barna developed a phenomenological model to describe the change of surface topography developing due to ion sputtering. Based on his results, an Auger in‐depth profiling device has been built. The capability of the device was checked by measuring in‐depth profiles of NiCr multilayer structure. The depth resolution determined from the measured profile is roughly constant along the depth.
Composition and thickness of surface layer on molybdenum tips for scanning tunnelling microscopy (STM) studied by SEM/AES/(AR)XPS
Authors: Lisowski W. , Van Den Berg A. H. J. , Hanekamp L. J. , Van Silfhout A. 
Published: December 2004

AbstractA combination of SEM, AES and angle‐resolved XPS (ARXPS) has been applied to analyse the distribution of chemical compounds in the surface region of electrochemically etched molybdenum tips and to determine the contamination layer thickness. Carbon monoxide, graphite, molybdenum carbide and molybdenum oxide were found to be the main surface contaminants on molybdenum tips. Auger line profiling revealed a significant enrichment of carbon and oxygen upon the tip. The thickness of the oxygen–carbon contamination layer on the tip was estimated to be 13.5 ± 1.0 nm as measured by AES. The thickness of the contamination layer on a molybdenum sheet was found to be 8.0 ± 1.5 and 6.8 nm using AES and ARXPS respectively. Quantitative analysis of the surface concentrations of carbon, oxygen and molybdenum has been performed.
Characterization of polymer surfaces and polymer–metal interfaces by static secondary ion mass spectrometry
Authors: Van Ooij W. J. , Sabata A. 
Published: December 2004

AbstractThe applicability of Time‐of‐Flight SIMS (TOFSIMS) to the study of adhesion phenomena is discussed. The technique is especially powerful for the study of interactions at polymer–metal interfaces. This is demonstrated by a number of examples of TOFSIMS analysis of polymer surfaces, metal pretreatments and paint–metal interfaces of materials used in the automotive industry. The TOFSIMS high‐resolution spectrum of a film of Nylon‐6® is interpreted in some detail. The metal pretreatments that are discussed are by functional silanes. Thin organic films deposited on metals by plasma polymerization of silanes have also been analyzed. It is demonstrated that such films can be characterized by TOFSIMS. In several cases surface analyses by XPS and AES were also carried out in order to illustrate the complementary information that can be obtained by the application of these three major surface analysis techniques. The analysis of the paint–metal interfaces by TOFSIMS allows conclusions to be drawn about the state of cure of the paint and about preferential segregation of low‐molecular‐weight paint constituents to the metal surface.
An in situ XPS study of the formation of aluminium–polymer interfaces
Authors: Marcus P. , Hinnen C. , Imbert D. , Siffre J. M. 
Published: December 2004

AbstractXPS was used to study the initial stages of aluminium deposition on polypropylene. Aluminium was ion sputtered in the preparation chamber of the spectrometer with controlled oxygen and H2O partial pressures. The surface composition of the polymer before and after metallization was analysed by XPS and the core levels Al 2p, O 1s and C 1s were used to obtain information on the chemical bonds formed during the deposition of aluminium. By minimizing the principal sources of oxygen during deposition, aluminium films with low oxygen content could be obtained, allowing for investigation of the aluminium‐carbon interaction. The appearance of new peaks in the Al 2p region with a chemical shift of 1.3 ± 0.3 eV with respect to aluminium and in the C 1s region with a chemical shift of 2.6 ± 0.4 eV with respect to carbon in polypropylene indicates a chemical reaction between aluminium and carbon with a charge transfer from aluminium to carbon. The XPS peak intensities are used to estimate the stoichiometry of this interfacial compound.
Adsorption of hydrogen fluoride on alumina
Authors: Haverkamp R. G. , Metson J. B. , Hyland M. M. , Welch B. J. 
Published: December 2004

AbstractIn the smelting of aluminium, HF fumes are produced that are subsequently trapped by absorption onto alumina. The factors that affect the adsorption capacity of alumina have been studied previously and are well established, but the mechanism by which HF adsorbs onto the alumina surface is not well understood.In this study, x‐ray photoelectron spectroscopy (XPS) was used to investigate the nature of the surface adsorption of HF on alumina. XPS is particularly well suited to the study of this type of gas adsorption process.Laboratory‐prepared samples were studied with particular interest in evidence for AlF bonding, or in fluoride species formed by reaction with OH or O. Also of interest was the role of sodium, since it is segregated to the surface of the alumina during calcination.AlF bonding was observed on only one sample type. An AlF interaction was identified when the alumina had been predried and dry HF was absorbed. When moisture was present no AlF3 formation was observed. This suggests that under conventional conditions (i.e. moisture present) the adsorption of HF involves a weak interaction, probably hydrogen bonding, with intermediate layers of water. After heating the samples containing weakly bound HF to 500°C, no AlF interaction was observed. Much of the HF was desorbed at 700°C.An Na–F interaction was observed in all fluoride‐adsorbed samples; however, this can only account for a small proportion of the total fluoride adsorbed.
Effect of the nature of the etchant on the adhesion strength of a Ti alloy
Authors: Gila L. , Morra M. , Occhiello E. , Garbassi F. 
Published: December 2004

AbstractThe effects of the surface chemistry and morphology of three different adhesion‐promoting treatments on Ti–6Al–4V alloy were evaluated by x‐ray photoelectron spectroscopy (XPS), Auger depth profiling (AES) and scanning electron microscopy (SEM). The lap shear strength of Ti–6Al–4V/polyimide joints was evaluated immediately after curing and after dry and wet ageing. While all the treatments produced nearly the same immediate shear strength, treatment‐related effects, most likely connected to the nature and amount of the elements introduced by the treating routine, were observed in aging studies.
Maximum entropy: A new approach to non‐destructive deconvolution of depth profiles from angle‐dependent XPS
Authors: Smith G. C. , Livesey A. K. 
Published: December 2004

AbstractThe application of the maximum entropy method to non‐destructive depth profiling by angle‐dependent XPS is described. The algorithm gives the set of depth profiles that has maximum Skilling‐Jaynes entropy, subject to the condition that the calculated data agree with the measured data within the experimental precision. The method does not require an inverse transform, is robust to experimental noise and is not restricted to small numbers of components. The programme can determine which of a set of prior estimates for the depth profiles is most probable; however, the reconstruction near the surface is virtually independent of this choice. Further, the method also estimates the accuracy of the reconstruction from a single data set. It is illustrated using model data and by a re‐analysis of angle‐resolved XPS data sets available in the literature.
Preliminary results on multiple angular detection Auger spectroscopy
Authors: Cazaux J. , Bardoux T. , Mouze D. , Patat J. M. , Salace G. , Thomas X. , Toth J. 
Published: December 2004

AbstractFrom elementary calculations of the Auger signal intensities from a specimen at two different take‐off angles, θ1 and θ2, it is shown that the simultaneous acquisition of these spectra allows homogeneous alloys and stratified samples to be identified and also the presence of topographic effects.The preliminary results confirm the potential of multiple angular detection Auger electron spectroscopy (MADAES) that can be developed by using only one analyser of cylindrical mirror type. Further developments are also indicated.
Application of AQUA and QUAX to matrix corrections in AES and XPS
Authors: Fitzgerald A. G. , Moir P. A. , Storey B. E. 
Published: December 2004

AbstractThe rapid determination of surface composition from raw spectral data using interative procedures contained in the computer programs AQUA and QUAX is described. The establishment of this system of programs has required the compilation of library files of basic elemental data to enable the automatic execution of matrix calculations. This system has been designed so that the effect of different methods of calculation of attentuation length or backscatter factor on calculated matrix factor and final surface composition can be readily investigated. These calculations would be tedious without the use of the AQUA and QUAX computer surface analysis system. In this investigation matrix factors and surface compositions have been calculated for a number of materials, including NiFe and CuAg alloys. Application of the option in the QUAX program for standardless surface analysis by XPS has been investigated in GaNx(Oy) films.
Quantitative XPS analysis of SiNx(:H) films using simple methods without sputtering
Authors: Kazuta Mayumi , So Noriko , Kasamura Hideaki , Kudo Masahiro 
Published: December 2004

AbstractThe use of Ar ion sputtering to remove the native surface oxide on SiNx(:H) is known to cause underestimation of its N/Si ration in XPS or AES analysis owing to preferential sputtering. We have carried out an XPS analysis of the N/Si ratio of plasma‐enhanced chemical vapour deposition SiNx:H (x <1.5) films using two simple methods without sputtering. In the first method samples were analysed with no surface treatment. In the second method the surface oxide was removed by chemical etching with HF solution. Curve fitting of Si 2p spectra was carried out to remove the influence of the surface oxide in both methods. There were good linearities between the N/Si ratios obtained by these methods and those estimated by RBS and absorption edge measurement. In particular, after correction for an error caused by differences in the attenuation length of photoelectrons, both methods proved to give results of sufficiently high precision for practical analysis.
Investigation of hydrogen sensitivity of SIMS method
Authors: Pavlyak F. 
Published: December 2004

AbstractGenerally, papers in which hydrogen detection by the SIMS method is described do not touch upon the sensitivity and background level of hydrogen during the SIMS analysis. Problems connected with the detection and sensitivity of hydrogen in our SIMS equipment are discussed in this paper. In order to determine the hydrogen sensitivity, pure zirconium, zirconium hydride and high‐purity silicon samples as well as the composition of the residual of the vacuum system were investigated. The composition data of the argon gas used for sputtering were considered too. From the results of the measurements the sensitivity and the sensitivity factor of hydrogen can be stated.
The NIST x‐ray photoelectron spectroscopy database
Authors: Rumble J. R. , Bickham D. M. , Powell C. J. 
Published: December 2004

AbstractThe National Institute of Standards and Technology (NIST) has made available the second version of the NIST X‐ray Photoelectron Spectroscopy Database. This paper reports on recent upgrades to the database to make the information more up‐to‐date and to make data searching and display more convenient and efficient for the user. Additional data are included in the database together with the capability to search using large chemical synonym lists, chemical formulae and other chemical classification schemes. A list of reference energies is given for the principal photoelectron and Auger electron lines of most of the elements and these values can be used for calculations of chemical shifts. Pull‐down menus are now available to initiate searches for the identification of unknown lines more conveniently, to retrieve data on photoelectron lines, Auger electron lines and chemical shifts for a set of elements, to calculate and display chemical shifts, and to calculate and display information for Wagner plots to identify chemical state. In addition, the use can initiate searches based on specified fields of the database.
Characterization of implanted surfaces by unenhanced surface Raman scattering
Authors: Mathur M. S. , McKee J. S. C. 
Published: December 2004

AbstractThe implantation of surfaces by energetic gaseous ions often results in the formation of molecular complexes which in turn can be adsorbed on the solid surface. Characterization of such complexes is of concern to surface scientists. Conventional characterization techniques involving low‐energy electron beams operate under ultrahigh‐vacuum condition and cause dislodging and desorption of these complexes. We have undertaken the characterization of the implanted surfaces under ambient conditions by the technique of unenhanced surface Raman scattering (USRS).
An AES study of LPCVD Ta2O5 films on Si
Authors: Kajiwara K. , Isobe C. , Saitoh M. 
Published: December 2004

AbstractMethods of evaluation of the chemical composition of tantalum oxide films and of the interface between tantalum oxide films and Si substrates were studied by means of sputter‐assisted Auger electron spectroscopy (AES). Tantalum oxide films 10–50 nm thick were grown on Si single‐crystal substrates by low‐pressure chemical vapour deposition (LPCVD). It has been found that reduction of the oxides is induced by ion sputtering during Auger depth profiling. Therefore we optimized the ion‐sputtering conditions to minimize the reduction rate. Then, using stoichiometric β‐Ta2O5 as reference, it was confirmed that as‐deposited tantalum oxide films were oxygen‐deficient and that the oxygen content of these films was increased by subsequent annealing in an O2 ambient. By means of Auger depth profiling, we evaluated the thickness of silicon native oxides formed at the Ta2O5/Si interface as 1.5–2 nm. Moreover, we revealed the oxidation mechanism of a silicon nitride intermediate layer (e.g. 10 nm thick) deposited between tantalum oxide film and an Si substrate during heat treatment at 900–1000°C in O2.
A cross‐sectional TEM study of corrosion initiation in rapidly solidified Mg‐based ribbons
Authors: Warner T. J. , Thorne N. A. , Nussbaum G. , Stobbs W. M. 
Published: December 2004

AbstractThe microstructures across the whole thickness of uncorroded and corroded rapidly solidifed Mg and Mg‐9% Al ribbons have been characterized using TEM cross‐sectional techniques. In this way, differences in susceptibility to and mechanisms of corrosion initiation between four clearly different magnesium alloy microstructures have been observed. These observations demonstrate that corrosion initiation occurs preferentially at grain or cell boundaries in both ‘pure’ magnesium and Mg‐Al ribbons and that aluminium in solid solution clearly improves the corrosion resistance of magnesium alloys. Mg17Al12 precipitates at grain cell boundaries appear to promote corrosion initiation locally, but intragranular Mg17Al12 precipitates do not appear to promote corrosion to the same extent.
XPS study of passive films formed on molybdenum‐implanted austenitic stainless steels
Authors: De Vito E. , Marcus P. 
Published: December 2004

AbstractAustenitic stainless steels (Fe–19Cr–10Ni (at.%)) have been implanted with molybdenum ions (Mo+, 100 keV, 2.5 × 1016 atoms cm−2). The implanted material has been characterized by XPS and RBS. The implanted region has a thickness of ∼1000 Å with a maximum molybdenum concentration of ∼9 at.% Mo located at ∼210 Å from the surface. The effects of implanted molybdenum on the passivation of the alloy in 0.5 M H2SO4 have been investigated by electrochemistry and XPS. Prior to electrochemical experiments, surfaces with well defined Mo concentrations were produced by argon ion sputtering the implanted alloy for a fixed time in the preparation chamber of the spectrometer in order to reach a well defined point on the molybdenum depth profile. After XPS analysis the samples were transfered without exposure to air into a glove‐box with an inert atmosphere. The electrochemical behaviour of the alloy is significantly modified by the implanted molybdenum. The major effect is that the activation peak disappears. A bilayer structure (outer hydroxide/inner oxide) of the passive film is observed for both the implanted and non‐implanted alloys and the thicknesses of the films are similar. On the implanted alloy the outer hydroxide layer contains molybdenum cations in the 6+ state and Mo4+ is also detected. The mean Mo6+ concentration in the film increases up to 7 at.% with increasing Mo concentration in the alloy. The hydroxide/oxide ratio [Cr3+(hyd)]/[Cr3+(ox)] increases from ∼0.8 to ∼3 for Mo concentrations in the alloy from 0 to 9 at.% respectively. A marked enrichment of Cr, Ni and Mo is observed in the metallic phase near the alloy/passive film interface.
Surface precipitation of graphite layers on carbon‐doped nickel and their stabilization effect against chemisorption and initial oxidation
Authors: Fujita D. , Homma T. 
Published: December 2004

AbstractA new method for coating the inner surface of ultrahigh‐vacuum (UHV) vessels with an inert material is proposed, namely coating with highly oriented graphite layers which precipitate on the surface of a carbon‐doped nickel substrate. By using various surface analytical methods, characterization of the precipitated graphite has been performed. AES measurements at elevated temperatures clarified the surface precipitation process on polycrystalline Ni–C. Low‐energy electron diffraction studies on Ni(111) showed that the surface‐precipitated graphite grew epitaxially with the substrate and its structure was found to agree with that of highly oriented pyrolytic graphite. Reflection high‐energy electron diffraction studies revealed that the basal planes (0001) of precipitated graphite preferentially cover the surface even in the case of polycrystalline Ni–C. AES measurements in an O2 atmosphere showed that the graphite‐covered surface was hardly oxidized by prolonged oxygen exposure. Thermal desorption spectroscopy measurements suggested that the desorption of CO after O2 dosing was much smaller from the graphite‐precipitated surface than from a stainless steel surface. From the standpoint of applications to problems in engineering, graphite precipitation on metals is found to be a promising method for making an inert and low‐outgassing surface for UHV use.
Copper speciation by analytical electron spectroscopies: Case of the intercalation phase Cu0.5V2O5 · 0.5H2O
Authors: Malitesta C. , Sabbatini L. , Torsi L. , Zambonin P. G. , Ballivet‐Tkatchenko D. , Galy J. , Parize J.‐L. , Savariault J. M. 
Published: December 2004

AbstractOctahedral‐Cu(II) and Cu(I) species have been found on the surface of the intercalation phase Cu0.5V2O5 · 0.5H2O by XPS and x‐ray‐excited Auger Electron Spectroscopy (XAES). The reduced species appears more abundant in the surface region, as indicated by variable‐angle XPS measurements. Reduction or dehydration of the substance preserve its qualitative composition, confirming Cu speciation and showing that water is not Cu‐bonded. Vanadium chemistry is in good agreement with results obtained on copper speciation, which consider an intermediate electronic strucure between VO2 and V2O5 for the intercalation phase.
Polyaniline with high intrinsic oxidation state
Authors: Kang E. T. , Neoh K. G. , Tan K. L. 
Published: December 2004

AbstractPolyaniline (PAN) samples of high intrinsic oxidation states, such as the nigraniline (NA) and pernigraniline (PNA) oxidation states, were prepared by chemical oxidation of the 50% oxidized emeraldine (EM) base and the fully reduced leucoemeraldine (LM) base, according to the methods reported in the recent literature. X‐ray photoelectron spectroscopy (XPS) was used as a primary tool for the quantitative analysis of the benzenoid amine, quinonoid imine and positively charged nitrogens corresponding to any particular intrinsic oxidation state and protonation level of the polymer. The use of iodine and ammonium persulfate as oxidants can lead to structural alterations, such as halogen addition in the former and over‐oxidation and degradation in the latter. Less structural changes are observed in the m‐chloroperoxybenzoic acid‐oxidized material. In all the cases studied, XPS results indicate that only the 75%‐oxidized NA base has been obtained in the dry state. The fully oxidized PNA probably exists in the m‐chloroperoxybenzoic acid‐oxidized material before drying, as suggested by optical absorption spectroscopy. The charge transfer interactions of the NA powders and films with dopants in aqueous and non‐aqueous media were also investigated briefly.