Abstract: Pumice-supported nickel catalysts, prepared by the method of slow homogeneous precipitation with urea, were analysed by x-ray photoelectron spectroscopy (XPS). By comparison with similarly prepared silica- and alumina-supported nickel catalysts, a preferential interaction of Ni2+ with Al3+ of the support has been determined. A quantitative XPS analysis indicated large segregation of nickel to the surface. The treatment with H2 at 673 K and 1073 K produced a partial reduction of Ni+2 to Ni0. The extent of the reduction was largest at 1073 K and in this case the reduced Ni in the metallic phase was detectable by x-ray diffraction. A decrease of the Ni 2p/Si 2p intensity ratio occurring in the lower temperature H2-treated catalysts was attributed to diffusion of nickel as Ni2+, as a consequence of a solid-state reaction between nickel ions and support oxides, whereas the decrease of the intensity ratio in the high-temperature reduced catalysts was attributed to sintering of the nickel particles and to diffusion of nickel atoms interacting with oxygen vacancies of the support.

Abstract: Cerium-rich conversion coatings have been deposited onto aluminium 2024-T351 alloy by immersion into a solution containing 10 g L -1 CeCl 3 and 1% H 2 O 2 in a process described as 'cerating'. Prior to deposition the alloy had been prepared either by using a standard chemical pretreatment used for aerospace alloys before conversion coating or by polishing. X-ray photoelectron spectroscopy and scanning electron microscopy have been used to characterize these cerium-containing conversion coatings. It was found that, during deposition, hydrated cerium oxide initially covered the intermetallics present in the alloy surface and then covered the surface generally. Deposition continued over the intermetallics throughout the conversion coating process, resulting in thick, heavily-racked regions considerably greater than the average thickness of the film (>0.3 μm). Elsewhere the coating was generally up to 0.2 μm thick, and appeared to comprised of deposited particles around 100 nm in size.

Abstract: This paper describes the effects that a low-power plasma (< 1 W) has on the chemistry, topography and surface energy of polyethylene (PE) film. The gases used for treating the film were air and nitrogen. The plasma cell was attached directly to the preparation chamber of an x-ray photoelectron spectrometer, enabling the immediate effects of the plasma on the chemical nature of the films to be monitored. Significant amounts of chemical functionality were introduced onto the surface using both plasmas even after a few seconds of treatment. Carbon/oxygen functionality dominates surfaces treated with an air plasma. Nitrogen plasma treatment, as expected, introduced amines, imines and amides. Exposing the treated surfaces to air results in oxygen adsorption, the amount of oxygen pick-up being time dependent. This ageing of the treated polymer films is thought to occur via two processes: short-term hydrolysis of the amines and gradual oxidation of the polymer chain itself. The topographical changes were studied using atomic force microscopy, which was performed after the films bad been exposed to air. Both plasmas caused the polymer surface to roughen, with nitrogen plasma treatment having a more pronounced effect. The surface energy of the film was increased from 37 dyn cm −1 (untreated) to 47 and 46 dyn cm −1 after 20 s of exposure to air and nitrogen plasmas, respectively. After 1 min of treatment, the polar surface energy component of the film treated with a nitrogen plasma (12 dyn cm −1 ) was much higher than that treated with an air plasma (7 dyn cm −1 ). This is supported by the XPS results in that the concentration of chemical groups introduced onto the surface after nitrogen plasma treatment was greater than that for air. The greater changes in polymer surface properties observed for nitrogen plasma treatment were not reflected in the values obtained for the level of polymer/metal adhesion. Only air plasma-treated samples showed significant improvement in the adhesion between polyethylene and alumininm and we conclude that the presence of oxygencontaining functional groups plays a major role in this improvement

Abstract: Focused ion beam (FIB) systems using gallium liquid metal ion sources can remove material with a lateral resolution below 50 nm and can produce metal deposition at a similar resolution with ion beam-enhanced chemical vapour deposition. These capabilities have resulted in many valuable applications for the microelectronics industry. Circuit modifications are possible because existing connections can be severed and reconnected to different locations. Testing of circuitry can be enhanced by isolation of specific circuits, removal of overlayers and by creation of probe pads where desired. Grain sizes can be determined from secondary electron images by the delineation of individual grains due to orientation-dependent channeling of the ion beam. Secondary ion mass spectrometry analyses of small areas can provide ion images, elemental identification of small areas and endpoint detection with depth profiles. Scanning electron microscopy and transmission electron microscopy sections are prepared routinely using the FIB. These FIB-prepared sections are notable because specific features, such as defects, can be exposed and a range of materials including silicon, indium phosphide, gallium arsenide and even metal layers can be cut without distortion. Transmission electron micrographs of superior quality have been obtained with a large area of very uniform thickness that permits identification of features such as areas under stress.

Abstract: The common formalism of quantitative XPS can be easily modified, with two additional correction factors βeff and Qx, to account for the elastic scattering effects. These corrections, for a given solid, depend on photolectron line, the radiation used and the XPS configuration. The database compiled in the present work contains parameters describing the dependence of the correction factors on experimental geometry. These dependences are listed for 496 photoelectron lines emitted by the Mg Kα and Al Kα radiations. The database makes it possible to predict the photoelectron intensity in a geometry in which the direction of x-rays, the direction towards the analyser, and the surface normal are situated in one plane. This intensity corresponds to a theoretical model taking into account the elastic photoelectron collisions. Examples of applications of the database are briefly demonstrated.

Abstract: Results are reported of an interlaboratory comparison conducted to evaluate a proposed procedure for calibration of the binding energy (BE) scales on x-ray photoelectron spectrometers. The calibration was performed at two points on the BE scale (the Au 4f7/2 and Cu 2p3/2 lines) and checks were made of the assumption of BE-scale linearity from measurements on other lines. It is shown here that small offsets (up to ∼0.05 eV) can arise if peaks are located with assumed backgrounds of non-zero slope or if multipeak fits are made to Cu L3VV and Ag M4VV Auger spectra. The two parameters in the linear calibration equation could vary with analyzer pass energy and choice of x-ray source on a particular instrument. Check measurements of the calibrations were performed with the Ag 3d5/2 photoelectron line and the Cu L3VV and Ag M4VV Auger lines; difference between the corrected positions of these lines and the corresponding reference data were satisfactorily small in most cases. For Auger lines excited by monochromatized aluminum x-rays, however, the differences were significant and were interpreted in terms of different average x-ray energies for the monochromated and unmonochromated x-ray sources. The interlaboratory comparison was useful in testing the proposed calibration procedure and in providing guidance for some improvements.

Abstract: An approach is developed to separate the spectral contributions of electrons that have experienced a certain number of inelastic collisions and together constitute the observable lineshape in AES/XPS. The only assumption concerning the emission process that is made in this general approach is that energy losses and deflections occur separately. This means that the method can account for elastic scattering with arbitrary sophistication, while it can also be applied to spectra from samples exhibiting surface roughness or specimens with an arbitrary depth profile and even single crystals where diffraction effects dominate the peak intensities. If the details of the emission process are properly understood, such a so-called partial intensity analysis may serve to assess the structural characteristics of an unknown specimen. Conversely, if the sample structure is known, it can be employed to assess experimentally the details of the emission process (elastic scattering, roughness, diffraction). At any rate, a partial intensity analysis allows proper background correction of the spectral lineshape to be performed if this is the ultimate aim of analysis. This again holds true without regard to the emission process and is possible without any kind of fitting or ad hoc assumptions. On a very similar basis, a method is derived to gain accurate information about the inelastic transport characteristics from reflection experiments in the case when the other quantities governing the particle transfer are known. The results are general in that the starting point of the method, i.e. the yield equation, in principle also describes the fundamentals of other techniques employing particle–solid interaction.

Abstract: Materials used in biomedical applications often function based upon their surface properties. Thus, understanding their surfaces is critical to the design and engineering of new biomaterials and medical devices. Modern surface analysis tools have been developed largely around the needs for the microelectronics and petrochemicals industries, where durable, inorganic surfaces are studied. This paper examines how surface analysis methods can be applied to biomaterials which are typically hydrated and fragile. In particular, vacuum compatibility, sample damage, the aqueous/solid interface; spatial information, buried interfaces, chemical complexity and correlation with bioreactivity will be addressed.

Abstract: Teflon PFA (polytetrafluoroethylene-co-perfluoroalkoxy vinyl ether) was treated by a low-pressure microwave (2.45 GHz) plasma in O2, N2, H2, He and their mixtures. X-ray photoelectron spectroscopy measurements showed ablation of fluorine and incorporation of new O- and N-containing groups into the surface. Among the different gases, H2 is the most efficient for defluorination, N2 + H2 for surface functionalization, while O2 showed the least performance for both effects. Plasma treatments using N2 + H2 and O2 + H2 resulted in intermediate defluorination, i.e. between those in the pure gases, and sequential treatment by He/(N2 + H2) showed an additive effect of He and N2 + H2 alone. Angle-resolved XPS measurements revealed a pronounced gradient in the near-surface composition following H2, N2 + H2 and He/(N2 + H2) plasma treatments, in contrast to a more uniform depth distribution upon O2, N2 and He exposures. The surface modification of Teflon PFA leads to an enhanced adhesion of metals such as Cu, Ag and Au.

Abstract: Samples of InP(100) n-doped with S atoms to 4 × 1018 cm−3 and to 6 × 1018 cm−3 were bombarded with 0.5 and 5 keV argon ions. The angle of incidence of the 5 keV ions was 71° with respect to the sample normal and 41° for the 0.5 keV ions. The resulting topography development was investigated by means of atomic force microscopy (AFM) and transmission electron microscopy (TEM) of Cr–C replicas of the bombarded surfaces. There was a correlation between the AFM images and those from the TEM replicas. At the same magnification the AFM images showed more detail. The surface roughness in the AFM images and those from the TEM replicas. At the same magnification the AFM images showed more detail. The surface roughness in the AFM images was quantified using the software of the AFM instrument. In the range 5 × 1014−2 × 1018 Ar+ cm−2, there was a linear relationship between the roughness parameter and the logarithm of the ion dose density. This fact excludes a seeding sputter erosional theory for the explanation of the development of bombardment-induced topography on InP. At the higher does densities, ripple formation was observed. The dose density dependence of average wavelength of the ripples did not correlate with the predictions of the Bradley–Harper theory.

Abstract: The potential applicability of time-of-flight secondary ion mass spectrometry (ToF SIMS) as an independent quantitative technique has been studied using a more complicated copolymer system: styrene-butadiene copolymer, The complication of this system is that the characteristic SIMS peaks are not unique to each monomer. It has been found that quantitative information can be obtained from the relative SIMS intensities of certain characteristic peaks, i.e. m/z = 63, 89, 103 and 115 for styrene and 53, 67 and 79 for butadiene. In particular, the intensity ratios A/(A + B), where A and B represent, respectively, the above characteristic peaks of styrene and butadiene, have been found to be linearly related to the bulk styrene molar concentration, These results suggest that a sensitivity factor that is constant and independent of the copolymer composition can be defined for these peaks. However, this conclusion cannot be generalized for other SIMS peaks, such as m/z = 77, 91 and 105.

Abstract: Roughening procedures including the early stage of the O 2 + -induced ripple formation of GaAs were studied quantitatively by scanning tunnelling microscopy (STM). Detailed examinations of the beginning of topography development using fast Fourier transform of the STM images revealed that the ripple formation was not caused by any accidental defects, particles or original irregularity on the substrate, but solely by the conditions of the ion beam. A systematic investigation of the rippled GaAs surface produced under various O 2 + bombardment conditions was conducted. The ripple wavelength and the transition depth were almost exactly proportional to E P cos θ, where E P and θ are the energy of the ion beam and the incident angle, respectively. For GaAs, the secondary ion yield transition occurs when the slope of ripples facing the incident O 2 + beam reaches a saturation angle of 20-30° from the macroscopic surface plane. Topography change on other III-V semiconductors was also examined for comparison. There was no ripple generation observed for GaP; InP gave a ripple-like structure without secondary ion yield change. A relatively rough surface resulted on GaSb and InAs at a much shallower depth than for GaAs. Rippling and ion yield changes during depth profiling have been suppressed successfully by sample rotation even in a magnetic sector-based instrument.

Abstract: The influence of surface roughness on total as well as angle-dependent signal electron intensities has been studied by means of an effective and simple theoretical model. It was found that the influence of surface roughness may be accounted for in the usual formalism for AES/XPS by using an effective depth distribution function (DDF). Comparison of the model with experimental results and Monte Carlo calculations are very satisfactory and indicate that the model developed here should provide useful guidance for quantifying the influence of surface roughness in XPS/AES. For an emission angle of ∼ 35°, the depth distribution function assumes an exponential form with an effective attenuation length varying only by a few per cent as the relative surface area, which characterizes the roughness, is varied over a large range. This result implies that the influence of surface roughness on a given intensity ratio is very small for this geometry and may usually be neglected. This statement not only pertains to a layered sample but applies to a specimen with an arbitrary depth profile. Generally, the effective DDF is dominated by the influence of surface roughness, while the effects of elastic scattering are less pronounced. In this case, the combined influence of surface roughness and elastic scattering is simpler to describe than the influence of elastic scattering on the signal electron emission process from an ideally flat sample.

Abstract: A low-power plasma treatment has been adapted to work on a pilot plant scale to continuously treat a tow of carbon fibres. This treatment successfully increases fibre-resin adhesion to levels comparable it not higher than those obtained by commercial electrochemical treatments. One advantage is that the plasma treatment does not appear to affect the tensile properties of the fibre, unlike the electrochemical oxidation. We have also shown that the chemical groups introduced during air plasma treatment play a significant role in fibre-resin adhesion whereas those introduced by electrochemical oxidation do not. A possible explanation for this is that plasma treatments introduce chemical groups onto the immediate surface of the fibres that have the potential to react with the resin, whereas electrochemical oxidation occurs predominantly at the edge sites and proceeds into the sublayers of the fibre. The vast majority of the functional groups are therefore inaccessible to the resin. This type of plasma treatment, however, is unlikely to remove all of the weakly bound layers as in the case of electrochemical treatment because the sputtering capability of the plasma is very low. The tact that these conclusions can be drawn from both the single-fibre fragmentation test and the short-beam shear test is encouraging and goes to prove that both these tests are suitable for looking at trends in fibre-resin adhesion

Abstract: Copper-nickel alloys are important materials for application in corrosive environments. As for many other systems, this property is a consequence of thin oxide films that are protective in weakly acidic and alkaline solutions. The passive layer formed potentiostatically in 1 M NaOH on Cu50Ni has been examined with XPS and ISS. Angular-dependent XPS measurements provide an insight into the layered structure of depth profiles that are confirmed qualitatively and quantitatively by ISS sputter depth profiles. A method is presented to evaluate the XPS results on the basis of a multilayer structure. Thicknesses and the composition of the sublayers of the passive film, as well as the composition of the metal surface underneath, are obtained in dependence on electrochemical parameters such as potential and time of passivation. Thus, one obtains not only the chemical structure but also the changes of the passive layer during its formation. A specimen transfer in a closed system from the electrolyte into the ultrahigh vacuum of the spectrometer prevents possible changes of the passive layer. These measurements are a further example of detailed studies of passivating films on technically important alloys.

Abstract: The formation of the interface between thermally evaporated metals (aluminium, copper) and polymers [poly(ethylene terephthalate) (PET), poly(methyl methacrylate) (PMMA)] has been investigated by static SIMS. Two generations of instrument have been used. The first one, using a quadrupole mass spectrometer directly connected to the same ultrahigh vacuum environment as the metallization chamber, has allowed an in situ characterization of the interface formation after each metal deposition in the submonolayer regime. The second system, using a time-of-flight (ToF) mass spectrometer, has allowed ex situ analyses of Al/PET, Cu/PET, Al/PMMA and Cu/PMMA interfaces. The high mass resolution of the ToF spectrometer led to the unambiguous identification of the molecular fragments that are characteristic of polymer-metal interaction. The results show that Al atoms react with the oxygenated parts of PET and PMMA. This interaction limits the lateral diffusion of Al atoms on the polymer surface and, consequently, induces a two-dimensional growth of the Al film on these polymer substrates. In the Cu deposition case, a weaker metal-polymer interaction is observed. This leads to Cu clustering and a three-dimensional growth. Time-of-flight SIMS molecular imaging clearly reveals Cu clusters on the PMMA surface.

Abstract: We report on our recent x-ray photoemission spectroscopy investigations of the interface formation of metals with poly(p-phenylene vinylene) (PPV) prepared under various conditions. We have found that during deposition the metal reacts with residual hydroxyl groups in the polymer. In addition, we have found that Schottky barrier formation and the associated band bending depend strongly on surface preparation. In the case of Al deposition, samples converted in situ, containing 5% surface oxygen, show band bending that depends on the thickness of the metal overlayer, with effects arising after as little as 1 A of metal. On the other hand, a sample converted ex situ, with 10% surface oxygen, is insensitive to aluminium deposition. We feel that surface impurities and adsorbed species may delay Schottky barrier formation by acting as a butter layer that prevents the PPV substrate from interacting with the growing layer of Al. By constrast, the Ca/PPV surface surface exhibits delayed band bending, with strong interactions between surface oxygen and Ca. Our results indicate that band bending at the metal/PPV interface is governed by the metallicity of the metal overlaryer, which itself is influenced by the interface reaction of the deposited metal with the PPV substrate or the surface residual impurities. Finally, the degree of band bending observed did not correlate directly with the differences in work functions between the metals and PVV

Abstract: Surface properties of Kapton® were analysed after different exposures to ground state fast atomic oxygen (FAO) and vacuum ultraviolet radiation in the atomic oxygen beam facility at the University of Toronto Institute for Aerospace Studies X-ray photoelectron spectroscopy, scanning electron microscopy and contact angle measurements were used to characterize the chemical and physical changes to the surfaces of the materials analysed. The most important changes in the surface chemistry of Kapton induced by the various exposures to FAO were oxidative degradation of the polymer and substantial changes in supermolecular organization and morphology of the surface layer. A very weak adhesion of the rough top layer to the original Kapton has been observed after an atomic oxygen irradiation with a total fluence of 1.3 × 10 21 atoms cm −2 , which is comparable to some low earth orbit (LEO) exposures. Comparison was made between pristine samples and the cleaned surface of samples that had been exposed in the atomic oxygen beam facility and in the LEO environment. An ageing effect was observed in the surface layer of exposed samples after a prolonged storage. For several polymer materials, a correlation was found between the erosion yield when exposed to FAO and the dispersion component of the surface tension of the pristine material

Abstract: Ellipsometry and atomic force microscopy (AFM) were used to study the film thickness of continuous and discontinuous polymer films in the 1-20 nm thickness range on smooth silicon wafers and on structured aluminium substrates. The methods of exploiting AFM for thickness measurements with a high spatial resolution are described. For continuous films, the AFM method is a direct one, i.e. it does not rely on any model. There is excellent agreement between AFM and ellipsometry in the 1-10 nm thickness range. Very small systematic deviations occur in this range but big deviations occur above 10 nm, and are discussed. The film preparation method, spin coating, was characterized to result in prepolymer films with a very homogeneous thickness. Discontinuous films of 2-9 nm thick were also evaluated by both methods of thickness determination. In this case, for one of the AFM approaches a model has to be used too. The agreement between both methods ranged from very good to poor, depending on the kind of sample and on the kind of AFM determination method.

Abstract: Electrochemical oxidation of polyacrylonitril-based carbon fibers in a basic electrolyte was studied and the surface chemical changes monitored by core and valence-band x-ray photoelectron spectroscopic studies. These studies show that potentiostatic treatment under strongly oxidizing conditions in a sodium hydroxide electrolyte for 20 min leads to a surface consisting of a substantial amount of weakly attached carbonate ions with a lesser contribution from carboxylate and other C/O groups attached to the carbon-fibre surface. The valence-band spectrum for a carboxylated carbon fibre calculated by a multiple-scattered wave Xα calculation on a Co 2 - -substituted coronene (C 36 O 12- 24 ) shows that a carboxylate-functionalized carbon fiber would make only a partial contribution to the observed spectrum, which shows considerable similarities with the spectrum of the carbonate ion. The weakly attached carbonate ions were reduced in surface concentration by repeated washing.

Abstract: Thin (750 A) plasma-polymerized films of acetylene were deposited onto polished steel substrates in an inductively coupled r.f. reactor. The films were characterized by XPS, FTIR spectroscopy, Auger electron spectroscopy (AES) and secondary ion mass spectrometry (SIMS) immediately after deposition and after aging in the atmosphere. The FTIR spectra of the as-deposited films were characterized by bands related to mono- and disubstituted acetylene groups and by bands related to methyl and methylene groups. During exposure to the atmosphere, bands related to acetylenic groups decreased in intensity while new bands due to carbonyl groups appeared. When XPS spectra were obtained from films that were exposed to the atmosphere, new components assigned to oxidation products were observed in the C 1s spectra that were not observed for as-deposited films, verifying that oxidation had occurred. Numerous peaks related to aromatic structures were observed in positive SIMS spectra of as-deposited films. Results obtained from AES showed that the plasma-polymerized films were continuous and that the oxide on the substrate surface was partially reduced during deposition. Plasma-polymerized acetylene films were excellent primers for rubber-to-steel bonding. Miniature lap joints were prepared by using rubber as an «adhesive» to bond together pairs of polished steel adherends primed with plasma-polymerized acetylene films. The force required to break the as-prepared joints was ∼ 2000 N for a bonded area of 64 mm 2 and failure was 100% cohesive in the rubber. Similar results were obtained for joints prepared using polished brass substrates. Because of the complexity of reactions between rubber and the plasma-polymerized primer, a model «rubber» consisting of a mixture of squalene, zinc oxide, carbon black, sulfur, stearic acid cobalt naphthenate, N,N- dicyclohexylbenzothiazole sulfenamide and diaryl-p-diphenyleneamine was used to simulate the cross-linking reaction. The results obtained using XPS, SIMS, AES and FTIR showed that sulfur diffused through the primer to form a layer of sulfide at the primer/substrate interface. Zinc and cobalt sulfides and pertiomercaptides, which formed at the interface between squalene and the plasma-polymerized acetylene primer, catalyzed the reaction between squalene and the primer. Cross-links between squalene and the primer were mostly mono-sulfidic, although some evidence for di- and trisulfidic cross-links was observed

Abstract: Dead time corrections in particle counting systems are important for quantitative analysis. It is often not appreciated, however, that these corrections depend on the experiment performed. For surface analysis systems using a stationary beam and a steady counting rate from a spectrometer with single particle detecting electronics, the dead time corrections lead to the simple equations discussed in our earlier work. These concepts translate very directly into SIMS and AES systems with rastered beams and SIMS, XPS and AES systems with multidetectors, to use the same equations, but with area average and multidetector dead times, respectively. The relations of these dead times to the original electronic dead time are presented here.

Abstract: A mass-separated low-energy ion beam system was used to deliver pure OH+ and NH+ to 15nm thick polystyrene films on silicon in ultrahigh vacuum. This was done in an effort to produce specific surface chemical functional groups. X-ray photoelectron spectroscopy showed that when the bombardment energy of OH+ exceeded 10 eV, or the dose was higher than 1 × 1016 ions cm−2, a mixture of COH, CCO and CCOOH groups was produced, along with severe damage to the aromatic rings. However, for bombardment at 10 eV with a dose of 1 × 1016 ions cm−2, only COH (or COR) groups were found. Similarly, bombardment with NH+ at 10 eV and a dose 1 × 1016 ions cm−2 induced incorporation of a single nitrogen-containing functionality. The C 1s data indicated that the major chemical functionality on such surfaces in a CNH2 (or CNHR) group with a minor component of C(NH2)2. Hence, surface functionality can indeed be controlled by altering the molecular nature, energy and dose of the bombarding species.

Abstract: The current and voltage terms of the SIMR approach are combined with the pressure approach of BHP to derive an empirical equation that describes the relationship between recorded emission signal and current, voltage and pressure in a model-independent way. To test the equation, an emission line from each of five different elements in up to five different matrices recorded in all three operational modes of the glow discharge lamp for thirty different values of current, voltage and pressure were combined to give an average of 114 data points per line. The equation was then fitted to the data through multiple linear regression to derive a best estimate of the separate contributions of current, voltage and pressure to intensity and emission yield. The results show that current, voltage and pressure all contribute significantly to the recorded signals and emission yields. Typically, emission yield is proportional to current, decreases as the square root of over-voltage and increases linearly with pressure at low pressures but decreases exponentially at higher pressures.

Abstract: We report scanning Auger microscopy (SAM) and x-ray photoemission spectroscopy (XPS) analysis of a Roman lead pipe fistula, the main emphasis being placed on the comparison between the surface and interface chemical composition of the joint and of the rest of the pipe. We find that the tertiarium, a Pb-Sn alloy that the Romans used for soldering the joint, has a beneficial effect in limiting the formation of white lead, 2PbCO 3 .Pb(OH) 2 . Comparison measurements performed in the alloy and the pure separate metals show that tin markedly limits the ambient surface oxidation of lead. Conversely, tin is much more oxidized in the alloy than when analysed alone. Auger point spectra indicate that carbon is the main surface contaminant of the patina of the fistula, and Auger imaging is used to pinpoint, with a spatial resolution of ∼0.5 μm, the distribution of this element at the interface of a lead/tertiarum solder, performed according to the procedures described by Plinius. The diagnostic capability of Auger transitions of lead and tin for distinguishing between different phases is discussed on the basis of their chemical shifts and surface sensitivities

Abstract: In this study we investigated the contrast of lateral force at highly oriented pyrolytic graphite steps in an electrolytic environment with a scanning force and friction microscope. A characteristic enhancement of lateral force was visible. Steps were imaged with and without electrochemical potential control whereby a change of friction with potential could be observed. The behaviour of lateral force at the steps indicated that the observed contrast enhancement must be a real friction effect and is not caused solely by the topography.

Abstract: In the present interlaboratory comparison, the consistency and validity of the Shirley, straight-line and Tougaard methods for determination of peak intensities from measured XPS spectra have been studied by analysis of data on Au and Ni taken at eight laboratories. The reproducibility of the individual measuring systems was determined to be 2–6%. The RMS scatter around their mean values of the ratio of the peak intensity to the Au 4d peak intensity was 6% for the Tougaard method, 9–10% for the Shirley method and 8–9% for the straight-line method. The increase in root mean square (RMS) scatter of data due to data being recorded in different laboratories amounts to 3–4%, independent of the method applied for background correction. The RMS deviation from theory of intensity ratios of peaks from Ni and Au to the Au 4d peak intensity is 14% for the Tougaard method, 33% for the Shirley method and 31% for the straight-line method. The absolute accuracy of the methods cannot be established to better than the accuracy on the theoretical peak intensity ratios and the uncertainty in the energy dependence of the analyser response function. It is, however, reasonable to expect the combined uncertainty of these factors to be at least 10–15%. The peak intensity ratios obtained with the Tougaard method then falls within the expected accuracy of the theoretical ratios.

Abstract: Relative surface silanol (SiOH) concentration levels on low-surface-area crystalline silica (synthetic quartz crystal) have been determined using the static secondary ion mass spectroscopy (SIMS) technique Various sample pretreatments, including water plasma (maximum silanol/hydroxylation), heating in a vacuum to ∼550°C, heating in a vacuum to > 1000°C (minimum silano/hydroxylation) and inert gas ion bombardment in ultrahigh vacuum (UHV), are examined Both positive ion ration (SiOH+/SiO+, SiOH+/Si+) and a negative ion ratio (OH−/O−) were monitored as a function of temperature as the pretreated surface dehydroxylated (increasing temperature) and rehydroxylated (decreasing temperature) in the UHV analysis chamber Plots of positive ion and negative ion ratios for all data at the various stages of hydroxylation indicated a linear relationship Deviations from this were attributed to the presence of physisorbed water and/or surface hydrocarbon contamination

Abstract: A generalization of the Tougaard method for subtraction of the background of inelastically scattered electrons from an electron-energy spectrum is presented. Firstly, a depth dependence of the inelastic mean free path is introduced, which enables the analysis of electron-energy spectra from elements in inhomogeneous samples. The incorporation of the depth dependence of the inelastic mean free path also provides an equation for the calculation of peak intensities of electron-energy spectra from elements in inhomogeneous samples and the possibility of estimating the effect of elastic scattering of signal electrons. Secondly, it is shown that the Tougaard method allows the direct calculation of the background of inelastically scattered electrons from a known primary excitation spectrum for an arbitrary in-depth distribution of electron emitters. The validity of these generalizations is demon-strated for the case of an XPS model spectrum originating from a substrate covered with an overlayer, by comparing the results obtained in the present study with those reported previously.