bluuebunny/crossref_metadata_2025 huggingface dataset:
Helium ion and fast atom scattering from polycrystalline copper surfaces
Authors: Xu N. S. , Sullivan J. L.
Published: May 2005

Low‐energy ion scattering from surfaces is an established technique that gives unique information from the first one or two atomic layers on a surface. The standard technique employing an electostatic analyser, however, has some disadvantages. It detects only scattered ions whose yield from surfaces is relatively low and thus high incident ion fluxes must be used. A high flux of ions will change the nature of the surface in a number of ways. It will lead to significant preferential sputtering and to charging effects, particularly in insulating and semiconducting samples. It has been shown also that ions produce more chemical damage in surfaces that do neutrals of the same energy and species. Many of these disadvantages may be overcome if neutrals are used as the bombarding particles instead of ions.

Conventional electrostatic methods cannot be employed to detect neutral sacttered spectra. Hence, a time‐of‐flight mass spectrometer with a pulsed ion/fast atom source (energy range 100–5000 eV) has been developed. This instrument has been used to measure the energy of particles scattered from a polycrystalline copper surface bombarded with either ions or fast atoms. In this study, spectra of He scattered from both ‘ion‐cleaned’ and ‘ion‐cleaned and heated’ copper surfaces were monitored for incident angles ranging from 5° to 75° with a constant scattering angle of 90°. For the ‘ion‐cleaned’ surfaces, spectra of both ion and neutral projectiles show that the technique is sensitive to the outermost surface atomic layer, but that fast atom bombardment seems the more surface specific. For the ‘ion‐cleaned and heated’ surface, spectra for both projectiles are qualitatively identical and first‐order effects can be accounted for by the single binary collision model; however, small but significant differences in peak energy were observed and these may be explained in terms of inelastic collision processes.
Novel chromium layers formed by nitrogen‐ion implantation of conventional and ABCD electrodeposited films, part 4
Authors: Ferber Hermann , Hoflund Gar B. , Mount Charles K. , Hoshino Shigeo
Published: May 2005

Nitrogen‐ion implantation of conventional Cr and amorphous bright chromium‐deposited (ABCD) films which were preannealed at various temperatures, has been carried out in order to determine the effect of implantation on the hardness of the Cr layers. The implantation was carried out using low ion beam fluxes in order to maintain a sample temperature below 250°C. Implantation leads to increased hardness, but the extent is most pronounced for conventional films which were not annealed and ABCD films which were annealed at or below 400°C for ½ h. The surface sensitivity of the hardness measurements was varied by altering the load used during the test. Data obtained in this manner show that the more surface‐sensitive hardness is greater than the more bulk‐sensitive hardness for both the implanted and non‐implanted ABCD films and the implanted conventional Cr films. The compositions of the implanted films have been characterized using Auger electron spectroscopy in conjunction with sputter depth profiling. These data show that all of the Cr in the implanted region is bound as CrN, Cr oxides and Cr carbides at large total N+ doses. Furthermore, the N displaces the C in ABCD films producing N and C profiles that mimic each other in an inverse manner.
SIMS analysis of InP, GaAs and InGaAs layers grown by chemical beam epitaxy
Authors: Gao Y. , Godefroy S. , Benchimol J. L. , Alaoui F. , Alexandre F. , Rao K.
Published: May 2005

SIMS analysis was applied to the characterization of InP, GaAs and InGaAs grown by chemical beam expitaxy (CBE). It includes the control of purity and doping, and the determination of growth rate and matrix composition. Some important characteristics of CBE growth, such as carbon incorporation, the temperature dependence of the growth rate and contamination by isoelectric elements, were studied carefully.
Surface analysis of chrysophosphate materials
Authors: Berghmans P. A. , Muir I. J. , Adams F. C.
Published: May 2005

In this paper, we present results from SIMS, XPS and Fourier transform infrared photoacoustic spectroscopy (FTIR‐PAS) in order to determine the nature of the phosphorus compounds produced by the reaction of POCl3 gas and chrysotile asbestos. SIMS ion images show that the phosphorus compounds are evenly distributed over the surface of the chrysotile fibres (within the resolution of the Cameca ion microscope) XPS and FTIR‐PAS were used to monitor the conversion of the adsorbed POCl3 to a proposed polyphosphate coating. The formation of the polyphosphate coating occurs during the heating of the POCl3‐treated chrysotile fibres to 300°C for 2 h. The resulting material is known as chrysophosphate. This study relates to the use of chemical coating to reduce the carcinogenic behaviour of chrysotile asbestos fibres.
AES, EELS and XPS study of ion‐induced GaAs and InP(110) surface and subsurface modifications
Authors: Valeri S. , Lolli M.
Published: May 2005

Low‐energy Ar+‐induced modifications of III–V semiconductor (110) surfaces have been investigated. XPS, angle‐resolved AES and Auger profiles have been used to check the in‐depth composition over the range of tens to hundreds of angstroms. The actual composition of the sputtered surfaces has been determined by either the elemental standard method or normalization to the cleaved surface signals. Auger and XPS lineshape analysis and EELS spectra provided information on the chemical state of the components in the sputter‐altered region.

GaAs and InP surfaces have been found to be metal enriched, the enrichment being larger at high ion beam energy. The 5 keV Ar+bombardment of the cleaved InP target results in the steady‐state composition In(67)P(33) at the surface. The composition is graded in the subsurface region up to the stoichiometric value In(50)P(50). Although the sputter‐altered GaAs region can be depicted roughly as As‐depleted, the As concentration is larger at the surface than in the subsurface region. The surface ‘spike’ and the subsurface ‘dip’ in the As concentration strongly depend on the ion beam energy in terms of both the intensity and the extension in depth. These results indicate that As radiation‐enhanced Gibbsian segregation and P preferential sputtering are the dominant mechanisms of surface modification in GaAs and InP, respectively.
Determination of sputter damage on InP by MAI ellipsometry
Authors: Dinges H. W. , Kempf B. , Burkhard H.
Published: May 2005

InP wafers were ion‐beam‐etched using different energies. The damaged surfaces were investigated by ellipsometry at different angles of incidence as a function of wavelength. Penetration depths and changes in refractive indices nD – iKD are shown. Si3N4− coated sputter‐etched InP wafers are also measured with multiple angle of incidence (MAI) ellipsometry. Coatings are removed step by step by wet chemical etching, and MAI ellipsometry is carried out after each step. The results are fitted to the model InP/sputter‐damaged layer/Si3N4. The parameters for the damaged layers are given.
Short‐range‐order investigation by low‐energy electrons
Authors: De Crescenzi M. , Derrien J. , Lozzi L. , Picozzi P. , Santucci S.
Published: May 2005

During the last few years a number of experimental techniques have been developed with the general purpose of obtaining structural information from EXAFS‐like spectra without resorting to synchrotron radiation. The aim of this paper is to show the physical principles and the experimental results concerning two of these techniques, which basically use low‐kinetic‐energy electrons instead of x‐rays to excite the investigated system. EELFS (extended energy loss fine structure) and EXFAS (extended fine Auger structure) spectroscopies refer to the detection of the features that appear in the secondary electron distribution diffused inelastically from a solid surface. These features are located in energy a few hundreds of electron‐volt above a core edge ionization and above a few selected Auger transitions, respectively.

The satisfactory agreement in the structural determination (position of the nearest‐neighbour distance, back‐scattering amplitude, total phase shift…) obtained by the EELFS technique allows us to conclude that the EXAFS formalism is a valid and correct method of analysis. Moreover, we present a complete calculation of the inelastic cross‐section actually measured in an EELFS spectrum, taking into account the various weights of the final‐state angular momenta. The main result of this computation ensures the predominance of the dipole channel over the other multipole contribution, even for very low primary beam energies.

The interpretation of the EXFAS singal is closely related to that of the EELFS singal, both arising from an interference effect between the core excited and back‐scattered components of the final‐state wave function. Although the proposed EXAFS‐like origin awaits a more complete theoretical support, the EXFAS technique provides a very attractive extension of Auger spectroscopy to study also the local surface structure.
Take‐off angle and film thickness dependences of the attenuation length of X‐ray photoelectrons by a trajectory reversal method
Authors: Gries W. H. , Werner W.
Published: May 2005

The meaning of attenuation length (AL) of x‐ray photoelectrons (and Auger electrons) in solids is reviewed in the light of new evidence pointing to strong dependences of AL on take‐off angle and film thickness, which can be traced back to elastic scattering. Since signal attenuation in XPS (and AES) can deviate significantly from an exponential form, it is concluded that the AL can no longer be regarded as a material constant. Instead, the AL becomes an approximating parameter whose numerical value must be determined for each experimental condition.

The take‐off angle dependence of the AL was investigated by an efficient Monte Carlo computer code, which is based on the concept of trajectory reversal; this concept is explained.

Strong dependences of the AL on take‐off angle and film thickness were found for the more oblique (> 60° off‐normal) emission.
A time‐of‐flight study of water molecular ion and neutral scattering from copper surfaces
Authors: Xu N. S. , Pearce C. G. , Sullivan J. L.
Published: May 2005

Collision of water molecule ions with solid surfaces can result in neutralization and fragmentation of the molecule. The energy distribution of total scattered yield was measured with a time‐of‐flight mass spectrometer. The major spectral peak energy is close to the value expected for a binary collision of OH with a copper atom, and the energy distribution can be accounted for by the existing dissociation models. Comparisons are made between the scattering of water molecule ions and that of He+ and Ne+ ions in terms of the spectral full width at half‐maximum, shape and the scattered yield. It is found that significant water vapour neutral peaks appear in the spectra of scattered Ne. This implies that strong non‐resonance charge exchange mechanisms occur in the projectile beams. The spectral peak heights of the water ion and neutral scattered at different incident angles are compared to those of Ne.
Determination of ultrathin film growth modes using inelastic Auger electrons: Sm/Cr (211)
Authors: Dubot P. , Barthés‐Labrousse M. G. , Langeron J. P.
Published: May 2005

A new method for the characterization of ultrathin films adsorbed onto clean metal crystals is proposed by monitoring the variation of the substrate peak‐on‐tail (P/T) ratio in the direct Auger spectrum as a function of adsorbate deposition time. Because the inelastic tail on the low‐ energy side of the Auger peak is strongly dependent on the in‐depth concentration of the emitting atoms, a comparison of the experimental P/T values with computational simulations based on a numerical layer‐by‐layer model allows determination of the adsorbate and substrate indepth distribution, thus giving some insight on the growth mode. We have used this technique to follow the adsorption of Sm onto a Cr(211) surface at 300 and 900 K. Comparison has been made with the results obtained when monitoring variations of the Auger peak‐to‐peak heights as a function of adsorbate deposition time in the derivative spectrum (AS–t plots). At 300 K, both methods clearly show evidence of the formation of a dense Sm monolayer followed by three‐dimensional crystallites (Stranski–Krastanov growth mode). At 900 K, the AS–t plots do not allow discrimination between the formation of a CrSm surface compound and a pure low‐density Sm overlayer. By using P/T ratios, the formation of a surface compound can be set aside in favour of a pure Sm monolayer with a density approximately equal to half the density of a close‐packed Sm overlayer.
Hydration of oxide films on aluminium and its relation to polymer adhesion
Authors: Thorne N. A. , Thuéry P. , Frichet A. , Gimenez P. , Sartre A.
Published: May 2005

In the flexible packaging industry, aluminium foil is used to fabricate metal–polymer complex systems without any prior surface treatment (e.g. anodic oxide, chemical conversion coating). The inevitable delay between foil rolling and subsequent application of the polymer, in this case polyethylene, allows ageing of the aluminium oxide to occur, which may significantly reduce the adhesion strength of the metal/polymer joint.

To enable a better understanding of the ageing phenomena occurring and hence to improve the industrial control of the key parameters, controlled ageing of mini‐coils of a 1200 aluminium alloy has been performed in H2O and D2 atmospheres, with some material being subsequently stored under dry conditions. The resultant hydration of the surface oxide has been followed by XPS, SIMS and electrochemical impedence spectroscopy (EIS).

The combination of XPS and EIS indicates that loosely bound physisorbed water, partly removed by dry storage, plays a key role in the adhesion strength of the metal/polymer joint. SIMS imaging of deuterium incorporated in the film as Al(OD)3 shows clearly the heterogeneous nature of the hydration process, with preferential sites being associated with iron‐rich intermetallic phases. For storage periods of >50 days, the formation of these friable bayerite islands predominates and will cause catastrophic loss of adhesion. For shorter periods, however, the loosely bound water plays a major role, and its reversible nature points to the possibility of at least partial recovery of the joint strength by dry storage of the foil prior to application of the polymer.
Influence of plasma pretreatment of polypropylene on the adhesion with aluminium: An Auger spectroscopic study
Authors: André V. , Arefi F. , Amouroux J. , Lorang G.
Published: May 2005

The adhesion of polypropylene (PP) films with respect to an aluminium coating has been improved with the help of a non‐equilibrium plasma process, and the metal layer is deposited in situ immediately after pretreatment. Elsewhere, with the help of many complementary surface analyses (XPS, ISS, static SIMS), the modifications created by plasma treatment on the non‐metallized polymer have been explained partially. In this paper, the aluminium/PP interface has been studied by AES. The problems encountered during analyses of the metallized films are mentioned, which lead to the definition of the polymer–metal interface. It has been shown that independently of the pretreatment carried out on the polymer, the interface consists of an oxidized film of ∼4 nm thick. Furthermore, the role of the experimental conditions of the Auger analyses on the obtained profiles has been studied and discussed.
Surface and microanalytical studies on the corrosion of a Ti5Ta alloy in concentrated nitric acid
Authors: Eickmans J. , Holm R. , Müller G. , Horn E.‐M. , Droste R.
Published: May 2005

The Ti5Ta alloy shows interesting corrosion behaviour and is becoming technologically important, e.g. for chemical plant construction. Welding and further mechanical tests gave good mechanical properties. Therefore, the corrosion of this alloy was studied in comparison with the corrosion of unalloyed Ti and Ta. The samples were corroded for up to 24 days in hot 67.5% nitric acid.

The resulting surface layers were investigated with SEM, transmission electron microscopy (TEM), energy dispersive x‐ray microanalyses (EDX), AES and sputtered neutral mass spectrometry (SNMS). Under these conditions, the oxide growth seems to be dependent on the orientation of the crystallites at the surface, which was not observed under milder attack. When Ti5Ta samples were immersed for 5 days in boiling HNO3, the oxide layer was ∼300 nm thick and a particular crack pattern developed on some grains during drying in air at room temperature. This was observed only for oxide layers thicker than 300 nm.

After corroding Ti5Ta in boiling HNO3 we observed a TaTi atomic ratio of up to 1:1 using ESCA and up to 5 μm thick Ta oxide‐rich scales. The selected area diffraction pattern in the TEM indicates that the oxide film may contain mixed Ti/Ta oxides. The extraordinary Ta oxide enrichment, which is due to the selective dissolution process of Ti, is believed to cause the good corrosion resistance of the alloy. It was not observed after heat treatment in air up to 800 °C or after corrosion tests in HNO3 at room temperature.
In‐depth profiling of hydrogen in oxidic multilayer systems
Authors: Wagner W. , Rauch F. , Ottermann C. , Bange K.
Published: May 2005

The hydrogen concentration profiles of electrochromic multilayer systems produced by evaporation have been determined by means of nuclear reaction analysis. The H content of individual oxidic materials was found to be larger than for single films, especially for SiO2. The time‐dependent H uptake under various ambient conditions was investigated. Systems produced by ion plating were also profiled for hydrogen.
The preparation and characterization of a model supported ruthenium catalyst
Authors: Aas N. , Sakakini B. H. , West R. H. , Vickerman J. C.
Published: May 2005

A model supported ruthenium catalyst was prepared by sputter depositing the metal onto a thin alumina film that had been formed by anodic oxidation of aluminium foil. The metal loading could be varied by changing the time of sputtering, and in this way the growth of the metal was investigated with XPS. Static SIMS combined with temperature‐programmed desorption (TPD) was used to study CO adsorption and to evaluate the metal–gas bonding, as well as the metal–oxide interaction.
Surface characterization of plasma‐treated PTFE
Authors: Morra M. , Occhiello E. , Garbassi F.
Published: May 2005

PTFE was treated with oxygen and argon plasmas and the effects of treatment were evaluated by actinometry, SEM, XPS, static SIMS and contact angle measurements. At short treatment times for both plasmas and at long treatment times for argon plasmas, chemical modification of the surface was dominant, while at longer oxygen plasma treatment times, surfaces are deeply etched but chemically equivalent to untreated PTFE. Interestingly, the change in surface chemistry is paralleled by a simultaneous variation in plasma chemistry, suggesting that the two vary accordingly. The wetting behaviour of treated surfaces is interopreted on the basis of current theories on surface dynamics and contact angle hysteresis.
Application of X‐ray emission spectrometry (LEEIXS) to the study of insulator surface—molecular characterization of some metallic oxides or compounds
Authors: Gaillard F. , Romand M.
Published: May 2005

Low‐energy electron‐induced x‐ray spectrometry (LEEIXS) is a soft and ultrasoft x‐ray emission technique. The wavelength‐dispersive x‐ray spectrometer used is equipped with a cold cathode tube. This device acts as an excitation source by bombarding the sample surface with a quasi‐monoenergetic electron beam, the energy of which is selectable over the range from 0.5–5 keV. The probed depth, depending among other parameters upon the incident electron beam energy and upon the sample nature, typically ranges from 5 to 150–200 nm, the probed area being ∼1 cm2. The capabilities of this technique in the fields of atomic and molecular surface analyses have been shown for a wide range of applications. The aim of this paper is to point out the ability of this technique to solve some problems dealing with the near‐surface analysis of insulating materials and, more particularly, of some metallic oxides.
Defect formation observed by AES in a‐SiO2 films prepared by photochemical vapour deposition
Authors: Nonaka H. , Ichimura S. , Arai K. , Le Gressus C.
Published: May 2005

Damageless conditions in AES measurement were examined carefully on both thermally oxidized and photochemical vapour deposited amorphous SiO2 films as a function of dose rate and total dose. The lower dose rate resulted in the formation of a higher density of oxygen‐deficient defects under the constant total dose condition. Among the films examined, it was found that F‐doped films prepared by photochemical vapour deposition best resisted electron damage. The results are discussed using the model of defect generation consisting of a cascade process, bond breaking and diffusion of oxygen.
A third‐generation Auger microscope using parallel multispectral data acquisition and analysis
Authors: Prutton M. , Walker C. G. H. , Greenwood J. C. , Kenny P. G. , Dee J. C. , Barkshire I. R. , Roberts R. H. , El. Gomati M. M.
Published: May 2005

The Design and construction of an ultrahigh vacuum multi‐imaging scanning electron microscope is described. The microscope is designed to contain two field electron emission columns and can acquire simultaneous digital images from a 16‐channel electron spectrometer, a four‐quadrant back‐scattered electron (BSE) detector, an Si(Li) x‐ray detector, a SEM detector and the current flowing to ground through the sample. Because there is exact spatial registration between corresponding pixels in each of the images, it is possible to use the image set to make quantitative interpretations of the surface and subsurface chemistry. This is done using mathematical manipulations of the image set, together with models for the SEM, BSE and Auger signals. Techniques are described for setting up the alignment and characterizing the field of view and transmission function of the microscope and its spectrometer. Examples of multi‐imaging from simple samples are given. The close coupling between the microscope and its control and interpretation computers provides considerable power for the analysis of inhomogeneous surfaces.
Curve synthesis and optimization procedures for X‐ray photoelectron spectroscopy
Authors: Evans Stephen
Published: May 2005

The selection of functions to represent XPS lineshapes is discussed. An improved Lorentzian/Gaussian product function is proposed for fitting symmetrical XPS peaks, and a further empirical modification is shown to represent asymmetric (metallic) XPS peak profiles very closely. One additional parameter sets the asymmetry at half‐height, while a second governs the tail profile.

An approach to curve synthesis that rapidly yields good first approximations to complex multicomponent spectra is described. Previous fits to model systems may be incorporated, and background intensity differences between the high‐and low‐energy sides of each model peak may be retained in the fit.

A simple least‐squares optimization procedure is described in which divergence is impossible but which is still sufficiently fast for microcomputer implementation. Physically desirable parameter constraints can be applied, and excessively large parameter changes are prevented, even for small components of the fit. The relative precisions of the computed parameters also estimated.
New glow discharge lamp with Co–axially–arranged dual hollow anodes
Authors: Morita Hiromi , Wagatsuma Kazuaki , Hirokawa Kichniosuke
Published: May 2005

A glow discharge lamp consisting of two hollow anodes set co‐a‐axially has been developed to attempt to improve the resolution at interfaces in depth profiling. The structure and the operating conditions of the lamp are described. In addition, an in‐depth analysis of Fe/Zn layers on steel plates has been attempted with this glow lamp. Compared to a conventional glow lamp, the measurements can be performed with improved depth resolution.
The effects of photoelectron diffraction on quantitative X‐ray photoelectron spectroscopy
Authors: Bishop H. E.
Published: May 2005

Although not discussed in most reviews of quantitative x‐ray photoelectron spectroscopy (XPS), diffraction of the photoelectrons leaving a single crystal can lead to potential errors of a factor of two or more in the calculated surface composition. A series of experimental measurements has been made to demonstrate the magnitude of the diffraction effects. These results are used as the basis for a discussion of the influence of crystalline effects on quantitative XPS. If the full solid angle of modern electron spectrometers is used, the potential errors are relatively small and can be minimized by adopting suitable procedures. If the acceptance angle of the analyzer is restricted for angular‐resolved or for small‐area measurements, the potential errors are substantial and great care is required to avoid them.
Topographical contrast using scatter diagrams and correlated images form four backscattered electron detectors
Authors: Barkshire I. R. , El Gomati M. M. , Greenwood J. C. , Kenny P. G. , Prutton M. , Roberts R. H.
Published: May 2005

The York multi‐spectral Auger electron microscope has been used to examine the correlations between four images measured simultaneously by collecting energetic backscattered electrons (BSEs) with four quadrants of an Si p‐n junction BSE detector. Digital signal processing of the four images reveals the topography expected of the polyhedra on the surface of an Ag‐coated, anisotropically etched Si sample. Scatter diagrams formed form the pair of topographical images appear as distorted stereographic projections of the distribution of local surface normals. The use of such projections via models of the scattering process is proposed as a means of correcting topographical artifacts in Auger, EDX and other chemically specific images.
Image correlation: Application to correction of beam current fluctuations in quantitative surface microscopy
Authors: Barkshire I. R. , Greenwood J. C. , Kenny P. G. , Prutton M. , Roberts R. H. , El Gomati M. M.
Published: May 2005

The York multi‐spectral Auger microscope has been used to demonstrate the use of the anticorrelation between a SEM and a sample current image fluctuations. Such fluctuations may be important when using very bright electron sources or when collecting image data over long periods of time.
Maximum likelihood common factor analysis in Auger electron spectroscopy
Authors: De Volder P. , Hoogewijs R. , De Gryse R. , Fiermans L. , Vennik J.
Published: May 2005

An advanced multivariate statistical technique, maximum likelihood common factor analysis (MLCFA), is proposed as an alternative method to principal component analysis (PCA). From a critical review of both methods, it is shown that MLCFA is superior by far to PCA for decomposing overlapping peaks into their component spectra since it is not subject to the various arbitrary factors that characterize the PCA procedure and since it requires less a priori information about the system under study. Investigation of computer‐simulated sets of related spectral mixtures that simulate a series of background‐corrected Auger spectra in a depth profile confirms that, compared to PCA, MLCFA leads to an improved determination of the correct number of relevant components. When treating real Auger spectra, a correct interpretation of the experimental background, ion sputtering effects, etc. is necessary, as discussed previously in the literature. The present results, however, indicate that the implementation of MLCFA in the field of Auger electron spectroscopy contributes substantially to the correct characterization of the chemical composition of solid surfaces and interfaces.
Quantitative analysis of W(N), TiW and TiW(N) matrices using XPS, AES, RBS, EPMA and XRD
Authors: Alay J. L. , Bender H. , Brijs G. , Demesmaeker A. , Vandervorst W.
Published: May 2005

The structural and quantitative chemical analyis of tungsten nitrides and titanium–tungsten nitrides with variable N content (denoted as W(N) and TiW(N)) are explored by a combination of different analysis techniques. Special attention is given to the unraveling by XPS of the different binding states that are present in the surface contamination layer and in the bulk of the layers. The determination of our own sensitivity factors is essential for accurate quantification of both XPS and AES data. Comparison of the different techniques shows the presence of strong preferential sputtering for W(N) alloys, whereas this effect is unimportant for TiW(N). The influence of the vacuum of the analysis chamber of XPS and AES on the results is studied thoroughly.
Interfacial chemistry and adhesion: The role of surface analysis in the design of strong stable interfaces for improved adhesion and durability
Authors: Cayless R. A.
Published: May 2005

Durability is a key issue in widening the application of adhesive bonding technology. This paper describes a fundamental study of the adhesion loss in epoxy‐steel bonds exposed to water, and the development of steel pretreatments, which significantly enhance durability. XPS studies have revealed two weak links in epoxy/steel bonds, both of which must be improved for optimum performance. They are displacement of the adhesive from the steel and breakdown of the oxide on the metal surface. The former has been addressed by applying monomolecular layers of an aminosilane adhesion promoter to the steel surface. Oxide instability has been remedies by use of a novel and simple treatment that modifies the oxide chemistry to a depth of 2–5 nm. Combining these, results in a joint that loses no strength after 2000 h of water immersion at 50°C, whereas untreated joints lose 68% of their strength after only 400 h. The study shows how careful identification of failure modes, combined with appropriate modification of the substrate surface, can be used to design strong stable interfaces. These modification, which affect only a few molecular layers, have a large impact on both bond strength and durability.
The effect of surface pretreatment on carbon fibre–polyimide matrix composite bonding
Authors: Moyer Denise J. D. , Wightman J. P.
Published: May 2005

The single lap shear test and the wedge test were used to evaluate the effect of surface pretreatment on the strength and durability of adhesively boned composite joints. Both types of joints were placed in three different environments: (1) room temperature, desiccator, 1000 h; (2) 204°C, 1000 h; (3) immersion in boiling water for 3 days for the single lap shear test and until failure for the wedge test. The failure surfaces were analyzed using XPS to determine the locus of failure. An oxygen plasma was found to be the best pretreatment. The improvement in adhesive bonding following exposure to an oxygen plasma in comparison to the other surface pretreatment was attributed to several factors—a reduction in fluorocarbon contamination caused better wetting of the composite surface and also may lead to covalent bonding at the composite/primer interface.
Fracture mechanisms of the fiber/matrix interfacial bond in fiber‐reinforced polymer composites
Authors: Latour Robert A. , Black Jonathan , Miller Bernard
Published: May 2005

The fracture behavior of the fiber/matrix interfacial bond is an important governing factor of both composite fracture behavior and its environmental resistance. Methods have been developed to investigate the ultimate and dynamic fatigue fracture behavior of the interfacial bond in both a dry and a saline environment at 37°C. a single fiber embedded within a thermoplastic microdroplet pull‐out test was used as the sample model for this work. Ultimate bond strength testing was conducted on a CGS mechanical test machine while fatigue testing was conducted on a custom‐built miniature closed‐loop mechanical test machine designed to apply accurately controlled dynamic loads to test samples within the range 0.000–0.200 N. The fracture behavior of the interfacial bonds formed between polysulfone thermoplastic and both carbon fiber and polyaramid fiber were investigated using these methods. Results show that the ultimate and fatigue strength of the carbon fiber/polysulfone interface is significantly greater than the polyaramid fiber/polysulfone interface in both the dry and saline invironments. The ultimate and fatigue strengths of the interfaces of both sample types were significantly lower in the saline environment compared to the dry condition. Evaluation of interfacial bond fracture surfaces by SEM indicated that interfacial bond fracture occurred by a combination of both interfacial adhesive and matrix cohesive failure. Results indicate that matrix cohesive failure occurs as a function of both the absolute magnitude of the applied interfacial shear stress and its value relative to the ultimate strength of the interface.
Acid–base interactions at carbon fibre/PEEK interfaces
Authors: Nardin M. , Asloun E. M. , Schultz J.
Published: May 2005

The stress transfer from the matrix to the fibre in composite materials depends to a large extent on the level of adhesion between these materials. In the present study, the work of adhesion between carbon fibres and PEEK polymer is estimated from the surface characteristics of the fibre and the matrix and, more precisely, from the dispersive component of the surface energy and the acid–base character of both material, determined by inverse gas chromatography at infinite dilution.

The interfacial shear strength at the carbon fibre/PEEK interface is measured also by means of a fragmentation test on the respective single‐fibre composites.

For PEEK polymer, it is shown that the acid–base characteristic of fibres and powder are different, indicating that the orientation of the macromolecules near the surface may be affected by the processing of such materials. Nevertheless, as already shown in previous studies for other systems, a linear relationship between the interfacial shear strength and the adhesion at the fibre/matrix interface can be established.
Surface study of polycarbonate membranes used as a substratum for animal cell culture
Authors: Dewez Jean‐Luc , Deren Aurora , Rouxhet Paul G. , Schneider Yves‐J. , Legras Roger
Published: May 2005

The aim of this work is to investigate the relationships between the chemical composition of a polymer surface and its physico‐chemical properties. The study of track‐etched membranes was undertaken in order to understand and control better the attachment of epithelial cells for reconstituting a highly differentiated cell tissue.

The bis‐phenol A polycarbonate membrane surface properties have been modified by various procedures: sulphochromic acid, nitration, oxygen and ammonia radio frequency (rf) glow discharge, corona discharge. The surface chemical composition was determined by x‐ray photoelectron spectroscopy and the surface free energy was computed from the contact angle of various liquids.

The presence of sulphur and nitrogen‐containing groups bound to the surface has been demonstrated after application of the corresponding wet surface treatments. All surface treatments lead to an increase of the oxygen surface concentration, the highest value being obtained after nitration. As a result, the polar contribution to the surface free energy also is increased; this seems to be correlated with the surface concentration of oxygen bearing a high electron density.

The cell adhesion and growth on the membranes is improved by the surface treatments applied, in particular by oxygen rf glow discharge. However, steam sterilization tends to remove the effects of earlier surface modification; this seems to be more pronounced when the sample is in direct contact with liquid water.
Fractured interface characterization of epoxy‐bonded steel joints
Authors: Dodiuk H. , Kenig S.
Published: May 2005

Characterization of epoxy–maraging steel failure interface was carrier out using SEM/EDAX, Auger and FTIR spectroscopies. The steel surface was either sand blasted and/or treated in superheated steam (SHS) prior to epoxy bonding. Acetone wipe served as a reference. Experimental results showed that sand blasting is necessary prior to SHS treatment to avoid premature oxide–steel interfacial failure. In opening crack‐type wedge specimens, the interfacial failure that appears visually to be interfacial in nature, is really a mixed mode type failure as indicated by EDAX analysis and Auger spectroscopy. FTIR indicated that SHS treated maraging steel is superior, with respect to resistance of water absorption, when the bonded wedge specimens have been exposed to high humidity.
Interfacial layers and adhesion in the moulding of nitrile rubber
Authors: Lotfipour M. , Packham D. E. , Turner D. M.
Published: May 2005

The mould release of rubber gives a good example of circumstances where a consistent but low level of adhesion is of importance.

In this paper, XPS work on mould release of rubber is described, and the influences on the adhesion of nitrile rubber to moulds are discussed.

Two tests of adhesion have been developed, the ‘TMS’ rheometer and the blister test. XPS has been used to characterize the interfaces after separation.

The fracture path during demoulding is close to the interface between the alloy and the polymer, within a layer consisting of residues such as coagulants and emulsifiers from the initial polymerization. Thus, the level of adhesion depends upon the nature of this layer formed at the interface during moulding.
Separation of spectral components and depth profiling through inelastic background analysis of XPS spectra with overlapping peaks
Authors: Hansen H. S. , Tougaard S.
Published: May 2005

A Method for simultaneous separation and quantitative analysis of overlapping XPS spectral components originating from two different elements has been developed. The method is based on a detailed theory for electron transport in solids and involves deconvolution of the inelastic spectral background from the surface electron spectra. The method is tested through analysis of model spectra of adsorbate/substrate systems following the Frank–van der Merwe, the Stranski–Krastanow or the Volmer–Weber modes of growth. It is demonstrated that the total amount of adsorbate can be found from one single spectrum with an error of ⩽ 10% independent of t he mode of growth. In addition, the method gives information on the structural properties of the adsorbate and its mode of growth, with a resolution of the order of the inelastic mean free path.
In situ FTIR study of ethyl xanthate adsorption on gold, silver and copper electrodes under controlled potential
Authors: Talonen P. , Rastas J. , Leppinen J.
Published: May 2005

The applicability of a spectroelectrochemical method to the problems related to flotation was studied. The object of the study was to investigate the adsorption of ethyl xanthate on gold, silver and copper surfaces. Spectra were obtained using subtractively normalized interfacial Fourier transform infrared spectroscopy, which allows potential control of electrode while recording an infrared spectrum at the electrode surface. For each metal, a good correlation exists between the spectral intensities of the product of the surface reaction and the voltammogram of the metal electrode immersed in xanthate solution. On gold, xanthate is oxidized to dixanthogen, which is then adsorbed onto the gold surface. In the case of both silver and copper, xanthate reacts with the surface in two separate steps. The first comprises chemisorption of xanthate, the result being a monolayer of metal xanthate‐like surface compound. The second, more anodic, step is the formation of multilayers of metal xanthate.
Microcalorimetric and EGA study of germanium surfaces interacting with different gases
Authors: Stradella Luigi
Published: May 2005

An investigation of the adsorption of several vapours and gases (ammonia, water hydrogen, carbon dioxide, oxygen, carbon monoxide, nitrogen, dinitrogen oxide, propene) on polycrystalline germanium has been carried out at 305 K, in the pressure range between 1 × 10−4 Pa and 20 kPa, using a Tian‐Calvet microcalorimeter.

Water, ammonia, hydrogen and carbon dioxide apart, the adsorption is physical and fully reversible. The Calometric data suggest a dissociative chemisorption for hydrogen and a strong coordinative bond of water and ammonia with more active surface sites.

Evolved gas analysis experiments have been performed on the same sample in the range 300–1000 K, focusing on the H2–Ge, H2O–Ge and N2O–Ge systems. Temperature‐programmed mass spectra desorption mass spectra indicate that 700 K is the optimum temperature for H2O dissociation, while at 550 K there is a maximum in H2 chemisorption; as with the decomposition of N2O, a strong adsorption on the semiconductor of all the species present at the interface strongly interface with the chemical equilibrium.
XPS study of the Sc/SiOx interface at room temperature
Authors: Reichl R. , Gaukler K. H.
Published: May 2005

The reducing reaction of vapour‐deposited scandium layers on silicon oxide at room temperature has been investigated using XPS. The redox reaction took place during the deposition period and diminished the thickness of the silicon oxide layer by ∼ 0.3 nm. No further reaction during the 8 h following deposition was detected.
Quantitative trace analysis by non‐resonant laser post‐ionization
Authors: Hayashi S. , Hashiguchi Y. , Suzuki K. , Ohtsubo T. , McIntosh B. J.
Published: May 2005

In order to overcome the poor quantitativeness of conventional SIMS, sputtered neutral mass spectrometry (SNMS) employing non‐resonant laser post‐resonant laser post‐ionization has been studied. By studied. By combining a time‐of‐flight (TOF) analyzer with a powerful excimer laser, it was confirmed that non‐resonant laser post‐ionization is capable of quantitative analysis of impurities at the pm level. On comparing laser wavelengths, 193 nm (ArF) gave a higher post‐ionization efficiency than 248 nm (KrF). It was also demonstrated that the electronegative element sulphur can be detected as positive ions by post‐ionization. Furthermore, surface metallic contaminants in a small area (250 μm square) could be determined down to 1011 atoms cm−2.
Recent development in quantitative XPS in the USSR
Authors: Nefedov V. I.
Published: May 2005

A review of the recent theoretical and practical achievements in quantitative XPS in the USSR is presented. The following items are discussed: theoretical development—determination of in‐depth profiles on the basis of angular dependences of ESCA intensities, correction for contamination layer, quantitative characterization of the supported particles, determination or calculation of some physical parameters (photoionization) cross‐section, photoelectron mean free paths, (line shapes); practical application of quantitative ESCA surface analysis—high‐temperature superconductors, oxidation of alloys and metals, fluorination of alloys and metals, amorphous alloys, catalysts, semiconductors and related systems, oxides and related systems, adsorption, films on solids.
Study of tinplate structure using imaging secondary ion spectrometry
Authors: Ramamurthy S. , Walzak T. L. , Lu S. F. , Lipson T. C. , McIntyre N. S.
Published: May 2005

Tinplate surfaces have been analysed on a microscopic scale for differences in composition which are related to their effectiveness in providing cathodic protection of the underlying steel. Secondary ion mass spectrometric images of a number of elemental and molecular ions have been collected and collated in stacks that represent the three‐dimensional distribution of the ions in the tinplate. An iron–tin alloy structure at the interface of the tin and steel appears to be detectable by the measurement of the 176FeSn− molecular ion image. The localized corrosion behaviour of the tinplates studied has been correlated to the microscopic distribution of iron near the outer surface of the tinplate; the presence of such an iron‐rich phase could increase the dissolution rate of surrounding tin and thus reduce the effectiveness of the cathodic protection provided to the steel substrate. The steel substrate was shown to have a low but detectable concentration of oxygen from its interface with tin down to a depth of 1–2 μm.
XPS and SSIMS analysis of polymers: The effect of remote nitrogen plasma treatment on polyethylene, poly(ethylene vinyl alcohol) and poly(ethylene terephthalate)
Authors: Foerch R. , Johnson D.
Published: May 2005

A study has been undertaken in which both x‐ray photoelectron spectroscopy (XPS) and Fast atom bombardment static secondary ion mass spectrometry (FAB‐SSIMS) have been used to study the effects of remote nitrogen plasma treatment on polymers such as linear low‐density polyethylene (LLDPE), poly(ethylene vinyl alcohol) (EVOH) and poly(ethylene terephthalate) (PET). For comparison, remote oxygen plasma treatment was also performed on LLDPE. A very rapid uptake of nitrogen was observed for all polymers. Negative FAB‐SSIMS indicated CN−, CNO− and C2N fragments on each of the nitrogen plasma‐treated polmers. Positive FAB‐SSIMS spectra of plasma‐treated LLDPE showed relatively high intensity, high mass fragments, thought to originate from additives. These were not observed for the other two polymers. Significant amounts of aromatic‐type fragments were observed in the positive FAB‐SSIMS spectra of all treated polymers. Surface stability studies have shown that for both nitrogen and oxygen plasma‐treaed LLDPE there is a substantial decrease in the surface functionality on exposure to air. This effect was much less prevalent for EVOH and PET.
Depth profile analysis of aluminium metallization in microelectronics: Optimization of depth resolution
Authors: Pamler W. , Wangemann K.
Published: May 2005

Depth profiling of aluminium metallization in microelectronics devices by Auger or SIMS analysis is impeded by the severe sputter‐induced roughening which causes a serious loss in depth resolution. This paper discusses strategies to avoid this deteriorating effect: optimization of the bombardment angle, sample rotation during sputtering and the use of heavy or reactive ions. The best depth resolutions were achieved by sputtering with normal incidence 15 keV O2+ ions. In this case, an interface width of 12 nm was measured for a film of 1 μm thickness. This is an improvement by more than a factor of 10 compared to the extremely poor depth resolution of 160 nm resulting from routine analysis parameters (Ar+ ions incident at 55°).
Structural and electronic studies of clean and oxidized thin Fe films on polycrystalline copper
Authors: Di Nardo S. , Passacantando M. , Picozzi P. , Santucci S. , Lozzi L. , De Crescenzi M. , den Daas H.
Published: May 2005

The local structure of very thin films of iron, deposited in an ultrahigh vacuum (UHV) onto polycrystalline copper and submitted to oxidation and thermal treatments, has been studied by surface electron energy‐loss fine structure (SEELFS) spectroscopy in reflection mode beyond the L2,3‐edges of iron and the K‐edge of oxygen. These results have been correlated to x‐ray photoemission (XPS) measurements performed on the same samples. Our results can be summarized as follows: lowering of the lattice parameter of the iron deposit, supporting the hypothesis of a cluster growth; selectivity toward the oxidation process of the iron deposits with respect to the copper substrate; restoring the metallic behaviour of the iron deposit after thermal treatment.