bluuebunny/crossref_metadata_2025 huggingface dataset:
SIMS matrix effects in Alx Ga1 – xAs: Influence of instrumental parameters
Authors: Galuska A. A. , Wallace W. O. , Marquez N. , Uht J.
Published: December 2004

The influence of instrumental parameters on the matrix effects (ion and sputtering yield variations) observed in AlxGa1 – xAs are critically evaluated. Ion and sputtering yield data from three different SIMS instruments (ARL IMMA, Cameca IMS‐3F and Atomika SIMS) are examined. The influence of primary ion (O2 +) energy and incident angle on the extent of surface oxidation was examined using AES. Although relative ion yields varied linearly with the matrix composition in all instances, these ion yield variations differed greatly (a factor of 50) between instruments. These differences were attributed to differences in the surface oxygen concentrations produced by the SIMS instruments. AlAs was shown to be completely oxidized under each of the SIMS ion bombardment conditions. However, the oxygen levels incorporated in GaAs and the other Al poor specimens depended largely on the incident angle and to a lesser extent on the ion energy. Small incidence angles (normal incidence) promoted the most extensive oxidation of the Al‐poor specimens, resulting in the smallest ion yield variations with matrix. As with the relative ion yields, relative sputtering yields varied linearly with the matrix composition in all instances. However, in contrast to relative ion yields, the relative sputtering yields did not change significantly under the different instrumental conditions. It was concluded that incident angle and ion energy had approximately the same influence on the sputtering yields obtained from the reference and the sample matrices. Thus, the relative sputtering yields were insensitive to changes in these ion beam parameters.
Depth resolution improvements using specimen rotation during depth profiling
Authors: Geller Joseph D. , Veisfeld Nina
Published: December 2004

It has been well documented that depth resolution (interface width) degrades with depth when crystalline materials are sputtered by ion beams, whereas amorphous materials are less susceptible to this phenomenon.1 Several techniques have been employed to reduce this interface broadening problem. Amongst them have been reactive ion beam sputtering,2 ion sputtering with two ion beams at opposing angles,3,4 and finally, ion sputtering while the specimen is being mechanically rotated3,5,6. We elaborate upon this last technique, using a more stable sample rotation device, supporting Zalar's results that the depth resolution of a polycrystalline thin film material is nearly independent of depth. Further results indicate that the measured interface widths were independent of ion beam accelerating voltage between 1.0 and 3.0 keV only when sample rotation was applied; and that the loss of depth resolution near the specimen surface and within bulk occurs as a result of mono‐directional ion beam sputtering. We have also demonstrated that surface roughness can actually be reduced by rotation during sputtering, thereby restoring the interface depth resolution.
XPS study of metal/polymer interaction: Evaporated aluminum on polyvinyl alcohol polymer
Authors: Stoyanov P. , Akhter S. , White J. M.
Published: December 2004

The interaction between in situ evaporated aluminum and plyvinyl alcohol (PVA) polymer at 300 K was studied by XPS. The aluminum condenses on the PVA surface by a Volmer–Weber (clustering) mechanism; it takes about a 3.7 monolayer deposition to nucleate clusters sufficiently large to exhibit core binding energies characteristic of bulk metal. Changes in the lineshapes of the C 1s and O 1s peaks and the appearance of a shifted peak in the Al 2p region were interpreted in terms of Al interactions with the surface alcoholic group HCOH, resulting in the formation of an interfacial organometallic complex exhibiting a stoichiometry of 1:1:1.5 for Al, C and O. Polar angle‐resolved XPS measurements and differences in the attenuation factors of the signals from the complex show that the Al is on top and is closer to the oxygen atoms.
Electronic and structural characterization of electrochemically synthesized conducting polyaniline from XPS studies
Authors: Kumar S. N. , Bouyssoux G. , Gaillard F.
Published: December 2004

We report high‐resolution XPS data on three forms of the electrochemically synthesized polyaniline films: the highly conducting emeraldine salt form and the films obtained after KOH treatment and electrochemical reduction in HCI. The deconvoluted N 1s peaks in these films show clear evidence of the existence of the existence of four states of nitrogen, which are attributed to the amine, polaron and localized bipolaron defect configurations. The trends observed after the KOH treatment and electrochemical reduction in HCI in the N 1s spectra, plus the C 1s and O 1s peak shapes, support this assignment scheme.
A new approach in non‐destructive characterization and XY profilometry of coatings
Authors: Cazaux J. , Jbara O. , Thomas X.
Published: December 2004

A scanning electron microscope equipped with an x‐ray detector has been used to characterize the thickness and elemental composition of coating on substrates. The proportionality between the x‐ray signal intensity and the thickness, t, of the coating has been established experimentally and explained by applying a formalism similar to that used in Auger analysis.

The thicknesses under investigation range from that of Auger (∼ 3–4 nm) to a fraction of a micron. The accuracy of thickness determination (±5%) is mainly governed by the statistics when the operating conditions are optimized.

The x‐ray profiles and images obtained by incident electron beam scanning allow a rapid evaluation (with two‐ or three‐dimensional representations) of the lateral thickness and compositional changes of the coatings. At the same time, the use of the ‘scatter diagram’ technique improves their quantitative interpretation.

The lateral resolution (better than 1 μm) and limitation of the technique are discussed. Both academic and practical examples are used to illustrate its application.
Improvement of the AES detection limit for phosphorus in silicon by principal component analysis or spline smoothing
Authors: Procop M. , Weber E.‐H.
Published: December 2004

The detection limit of Auger electron spectroscopy (AES) can be improved by mathematical methods that reduce the influence of noise. We compared principal component analysis (PCA) and spline smoothing and applied them to the analysis of a phosphorus depth profile in silicon. Both methods yield similar results under typical conditions, namely detection limits of ∼0.04 at.% P compared with a limit of 0.09 at.% for the raw data. At a reduce signal‐to‐noise ratio, the PCA failed and the improvement by smoothing remained constant.
The interaction of water and Mn with surfaces of CaCO3: An XPS study
Authors: Baer D. R. , Blanchard D. L. , Engelhard M. H. , Zachara J. M.
Published: December 2004

This paper reports an examination of the chemistry of single‐crystal calcite (CaCO3) using x‐ray photoelectron spectroscopy (XPS). This calcite cleavage surface was examined as freshly opened in vacuum and after several different treatments, including exposure to water vapor, covered with different amounts of evaporated Mn, ion sputtered and immersed in pure water. Clean and ion‐sputtered calcite were not observed to react with water vapor. Ion sputtering caused significant changes to both oxygen and calcium bounding at the surface. However immersion of sputtered calcite in water caused removal of the sputter damage and produced an XPS spectrum nearly indistinguishable from that of the fresh cleavage surface. The shapes and positions of the Mn and O peaks in the spectra of CaCO3 with submonolayer coverages of Mn indicate partial oxiation of the metal as deposited presumably owing to reaction with the calcite surface. Immersion of the Mn‐coated calcite in water caused further changes in the Mn peak, suggesting additional oxidation of the Mn.
The oxidation and oxide overlayer stability of AgMn alloys
Authors: Mencer D. E. , Cocke D. L. , Yoon Cheonho
Published: December 2004

The oxidation of several compositions (5, 9 and 14% Mn) of polycrystalline Ag‐Mn alloys from room temperature to 650 °C in high vacuum and in 5 m Torr O2 has been investigated by x‐ray photoelectron spectroscopy (XPS). The behavior of the oxidation and the nature of the oxide films are controlled by tempearature, oxygen pressure, bulk alloy composition and the stability of the oxide overlayers. At low temperatures and pressures, the oxidation process is controlled by the relative free energies of oxide formation of the alloy components. At high temperatures the oxide of stabilities play a large role in determining the oxidation state of the oxide overlayer. The chemical state and the morphology of the oxide of manganese formed during the alloy oxidation has been examined. The chemical state and the morphology of the oxide overlayers have been studied by XPS, x‐ray diffraction (XRD) and scanning electron microscopy (SEM). The complex oxidation process has been delineated.
A marker technique to identify diffusing elements during initial reactions using ion scattering spectroscopy
Authors: Schmidt Michael T. , Wu Zhen , Osgood Richard M.
Published: December 2004

A variation of classical marker techniques has been combined with low‐energy ion scattering spectroscopy (ISS) to study the diffusion of species during the initial formation of several reachted monolayers, allowing the study of thinner layers than standard marker techniques allow. Results are presented for the reaction of oxygen with GaAs under 248 nm laser illumination and at 400 °C, as well as for the well‐studied case of Ni oxidation at room information that can be obtained with his method. The results show that inward oxygen diffusion can be distinguished from outward metal diffusion as the reaction proceeds. This information is crucial for developing an understanding of reaction mechanisms in thin films.
Surface characterization of ruthenium‐exchanged Y‐zeolite used in ammonia synthesis
Authors: Wellenbüscher J. , Sauerland U. , Mahdi W. , Ertl G. , Schlögl R.
Published: December 2004

NaY zeolite was cation exchanged with Ru and tested in ammonia synthesis at atmospheric pressure. Activities up to ∼10% of the commercial iron catalyst scaled by the active surface area were observed. Characterization of the zeolites with XPS was complemented with reference thermal desorption spectroscopy data on a polycrystalline Ru metal surface. The catalysts showed high thermal stability in in situ reduction–oxidation cycles. The chemical state of the Ru will be discussed. From shift measurements the Ru is metallic in the active state, but line shape arguments point to a cluster‐like particle morphology. The location of the Ru inside or outside the zeolite framework will be discussed.
Thermal and surface characterizations of 25.5 (wt.%) CeO2–2.5 Y2O3–72 ZrO2 fine powder
Authors: Ingo G. M. , Maschio R. Dal , Scoppio L.
Published: December 2004

By means of X‐ray photoelectron spectroscopy (XPS), simultaneous differential thermal analysis (DTA) and thermogravimetric analysis (TGA), changes of valence state and surface chemical composition of a 25.5 (wt.%) CeO2–2.5 Y2O3–72 ZrO2 fine powder have been studied as a function of temperature (up to 1550°C) and atmosphere (flowing 90% N2‐10% H2 and static air). The XPS results lead to the evaluation of the valence state of cerium, zirconium and yttrium, both in the starting powder and in thermal‐treated powders. The analysis of the characteristic satellite structures, binding energies and peak shapes of the Ce 3d spectra show that cerium in the starting powder is confirmed to be Ce(IV) with a small amount of Ce(III), and that after thermal treatment the cerium is either unaffected or partially or fully reduced to Ce(III). The DTA and TGA thermograms confirm this redox behaviour and disclose, for air treatment, the presence of a strong, sharp exothermic peak at ∼410°C, which is interpreted as being due to the oxidation of a small amount of Ce2O3. On the contrary, under reducing conditions in the temperature range 630–730°C, the powder is affected by a remarkable weight loss owing to the Ce(IV) reduction to Ce(III) oxide. The change of valence state of zirconium, due to the reduction of ZrO2 to ZrO2−x under reducing conditions at high temperature, has also been monitored by XPS. Furthermore, on high temperature (≥900°C)‐treated powders, XPS results show the occurrence of segregation phenomena of both bulk dissolved impurities, such as silicon, sodium, iron and aluminium, as well as yttrium stabilizing oxide. The Wagner two‐dimensional chemical state plots for silicon, sodium and aluminium indicate that the chemical nature of the segregated phase can be ascribed to a silicate of sodium and yttrium with the presence of aluminium at higher temperatures. The effect of the above‐mentioned chemical aspects on the final properties of sintered materials is also discussed.
High‐temperature oxidation of iron covered by electroless NiP coating: A GDOS depth profiling study
Authors: Weiss Zdeněk
Published: December 2004

Steel samples coated by electroless nickel were annealed in air. Oxide growth kinetics and iron diffusion through the structure were investigated by glow discharge optical emission spectroscopy (GDOS) depth profiling. Protection against high‐temperature oxidation was found to be given mostly by the austenitic interdiffusion layer formed at the interface between the substrate and the NiP film during annealing of the sample, which acts as a diffusion barrier for diffusion of iron to the surface.
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

On 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

The 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

In 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

A 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

The 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

XPS 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

In 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

The 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

The 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

From 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

The 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

The 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

Generally, 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

The 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

The 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

Methods 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

The 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

Austenitic 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

A 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

Octahedral‐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

Polyaniline (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.
Scattering in electron spectrometers, diagnosis and avoidance. I. Concentric hemispherical analysers
Authors: Seah M. P.
Published: December 2004

The unwanted scattering of electrons in electron spectrometers leads to a loss of sensitivity, distortion of the spectral background and problems in calibrating spectrometer intensity/energy transmission functions. Here we develop three methods to analyse the extent of the contribution and how to reduce it to an insignificant level. The three diagnostic methods involve either the measurement of the region of the M4,5VV Auger electron peaks from Ag in AES, or the reflection of an electron beam from a biased sample, or the 3p1/2 photoelectron peak from Ag irradiated with Mg Kα x‐rays. In this work analyses are made for concentric hemispherical analysers. In Part II, cylindrical mirror analysers are studied. It appears that in our spectrometers, a modified VG scientific Escalab II with either the original analyser or a 210 analyser, the major scattering contributions arise from high‐energy electrons that strike the outer hemisphere giving rise to a spectrum of secondary electrons. These cause the scattered electron contribution to vary approximately as E, where Ep is the pass energy, to increae approximately in proportion to the spectrometer input slit area for AES studies, to fall approximately inversely with an increase in the lens magnification from 1 to 3 and, in the constant ΔE mode, to increase with the analysed electron energy. Thus, for each lens magnification, there exists a range of slits and pass energies for which the scattering may be maintained at <1%. In the constant ΔE mode, pass energies of ≥50 eV are generally safe, whereas in the constant ΔE/E mode, retardation ratios of ≤4 are required.
Controlled chemical oxidation of carbon fibres: An XPS–XAES–SEM study
Authors: Desimoni E. , Salvi A. M. , Casella I. G. , Damiano D.
Published: December 2004

High‐modulus, polyacrylonitrile‐derived carbon fibres were chemically oxidized in concentrated sulphuric acid containing potassium permanganate. The pre‐ and post‐oxidation surface status of the fibres was characterized by x‐ray photoelectron spectroscopy, x‐ray‐excited Auger spectroscopy and scanning electron microscopy. Tests were made to evaluate the effects of temperature, time of treatment and permanganate concentration. The overall results are discussed in terms of flexibility and easiness of the treatment and of reproducibility of the chemical composition of the oxidized fibre surface.
Quantitative analysis with d.c.‐ and r.f.‐glow discharge spectrometry
Authors: Payling Richard , Jones D. G. , Gower S. A.
Published: December 2004

Glow discharge spectrometry (GDS) is a technique for rapid depth profiling and bulk analysis of materials. The latest instruments can be operated in either d.c. or r.f. modes. The d.c. mode provides analysis of conductive materials only, while the r.f. mode allows analysis of both conductive and non‐conductive samples. Until now, no theory for r.f.‐GDS has been available. The recently proposed d.c. theory, which assumes that emission yield depends only on pressure, is extended to r.f.‐GDS and is shown to be valid for the r.f. mode as well. A key to the success of the theory is that, in support of Duckworth and Marcus, the two modes are shown to have similar analytical characteristics, e.g. in comparing the two modes most elements examined had similar sensitivity factors and background equivalent concentrations. This will facilitate calibration of the light elements hydrogen, oxygen and nitrogen for use in the d.c. mode. Recommended procedures for bulk analysis, in either d.c. or r.f. modes, are presented and illustrated for manganese in steel. Both modes provide calibration curves of high linearity. Quantitative depth profiles of three commercial metallic‐coated steel samples are compared in d.c. and r.f. modes and the similarity of the quantitative profiles, given the very different lamp parameters operating between the modes, confirms that the theory works for both d.c. and r.f. The theory is then applied to data from a commercial prepainted metallic‐coated sample to provide the first quantitative GDS depth profile of a non‐conductive material.
Influence of crystalline structure and amorphous materials in the depth resolution of sputter etching
Authors: Henneberg Matthias M.
Published: December 2004

The dependence of depth resolution Δz/z on the sputtering angle θ is investigated for three sputter‐deposited films: Cr (bee), SiNx (amorphous) and FeCoTb (amorphous). The depth resolution for the Cr system exhibits two maxima at θ = 35° and 45°. These are characteristic for bee textured material but different from fee textured material. The amorphous films show a very weak dependence, if any, owing to the absence of crystallites and crystalline texture. These results are in accordance with channeling theory.
GaAs/AlAs superlattice as a proposed new reference material for sputter depth profiling
Authors: Yoshihara K. , Moon D. W. , Fujita D. , Kim K. J. , Kajiwara K.
Published: December 2004

A GaAs/AlAs superlattice growth by metal–organic chemical vapour deposition is being proposed as the single crystalline multilayer reference material for sputter depth profiling. This material was characterized by transmission electron microscopy experiments, which showed that the interface between GaAs and AlAs is atomically flat. The preliminary depth profiling experiments were carried out by AES and SIMS.

The AES experiments were performed using a Perkin‐Elmer SAM 660 scanning Auger microprobe and the SIMS experiments were carried out using a VSW multitechnique XPS/SIMS surface analysis system.

The AES and SIMS sputter depth profiling experiments proved that the depth resolution was found to be almost constant for each interface when an Ar+ beam was used for sputtering. Therefore the sputtering‐induced roughness is very small for this material with Ar+ beam profiling, the depth resolution deteriorated as a function of depth, indicating oxygen ion beam‐induced surface roughening.

For both AES and SIMS, the depth resolution improved for ion beams with lower kinetic energy and more glancing angles of incidence.
Compound requirements for vinyl siding
Authors: Shaidle A.
Published: December 2004

Basic principles of good compounding for weatherable vinyl siding are discussed. Appropriate level of stabilizer is such that 50 percent of initial should remain after the extrusion process. Balanced lubrication is necessary. Judicious choice of pigments and impact modifiers is called for. The cited references give added substance to this review paper.
New developments in profile extrusion expand the applications for plastics in the building industry
Authors: Fow Louis F.
Published: December 2004

The potential market for plastics in the building industry is discussed with particular emphasis on vinyls. Equipment advances for co‐extrusion and complex profiles are described. The use of capstock co‐extrusion is proposed as a route to dark‐color weatherability of PVC siding and building products. The transfer of European technology is suggested.
Weatherability of rigid vinyl siding
Authors: Weaver Leonard W.
Published: December 2004

Vinyl siding is described as a product in the early maturity stage of business development. The competitive position of rigid vinyl siding vis‐a‐vis other products is discussed. Total weathering exposures from point sources not usually thought of are reviewed. Methods of control for weathering caused changes as well as resistance evaluation are covered. The impact on the industry of the voluntary product standard PS55‐72 is mentioned.
Low temperature impact modification of injection molding PVC
Authors: Malpass V. E. , Gaggar S. K.
Published: December 2004

To meet the stringent requirements of PVC compounds intended for use in injection molded cabinets, housings and other electrical applications, impact modifiers are required which permit good melt flow while processing and allow passage of falling ball impact at −20°C. Extensive testing is described as differentiating the low temperature toughness imported by two similar impact modifiers which give the same mold flow in modified PVC.
Application of atactic polypropylene in technology of chemical foaming of PVC pastes
Authors: Šimoník Josef , Drexler J.
Published: December 2004

A preliminary study of the use of by‐product atactic polypropylene as a replacement for plasticizer in chemically blown plastisol is presented. The effect of varying amounts of PP and plasticizer on the elastic property was studied. Atactic PP has been shown to be useful as a plasticizer substitute in plastisols in amounts apt. 10%.
On the particle formation mechanism of poly(vinyl chloride) (PVC) powder produced by suspension polymerization—development of external morphology of particles
Authors: Máriási Béla
Published: December 2004

In the first part of the paper the author critically surveys literature dealing with the main factors determining the external morphology of particles of polyvinyl chloride powders, then offers a new model and theory of particle formation. By means of new experimental and evaluational methods he unambiguously proves the primary role of dynamism of processes occurring in the dispersed stage of the stirred system, and points out that the dynamism of disintegration—coalescence and aggregation—disaggregation processes is one of the most important factors in the development of external morphological characteristics of the particle. These experimental methods also allowed the author to explain the external morphological role of the skin formed at a relatively low conversion value in suspension polymerization.
An investigation of acrylic processing aids for low molecular weight PVC
Authors: Casey William J. , Okano Kenji
Published: December 2004

Acrylic processing aids have long been used in rigid PVC to increase fusion, decrease jetting and blushing down in blow molding, decrease parison draw down in blow molding, improve the rolling bank in calendering, improve thermoforming, and improve cell structure in foam extrusion. It has generally been thought that the specific viscosity (Nsp/c) of process aids were limited to a fairly limited narrow range. Recently, significantly higher molecular weight process aids have been developed and commercialized. Very little work though has been done with low molecular weight process aids as these products were assumed to be ineffective when compared to the commonly used products. This paper will investigate currently available products and some experimental products well above and below the Nsp/c of currently available products. The major area of investigation will be in very low to low molecular weight PVC resins and will deal with the applicability of these products in injection molding.