bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification of polymeric films and membranes to achieve antibacterial properties
Authors: Cen L. , Neoh K. G. , Ying L. , Kang E. T.
Published: August 2004

A surface modification technique was developed to impart antibacterial properties on polymeric films and membranes. Poly(ethylene terephthalate) (PET) films and poly(vinylidene fluoride) (PVDF) membranes were first graft‐copolymerized with 4‐vinylpyridine (4VP) and subsequently quaternized with hexylbromide. Both these substrates can be functionalized with varying amounts of pyridinium groups and these groups possess antibacterial properties as shown by assay using waterborne Escherichia coli. The stability of the antibacterial properties of the N‐hexyl pyridinium groups on the PET film was investigated and the same efficiency in killing the E. coli on contact was observed for the modified film after a 60 day storage in air. Thus, the present surface modification method offers the advantages of simplicity in processing, good control over the surface concentration of pyridinium groups, long‐term stability as well as wide applicability. Copyright © 2004 John Wiley & Sons, Ltd.
Characterization of metal decorated protein templates by scanning electron/scanning force microscopy and microanalysis
Authors: Habicht Wilhelm , Behrens Silke , Wu Jin , Unger Eberhard , Dinjus Eckhard
Published: August 2004

Highly ordered protein assemblies have been used as bio‐organic templates either for the alignment of metallic nanoparticles or for the generation of continuous nanowires. A defined metallization of microtubules (MTs) is potentially interesting for the fabrication of conductive nanowires. Characterization of the in vitro assembled biomolecular templates and the subsequent metal deposition was performed by electron microscopic methods (SEM, TEM) and by scanning force microscopy (SFM). The SEM was equipped additionally with a special device to obtain transmission‐type images (STEM‐in‐SEM operation). Palladium particle deposition and also a continuous silver coverage of the protein templates was demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
XPS and FT‐IR spectroscopy study of albumin adsorption on the surface of a π‐conjugated polymer film
Authors: Iucci G. , Polzonetti G. , Infante G. , Rossi L.
Published: August 2004

The interaction between thin films of polyphenylacetylene (PPA) and bovine serum albumin (BSA) dissolved in phosphate buffer solution (PBS) was studied by x‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared spectroscopy (FT‐IR) performed in reflectance mode. PPA is a semiconducting π‐conjugated polymer consisting of a polyene backbone with phenyl pending groups, that has been used in the preparation of humidity sensors; therefore, we have tried to pre‐test PPA films for possible applications as biosensors.

Thin films of PPA were incubated in buffered albumin solution (BSA/PBS) for increasing exposure times (24–96 hours). BSA adsorption on the PPA film surface takes place as demonstrated by the appearance of the N 1s signal and by the modifications in the C 1s core‐level signal in the XPS spectra of the samples treated with albumin solution; time‐dependent adsorption is also observed. Phosphate salts are co‐adsorbed on the PPA surface upon treatment with BSA/PBS solution. Albumin adsorption on the PPA surface was confirmed by FT‐IR measurements. Copyright © 2004 John Wiley & Sons, Ltd.
Influence of polymer surface hydrophilicity on albumin adsorption
Authors: Henry M. , Bertrand P.
Published: August 2004

X‐ray photoelectron spectroscopy (XPS) and time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) were used to characterize human serum albumin (HSA) adsorption on polycarbonate membranes: a native PC membrane (PC) and a hydrophilic treated one (PCOx/PVP). Principal component analysis was used to reveal the difference in the amount of HSA adsorbed on the two substrates. The treated membrane was found to have a lower affinity for albumin than the native one. Copyright © 2004 John Wiley & Sons, Ltd.
Ion‐beam treatment of PEO; towards a physically stabilized anti‐fouling film
Authors: Manso‐Silván M. , Valsesia A. , Gilliland D. , Ceccone G. , Rossi F.
Published: August 2004

Polyethylene oxide (PEO), widely used in the biomedical field because of its anti‐fouling properties, has been deposited by spin coating and stabilized by modifying its molecular structure through ion‐beam treatments (IBT). The polymer films were exposed to different gas mixtures in order to observe the changes related to physical (Ar), soft chemical (Ar/N2) and strong chemical (Ar/O2) modification. The surfaces of the polymers were characterized after different modification times. The film composition analysis has been performed by correlating Fourier transform‐infrared spectra and x‐ray photoemission spectra. The characterization has been completed with a morphological evaluation by atomic force microscopy. Contact angle measurements were used to show the efficiency of the stabilizing treatment. By using physical masking during IBT, culturing bovine serum albumin and analysing the surface by time‐of‐flight secondary ion mass spectrometry, it has been shown that ion beam treatments are an effective way to produce PEO films that retain their anti‐fouling properties. Copyright © 2004 John Wiley & Sons, Ltd.
Effect of the support on the surface composition of vanadium phosphate catalysts in the oxidative dehydrogenation of ethane
Authors: Casaletto M. P. , Lisi L. , Mattogno G. , Patrono P. , Ruoppolo G.
Published: August 2004

Vanadyl phosphate catalysts supported on different oxides (γ‐Al2O3, TiO2, SiO2) have been investigated by x‐ray photoelectron spectroscopy (XPS). The surface chemical composition has been studied as a function of the thermal treatment under oxidizing (calcination) or reaction conditions in the oxidative dehydrogenation of ethane. Dispersion of vanadyl phosphates on γ‐Al2O3 and TiO2 results in the formation of vanadium species in different oxidation states, i.e. V5+ phosphate, V5+ and V4+ oxide species, whose relative fraction depends both on the support and on the reaction temperature. A progressive reduction of vanadium species occurs in the samples as an effect of the temperature. Vanadyl phosphates exhibit a stronger interaction with the titania support, which undergoes surface modifications after impregnation, thermal treatments and catalysis runs. A noticeable interaction of the alumina support and a poor dispersion of the active phase on silica are also revealed by XPS. Copyright © 2004 John Wiley & Sons, Ltd.
The effect of platinum on the reducibility of Rh oxides on CeZr modified alumina supported automotive catalysts
Authors: Polvinen R. , Vippola M. , Valden M. , Lepistö T. , Suopanki A. , Härkönen M.
Published: August 2004

The reducibility of Rh oxide on Rh‐only and PtRh catalysts was investigated. The catalyst washcoats were composed of alumina modified by La and CeZr mixed oxide. The catalyst ageing was performed in air at 1000°C for 3 h. In order to study the synergistic effect of Pt and Rh on the reducibility of Rh oxide, the propensity of the noble metal oxides to reduction was investigated by exposing the fresh and aged catalysts to 400 mbar of H2 at 300°C. XPS was used to observe the changes in chemical state of the noble metals and TEM and XRD were employed to determine the catalyst composition and morphology. Differences were revealed in the behaviour of Rh‐only and PtRh catalysts in H2‐reduction. Rhodium supported on alumina‐containing washcoats without Pt was found to react with the support at elevated temperatures to form a reduction‐resistive oxide phase. On the PtRh bimetallic catalyst Rh was found to be partly reducible after air ageing and the Rh 3d transition emerged with an unusually low binding energy after H2‐reduction. PtRh alloy particles were also formed in air ageing. Copyright © 2004 John Wiley & Sons, Ltd.
Surface state of sulfated zirconia: the role of the sol–gel reaction parameters
Authors: Bianchi Claudia L. , Ardizzone Silvia , Cappelletti Giuseppe
Published: August 2004

Sulfated zirconia powders have been prepared by following a single‐step sol–gel preparative route using zirconium propoxide as the starting compound. Sulfuric acid was employed both as the sulfating agent and as the catalyst of the polycondensation reaction in the gel formation. Three different series of precursors were obtained by varying the water/alkoxide ratio in the reacting sol–gel mixture. The solvent was removed from the gel by freeze‐drying (cryogels). All the samples were calcined at three temperatures (840, 890 and 940 K) for the same time length (5 h). XPS analyses of the samples were performed by elaboration of the S 2p, O 1s, Zr 3d and C 1s spectral regions. The liquid‐medium catalytic activity of the calcined samples was tested in the esterification reaction of benzoic acid with methanol. The role played by the conditions of the sol–gel reaction in affecting the surface state and the catalytic properties of the powders is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation and characterization of CeMnO composites with applications in catalytic wet oxidation processes
Authors: Blanco G. , Cauqui M. A. , Delgado J. J. , Galtayries A. , Pérez‐Omil J. A. , Rodríguez‐Izquierdo J. M.
Published: August 2004

A series of CeMn composites with different compositions was prepared by co‐precipitation. All samples were characterized by x‐ray diffraction (XRD), x‐ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). According to their size and chemical composition, two different kinds of particles were observed: (a) small crystallites of CeMn solid solution (<7 nm), and (b) large particles of manganese oxides with different reduction degrees (>50 nm). These results were used to explain differences between the surface and bulk compositions of the samples as well as the specific surface area. Furthermore, from XPS studies, the presence of various Mn species with different oxidation states could be stated. This fact might clarify the exceptional catalytic behaviour of the samples for the catalytic wet oxidation of toxic organic compounds. Copyright © 2004 John Wiley & Sons, Ltd.
A decomposition procedure for the determination of copper oxidation states in Cu‐zeolites by XPS
Authors: Meda L. , Cerofolini G. F.
Published: August 2004

A procedure to determine the chemical state of copper in differently prepared catalysts is proposed. It is based on a peak decomposition of the main Cu 2p3/2 signal only, which involves both Cu(II) and Cu(I) contributions. The presence of the closest shake‐up satellite is related to the Cu(II) contribution only, in fact a linear dependence of the satellite area versus the Cu(II) area has been found. This method has been applied to characterize variously prepared catalysts and to quantify the different copper states at the surface. A molecular picture is formulated to describe a possible mechanism for copper reduction occurring during the catalyst preparation route at the zeolite surface. Copyright © 2004 John Wiley & Sons, Ltd.
Composition, structure and mechanical property analysis of DC sputtered CNi and CNxNi nano‐composite layers
Authors: Ujvári T. , Tóth A. , Kovács Gy. J. , Sáfrán G. , Geszti O. , Radnóczi G. , Bertóti I.
Published: August 2004

Carbon–nickel (CNi) and carbon‐nitride–nickel (CNxNi) films were deposited onto native SiO2 covered Si substrates by DC magnetron sputtering from a graphite–nickel composite target using Ar or N2 for sputtering at about 2.6 Pa. The substrate temperature varied between 25 and 800°C. The structure, composition and mechanical properties of CNi and CNxNi thin layers (200–300 nm) have been investigated by high‐resolution transmission electron microscopy (HRTEM), XPS, nano‐indentation and nano‐scratch techniques. The layers were predominantly crystalline irrespective of their deposition conditions. At low deposition temperature, up to 200°C, the columnar crystallites were identified as hexagonal Ni3C, separated by narrow ‘walls’ of amorphous carbon. At substrate temperatures above 400°C, however, a graphitic multilayer arrangement of the carbon matrix was developed around the nano‐crystalline cubic nickel–nickel carbide islands. The mechanical properties of the films varied also significantly with the deposition temperature. The highest nano‐hardness of about 14 GPa was measured for the film grown at 200°C, while lower values (2–4 GPa) were obtained for high‐temperature films. High hardness values were related to the presence of Ni3C. The lowest friction coefficients were obtained for films containing high amounts of multi‐layered graphite‐like carbon developed at intermediate deposition temperatures. Copyright © 2004 John Wiley & Sons, Ltd.
Organic–inorganic hybrid nanoparticles: adsorption characteristics of polyester resins
Authors: Jesson D. A. , Abel M.‐L. , Arkhireeva A. , Hay J. N. , Smith P. A. , Watts J. F.
Published: August 2004

The adsorption of polyester onto organically modified silicas (ormosils) and commercial fumed silica has been compared using ToF‐SIMS. The thermodynamics of each system was examined by constructing adsorption isotherm plots which indicated that the adsorption of polyester onto one of the modified silicas used may be a two‐stage process. Adsorption onto the fumed silica is in accord with the Langmuir model. Copyright © 2004 John Wiley & Sons, Ltd.
Corrosion performance of a two‐step pre‐treatment for galvanized steel based on lanthanum nitrate and silanes
Authors: Montemor M. F. , Ferreira M. G. S.
Published: August 2004

The present work investigates a two‐step pre‐treatment for coil‐coated galvanized steel based on the use of La(NO3)3 and silanes. The pre‐treated surfaces were characterized by Auger spectroscopy and XPS. The analytical results give the chemical composition of the films. The work discusses the role of the functional group (sulfur) present in one of the silanes on the formation of the surface film. Corrosion resistance was assessed by electrochemical impedance spectroscopy and the results show that the pre‐treatment improves the corrosion resistance of the uncoated and coated substrates. Copyright © 2004 John Wiley & Sons, Ltd.
XPS and AES surface characterization of WC–Co after electro‐discharge machining
Authors: Stössel‐Sittig C. , Schnyder B. , Kötz R.
Published: August 2004

The surface of tungsten carbide with Co‐binder (WC–Co) after wire electro‐discharge machining (W‐EDM) with and without induced discolouration was investigated by XPS, AES and SEM. The measurements show that the eroded surface is at least partly covered by a layer containing Zn and Cu oxides, and also small amounts of W and Co. The Zn and Cu originate from the wire (brass wire covered with Zn) used during the W‐EDM and/or from the water, which contains Zn, Cu, W and Co from W‐EDM processes performed earlier on the same machine. The W and Co stem from the water or from the base material of the work piece. On the samples with induced discolouration a dark pattern is visible at the surface. Measurements on these samples show an increased amount of Co within the dark pattern. Copyright © 2004 John Wiley & Sons, Ltd.
Corrosion behaviour of gold surfaces protected with bonded perfluoro polyethers
Authors: Alamarguy D. , Bertoglio M. , Lécaudé N. , Noël S. , Ruaut L. , Tristani L.
Published: August 2004

Perfluoro polyethers (PFPE) are known to offer some protection against the corrosion occurring on electroplated gold surfaces used in electrical contact applications. In this field, reliability requirements and severity of the environment of use are permanently increasing. We describe here the results of corrosion tests performed on electroplated gold coupons protected with layers of various PFPE. XPS measurements show that functionalized PFPE can be grafted to the surface. Attempts to bond the PFPE layer to the surface were also performed by exposure to UV light. Lubricant layers are shown to have better properties of protection against corrosion when they are bonded to the surface. Correlation with the mechanical and electrical performances required from such layers is also discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Corrosion behaviour of coated cellular material
Authors: Oriňáková Renáta , Šupicová Magdaléna , Arlinghaus Heinrich F. , Kupková Miriam , Vering Guido , Oriňák Andrej
Published: August 2004

Cellular solids are developed, improved and investigated in connection with the search for new lightweight structural materials. Interest in the applications of lightweight metal foams and novel cellular materials is rapidly increasing. They can be used as components in heat exchangers, as weight‐saving constructive elements, deformable energy absorbers, catalyst surfaces, filters, etc.

Metal foams (or cellular solids) can be produced by a variety of methods. The regular‐structured cellular material might be accessible by powder metallurgical methods, using hollow powder. The metal coatings can be applied to improve the mechanical properties, surface morphology, and wear and corrosion resistance of basic materials.

In this contribution the corrosion behaviour of copper + nickel coatings on the iron hollow particles has been studied. Electrodeposition of one‐component Ni and then Cu coatings and binary NiCu coatings were realized in a fluidized bed. Also the deposition of copper by cementation was investigated. The main attention was focused on the combination of electroless deposition of Cu and electrolytic deposition of Ni. The corrosion resistance of the coatings was investigated by using SEM and ToF‐SIMS methods. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative analysis of AuPd alloys from the shape of XPS spectra by the fuzzy rule
Authors: Lesiak B. , Jozwik A.
Published: August 2004

The quantitative analysis of solid surfaces by XPS requires the determination of spectra intensities, related to atomic concentrations, recorded for constituents of investigated systems. The most reliable method of quantitative analysis is the multiline approach. The estimation of intensities requires satellites and background subtraction. The quantitative and qualitative information from intensity or binding energy shifts may be disturbed by overlapping spectra. To avoid these problems analyses based on the spectra lineshape were developed. These analyses use methods of statistical pattern recognition possible after selecting the set of standard spectra (reference set) consisting of a set of spectra recorded for different chemical states or atomic compositions (classes). The classification quality is characterized by the misclassification rate (error rate) estimated from the reference set. Fuzzy identification referring to the fuzzy membership results in quantitative estimation of chemical states and/or atomic compositions of constituents. The application of such algorithms to different lineshapes recorded at various kinetic energies results in quantification at various information depths. In the present work the fuzzy rule for analysing lineshapes of valence band, Au 4f, Pd 3d and Pd MNN Auger spectra recorded for AuPd alloys, Au and Pd, was found to be efficient and applicable for quantitative analysis of complex systems. Copyright © 2004 John Wiley & Sons, Ltd.
Experimental and theoretical study of CVV Auger peaks of selected aluminium and carbon compounds
Authors: Timmermans B. , Hubin A. , Vaeck N. , Reniers F.
Published: August 2004

The Auger valence peak of Al2O3, Al and carbon compounds (graphite, fullerene, carbides) has been studied experimentally and theoretically. It is demonstrated, from a comparison of the experimental spectrum with the self‐convolution of the valence band, that the Al CVV transition in Al2O3 is an intra‐atomic transition. The behaviour of the C KVV Auger peak is shown to be intermediate between atomic and band‐like transitions. The different experimental carbide peaks could be reconstructed by a self‐convolution of the valence band and the introduction of a hole–hole repulsion term extracted from the Cini–Sawatzki equation. A non‐expected behaviour of the satellite peak at 280 eV for tungsten and chromium carbide is shown and interpreted, with a comparison with the Ramaker approach. Copyright © 2004 John Wiley & Sons, Ltd.
Sputtering rate measurements of some transition metal silicides and comparison with those of the elements
Authors: Yoshitake Michiko , Yamauchi Yasuhiro , Bose Chandra
Published: August 2004

Sputtering rates of nickel, cobalt, titanium, and tungsten silicides for Ar+ ions of 0.5–4 keV energy at a normal incidence were measured by a conventional method. Sputtering yields were calculated by approximating the atomic density of specimens from the bulk crystal structures. The sputtering yields were compared with those of pure elements in the silicides. It was found that a linear combination of the sputtering yield of each component agreed with the sputtering yields of the silicides except for tungsten silicide, in spite of the existence of preferential sputtering. Copyright © 2004 John Wiley & Sons, Ltd.
Calculation of overlayer thickness on curved surfaces based on XPS intensities
Authors: Mohai M. , Bertóti I.
Published: August 2004

Accurate determination of overlayer thickness on samples with curved surfaces is of growing importance, especially in connection with nanometric materials systems. In this work two simple geometries are treated; closely packed spheres, well representing powder samples, and close‐packed cylinders, modelling fibrous samples. In the case of the powder samples (the arrangement is similar to the structure of the closest packed spheres) in addition to the intensity originating from curved layers of the top row of the spheres, the contribution of the partially visible spheres of the second and third rows below the top row are also considered, enhancing the accuracy of the calculations. As is shown, the method of calculation for spheres and cylinders is similar but the values of the geometry correction factors are different. The applicability of the derived geometry correction factors, based on pure geometrical considerations, is supported with experimental data obtained in two material systems: the thickness of oxide and carbonaceous contaminant layers on Si3N4 powder and Al foil were determined.

These types of calculations were conveniently performed by the XPS MultiQuant program providing not only the geometry correction factors but also other parameters, such as cross‐sections, asymmetry parameters, etc. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative analysis of the x‐ray photoelectron spectrum of zirconium
Authors: Lyapin A. , Graat P. C. J.
Published: August 2004

A procedure for the evaluation of XPS spectra is presented that allows the determination of intrinsic and extrinsic contributions to the spectra. It is based on the convolution of physically realistic functions for the x‐ray energy distribution, the core‐level main peak, the cross‐sections for intrinsic and extrinsic excitations and instrumental broadening. Surface effects have been accounted for by describing the material as a bulk substrate covered with a surface layer of the same material but with different excitation properties. The procedure has been applied to angle‐resolved Zr 3d spectra of pure zirconium. The results show that 28% of the total intrinsic intensity of the Zr 3d spectrum is not contained in the main peak. Copyright © 2004 John Wiley & Sons, Ltd.
Elastic electron backscattering from Ti: grain size effect
Authors: Lesiak B. , Zemek J. , Jiricek P. , Čerňanský M.
Published: August 2004

Measurements of elastic electron backscattering probabilities may provide the electron inelastic mean free paths (IMFP). This technique is known as elastic peak electron spectroscopy (EPES). The IMFPs in Ti can be determined from optical data by Tanuma et al., Gries or the TPP‐2M predictive formulae. Studies on Si and Ni show a weak influence of surface roughness, but a stronger influence of atomic composition, density, texture, average grain size and surface excitations on the IMFPs. In the present work, the elastic electron backscattering probability and IMFPs are determined for Ti exposed to sputtering and annealing. The atomic composition of Ti is determined by XPS and texture and grain size is determined by x‐ray diffraction (XRD). Ti samples exhibit no texture and grain size from 1 µm to 100 µm. For annealed samples the titanium hydride phase can be observed from the binding energy shift of Ti 2p XPS spectra. Scatter in the resulting IMFPs due to density and composition change (O and C contamination, and H from vacuum background) is negligible in comparison to scatter due to the grain size and standard used (Al and Cu). The IMFPs in Ti of grain size 1–10 µm are smaller than IMFPs in Ti of grain size 100 µm. These differences are explained by effects not accounted for in the calculations, i.e. the inelastic losses on the grain boundaries which are more pronounced in Ti of small grain size, and surface excitations which differ for Ti, Al and Cu. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative REELS of amorphous carbon and carbon nitride films
Authors: Prieto P. , Quirós C. , Elizalde E. , Sanz J. M.
Published: August 2004

The dielectric properties of amorphous carbon (a‐C) and carbon nitride in the 3 to 80 eV energy range were determined by quantitative analysis of reflection electron energy‐loss spectroscopy (REELS) spectra of these films. The energy loss function (ELF) of each material has been obtained by a trial‐and‐error procedure, when a good quantitative agreement between the simulated and experimental electron inelastic cross‐sections at three different primary energies (i.e. 0.5, 1 and 1.5 keV) is achieved. Kramers–Kronig transformation is then used to obtain the dielectric function. The loss functions of a‐C and CNx are characterized by two main features which result from collective excitations of the π and the π + σ electrons, respectively. The incorporation of nitrogen in the amorphous carbon matrix is discussed in terms of changes in the dielectric function. Copyright © 2004 John Wiley & Sons, Ltd.
QUEELS software package for calculation of surface effects in electron spectra
Authors: Tougaard S. , Yubero F.
Published: August 2004

Surface analysis based on the interpretation of electron spectroscopy such as x‐ray photoelectron spectroscopy, Auger electron spectroscopy, or reflection electron energy loss spectroscopy are influenced by the inelastic scattering processes that take place when an electron moves in the region near a solid surface. The actual energy losses depend on the particular experimental situation. Thus, an electron is attracted by its image charge when it is moving in the vacuum. It will therefore lose energy even after it has left the surface and, similarly, an electron that moves in the vacuum towards the solid surface gains energy. Likewise, the scattering properties for an electron moving close to the surface are different from those of an electron moving in the bulk of the solid. In photoemission and Auger experiments the effect of the static hole will also affect the scattering probabilities of the electron in the first few ångströms as it moves away from the point of excitation. These effects will also cause the ‘effective’ inelastic mean free path to depend on the position of the electron with respect to the surface and with respect to the point of excitation. In the past years, we have developed models to describe these effects within a dielectric response theory for different cases of electrons moving near surfaces in general geometries with or without a static core hole. The formulas are quite involved with many infinite integrals and this is a major barrier for people to apply them in practice. With the purpose of making the calculations easier to perform, we have developed software (QUEELS: QUantitative analysis of Electron Energy Losses at Surfaces) that will do this in a user‐friendly way. It is hoped that with this tool at hand, we will be able to more effectively and quickly get a more complete understanding of the importance of these different effects for quantitative analysis of surface electron energy spectra. Copyright © 2004 John Wiley & Sons, Ltd.
XPS MultiQuant: multimodel XPS quantification software
Authors: Mohai M.
Published: August 2004

A program for quantitative evaluation of x‐ray photoelectron spectra has been developed to serve as a practical tool for surface chemists. The program uses the ‘classic’ approach of quantification and requires as input the integrated intensities of the measured XPS lines. The usual correction methods and factors can be applied and controlled independently. All necessary basic data for calculations are integrated into the main library of the program. Besides the usual ‘infinitely thick homogeneous sample’ geometry model, the program is able to calculate models for layered structures, both on flat and curved surfaces. Calculation for several samples or experimental data sets can be done together. Results can be presented in several forms, such as atomic %, atomic ratio, oxide molar ratio, etc., and can be stored, printed and charted. Data can be labelled and annotated. XPS MultiQuant is equipped with a user‐friendly interface, full text help system and a ‘wizard’ for easy set‐up of calculations. Copyright © 2004 John Wiley & Sons, Ltd.
Thin film analysis in microprocessor manufacturing using Auger electron spectroscopy
Authors: Dittmar Kornelia
Published: August 2004

In the semiconductor industry, Auger electron spectroscopy is widely used for advanced process control and physical failure analysis. Quantified Auger depth profiles are typically based on the peak‐to‐peak intensities of the derivative Auger spectra and do not fully use the spectral information of the Auger peak. More sophisticated data processing procedures based on linear least square (LLS) fits are capable of separating superimposed Auger peaks thus providing access to any chemical state information.

One example of an Auger analysis using LLS is the investigation of the interface reaction between copper interconnect and its silicon nitride based cap layer. The effect of the local environment on the silicon LVV Auger peak enables one to identify the chemical bonding of the modified copper. Another study of lead–tin alloy bump surfaces using chemical state analysis provides information about inhomogeneities of the tin oxidation and segregation. Copyright © 2004 John Wiley & Sons, Ltd.
Depth profiling of thin films of binary metal oxides
Authors: Kaciulis S. , Pandolfi L. , White R.
Published: August 2004

Our previous results on the XPS depth profiling of binary metal oxides are compared with the new experimental data obtained for the films of SnW, MoTi and MoSn oxides. The samples have been prepared by sol–gel and magnetron sputtering techniques. XPS depth profiling of the samples has been carried out by using cyclic Ar+ sputtering at the energies of 0.5–2.0 keV. In order to compare the chemical states of constituent elements at different sampling depths, angle‐resolved XPS depth profiling has been performed on selected samples.

Starting from the stoichiometric oxides on the surface and going deeper into the volume of the films, the depth profiling revealed there the presence of reduced Mo and W ions. The amount of reduced species and their distribution in depth was found to be independent of the sputtering energy and photoelectron collection angle. These metal ions in lower oxidation states were attributed to the sample preparation processes rather than to the detrimental effect of ion sputtering, dominating at higher ion energies. Copyright © 2004 John Wiley & Sons, Ltd.
Factor analysis of AES sputter depth profiles of B, C and N sequentially implanted in silicon
Authors: Morant C. , Prieto P. , Hernández M. J. , Cervera M. , Elizalde E. , Sanz J. M.
Published: August 2004

In this work, a crystalline silicon wafer was sequentially implanted with N+, C+ and $\hbox{BF}_{2}^{+}$ ions of 25, 21 and 77 keV and doses up to 5 × 1017, 1 × 1018 and 5 × 1017 cm−2, respectively. The energies and doses of the respective ions were chosen according to standard simulations to obtain an implanted layer with the appropriate BC2N composition. After that, the sample was annealed at 1200°C for 3 h.

The sample has been characterized by Auger electron spectroscopy (AES) depth profiling in order to get a quantitative analysis of the components in the sample. Factor analysis has been used to deconvolute the different chemical states of Si, B, C and N, and to identify different compounds. The analysis of the as‐implanted sample indicates the formation of a quaternary compound with an estimated average composition of SiB0.3C0.6N0.1 in a broad region close to the surface, as well as a ternary compound with an estimated average composition of SiB0.1N0.05 at the interface with the silicon substrate. The major effect induced by the thermal treatment is observed at the interface which shows an out‐diffusion of boron from the interface. Copyright © 2004 John Wiley & Sons, Ltd.
Surface characterization of tungsten and tungsten carbide–cobalt probe materials for a fine‐pitch four‐point probe by variable excitation XPS using synchrotron radiation
Authors: Matsubayashi N. , Singh B. P. , Imamura M. , Tanaka T. , Sato Y. , Ogiwara T. , Suzuki M. , Kiyota S.
Published: August 2004

In the course of the development of a new fine‐pitch four‐point probe, surface oxide layers of the probe material were characterized by a non‐destructive depth profiling analysis with a variable excitation XPS using synchrotron radiation. The high surface sensitivity of this technique has allowed us to measure the ultra‐thin thickness of the oxide layer on the probe material without damage. The XPS of W 4f of the tungsten metal was measured in the excitation x‐ray energy range 100–1200 eV at the Photon Factory (BL‐13C), Tsukuba, Japan and analysed by the simulation of attenuation in the layer models using the values of inelastic mean free path (IMFP) and effective attenuation length (EAL) calculated by the National Institute of Standards and Technology (NIST) database programs 71 and 82, respectively. The values of practical EAL at 1 nm depth were smaller than the IMFP by 20–40% and resulted in a smaller thickness of the surface oxide layer than for that of IMFP by about 20%. The result showed that the thickness of the surface oxide layer of the tungsten metal was 1.0 nm ‘as received’ and 0.5 nm after polish. The XPS of W 4f of the superfine grain (grain size < 0.5 µm) tungsten carbide–cobalt wires with 0.45 mm diameter, which is a probe size of conventional four‐point probes, were measured and the results indicated that the thickness of the surface oxide layer of the tungsten carbide–cobalt was 0.4 nm ‘as received’, and the thickness of the oxide layer was increased to 0.5 nm after polish. The XPS of W 4f of the tungsten carbide–cobalt wire with 0.05 mm diameter of an actual probe for a new fine‐pitch four‐point probe system was also measured and the results indicated that the thickness of the surface oxide layer was 0.6 nm. The XPS of W 4f also indicated the existence of an intermediate thin layer of WO2 between W and WO3. Copyright © 2004 John Wiley & Sons, Ltd.
Depth‐resolved analysis of traffic soot sampled in the vicinity of a German motorway
Authors: Goschnick J. , Natzeck C. , Sommer M.
Published: August 2004

Particulate air pollution is caused to a high extent by soot particles arising from traffic. The formation of soot particles and their interaction with the atmosphere usually results in an inhomogeneous depth distribution of its chemical inventory. Because the potential reactivity of the compounds strongly depends on their distance from the surface, the chemical composition at or near the surface is important. Therefore, airborne particles were sampled for depth‐resolved analysis near a busy German motorway. The particles' sizes were classified with a multi‐stage impactor and deposited on indium foil for analysis with plasma‐based secondary neutral mass spectrometry (Plasma‐SNMS), dynamic secondary ion mass spectrometry (SIMS) as well as XPS. At a distance of 2 m from the motorway, the fine particles smaller than 100 nm mainly consisted of carbon and organic hydrogen similar to virgin diesel soot particles produced by a test diesel engine. With increasing particle size, nitrogen, sulfur and oxygen occurred additionally in substantial amounts with a sulfur–oxygen ratio of 1:4. These elements were found in the surface region not deeper than 30 nm predominantly as ammonium sulfate. A minor fraction of the nitrogen was found to be part of nitro‐organic compounds in the surface. Further away from the motorway no virgin soot particles were found. All soot particles (except for minor soil dust contributions) were found covered by the same surface layer as the motorway‐near particles. Copyright © 2004 John Wiley & Sons, Ltd.
Monitoring the environmental degradation of paint dosimeters used to assess risk for fine art paintings on display by XPS
Authors: West R. H. , Odlyha M. , Pratt K. , Roberts A. , Hutton S.
Published: August 2004

Degradation mechanisms due to the effect of environmental pollutants on ingredients used in cultural objects such as fine art paint media have been investigated by surface analysis and other methods. Painters have used proteinaceous materials such as egg tempera and resinous additives, for example triterpenoid mastic, for many centuries. These paint components degrade by different mechanisms under the influence of atmospheric pollutants such as nitrogen dioxide. In this study, thin layers of egg tempera and mastic resin layers on quartz crystal microbalances (QCM) have been exposed to nitrogen dioxide at up to 100 ppm for 6 h. Surface characterization before and after exposure has been undertaken by monochromatized Al Kα XPS.

Before exposure, egg tempera possesses a surface rich in proteins and phosphatidyl dicholine which forms part of its lipid structure. Unexposed mastic resin coating is chemically less complex than the egg coating. Exposure of egg tempera to nitrogen dioxide causes a reduction in the surface concentration of phosphatidyl dicholine and an increase in fatty acid components at the surface. Exposure of mastic resin to nitrogen dioxide increases carbonyl/hydroxyl surface concentrations. Shifts in the QCM resonance frequencies are correlated with the hydrocarbon content of the coating for a fixed exposure to nitrogen dioxide. Copyright © 2004 John Wiley & Sons, Ltd.
Microchemical investigation of archaeological copper‐based artefacts used for currency in ancient Italy before the coinage
Authors: Ingo G. M. , Angelini E. , De Caro T. , Bultrini G. , Mezzi A.
Published: August 2004

By means of the combined use of XPS and scanning electron microscopy + energy dispersive spectrometry (SEM + EDS), the microchemical structure of long‐term corrosion products grown on Aes Rude, i.e. archaeological unworked lumps of Cu‐based materials, has been carried out. In ancient Italy, these materials have been used as currency, as a medium of exchange and as a form of saving, from the sixth to the third centuries BC before the use of the struck metallic coins. The results of the microchemical investigation disclose their apparently unusable nature for any functional applications or possible use, being constituted of highly ferruginous leaded copper, and demonstrate that Aes Rude were a primitive form of currency as suggested by archaeologists. Furthermore, XPS and SEM + EDS results give evidence on the corroded external region of the presence of Cu (II) hydrates mixed with hydrated iron oxide and aluminium–silicon phases coming from the soil that have been incorporated into the patina. This information is useful to identify the material nature of these archaeological artefacts and to select tailored conservation strategies finalized to ensure long life to these relevant ancient materials. Copyright © 2004 John Wiley & Sons, Ltd.
Combined use of XPS and SEM + EDS for the study of surface microchemical structure of archaeological bronze Roman mirrors
Authors: Ingo G. M. , Angelini E. , De Caro T. , Bultrini G. , Mezzi A.
Published: August 2004

By means of the combined use of XPS and scanning electron microscopy + energy dispersive spectrometry (SEM + EDS) the study of the surface microchemical structure of two archaeological Roman mirrors is carried out in order to obtain useful information to identify the ancient production technology, the degradation state and, further, for understanding the origin of their high chemical stability and appearance. Indeed, one of the selected archaeological bronze mirrors is characterized by a reflecting surface and the other one by a black and uncorroded surface. The results show that via XPS and SEM + EDS, it is possible to obtain detailed elemental composition depth profiles and microstructural information for the outermost layers of these ancient bronze works of art. The results provide good insight into the nature of the external layers showing the presence of different copper–tin phases and lead selective corrosion and depletion phenomena leading to the formation of complex microchemical structures and, further, show the presence of different chemical states of tin as a function of the mirror appearance. Finally, the results indicate that the combined use of XPS and SEM + EDS has significant potential in tailoring the restoration and conservation methodologies of these high‐tin bronze archaeological artefacts. Copyright © 2004 John Wiley & Sons, Ltd.
XPS study of the atmospheric corrosion of copper alloys of archaeological interest
Authors: Hayez V. , Franquet A. , Hubin A. , Terryn H.
Published: August 2004

XPS analysis of different forms of copper sulfate, including antlerite, brochantite, posnjakite, chalcanthite and anhydrous copper sulfate, as well as pure copper and its oxides cuprite and tenorite, was carried out. These products most often occur when dealing with atmospheric corrosion of copper and bronze in sulfur‐bearing environments. These compounds were minerals, commercial products, or grown on pure copper by artificial weathering. Spectral features such as peak energy and line shape for Cu 2p, Cu LMM, O 1s and S 2p bands were examined. Comparison of the measurements obtained proves the efficiency of XPS in differentiating the various compounds. Copyright © 2004 John Wiley & Sons, Ltd.
Low‐energy and low‐dose electron irradiation of potassium–lime–silicate glass investigated by XPS. Part II. Chemical bonding
Authors: Zemek J. , Gedeon O.
Published: August 2004

XPS has been used to study changes in chemical bonding occurring in a surface region of potassium–lime–silicate glass. The surface was prepared by fracturing in ultrahigh vacuum and step‐by‐step irradiated with low‐energy and low‐dose electron beam. The modified near‐surface region thickness is in this case comparable with the mean sampling depth of XPS. Therefore, possible changes due to electron irradiation could be recorded with high sensitivity. The irradiation resulted in potassium accumulation at the glass surface. As a consequence, changes in surface charging, binding energy shift, peak width (FWHM), and peak area ratios of non‐bridging oxygen (NBO) and bridging oxygen (BO) contributions to the O 1s lines with electron dose were observed. Copyright © 2004 John Wiley & Sons, Ltd.
Use of Auger imaging for three‐dimensional visualization of interface morphology at isoconcentration
Authors: Lahaye M. , Bernard D. , Arvieu C.
Published: August 2004

Depth or line profiles on polished sections only provide partial and local information about the chemical distribution at the interface between two solids. Germination and growth, which happen during the reaction phase, can only be explored by a three‐dimensional in‐situ visualization. The most powerful means presently at our disposal are: (i) for non‐destructive analysis, synchrotron microtomography, with a maximum lateral resolution of 0.29 µm (ESRF, European Synchrotron Radiation Facility, Grenoble, France), and, (ii) for destructive analysis, SIMS image reconstruction (resolution 0.2 µm), with a difficult quantitative interpretation.

The object of this paper is to demonstrate that a 3D analysis of a series of AES images is possible at an unrivalled spatial resolution (lateral and depth) and coupled with chemical analysis.

The interaction between titanium and carbon at moderate temperatures is considered here to illustrate the method. The sample is elaborated from a polished substrate of carbon on which a thin layer of titanium is deposited by PVD. Thereafter the sample has been thermally treated under secondary vacuum.

The data set comprises 50 images (squares of side 7 µm) separated by 20 nm, yielding to an analysis volume corresponding to a parallelepiped of 7 × 7 × 1 µm3. On a sample maintained at 450 °C for 30 min, the formation of TiC islands on a thickness of about 100 nm has been observed. Copyright © 2004 John Wiley & Sons, Ltd.
Analysis of labelled gas movements at metal/oxide interfaces by secondary ion mass spectrometry
Authors: Horita Teruhisa , Yamaji Katsuhiko , Kato Tohru , Sakai Natsuko , Yokokawa Harumi
Published: August 2004

SIMS imaging analysis was applied to visualize the distribution of active parts for decomposition of CH4 and/or adsorption and reaction with reformed gases (H2, CO, CO2, O2 and C) around metal/oxide interfaces. To analyse the metal/oxide interfaces in a sub‐µm level, mesh‐shape metals were applied on the oxide substrates. The catalytic activity was compared between two samples in the mixture of CH4, 18O2, and D2O: nickel (Ni) on Y2O3‐stabilized ZrO2 (YSZ) and Ni on Sm2O3‐doped CeO2 (SDC). Stable isotope label annealing was conducted at 1073 K for 300 s, and the quenched samples were analysed by SIMS. The SIMS images and line analyses clearly showed the difference of catalytic activity for CH4 decomposition between Ni/YSZ and Ni/SDC samples: a significant carbon deposition was observed at the Ni‐mesh of Ni/YSZ, whereas homogeneous distribution of C was observed on the Ni/SDC surface. The 16O/18O exchange was distinct at the Ni/SDC samples, whereas that reaction was low at the Ni/YSZ sample. Copyright © 2004 John Wiley & Sons, Ltd.
Specular and off‐specular x‐ray reflectivity study of ion irradiated Co/Pt multilayers
Authors: Schug C. , Grimm H. , Berger R. , Dietzel A. , Wormington M.
Published: August 2004

Co/Pt thin film superlattices with strong perpendicular anisotropy and out‐of‐plane coercivities of 5–11 kOe were irradiated with Xe+ ions to tailor their magnetic properties. Specular and off‐specular x‐ray reflectivity (XRR) studies were performed to correlate the irradiation‐induced coercivity reduction with changes of the interfacial properties. Off‐specular XRR turned out to be particularly sensitive to the Co/Pt superlattice period. By applying the distorted wave Born approximation to simulate the diffusely scattered intensity, we were able to quantify the vertical roughness correlation throughout the superlattice stack. Study of a Co/Pt multilayer exposed to different Xe+ ion doses suggests that progressive ion bombardment causes a gradual loss of conformality between the different interfaces and a change of the interface morphology, whereas initial vertical RMS roughness values are not affected. Copyright © 2004 John Wiley & Sons, Ltd.
AES, XPS and EDS analyses of an iron‐based magnetic powder and an SMC material
Authors: Mandrino Dj. , Godec M. , Škraba P. , Šuštaršič B. , Jenko M.
Published: August 2004

A soft magnetic composite material was prepared from a commercial, iron‐based, soft magnetic powder. Its morphology and composition were examined using SEM, EDS and AES. The flat surface of the sample was found to be of a homogeneous composition, corresponding to the basic soft magnetic powder, whereas phosphorous and zinc were found in the subsurface layers of the sample. These were accessed and probed through the pores in the sample surface. AES and XPS analyses was also performed on non‐compressed soft magnetic powder particles, yielding phosphorous compounds. Copyright © 2004 John Wiley & Sons, Ltd.