bluuebunny/crossref_metadata_2025 huggingface dataset:
TOF‐SIMS analysis of the surface of insulators. Examples of chemically modified polymers and glass
Authors: Lub J. , van Velzen P. N. T. , van Leyen D. , Hagenhoff B. , Benninghoven A.
Published: May 2005

A metod to compensate for surface charging of insulator surfaces during TOF‐SIMS experiments is described. For this purpose a pulsed low energy electron source is used, immediately after the ion extraction period. The surface potential is self adjusting, resulting in a stable spectrum. Besides, ESD effects are strongly suppressed. Positive and negative ion spectra of thick PMMA and PC substrates, containing surface active additives and of UV‐ozone cleaned glass substrates before and after trimethylsilylation are presented. From the glass samples the positive ESD spectra were also recorded by using a continuous electron beam. Comparison between the SSIMS and ESD results indicates that ESD is more surface sensitive and sufferes less from ion fragmentation than SSIMS.
Redeposition in AES sputter depth profiling of multilayer Cr/Ni thin films
Authors: Zalar A. , Hofmann S.
Published: May 2005

During sputter depth profiling, a part of the sputtered matter is redeposited on the sample surface. In particular for rough surfaces, redeposition is expected to have a strong influence on the accuracy of the indepth analysis and on the depth resolution. To study these effects, simple model arrangements were utilized to simulate rought surfaces, which consisted of two differently inclined, adjacent planes of multilayer Cr/Ni thin films with smooth surfaces, inclined at two different angles. Depth profiling was performed by two‐point AES analysis, simultaneously on both planes, during sputtering with a rastered beam of 3 keV Ar+ ions at incidence angles of 33°, 61° and 76°. The results show that the influence of redeposition on the depth resolution of AES sputter profiles depends on the geometric position of the neighbouring planes and on the ion incidence angle.
Surface characterization by energy distribution measurements of secondary electrons and of ion‐induced electrons
Authors: Bauer H. E. , Seiler H.
Published: May 2005

Instruments for surface microanalysis (e.g. scanning electron or ion microprobes, emission electron or ion microscopes) use the current of emitted secondary electrons or of emitted ion‐induced electrons for imaging of the analysed surface. These currents, integrating over all energies of the emitted low energy electrons, are, however, not well suited to surface analytical purposes. On the contrary, the energy distribution of these electrons is extremely surface‐sensitive with respect to shape, size, width, most probable energy, and cut‐off energy. The energy distribution measurements were performed with a cylindrical miror analyser and converted into N(E), if necessary. Presented are energy spectra of electrons released by electrons and argon ions of some contaminated and sputter cleaned metals, the change of the secondary electron energy distribution from oxidized aluminium to clean aluminium, and the change of the cut‐off energy due to work function change of oxidized aluminium, and of a silver layer on a platinum sample. The energy distribution of the secondary electrons often shows detailed structures, probably due to low‐energy Auger electrons, and is broader than the energy distribution of ion‐induced electrons of the same object point.
Quantitative surface chemical analysis of AuCu alloys with aes
Authors: Yoshihara K. , Shimizu R. , Homma T. , Tokutaka H. , Goto K. , Uemura M. , Fujita D. , Kurokawa A. , Ichimura S. , Oshima C. , Kurahashi M. , Kudo M. , Hashiguchi Y. , Fukuda Y. , Suzuki T. , Ohmura T. , Soeda F. , Tanaka K. , Tanaka A. , Sekine T. , Shiokawa Y. , Hayashi T.
Published: May 2005

The Japanese VAMAS‐SCA working group is composed of 19 institutes. Three kinds of Au‐Cu alloys (Au25 at%‐Cu75 at%, Au50 at%‐Cu50 at%, Au75 at%‐Cu25 at%) were prepared, and these specimens were distributed to the members of Japanese VAMAS‐SCA working group and Auger peak amplitude ratios were measured to clarify the correlation factor of different types of spectrometers. The comparison was carried out by using the relative sensitivity factor for Au and Cu. The relative sensitivity factor for lower energy varied from spectrometer to spectrometer, but that for higher energy did not vary so much. Therefore, to carry out the inter‐laboratory comparison of the data, the transfer of the data of peak amplitude at higher energy should be recommended.
Crystaline effects in single crystal and highly textured TiNxfilms
Authors: Strandberg C. , Perry A. J.
Published: May 2005

The results of a study of AES spectra obtained from single crystal and highly textured fine grained TiNx films are presented. The existence of specimen crystallinity effects is demonstrated particularly in the single crystal samples. These can be large enough to affect quantitative analysis. Unexpected changes in the spectra were also found on changing the incident angle of the ion beam.
Quantitative surface analysis by XPS and XAS
Authors: Ebel H. , Ebel M. F. , Krocza H.
Published: May 2005

As X‐ray excited Auger spectra are included in quantitative surface analysis a careful investigation of all possible excitation mechanisms must be made. For instruments with a monochromator there is only the specific characteristic radiation but instruments without a monochromator offer a wide variety of Auger excitations: white x‐radiation (target); satellites (target); O Kα (oxidized target); Cu Lα (target substrate); and Al Kα (tube window).

The present paper deals with the quantification of additional X‐ray excitations of KLL‐Auger spectra from these sources. The numerical results illustrate our experimental situation. With these data it becomes possible to use X‐ray excited KLL‐Auger lines in a fundamental parameter approach for quantitative analysis.
Quantitative AES analysis of Ti silicide and Co silicide films
Authors: Chen W. D. , Bender H. , Vandervorst W. , Maes H. E.
Published: May 2005

The possibilities for quantitative Auger analysis in the derivative mode of Ti and Co silicide films are examined as a function of the composition. Both matrix and sputter corrections are taken into account. It is shown that the theoretical expressions for both corrections predict a weak composition dependence. However, the quantitative results obtained with this procedure strongly deviate from Rutherford backscattering spectroscopy and X‐ray diffraction measurements. It is concluded that the sputter and matrix corrections cannot sucessfully be applied for these materials. Experimental matrix and sputter correction factors are determined.
Quantitative auger electron spectroscopy of AlxGa1‐xAs layers and superstructures grown by MBE
Authors: Chen W. D. , Bender H. , Demesmaeker A. , Vandervorst W. , Maes H. E.
Published: May 2005

Quantitative Auger electron spectroscopy analysis is performed for the ternary system AlxGa1 ‐ xAs with different x‐values. Thick layers and superstructures are grown by molecular beam epitaxy. The relative sensitivity factors are determined by the method of the internal reference element. Correction for preferential sputtering of Ga is accounted for by a correction factor determined relative to electron probe microanalysis measurements. The matrix corrections are unimportant for this system. The results will be compared with photoluminescence measurements.
Surface layers on fe formed during plasma nitriding studied by XPS and reflection EELS
Authors: Strydom I. le R. , Wells A. , Ferreira N. P.
Published: May 2005

Anomalous compound surface layer growth is observed during plasma nitriding of ferrous materials under certain operating conditions. The formation of an iron oxy‐nitride layer by the redeposition of sputtered cathode material was found to influence the growth kinetics of the γ'‐Fe4N layer which forms during plasma nitriding of α‐Fe to the extent where the γ'‐Fe4N surface layer initially increases and subsequently decreases in thickness after deposition of the iron oxy‐nitride layer. The nature of these layers was studied by XPS and reflection EELS to elucidate the electron structure of the valence bands of these compunds. Results are Results are presented which explain the thermodynamic stability of the iron oxy‐nitride layer and the apparent de‐nitriding effect that this layer formation has on the underlying γ'‐Fe4N layer.
XPS and TRP/TPO Study of the behaviour of rhodium particles supported on TiO2
Authors: Muñoz A. , Munuera G. , Malet P. , González‐Elipe A. R. , Espinós J. P.
Published: May 2005

Oxidation/reduction processes occurring in rhodium particles supported on TiO2 have been studied by a combination of XPS and TPR/TPO. Rh(I) and Rh(III) are formed by calcination in excess of O2 at 773k, Rh(III) being favoured for samples with very small metal particles. For samples with particles in the range 2.0–10.0 nm, oxidation up to Rh2O of the whole particles occurs followed by a kinetically controlled growth of a thin Rh2O3 layer at their surface together with the formation of Rh(III) species at the particle/support interface. H2 adsorption at 300 K on the highly oxidized particles (up to Rh2O3) is an activated process which implies reduction of Rh(III) into Rh(I). Further reduction at 373 K leads to Rh(O) formation although some Rh(I) and Rh(III) species still remain unreduced up to T > 473 K. A model is proposed to decribe the evolution of these rhodium oxide particles as well as to explain their different behaviour against H2 adsorption at 300 K.
Oxygen interaction with Mo(100) studied by XPS, AES and EELS
Authors: Minni E. , Werfel F.
Published: May 2005

The adsorption, chemisorption and oxide formation of molecular oxygen was studied on the (100) surface of molybdenum single crystal by following the changes in Mo 3d photoelectron lines and the characteristic losses in EELS. For estimation of the oxygen content, both XPS and AES were applied. At the room temperature the oxygen content saturates rapidly resulting in a small broadening in the Mo 3d photoelectron lines. In EELS one loss line was detected sensitive to oxygen exposure. The estimated maximum coverage approaches two monolayers. When increasing the temperature and oxygen exposure the broadening of the Mo 3d lines stays quite constant but after certain temperature and exposure to oxygen the broadenings start to increase. At elevated temperatures the Mo 3d lines change to a broad band of overlapping Mo 3d lines which can be separated into individual components of Mo, MoO2 and MoO3. In EELS one bulk plasmon is split into two different structures and into an additional feature. At room temperature the chemisorbed oxygen determines the adsorption mechanism while at elevated temperatures a stepwise transition to Mo oxides seems established.
Ellipsometric studies on the interaction of oxygen with thin copper films at 460 K
Authors: Schmidt R. , Wißmann P.
Published: May 2005

The capability of optical measurements to elucidate adsorption as well as absorption phenomena is demonstrated by using oxygen interaction with copper films as an example. The films (thickness about 30 nm) deposited under UHV conditions on glass substrates show a polycrystalline structure with a marked (111) fibre texture. Gas doses were provided at 460 K while recording simultaneously the ellipsometric response (λ = 1152 nm) and the electrical resistivity. The optical properties of the clean films correspond to well‐known bulk data. O2 adsorption causes the ellipsometric angles σΔ and σψ to change by 0.05° and 0.02°, respectively. At pressures of about 1 Pa oxygen begins to penetrate into the interior of the sample which manifests itself in a further drastic increase of σΔ = 30° and σψ = 5°.
Study of thin corrosion films by in situ Raman spectroscopy combined with direct observation of nuclear reactions
Authors: Delichere P. , Hugot‐Le Goff A. , Joiret S.
Published: May 2005

The rôle played by molybdenum in the passivation and corrosion of nickel alloys has been investigated by Raman spectroscopy and nuclear reaction analysis (NRA). NRA showed that the thickness of ‘passive’ films increased with the molybdenum content. When the molybdenum content in the alloy was high (greater than 10% atom), the films were formed of nickel molybdate NiMoO4, poorly crystallized and possibly hydrated.
XPS characterization of coal surfaces: Study of aerial oxidation of brown coals
Authors: González‐Elipe A. R. , Martínez‐Alonso A. , Tascón J. M. D.
Published: May 2005

XPS was used to determine the surface concentrations of diferent elements present in two Spanish brown coals. Sputtering with Ar+ ions followed by XPS analysis permitted depth concentration profiles in both, fresh and oxidized coals, to be obtained, and show that aerial oxidation brought about a redispersion of the organic matter onto the mineral phase. Analysis of C 1s band shape together with Fourier transform infrared (FTIR) study of organic functional groups show that loss of hydroxyl groups from the organic phase occurs by thermal decomposition during the first stages of oxidation, leading to an increase of the hydroxyl groups in the mineral phase by proton transfer. At higher temperatures, oxidation gives rise to formation of new carboxyl groups. The usefulness of XPS and some bulk characterization techniques used for studying coal oxidation is compared.
Composition and thickness of submicron metal coatings and multilayers on Si determined by EPMA
Authors: Willich P. , Obertop D.
Published: May 2005

Electron probe micro‐analysis is applied to the determination of thin films (20–200 nm) deposited on a known substrate. Bulk standards are used for calibration and data reduction is based on the computation of Φ(pz) depth distribution functions. The Φ(pz) model of Pouchou and Pichoir and the Gaussian Φ(pz) expression of Packwood and Brown are compared by investigating Cu and Au films on various substrates. Particular refinements, mainly by introducing an effective atomic number, are discussed in respect of double layers and a large difference between the atomic number of the film(s) and that of the substrate. Mass thickness and composition of single layers as well as double layers can be determined with an accuracy of at least 5% relative. This was estimated in comparison with chemical analysis and Rutherford backscattering spectroscopy of alloys on Si applied to magneto‐optic recording.
An analytical SEM and XPS study of platinum–rhodium gauzes used in high pressure ammonia burners
Authors: Fierro J. L. G. , Palacios J. M. , Tomas F.
Published: May 2005

Scanning electron microscopy (SEM), combined with energy dispersive x‐ray analysis (EDS) and x‐ray photoelectron spectroscopy (XPS), has been used to study platinum–rhodium gauzes exposed to the conditions encountered during the oxidation of ammonia in high pressure converters. The intiial activation of gauzes in a hydrogen flame causes surface rearrangement and results in a slight Pt enrichment at the surface, while this trend is reversed in the further stages of ammonia oxidation in the reactor. Chemical analysis by both EDS and XPS techniques revealed that catalyst deactivation is caused by platinum (IV) oxide (PtO2) evaporation from the gauzes. The remainder, rhodium, is entirely oxidized to non volatile Rh2O3. The results indicate that the formation of this compound continuously stimulates platinum diffusion toward the surface.
VAMAS Surface chemical analysis standard data transfer format with skeleton decoding programs
Authors: Dench W. A. , Hazell L. B. , Seah M. P.
Published: May 2005

In surface analysis today many commercial instruments are operated through a computer. This computer is also used for processing the captured data, using routines from a built‐in set of options for peak synthesis, peak deconvolution, background subtraction, peak area measurement, quantification in various levels of sophistication, mapping, depth profile presentation, smoothing, differentiation and a host of other functions. However, many analysts wish to process their data on another computer in their own particular way using programs written to their specification and under their full control. They need to encode the data in the data‐capture computer into a form suitable for transmission then decode it into the form required in the receiving computer. A standard format for the transferred data would clearly lead to economies in the number of programs required to effect the encoding and decoding.

To meet the above requirement, as a result of a series of iterative discussions over the last three years, first within the UKESCA Users Group and then with the VAMAS National Representatives and users and manufacturers within the VAMAS Community as well as the ASTM Committee E‐42.11, we have produced a Surface Chemical Analysis Standard Data Transfer Format defined in a standard metalanguage. This Format is intended to be used by those wishing to transfer data from computer to computer via parallel interfaces or via serial interfaces over direct wire, telephone line, local area network or other communications link. It is suitable for AES, EDX, FABMS, ISS, SIMS, SNMS, UPS, XPS, XRF and similar analytical methods. It covers elemental maps, depth profiles and sequences of data resulting from a variety of experiments. Thus the application of the Format is very general.
Simulation of electron/solid interaction and its application to quantitative analysis by Auger electron spectroscopy
Authors: Ichimura S. , Ze‐Jun Ding , Shimizu R.
Published: May 2005

The simulation of electron/solid interactions is discussed, with emphasis on its applicability to the matrix correction in quantitative analysis by AES, and to its potential use in background substraction in AES. The Monte Carlo calculation models are first explained, which have been improved to allow the estimation of (i) back‐scattering correction factors, and (ii) energy profiles of back‐scattered electrons in the high‐energy region (i.e. elastically‐scattered electrons and the characteristic loss structures) and the slow secondary region. For this purpose, a dielectric approach is used for the treatment of the electron inelastic scattering in the solid. Then, the models are applied to samples with bi‐layer structures, and the change of Si Auger signals observed during sputter‐etching of a sample consisting of a Si thin film (7000 Å) on a W substrate is well explained. Changes in the energy distributions of back‐scattered electrons during the formation of very thin (5 to 100 Å) Cu films on a Si substrate are also estimated by the Monte Carlo calculation, together with the shapes of the elastic peak and the characteristic loss peaks.
High mass resolution time‐of‐flight secondary ion mass spectrometry. Application to peak assignments
Authors: Niehuis E. , Van Velzen P. N. T. , Lub J. , Heller T. , Benninghoven A.
Published: May 2005

The negative time‐of‐flight secondary ion mass spectrometry spectrum of a trimethylsilylated silicon oxide surface and positive ion spectra of polymethylmethacrylate (PMMA) surfaces before and after treatment with an oxygen plasma are presented. The spectra were recorded with a SIMS spectrometer equipped with a Reflectron‐type mass analyser. This instrument exhibits a mass resolution high enough to be able to determine the chemical composition of the secondary ions directly from the spectra and to resolve peaks of oxygen and non‐oxygen‐containing ions with mass differences of about 0.030 amu at masses well above 200 amu.

This information on the chemical composition makes it possible to determine structures of the ions originating from the surfaces, which increases insight into secondary ion formation processes. On the basis of the results from the plasma‐treated PMMA surface, a tentative mechanism is given for the interaction of an oxygen plasma with PMMA in which formation of new polymer chain‐ends containing acetyl groups plays an important role.
Methods for quantitative analysis in XPS and AES
Authors: Grant J. T.
Published: May 2005

One of the biggest problems in quantitative surface analysis with x‐ray photoelectron spectroscopy (XPS) or Auger electron spectroscopy (AES) is in obtaining an accurate measure for the number of photoelectrons or Auger electrons contributing to peaks in spectra. The approach taken for quantitative analysis often depends on the data acquisition method, although there are several subsequent data processing methods that can also be applied. In XPS, spectra are usually acquired by pulse counting, whereas in AES, spectra can be acquired by a variety of methods, e.g. pulse counting, voltage‐to‐frequency conversion and the use of a variety of modulation techniques. Processing methods involve peak or peak‐to‐peak height measurement, peak area measurement, background subtraction, deconvolution, differentiation, integration, spectrum addition and subtraction, curve fitting and factor analysis. The application of these techniques to quantitative analysis in XPS and AES will be reviewed.
Quantification of amorphous SiC: H films using XPS and AES with three standards
Authors: Fitzgerald A. G. , Henderson A. E. , Hicks S. E. , Moir P. A. , Storey B. E.
Published: May 2005

Quantification has been achieved on a range of a‐SiC: H films using the techniques of XPS and AES. The procedure of quantification, involving the use of three standards, four matrix factors and an effective matrix factor, is given. These results are compared with results from standless techniques. The correlation between matrix factors, local atomic bonding configurations and the effect on the deduced composition are discussed. Recommendations are made concerning the use of various quantification methods, and their inherent errors are discussed.
Dynamics of macromolecules: A challenge for surface analysis
Authors: Garbassi F. , Morra M. , Occhiello E. , Barino L. , Scordamaglia R.
Published: May 2005

XPS and contact angle measurement have been used to study oxygen–plasma‐treated polypropylene (PP) surfaces aged at variable temperatures. Surface rearrangement leading to low wettabillity has been observed, without alteration of the surface composition, as determined by XPS. Experimental results have been interpreted in terms of internal rearrangements of a modified layer, <5 nm thick, formed on top of the PP and immiscible with it.

We also modelled the composition of the surface layer and calculated the relative mobility of modified and non‐modified polymer chains. On this basis, the experimentally observed behaviour can be interpreted in terms of surface rearrangement driven by a compromise between striving for lower surface tension and maximizing inter‐and intramolecular interactions, mainly hydrogen bonds.

The surface composition observed after treatment with plasma, corona, flame or other for enhancing surface tension is then time dependent. For this reason, the procedure used for surface analysis, namely the time allowed for surface equilibration, should be specified in reports.
Auger electron spectroscopy from elemental standards. III. Backgrounds and peak‐to‐background ratios
Authors: Batchelor D. R. , Bishop H. E. , Venables J. A.
Published: May 2005

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

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

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

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

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

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

In Auger electron spectroscopy, both the primary electrons entering the sample and the Auger electrons leaving the sample may suffer strong diffraction effects. On well‐ordered single‐crystal surfaces, diffraction effects may result in variations in the intensity of an Auger peak by a factor of up to two or more when the incident beam direction is varied by a few degrees. The large angular acceptance angle of most Auger spectrometers normally averages out any diffraction effects of the Auger electrons themselves.

Diffraction effects of the primary electron beam (commonly called channelling) may be described qualitatively in terms of the two‐beam theory of electron diffraction. A more exact representation requires a multiple beam calculation similar to that used in electron microscopy.

For quantitative AES it is essential to establish whether diffraction is likely to influence the results and, is so, to take appropriate steps to eliminate or at least to minimize its effect. On the other hand, these channelling effects provide valuable information about the near‐surface order of the sample and potentially provide a technique complementary to x‐ray photoelectron diffraction.
NiCo alloy as a new reference material for quantitative surface analysis
Authors: Fujita D. , Tanaka A. , Goto K. , Homma T.
Published: May 2005

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

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

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

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

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

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

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

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

We have studied the formation of the Cu/MgO interface with Auger electron spectroscopy and high‐resolution electron energy‐loss spectroscopy (HREELS). Copper overlayers ranging in thickness from 1 to 20 Å were formed on an MgO single‐ crystal substrate by evaporation from a Knudsen effusion cell. Direct Auger spectra for the O KLL, Cu LMM and Mg KLL lines were collected. The evolution of the Auger peak intensities shows that the copper initially forms a complete monolayer, followed by island formation (i.e. Stransky–Krastanov growth). Low energy electron diffraction patterns recorded after Cu deposition confirmed the ordering of the first monolayer.

A significant decrease in energy of the surface MgO phonon peak was observed by HREELS following deposition of 20 Å of copper. Simultaneously with this shift of the phonon energy, we observed a decrease of the intensity ratio of the phonon‐loss and elastic peaks. These results have been interpreted using the dielectric theory. Theoretical spectra of MgO covered by a layer of Cu2O obtained by using dielectric constants taken from the literature were able to reproduce qualitatively the decreases in energy and intensity of the phonon‐loss peak with increasing copper thickness.
XPS investigation of impurity phase segregation in 25.5 wt.% CeO2−2.5 Y2O3−72 ZrO2 plasma‐sprayed thermal barrier coatings
Authors: Arfelli M. , Ingo G. M. , Mattogno G.
Published: May 2005

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

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

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

The effect of crystal orientation and surface morphology on the detected Auger current was investigated using a Polycrystalline Mo sample. The sample was initially polished to a uniform and featureless surface morphology. Two large grains were used in the study, with their crystal orientation determined as ∼(100) for the low‐index grain and ∼(1, 4, 11) for the high‐index grain. Ion bombardment conditions used were typical for surface analysis, i.e. 2KeV Ar+ at glancing incidence. The initial Auger current measured form the cleaned as‐polished surface was found to be essentially constant across both crystals. However, under continued ion bombardment, as the fluence was increased constant across both crystals. However, under continued ion bombardment, as the fluence was increased to ∼5 × 1019 ions cm−2, gross differences of up to 18% were observed in the detected Auger current from the two crystal surfaces. The gross difference is attributed to the extent of surface roughness that evolved, which is in turn mainly dependent on the crystal orientation. It was found that, relative to the polished surface, the high‐index grain developed considerable texture of macroscopic dimensions consisting mainly of ‘hills and valleys’ with a ‘furrowed’ fine structure in the direction of the ion beam, yielding a net decrease in the detected auger current. The low‐index grain became smoother, yielding a net increase in the detected Auger current. This latter effect was much larger than the decrease resulting from the increased roughening of the high‐index grain. The implications for quantitative surface analysis are discussed.
Formal databases for surface analysis: The current situation and future trends
Authors: Powell C. J.
Published: May 2005

Evaluated data are needed for surface analysis, just as for other measurements, so that analyses can be made reliably and effectively. Until recently, the principal sources of data were handbooks of spectra (mainly of elements) and review articles with values or equations for the parameters needed. This article describes three efforts to develop formal databases that can be incorporated into computer systems. Information is first given on a recently announced x‐ray photoelectron spectroscopy database, which contains over 13000 line positions, chemical shifts and splittings, together with associated software for searching by element, line type, line energy and other variables. Second, a summary is presented of a recent compilatation of evaluated elemental ion sputtering yields for applications in sputter depth profiling and secondary ion mass spectrometry. Finally, a description is given of a new database that is to contain Auger electron spectra and x‐ray photoelectron spectra; the database architecture is being designed also to accommodate depth profiles and the results of measurements by other surface analysis techniques.
Ion beam mixing and phase formation in NiAi multilayers studied by RBS and PAC
Authors: Weber Thomas , Lieb Klaus Peter , Uhrmacher Michael
Published: May 2005

NiAl bi‐ and multilayers were irradiated with 300–900 keV Xe ions and analysed by Rutherford backscattering spectrometry (RBS) and the perturbed gamma‐ray angular correlation (PAC) method. As PAC measures the interaction of radioactive probe nuclei (111In) with hyperfine fields, it is sensitive to changes in the nearest‐neighbour surrounding induced by a phase transformation. The formation of the crystalline NiAL phase during irradiation was indeed detected by PAC; it was found to start at ion fluences below that required for complete mixing of the constituents. Similar results were obtained after 600 keV Ar irradiations. The interface mixing rate in NiAI bilayers due to 300–600 keV Xe ions was measured with RBS to be k = 4.5(3) ×104 Å4 at room temperature.
Auger parameter shifts in the case of the non‐local screening mechanism: Applications of the electrostatic model to molecules, solids and adsorbed species
Authors: Moretti Giuliano
Published: May 2005

A simple electrostatic model is applied to predict and rationalize the auger parameter shifts in molecules, solids and adsorbed species. The model is valid in the case of the non‐local screening mechanism, i.e. when the screening of the core hole is due to the polarization of the nearest‐neighbour ligands (no charge transfer from the ligands to localized electronic levels of the atom with the core hole, as occurs with the main peak of the core‐ionized heavier 3dn transition metal ions or the light lanthanide ions). To good approximation it is shown that: (1) the Auger parameter shift is a function of the number, distance, electronic polarizability and local symmetry of the first‐neighbour ligands of the core‐ionized atom; (2) the dipole–dipole interactions can play a key role in determining the extent of the extra‐atomic relaxation energy and hence of the Auger parameter shift.