bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of macromolecules: A challenge for surface analysis
Authors: Garbassi F. , Morra M. , Occhiello E. , Barino L. , Scordamaglia R. 
Published: May 2005

AbstractXPS and contact angle measurement have been used to study oxygen–plasma‐treated polypropylene (PP) surfaces aged at variable temperatures. Surface rearrangement leading to low wettabillity has been observed, without alteration of the surface composition, as determined by XPS. Experimental results have been interpreted in terms of internal rearrangements of a modified layer, <5 nm thick, formed on top of the PP and immiscible with it.We also modelled the composition of the surface layer and calculated the relative mobility of modified and non‐modified polymer chains. On this basis, the experimentally observed behaviour can be interpreted in terms of surface rearrangement driven by a compromise between striving for lower surface tension and maximizing inter‐and intramolecular interactions, mainly hydrogen bonds.The surface composition observed after treatment with plasma, corona, flame or other for enhancing surface tension is then time dependent. For this reason, the procedure used for surface analysis, namely the time allowed for surface equilibration, should be specified in reports.
Auger electron spectroscopy from elemental standards. III. Backgrounds and peak‐to‐background ratios
Authors: Batchelor D. R. , Bishop H. E. , Venables J. A. 
Published: May 2005

AbstractBackground levels and Auger peak‐to‐background (P/B) ratios have been measured for the elements Si, Cu, Ag and W in two different machines. The relative contributions of secondary electrons and primary back‐scattered electrons to the background under the Auger peak, as a function of probe energy E0 and incident angle θ0, have been studied, and the trends are discussed. The P/B ratio is roughly constant for θ0 ≤ 60°, which is useful for minimizing topographic effects in scanning Auger microscopy. At high E0 and θ0, secondary electrons dominate the background and P/B tends to a constant. The ratio P/B1/2 is a measure of detectability; it decreases only slowly with E0 because of the reduction in back‐scattered background. This is favourable for Auger microprobes operating at higher E0 than presently available.
Applications of surface analysis and surface theory in tribology
Authors: Ferrante John 
Published: May 2005

AbstractTribology—the study of adhesion, friction and wear of materials—is a complex field that requires a knowledge of solid‐state physics, surface physics, chemistry, material science and mechanical engineering. It has been dominated, however, by the more practical need to make equipment work. With the advent of surface analysis and advances in surface and solid‐state theory, a new dimension has been added to the analysis of interactions at tribological interfaces. In this paper, the applications of surface analysis to tribological studies and their limitations will be presented. Examples from research at the National Aeronautics and Space Administration's Lewis Research Center will be given. Emphasis will be on fundamental studies involving the effects of monolayer coverage and thick films on friction and wear. A summary of the current status of theoretical calculations of defect energetics will be presented. In addition, some new theoretical techniques that enable simplified, quantitative calculations of adhesion, fracture and friction are discussed.
Quantitative AES: Determination of the effects of the relative orientations of the sample, electron gun and spectrometer on the direct spectrum shape for the establishment of standard reference spectra
Authors: Smith G. C. , Seah M. P. 
Published: May 2005

AbstractThe precise shape of the whole direct spectrum in AES depends on the processes in the sample and on the properties of the measurement system. In this paper we characterize, in detail, the intensities emitted from ion sputter‐cleaned copper and silver foils in the direct spectrum in order to understand better the processes in the sample controlling those intensities. Characterizations of the dependencies of the intensities on the angle of incidence of the electron beam and on the angle of emission of the detected electrons provide rules allowing the transference of reference spectra between different instrumental cinfigurations and conditions. The precise evaluation of the rules is essential if reference data banks are to be transferred for instrument to instrument. Furthermore, by tracing the spectra back to an instrument with known properties we may establish standard reference spectra, which may then be used to calibrate, in other instruments, the combined energy dependencies of the spectrometer transmission function and detector sensitivity with accuracy. This calibration enables all instruments to be used to measure true spectra for the first time.
Comparison of AES analyses of transition‐metal nitride coatings with carrier‐gas heat extraction analyses
Authors: Jehn Hermann A. , Grallath Erhard , Strydom I. LeRoux , Hofmann Siegfried 
Published: May 2005

AbstractIn spite of some work on the quantification of Auger spectra of transition‐metal nitride thin films (hard coatings), a correlation with the true nitrogen content is rather difficult. In order to get a measure of the validity of the generally applied calibration of AES results by means of Handbook relative sensitivity factors, TiNx, ZrNx, NbNx and MoNx films of different nitrogen content were deposited by reactive magnetron sputtering on thin high‐purity platinum foils and were analysed subsequently for their nitrogen content by carrier‐gas heat extraction analysis (GA). The GA results were compared with the above‐mentioned AES evaluation. Whereas the agreement between GA and AES is fairly good for TiNx (based on a special AES evaluation procedure), it depends significantly on the use of either high‐ or low‐energy Auger peaks for Zr, Nb and Mo. Corrections of AES elemental sensitivity factors for changes in density, Auger electron escape depth and primary electron back‐scattering only show a minor influence in the direction of higher nitrogen contents. Comparison of GA and AES results yields sensitivity correction factors for the used metal peak energies in the systems studied.
Segregation to grain boundaries in nimonic PE16 superalloy
Authors: Nettleship D. J. , Wild R. K. 
Published: May 2005

AbstractNimonic PE16 alloy is a nickel‐based superalloy containing 34 wt.% iron and 16 wt.% chromium with additions of molybdenum, titanium and aluminium. It is used in the fuel assembly of the UK advanced gas‐cooled reactors (AGR). This component supports significant loads in service and its mechanical integrity is therefore of paramount importance. Mechanical properties may be influenced by the grain size and grain boundary composition, both of which can themselves alter during service. Scanning Auger microscopy is a well‐established method for investigating grain boundaries, and has now been applied to the study of PE16. In order to expose PE16 grain boundary surfaces it is necessary to hydrogen charge samples and fracture by pulling in tension at a slow strain rate within the ultra‐high vacuum chamber of the Auger microprobe. A series of casts of nimonic PE16 alloy that have received a range of thermal ageing treatments have been fractured in an intergranular manner and the grain boundary composition determined. Segregation of trace and minority elements, particularly Mo and P, has been detected at grain boundaries. Significant variations between different as‐manufactured casts were observed, whilst ageing brought about the growth of chromium‐rich particles on the grain boundaries. Ductile fracture in PE16 followed a path through Ti(C, N) particles. Many of these particles incorporated large amounts of sulphur.
An XPS study of GaN thin films on GaAs
Authors: Carin R. , Deville J. P. , Werckmann J. 
Published: May 2005

AbstractThe energies of photoelectron and Auger lines of gallium and nitrogen in GaN thin films obtained by reactive sputtering are derived. From previous RBS investigations, such were found to be stoichiometric in the bulk. The XPS surface analysis of the films gives a chemical content of ∼20% gallium oxide. Depth profiling of GaN/GaAs samples is then performed by Ar+ (2 keV) sputter‐etching. The Ga L3M4,5M4,5 Auger line shows a partial dissociation of GaN by preferential sputtering of nitrogen and the production of metallic gallium. The Ga 3d and Ga 2p photoelectron lines, having different escape depths, give the same result. The etching rate is high: the GaN sputtering yield, which is almost the same as that for Ga, is found to be ∼8. The gallium oxide component disappears for depths larger than 10 nm: it is concluded that the surface gallium oxide is probably due to the partial oxidation of GaN films in atomospheric air.
The influence of diffraction effects on quantitative Auger electron spectroscopy
Authors: Bishop H. E. 
Published: May 2005

AbstractIn Auger electron spectroscopy, both the primary electrons entering the sample and the Auger electrons leaving the sample may suffer strong diffraction effects. On well‐ordered single‐crystal surfaces, diffraction effects may result in variations in the intensity of an Auger peak by a factor of up to two or more when the incident beam direction is varied by a few degrees. The large angular acceptance angle of most Auger spectrometers normally averages out any diffraction effects of the Auger electrons themselves.Diffraction effects of the primary electron beam (commonly called channelling) may be described qualitatively in terms of the two‐beam theory of electron diffraction. A more exact representation requires a multiple beam calculation similar to that used in electron microscopy.For quantitative AES it is essential to establish whether diffraction is likely to influence the results and, is so, to take appropriate steps to eliminate or at least to minimize its effect. On the other hand, these channelling effects provide valuable information about the near‐surface order of the sample and potentially provide a technique complementary to x‐ray photoelectron diffraction.
NiCo alloy as a new reference material for quantitative surface analysis
Authors: Fujita D. , Tanaka A. , Goto K. , Homma T. 
Published: May 2005

AbstractFor the improvement of quantitative surface analysis using Auger electron spectroscopy (AES) we propose an NiCo alloy system as a candidate for a ‘primary reference material’ to be used for evaluating the accuracy of quantitative surface analysis. A NiCo alloy was chosen for two reasons. Firstly, the concentrations of the alloys (Ni49Co51,Ni75Co25) at the surface and in the near‐surface region were found to be homogeneous, i.e. phenomena such as preferential sputtering and ion irradiation‐induced surface segregation were no observed with angle‐resolved XPS measurements during 1 keV Ar+ ion sputtering. Secondly, the corrections of matrix effects of NiCo alloys, such as the atomic density, the back‐scattering factor and inelastic mean free path corrections, were calculated and found to be negligibly small.
Determination of the intensity–energy response function of the ISA Riber MAC 2 electron analyser
Authors: Repoux M. , Darque‐Ceretti E. , Casamassima M. , Contour J. P. 
Published: May 2005

AbstractThe energy response function of the semi‐imaging ISA Riber MAC 2 electron spectrometer has been determinated over the kinetic energy range 150–1500 eV. The absolute transmission of the analyzer is proportional to KE, with n ranging from 1.02 to 0.43 and K from 157.5 to 23.2 when the focusing voltage VF1 of the retarding field grid increases from 5 to 20 V, i.e. When the analyzer resolution increases from 0.55 to 2.2 eV. The power factor n and the proportionality factor K are linearly decreasing when the focusing voltage is increasing: n = 1.23−0.043 VF1 and K = 211−10.8 VF1.
The failure mode of adhesively bonded aluminium following aqueous exposure
Authors: Watts J. F. , Blunden R. A. , Hall T. J. 
Published: May 2005

AbstractAdhesively bonded aluminium sheets pretreated by phosphoric acid anodizing (PAA) or chromic acid anodizing (CAA) were fabricated into 180° T‐peel test pieces. These were then exposed to cycles of aqueous exposure at elevated temperature, followed by a drying procedure at ambient or elevated temperatures. In the case of the CAA‐pretreated substrate, the aqueous exposure brings about a drastic reduction in joint strength and the locus of failure (as assessed by XPS) moves from the centre of the glue line to very close to the oxide/adhesive interface. The drying procedure increases the peel strength, and the failure path once again moves towards the bulk of the adhesive. This behaviour is ascribed to the agregation and to the subsequent removal of water molecules close to the interface. The behaviour of the PAA‐pretreated joints is completely different. The short water immersion times used in this work have little effect on peel strength but subsequent drying at elevated temperature does reduce the joint strength considerably. It is postulated that this may be the result of leaching and subsequent deposition of a component of the adhesive, perhaps some unreacted curing agent. This behaviour is also reversible and the peel strength can be increased by re‐exposing the joint to water. Thus, for both CAA and PAA pretreatments the strength can be affected greatly by environmental exposure, but both phenomena show a degree of reversibility.
Electrochemical and electron spectroscopic investigations of iron surfaces modified with thiols
Authors: Volmer M. , Stratmann M. , Viefhaus H. 
Published: May 2005

AbstractIn order to develop new composite materials between reactive metals and polymers, it is proposed to place organic monomers at the metal/polymer phase boundary, which can be coupled by covalent/ionic bonds to reactive centres of the metal substrate and later by covalent bonds to the polymer itself. As a first step, the model system iron/n‐decanethiol (n‐decylmercaptan, C10H21SH) has been investigated by AES and XPS. It is shown that the mercaptan binds to metallic clean iron surfaces through the sulphur atom, probably by cleavage of the SH bond. The S 2p3/2 peak has a binding energy of 162.4 ± 0.2 eV. Anodic polarization and ageing in the laboratory atmosphere do not oxidize these chemisorbed molecules; the oxidation reactions of the substrate are suppressed too. After cyclovoltammetry (−1.0 VSHE⩽ U ⩽ + 0.6 VSHE), better oriented chemisorbed molecules are packed more densely on top of the surface.
Study of the large non‐stoichiometry of copper(I) oxide on oxidized copper (T < 573 K, pO2 = 0.21 atm)
Authors: Lenglet M. , Machefert J. M. , Claude J. M. , Lefez B. , Lopitaux J. , D'Huysser A. 
Published: May 2005

AbstractThe study of the oxidation of copper at low temperatures shows that the metal is not recovered by a pure stoichiometric Cu2O but by a copper(I) oxide phase with the same crystalline structure as Cu2O, and that this phase exhibits a very large non‐stoichiometry (composition between Cu60O40 and Cu63O37). These results explain that the UV‐Vis‐NIR spectra are different from those of high‐purity Cu2O crystals and the position of the absorption bands attributable to defects could be justified easily by the Bohr theory of the hydrogen atom applied to semiconductors.
An XPS study of the initial stages of oxidation of hafnium
Authors: Morant C. , Galán L. , Sanz J. M. 
Published: May 2005

AbstractThe oxidation kinetics of polycrystalline hafnium (Hf) at room temperature and low oxygen pressure (Po2 ∼ 10−7 Torr) has been studied by x‐ray photoelectron spectroscopy (XPS). After a chemisorption stage for exposures ⩽ 5 L, Hf suboxides are initially formed and are dominant until ∼ 25 L. HfO2 appears at ∼ 10 L. Above 25 L, HfO2 grows by oxidation of the suboxides, whereas the oxide film thickness remains constant. Above 500 L, a saturation region is observed that corresponds to an oxide layer of 12 Å thick with an average composition HfO1.8.
A surface study of the CO hydrogenation reaction on fused iron catalysts
Authors: Loggenberg P. M. , Dry M. E. , Copperthwaite R. G. 
Published: May 2005

AbstractPromoted fused iron catalysts have been investigated after CO hydrogenation using x‐ray photoelectron spectroscopy. Three catalysts containing different levels of potassium were investigated. During synthesis at 600 kPa and 543 K, the K2O/(SiO2 + Al2O3) surface coverage ratios increased with time on‐line. The basicity of the catalysts as defined by the potassium/iron surface atomic ratio also increased. The corresponding hydrocarbon reaction products showed an increase in alkene selectivity and average molecular weight. As the surface coverage of potassium increased from one catalyst to another, so did the binding energy (BE) of the C (1s) signal associated with the adsorbed carbon species.
Surface analytical and photoelectrochemical investigations of conducting polymers
Authors: Kessel R. , Schultze J. W. 
Published: May 2005

AbstractSurface analytical and optoelectrochemical measurements were used to clarify the ionic, spectral and electronic changes during oxidation in 3 N NClO4 of electrochemically formed polycarbezole. The differences in band structure at various potentials could be shown using XPS and UPS measurements. Apart from a Fermi level shift, the transition form insulating behaviour to metallic conduction could be followed. The formation of polarons was derived from in situ reflection spectra and photocurrent measurements. Photoelectrochemical measurements also indicate a semiconducting third form in the potential range 0.4–0.7 V (SHE).
AES and HREELS studies of the Cu/MgO(100) interface
Authors: Conard T. , Vohs J. M. , Thiry P. A. , Caudano R. 
Published: May 2005

AbstractWe have studied the formation of the Cu/MgO interface with Auger electron spectroscopy and high‐resolution electron energy‐loss spectroscopy (HREELS). Copper overlayers ranging in thickness from 1 to 20 Å were formed on an MgO single‐ crystal substrate by evaporation from a Knudsen effusion cell. Direct Auger spectra for the O KLL, Cu LMM and Mg KLL lines were collected. The evolution of the Auger peak intensities shows that the copper initially forms a complete monolayer, followed by island formation (i.e. Stransky–Krastanov growth). Low energy electron diffraction patterns recorded after Cu deposition confirmed the ordering of the first monolayer.A significant decrease in energy of the surface MgO phonon peak was observed by HREELS following deposition of 20 Å of copper. Simultaneously with this shift of the phonon energy, we observed a decrease of the intensity ratio of the phonon‐loss and elastic peaks. These results have been interpreted using the dielectric theory. Theoretical spectra of MgO covered by a layer of Cu2O obtained by using dielectric constants taken from the literature were able to reproduce qualitatively the decreases in energy and intensity of the phonon‐loss peak with increasing copper thickness.
XPS investigation of impurity phase segregation in 25.5 wt.% CeO2−2.5 Y2O3−72 ZrO2 plasma‐sprayed thermal barrier coatings
Authors: Arfelli M. , Ingo G. M. , Mattogno G. 
Published: May 2005

AbstractX‐ray photoelectron spectroscopy (XPS), angular‐dependent XPS and x‐ray‐inducd Auger electron spectroscopy (XAES) have been used to investigate impurity (Si, Na and Al) segregation in 25.5 wt.% CeO2−2.5 Y2O3−72 ZrO2 plasma‐sprayed thermal barrier coatings (TBCs) as a function of high‐temperature air thermal treatment (up to 1460°C). The segregated phase, present in a similar composition both on the as‐thermally treated and fracture surfaces, forms a thin layer of ∼20 nm thick. This phase contains both silicon and sodium at a temperature ranging between 900 and 1350°C and it is also enriched with aluminium at higher temperatures. The XPS and XAES results are used to identify the chemical composition of this surface phase.
High‐resolution monochromated XPS of poly(methyl methacrylate) thin films on a conducting substrate
Authors: Beamson G. , Bunn A. , Briggs D. 
Published: May 2005

AbstractExperiments directed towards obtaining high‐resolution XPS data for spin‐cast thin films of poly(methylmethacrylate) (PMMA) on a silicon substrate are described. Thickness‐dependent charging and the effect of vertical differential charging on spectral resolution are demonstrated, and the conditions required for optimum spectral resolution are established. Evidence is provided for an interaction between the carboxyl group of PMMA and the substrate, and for an interaction between carboxyl groups of the polymer. The latter is manifested as a dependence of the CO and CO C Is chemical shift on polymer tacticity. Four different curve‐fitting schemes (nominally 1:1:3, 1:1:1:2, 1:1:2:1 and 1:1:1:1:1 component area ratios) are applied to the high‐resolution C Is data. The three‐peak scheme does not provide a good fit to the data, but the envelope is adequately described by any one of the three remaining possibilities.
Comparison of accuracy of various AES methods for quantitative analysis of refractory metal silicides
Authors: Zagorenko A. I. , Zaporozchenko V. I. 
Published: May 2005

AbstractThe aim of the present paper is to compare experimentally the existing methods of quantitative Auger analysis based on several approaches: published sensitivity factors, our own sensitivity factors, matrix correction, first principles calculation. Various methods were used to measure the intensity of Auger lines and to calculated the parameters of Auger emission. The results obtained enabled the most accurate algorithm for quantitative analysis of refractory metal silicides to be selected. The measuring error was reduced to <3%, which is much lower than the error usually obtained in quantitative AES.
Crystal orientation effects on the surface morphology produced by ion bombardment of a pure element: Implications for quantitative surface analysis
Authors: Dawson P. T. , Petrone S. A. 
Published: May 2005

AbstractThe effect of crystal orientation and surface morphology on the detected Auger current was investigated using a Polycrystalline Mo sample. The sample was initially polished to a uniform and featureless surface morphology. Two large grains were used in the study, with their crystal orientation determined as ∼(100) for the low‐index grain and ∼(1, 4, 11) for the high‐index grain. Ion bombardment conditions used were typical for surface analysis, i.e. 2KeV Ar+ at glancing incidence. The initial Auger current measured form the cleaned as‐polished surface was found to be essentially constant across both crystals. However, under continued ion bombardment, as the fluence was increased constant across both crystals. However, under continued ion bombardment, as the fluence was increased to ∼5 × 1019 ions cm−2, gross differences of up to 18% were observed in the detected Auger current from the two crystal surfaces. The gross difference is attributed to the extent of surface roughness that evolved, which is in turn mainly dependent on the crystal orientation. It was found that, relative to the polished surface, the high‐index grain developed considerable texture of macroscopic dimensions consisting mainly of ‘hills and valleys’ with a ‘furrowed’ fine structure in the direction of the ion beam, yielding a net decrease in the detected auger current. The low‐index grain became smoother, yielding a net increase in the detected Auger current. This latter effect was much larger than the decrease resulting from the increased roughening of the high‐index grain. The implications for quantitative surface analysis are discussed.