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An Alloy 600 C-ring has been sequentially stressed as in a classical deformation test, and the apex of the C-ring has been spatially mapped by Laue microdiffraction during the stress deflection sequence. The diffraction spots were analyzed to provide maps showing the distributions of deviatoric elastic deformations as they changed with increased stress. The Laue-derived elastic strains in the stress direction, averaged over small areas at the C-ring apex responded to stress in a classic manner expected of a system undergoing elastic and then plastic deformation. For small amounts of applied stress, maps of the strain tensor in the stress direction (exx) showed distributions that were reasonably homogeneous. As applied stress was increased to the elastic limit, distinct local pockets of the tensile strain tensor (exx) became apparent. As stress approached a maximum deformation of 10 times the elastic limit, the strain tensor distribution underwent further changes. Von Mises elastic strains were also mapped and, in general, appeared to reduce as stress is increased. The formation and distribution of geometrically necessary dislocations were also monitored. After annealing at 315 C, the exx strain tensor values were diminished from most areas excepting those bordering some grain boundaries. Strain changes in stressed Alloy 600 C-rings were also studied following two brief stages of accelerated aqueous corrosion at 315 C. Localized exx strain tensor and von Mises strain values gradually diminished except for areas near grain boundaries. Copyright © 2017 John Wiley & Sons, Ltd.

The oxide chemical composition on metallic Ni and NiCr alloy electrodes has been studied for changes in simulated reactor coolant solution chemistry, through a range of oxidizing potentials and pH settings at 25 °C and 150 °C. Even under strongly reducing conditions, the Ni surface has a 2-nm layer of oxide and hydroxide from which further oxides form, depending on the subsequent oxidative step. For basic (normal operating) pH conditions and under oxidation potentials near 0 volts (vs. SCE), a predominantly Ni(OH)2 layer is formed that appears to remain relatively stable up to at least 48 hours of oxidation at 150 °C. For the NiCr alloy, similar stability is imparted by a thin film of Cr(OH)3/ Cr2O3 and Ni(OH)2./NiO. Under milder oxidizing (but still basic) conditions, the surface is stabilized by a thin film that is mostly Ni(OH)2/NiO. Under neutral solution conditions, the same oxide/ hydroxide films do not seem to be as effective in stabilizing the surface. Copyright © 2017 John Wiley & Sons, Ltd.

Microscopic distributions of elastic and plastic strains have been studied at three intervals during an electrochemically accelerated corrosion test of a flat, polished surface of a mill-annealed a...

Laue diffraction measurements made using polychromatic synchrotron x-radiation have revealed significant changes to the microscopic strain distributions in an Alloy 600 (UNS N06600) tube following ...

The local effects of stress from a mechanical indentation have been studied on a Ni3Al single crystal containing submicron inclusions of molybdenum fibers. X-ray microdiffraction (PXM) was used to measure elastic and plastic deformations near the indents. An analysis of freshly acquired massive sets of PXM data has been carried out over the Science Studio network using parallel processing software called FOXMAS. This network and the FOXMAS software have greatly improved the efficiency of the data processing task. The analysis was successfully applied to study lattice orientation distribution and strain tensor components for both the Ni3Al and the Mo phases, particularly around eight indents patterned at the longitudinal section of the alloy.

The O/Ni ratios derived from the X-ray photoelectron (XP) spectra of a number of well-characterised Ni oxides were calculated and found to correspond well to the expected O/Ni ratios for these oxides. The measured ratios, combined with the characteristic XP spectra, provide a higher level of confidence to the assignment of O 1s chemical species, particularly for surfaces with multiple phases present. As examples of this, we discuss the additional information imparted by O/Ni ratios measured for oxides that were electrochemically grown on Ni and NiCr-20% alloy surfaces.

This paper reports several interrelated XPS investigations of the Cr–O system that provide additional interpretation of the Cr 2p3/2 spectra, along with more detail on the reaction mechanisms between O2 gas and H2O vapour with metallic Cr. The Cr 2p3/2 spectra of polycrystalline Cr2O3 contain multiplet structures that bear a strong resemblance to those calculated by Gupta and Sen for the free Cr3+ ion. The O/Cr ratio derived from the corrected Cr3+ and substitutional O2− intensities for all polycrystalline Cr2O3 samples was 1.5. Annealing of freshly cleaved polycrystalline Cr2O3 surfaces above 550 °C resulted in a sharpening of the multiplet structures that may be caused by the increased prevalence of the (0 0 0 1) Cr2O3 orientation on the surface. The slight difference in binding energies between the low energy (0 0 0 1) plane and the other major crystallographic orientations could contribute to the spectral broadening that is observed for the Cr 2p3/2 spectral line shapes. The Cr 2p3/2 spectrum for Cr(OH)3 was isolated from that produced by Cr2O3 and the multiplet structure was qualitatively re-assembled for that of the hydroxide. The Cr 2p3/2 and O 1s spectra of reaction products on polycrystalline metal surfaces were analysed using the above information. The oxidic portion of the Cr 2p3/2 spectra could be cleanly separated from the metallic substrate using spectral subtraction. Reactions of either O2 gas or H2O vapour both produced a thin Cr2O3 film that was deficient in Cr3+ and, depending on the reactant, showed varying concentrations of hypo-stoichiometric Cr moieties. The surface corrected O/Cr ratios calculated for all the oxidised surfaces were 1.7. There was little evidence to support the formation of Cr(OH)3 on these surfaces. For comparison, an aqueous reaction of a Ni–Cr (20%) alloy was studied where both Cr(OH)3 and Cr2O3 components could be analysed. For this example no sub-stoichiometric Cr oxide species were produced.

TM abstract The oxidation of polycrystalline nickel (Ni) metal surfaces with water (H2O) vapour was studied at 25 ◦C and 300 ◦ C using dose rates considerably higher than in previous studies. The reaction rate was followed to a point where the oxide thickness was several nanometers. This was done using X-ray photoelectron spectroscopy (XPS) and modeling of the spectral profiles using QUASES

We report a study of a full-coverage octadecylphosphonic acid (OPA or ODPA) self-assembled monolayer (SAM) spin-coated on the native oxide layer (SiO 2 ) of a single crystalline silicon (c-Si) wafer using spectroscopic ellipsometry (SE) and reflectometry (SR). The OPA SAM showed characteristics of being a dielectric film in visible range and becoming absorbing in deep-UV range. By assuming an optical stack model of OPA/SiO 2 /c-Si for the OPA monolayer system and adopting the parameterized Tauc–Lorentz dispersion model, we obtained an excellent fit of the model to the SE and SR data, from which dispersion of optical functions as well as thickness of the OPA film were deduced. The OPA film thickness measured by atomic force microscopy (AFM) on partial coverage OPA samples was used as the initial trial film thickness in the fitting processes. The deduced OPA film thickness from SE and SR data fitting was in good agreement with that obtained by AFM.

The Canadian Light Source, the University of Western Ontario, IBM Canada and BigBangwidth during 2006 developed the Remote Beamline Access (RBA) system. This system was demonstrated using a standalone soft X-ray machine as well on the VESPERS beamline. The RBA system serves as a proof of concept and basis for ScienceStudio, which is now under development.

We show that physisorbed octadecylphosphonic acid (OPA) self-assembled monolayer (SAM) molecules on a Si substrate can be removed by a biased conductive probe tip. Our experimental results suggest that the OPA headgroups are negatively charged and adsorbed on the Si substrate through weak electric charge interaction, allowing one to selectively remove these molecules from their SAMs with an electric field.

X-ray photoelectron spectroscopy (XPS) was used to examine the corrosion films formed on electroless nickel (EN) deposits prepared in an EN solution containing two different types and concentrations of bath stabilizers in Ar-purged and oxygenated neutral 5% NaCl solution. Two distinctive corrosion films were observed after long periods of immersion. An enrichment of elemental phosphorus compared to nickel was observed on the surface of the EN deposit produced with no stabilizer and with maleic acid (MA). By comparison, a high degree of surface oxidation was observed on the EN deposit prepared with thiourea. Trace impurities of sulfur in the EN deposit prepared with thiourea appear to result in enhanced corrosion and, in turn, lead to the build-up of corrosion products on the EN surface. By contrast, a P-enriched chemical passivation layer was formed on the EN deposits prepared either without any stabilizer or with MA present.

Using a diamond-tipped stylus, scratch tests were conducted on biaxially oriented polypropylene and poly(ethylene terephthalate) films in the two draw directions, i.e., the machine-direction (MD) and the transverse-direction (TD) along which the draw ratios are different. Atomic force microscopy study of those scratches revealed a significant anisotropy in the scratch resistance between the MD and TD for both of the polymer films. We confirmed that the scratch resistance of polymer strands is closely related to the draw ratios, which determine the mechanical strength and optical clarity of biaxially oriented polymer films.

As determined by scratch tests, self-assembled monolayers (SAMs) of octadecylphosphonic acid (OPA) on a muscovite mica substrate were found to be mechanically robust and to serve as a lubricant to protect the underlying mica substrate. For comparison purposes, three polymer films were subjected to scratch tests under the same conditions. The scratch tests were conducted using a diamond-tipped stylus, and the resultant scratches were examined using atomic force microscopy. The excellent mechanical strength of OPA SAMs is supported by analysis with time-of-flight secondary ion mass spectrometry, which suggests that the headgroup of the OPA is strongly bonded to the substrate atoms. The molecular lubrication provided by OPA SAMs suggests that the interaction between the headgroup and the substrate is sufficiently strong to endure significant shear force and that the hydrocarbon chains are able to dissipate shear energy.

(Fe(OD)2) layer over an inner oxide (FeO) layer. The extraordinary depth resolution of the ToF-SIMS profiles assisted in identifying the two phases; this resolution was achieved by compensation for surface roughness. A substantial concentration of deuterium was found in the subsurface oxide layer. This observation confirmed previous assessments that the formation of FeO was from the reaction of Fe(OD)2 with outward-diffusing Fe, leaving deuterium as a reaction product. Copyright  2005 John Wiley & Sons, Ltd.

The low temperature (

The surface chemistry associated with pitting corrosion on a nickel-based alloy, Inconel 600, has been studied using imaging x-ray photoelectron spectroscopy. The irregularity of the sample surfaces necessitated a more elaborate background correction than is usually applied in such imaging. Areas of active pitting were found to contain corrosion products that are high in chromium oxide and depleted in nickel and iron. Sites of anodic activity on the surface were able to be defined more clearly using principal component analysis. Elements that are dissolved preferentially are deposited cathodically within well-defined regions whose distance from the anodic pit appears related to the open-circuit potential. Copyright  2005 John Wiley & Sons, Ltd.

This work documents the behaviour of the positive secondary ion yield of bulk polytetrafluoroethylene (PTFE) under dual-beam depth profiling conditions employing 1 keV Ar+, Cs+ and SF5+. A unique chemical interaction is observed in the form of a dramatic enhancement of the positive secondary ion yield when PTFE is dual-beam profiled with 1 keV Cs+. The distinct absence of such an enhancement is noted for comparison on two non-fluorinated polymers, polyethylene terephthalate (PET) and polydimethylsiloxane (PDMS). The bulk PTFE was probed using 15-keV, 69Ga+ primary ions in dual beam mode under static conditions; 1-keV Ar+ (a non-reactive, light, noble element), Cs+ (a heavier metallic ion known to form clusters) and SF5+ (a polyatomic species) served as the sputter ion species. The total accumulated primary ion dose was of the order of 1015 ions/cm2, which is well beyond the static limit. The enhancement of the positive secondary yield obtained when profiling with 1-keV Cs+ far exceeds that obtained when SF5+ is employed. An explanation of this apparent reactive ion effect in PTFE is offered in terms of polarisation of CF bonds by Cs+ in the vicinity of the implantation site thereby predisposing them to facile scission. The formation of peculiar, periodic CsxFy+ (where y = x − 1) and CsxCyFz+ clusters that can extend to masses approaching 2000 amu are also observed. Such species may serve as useful fingerprints for fluorocarbons that can be initiated via pre-dosing a sample with low-energy Cs+ prior to static 15-keV Ga+ analysis. Copyright © 2005 John Wiley & Sons, Ltd.

Static secondary ion mass spectrometry was used to study the chemical reactions and lateral distributions of fatty amines, alcohols and esters spin coated onto gold surfaces and commercial aluminium-magnesium (Al-Mg) alloy surfaces, cleaned using UV-ozone. The aim of this study is to develop an understanding of the interactions of model lubricants with metal surfaces, such as gold and aluminium. This static SIMS study of organic thin films has been able to identify specific reaction products on the aluminium surface for each functional group. This work demonstrates that organic molecules with alcohol, ester and amine functional groups undergo specific chemical reactions with oxidized Al-Mg alloy surfaces. For example, films composed of the fatty alcohol dodecanol were observed to emit monomers, dimers and trimers with discrete distributions. In addition, negative secondary ion mass spectra indicate that a surface carboxylate is formed from the alcohol. The formation of carboxylate reaction products was confirmed by Fourier transform infrared spectroscopy. On Al-Mg alloy surfaces, a direct interaction with the amine and aluminium oxide surface is observed by the detection of a molecular ion that corresponds to the mass of dodecylamine and AlO - , characteristic of aluminium oxide. Ethyl laurate was shown to eliminate the ethyl group, leaving the laurate anion. This study demonstrates the ability of time-of-flight (ToF) SIMS to discriminate and detect chemical reaction products formed between model lubricant molecules and metal surfaces. As a result of this study, the use of ToF-SIMS to identify reaction products of model lubricants can be extended to provide a better understanding of the interactions of lubricants and metal surfaces at high temperatures and pressures that more closely resemble the conditions encountered in industrial rolling processes.

The open-circuit corrosion and anodic oxidation behavior of the C-series of Ni-Cr-Mo alloys (C-4, C-276, C-2000, and C-22) and alloy 625 have been studied at 25°C and 75°C in 1.0 mol·L−1 NaCl+1.0 mol·L−1 H2SO4. A combination of open-circuit potential, potentiostatic polarization, and electrochemical impedance spectroscopy were employed in the study. The composition of the films formed was determined by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry. Passive oxide film resistances increase and defect oxide film concentrations decrease as films thicken and chromium and molybdenum segregate to the alloy/oxide and oxide/solution interfaces, respectively. The high-chromium alloys exhibit higher film resistances and lower film defect concentrations consistent with the more positive potentials observed on these alloys. The results show that the observed ennoblement in corrosion potentials with time is coupled to the Cr/Mo segregation process and the suppression of defect injection at the alloy/oxide interface. By all measures, C-22 exhibited the best passive properties.

Partial and complete self-assembled monolayers (SAMs) of octadecylphosphonic acid (OPA) have been deposited onto air-exposed surfaces of the metals copper, silver, gold, iron, silicon and aluminium, as well as onto freshly cleaved, air-exposed surfaces of the minerals muscovite and biotite. The line width of the C(1s) signal in the XPS spectra of the surface narrowed, as the extent of coverage increased to 100%, to a half-width of 0.9 eV. Moreover, the line widths associated with the insulating muscovite substrate also became substantially narrower as OPA coverage increased. Binding energy differences on this chargeshifted surface were found to be more consistent when OPA was used as a charge reference, compared to using adventitious carbon as a reference. OPA coverage of the air-exposed metals copper, silver, gold and iron also produced narrow C(1s) spectra whose binding energies were consistently close to 284.9 eV. The C(1s) binding energy positions on Al and Si samples were charge-shifted by the insulating nature of the thin oxide formed on air exposure, or by the insulating nature of the substrate in the case of the minerals. Correction of the observed C(1s) energy position to 284.9 eV gave sets of elemental binding energies for the substrate materials that were reproducible. Thus, OPA coverage could be a possible alternative candidate for use in charge correction of binding energies of insulating materials. The OPA coverage cases were modelled using the software QUASES  Analyse. For the substrates copper, silver, gold, iron and aluminium, analyses of the metal core line spectra gave OPA overlayer thicknesses close to those measured by AFM (1.6 nm). However, QUASES  analyses of the C(1s) extrinsic backgrounds for the same surfaces required the use of an attenuation length of only 0.4 nm to derive a comparable thickness – much lower than literature values for carbon. This discrepancy is ascribed to the structured nature of the SAM. Copyright  2005 John Wiley & Sons, Ltd.

The oxidation of Fe by water (H2O) vapour was studied using X-ray photoelectron spectroscopy (XPS) and QUASES TM . The results indicated that the oxide formed at 25 � C and 150 � C was thinner than that formed when oxygen (O2) gas was present. The kinetics of the reaction were studied and found to follow a direct logarithmic relationship at both 25 � C and 150 � C. At 150 � C, a change in mechanism occurred after an oxide layer of approximately 0.7 nm had formed. It was determined the mechanism changed from a temperature-independent place-exchange to a temperature-dependent field-driven mechanism. The decreased rate of oxide growth in water vapour compared to that in O2 is proposed to result from the presence of H within the oxide as well as adsorbed to the surface. Its location within the oxide acts to restrict the amount of diffusion that can occur, while its presence on the surface restricts the number of surface states available for further adsorption of H2O. The slow conversion of hydroxide to oxide, as well as differences in transport properties between hydroxides and oxides, were also felt to decrease the thickness of the layer formed compared to equivalent reactions with oxygen. � 2004 Elsevier B.V. All rights reserved.

Oxidation of iron (Fe) by oxygen (O2) at low pressures was investigated using XP spectra and QUASES TM Analyze and Generate software programs. The results indicated that the oxide films produced after short oxygen exposure times contained a mixture of magnetite (Fe3O4) and maghemite (c-Fe2O3) without distinct interfaces between the two being seen. Further investigation suggested that a reaction mechanism involving cationic diffusion was mostly responsible for the formation of Fe3O4, while a mechanism involving anionic diffusion was responsible for c-Fe2O3 growth. The kinetics of the overall reaction were also investigated and found to follow a direct logarithmic relationship with increasing time. The rates of oxide growth were calculated for different pressures studied at the same temperature and found to be the same. This observation was used to conclude that the rate-limiting step was the formation of a thin oxide film by place-exchange and not anionic or cationic diffusion. � 2004 Elsevier B.V. All rights reserved.

Atomic force microscopy (AFM) uses a very sharp pointed mechanical probe to collect real-space morphological information of solid surfaces. AFM was used in this study to image the surface morphology of a biaxially oriented polypropylene film. The polymer film is characterized by a nanometer-scale, fiberlike network structure, which reflects the drawing process used during the fabrication of the film. AFM was used to study polymer-surface treatment to improve wettability by exposing the polymer to ozone with or without ultraviolet (UV) irradiation. Surface-morphology changes observed by AFM are the result of the surface oxidation induced by the treatment. Due to the topographic features of the polymer film, the fiberlike structure has been used to check the performance of the AFM tip. An AFM image is a mixture of the surface morphology and the shape of the AFM tip. Therefore, it is important to check the performance of a tip to ensure that the AFM image collected reflects the true surface features of the sample, rather than contamination on the AFM tip.

QUASES Analyze and Generate were used to model the extrinsic loss structures for XPS spectra of oxide films grown on iron in such a way that their thickness and structure could be determined. The Generate program used in conjunction with spectra of model iron oxides allowed for both magnetite (Fe 3 O 4 ) and maghaemite (γ-Fe 2 O 3 ) structures to be identified in all films studied. These structures were identified as overlying layers in the oxide films and were usually intermixed at their interface. The absence of other iron oxide structures within the film could be tested based on their goodness of fit to the experimental spectrum. Comparison of the thickness values obtained using Generate with those found using nuclear reaction analysis suggested that the Generate results were higher by 20%. This difference likely resulted from the use of a calculated inelastic mean free path value for Fe 2p electrons in the Generate calculation rather than using the real attenuation length. For oxide films whose thickness approached 10 nm, the QUASES results for photoelectron spectra obtained with a Zr achromatic x-ray source were compared with those from the standard Al monochromatic source. In this particular case, the oxide thicknesses obtained using Generate and Analyze were found to be more consistent when the Zr source was used.

A monochromatic Al K α source and magnetic confinement charge compensation yield an As 3 d line width of 0.52 eV for the bulk insulator As 2 S 3 (orpiment) which is as narrow as the As 3 d line width obtained for the semiconductor FeAsS (arsenopyrite). These results, and the XPS results for silicates, demonstrate that charge broadening of XPS spectra has been overcome for most insulators provided care is taken with sample preparation. XPS core level spectral investigations of these minerals now may be conducted at the same level of detail as have been conducted on semi-conductors and metals. The Si 2 p spectrum of a non-conducting orthosilicate (Mg-rich olivine) displays a total line width of 1.36 eV compared to very high resolution synchrotron XPS line widths of 1.1 eV for an Si 2 p spectrum of gaseous Si(OCH 3 ) 4 , and 1.42 eV for the Si 2 p peak of non-charging SiO 2 thin-films grown on Si metal. These results demonstrate that Si 2 p peak broadening of these silicates does not result from differential charging. Comparison of the Si 2 p spectrum of Si in olivine which contains non-polymerized, independent SiO 4 tetrahedra, with that of a gaseous analogue, Si(OCH 3 ) 4 , also composed of non-polymerized Si atoms tetrahedrally bonded to O, provides insight into the cause of Si 2 p peak broadening for olivine (and probably for all other silicates). The vibrational contributions to the Si 2 p spectrum of Si(OCH 3 ) 4 were used to fit the Si 2 p peak of olivine, with each vibrational contribution broadened to reflect the minimum line width of the XPS instrument. Although the Si 2 p envelope resulting from this procedure yields a reasonable fit to the olivine Si 2 p spectrum, additional minor vibrational contributions may be required to reproduce accurately the Si 2 p spectrum of olivine. Continued development of the technique should allow determination of transition metal oxidation states and other chemical state properties of non-conductor Al-silicates.

Ferrous (Fe2+) and ferric (Fe3+) compounds were investigated by XPS to determine the usefulness of calculated multiplet peaks to fit high-resolution iron 2p3/2 spectra from high-spin compounds. The multiplets were found to fit most spectra well, particularly when contributions attributed to surface peaks and shake-up satellites were included. This information was useful for fitting of the complex Fe 2p3/2 spectra for Fe3O4 where both Fe2+ and Fe3+ species are present. It was found that as the ionic bond character of the iron —ligand bond increased, the binding energy associated with either the ferrous or ferric 2p3/2 photoelectron peak also increased. This was determined to be due to the decrease in shielding of the iron cation by the more increasingly electronegative ligands. It was also observed that the difference in energy between a high-spin iron 2p3/2 peak and its corresponding shake-up satellite peak increased as the electronegativity of the ligand increased. The extrinsic loss spectra for ion oxides are also reported; these are as characteristic of each species as are the photoelectron peaks. Copyright © 2004 John Wiley & Sons, Ltd.

Air oxidation of Fe was compared with and without a pre-exposure to water vapour. Angle-resolved x-ray photoelectron spectroscopy (ARXPS) and QUASES were used to determine the thickness of the oxide layer formed and its composition. The extent of oxidation was found to be much less if the surface was pre-exposed to water rather than air alone. Studies performed using ARXPS were able to show that the hydroxyl-containing layer located at the surface after Fe was exposed to water vapour was located below the surface after exposure to air. This observation suggested that the oxidation of Fe in air is mediated by cation diffusion.

Photoelectron spectra of a number of chromium oxides and other compounds were studied under high spectral resolution conditions chosen to reduce the possibility of differential charging. Some of the suite of Cr(III) compounds chosen for study produced Cr 2p spectra containing fine structure that could be identified with multiplet splitting. The splitting patterns produced were similar for all trivalent binary and ternary oxides and sulphides whose patterns closely reproduced the splitting predicted for the Cr(III) free ion by Gupta and Sen. The fine structure observed for compounds such as chromium (III) chloride had a distinctly different pattern. A number of other chromium (III) compounds were studied that did not exhibit the fine structure described above; nonetheless, well-defined line shapes and reproducible peak centroids were obtained by fitting protocols. The use of such information to determine surface chemistry on chromated steels is described, based on the spectral knowledge of chromium (III) oxides and hydroxides and the chromium (VI) oxide systems.

X-ray photoelectron spectroscopy (XPS) has seen widespread use in applied and basic surface science studies since 1970. Its capabilities appear to be undergoing a series of improvements, due both to technological changes and to the culmination of efforts by the XPS community to solve a series of scientific questions that underlie the technique. This paper describes some of the advances made in the past 5 yr and uses two particular studies to illustrate the improvements: the use of mathematical deconvolution to study the initial and extended oxidation of nickel metal, and the use of XPS imaging to identify electrochemical processes during the pitting corrosion of a nickel-based alloy. Finally, the use of modern synchrotrons in further improving the spectroscopic capabilities of XPS will be described.

An atomic force microscopy (AFM) image of a surface is basically a convolution of the probe tip geometry and the surface features; it is important to know this tip effect to ensure that an image truly reflects the surface features. We have found that a biaxially oriented polypropylene (BOPP) film is suitable for checking tip performance and for cleaning contaminated tips, thus making it possible to collect images of the same area of a BOPP film surface before and after the tip was cleaned. Therefore, the difference between the two different images is solely due to the contamination of the tip. We took advantage of our ability to collect AFM images of the same area using the same tip, in one instance, contaminated and, in the other, after being cleaned. First we used blind reconstruction on the image collected using the contaminated tip. Blind tip reconstruction allows one to extract the geometry of the tip from a given image. Once we had estimated the geometry of the contaminated tip, we used it to simula...

The Auger parameter analysis in a conjunction with Au M3-edge XANES has been used to obtain the electronic configurations for Al2Au and Au2Al alloys. The net electron transfer from Al to Au (0.13 e− for Al2Au) has been estimated using the modified final state Auger parameter shifts in combination with the Thomas and Weightman model. The magnitude and direction of charge transfer appear to be in agreement with the differences in electronegativity values of the elements. Further, the opposite sign of the Auger parameter shift for Au and Al indicates that the Au core holes in the alloys are in a better screening environment than the core holes in pure Au while Al in the alloy environment is less screened. Au M3-edge XANES has been used to probe the unoccupied densities of Au 5d states. The appearance of the white-line features in Al2Au and Au2Al indicates the loss of 5d electrons at the Au site due to the charge redistribution caused by intra- [Au(5d)→Au(6s, 6p)] and extra-atomic [Au(5d)→Al(3s, 3p)] orbital hybridization. Al2Au exhibits an increased transfer of charge away from the gold compared to Au2Al due to the greater availability of empty states in the Al valence band. In general, the net charge transfer from Al to Au was substantially compensated by the 5d electron depletion, which is responsible for the shifts of core-level and valence band to higher binding energy. Changes in observed plasmon loss structures could be related to the strength of Au–Al bonding resulting from the localization of valence electrons. This further gives a clear picture of the charge rearrangement between Au and Al during alloying.

Secondary ion mass spectrometry (SIMS) image depth profiles have been made through grain structures on nickel alloy material that had displayed differing levels of intergranular stress corrosion cracking. The distributions of trace impurities, both within and outside the grain boundaries, are documented qualitatively through three-dimensional imaging, and quantitatively through the use of cross-correlation spectroscopy. Copyright © 2002 John Wiley & Sons, Ltd.

The oxidation behavior of Al2Au and Au2Al alloys during a 3-month laboratory air exposure has been investigated using SIMS, XPS and XANES. The oxide growth on both alloys and Al metal were found to be remarkably similar in the whole exposure range. XPS studies showed a rapid initial growth of oxide over the first 10 days. The oxidation of the aluminum component caused phase transitions at the near-surface to alloys which were more Au-rich. SIMS depth profiling showed that the oxide thickness was considerably greater than that estimated by XPS using a simple overlayer model. Both alloy structures were shown to be epitaxically grown homologues to the base aluminum grain structures; by contrast, oxide structures showed no preferred growth on particular alloy grains. Oxidation of the Au2Al results in a major depletion in the aluminum in the immediately below the oxide. Al L2,3-edge XANES was used to probe the nature of the oxide formed on the alloys as compared to that on pure Al. The chemical characteristics of the oxide was found to be affected by the presence of the gold. This difference in oxide structure is detected at the interface and not through the oxide generally.

The accumulation of adventitious carbon on Al and Au–Al alloy surfaces has been studied using XPS across a wide range of water vapour and air exposures. Carbon growth undergoes several discrete changes with the increase of exposure dose. X-ray irradiation effects on carbon growth were also investigated. Under x-ray irradiation Au–Al surfaces show a faster carbon growth than pure Al and Au metal surfaces. A fivefold increase of carbon contamination rate on an Au-rich Au–Al alloy (Au/Al = 5.0) surface has been observed. Copyright © 2002 John Wiley & Sons, Ltd.

Imaging XPS has been used to determine the distributional patterns of corrosion products of different chemistry on a nickel–copper alloy surface that has been subjected to pitting corrosion. Separate regions within corrosion pits can be identified with chemical processes that are suggested to be anodic and cathodic in nature. The anodic processes are indicated by a thin layer of cuprous oxide covering the base alloy, suggesting the preferential dissolution of nickel. Areas undergoing a cathodic process are indicated by the deposition of nickel as an oxide or hydroxide. Adjacent regions also were studied by XPS and characterized further by low-voltage SEM/energy-dispersive x-ray imaging and time-of-flight SIMS techniques to obtain confirmatory and complementary information. Typically, the anodic and cathodic areas were tens of microns in size. Copyright © 2002 John Wiley & Sons, Ltd.

The interactions of carbon dioxide and carbon monoxide at moderately high pressures with clean iron surfaces have been studied using x-ray photoelectron spectroscopy (XPS) and static time-of-flight secondary ion mass spectrometry (ToF-SIMS). Clean iron surfaces were analysed after exposure to CO2 or CO gas having pressures of 10–104 Pa at 25 °C. Exposure to either gas results first in a thin surface film of FeO. In addition, this oxide is completely or partially covered with a carbonaceous layer. The thickness of the carbon layer is influenced by the type of gas used and its pressure. The ToF-SIMS studies using isotopically labelled 13CO2 under the same reaction conditions show that the labelled carbon is not enriched on the surface and therefore no direct reaction occurs between the labelled carbon and the surface. It is proposed that the influence of either gas on the carbonaceous layer formed may be indirect: these gases may alter the equilibrium partial pressures of other adsorbates on the walls of the vacuum chamber. Copyright © 2002 John Wiley & Sons, Ltd.

The Maximum Entropy Method (MEM) has been used to deconvolute the valence-band XPS spectra of thin film Au–Al alloys. The enhanced resolution allows fine changes in the electronic structures of the thin film alloys to be distinguished with the aid of the Au4f core-level spectra. This particular alloy series allows one to examine the 5d electronic interaction between gold atoms as aluminum is gradually added to the matrix. Aluminum is shown to have a much stronger quenching effect on such interactions than has been found previously for copper.

The initial stages of oxide formation following the interaction of water vapour with polycrystalline aluminium surfaces have been studied using x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Attenuation of the electron signal from the metallic substrate has been used to follow the oxidation kinetics of aluminium as a function of energy and dose of Ar+ ion bombardment and temperature. The effects of energy and doses of Ar+ ion bombardment on oxidation kinetics have been examined in the energy range 1–5 keV and ion dose ranging from 1.3 × 1016 to 3.8 × 1017 ions cm−2. Although the increase in energy of Ar+ ion bombardment slightly modified the oxidation kinetics, the effects of ion dose on oxidation kinetics are shown to be more complex. There is a threshold dose of Ar+ ions above which the surface activity becomes significantly reduced; this is ascribed to cluster formation blocking the surface diffusion pathway in the near-surface region. The oxidation kinetics of aluminium also have been studied in a range of temperature from room temperature up to 573 K. As the temperature increases, the oxidation rate of aluminium decreases due to a decrease in the sticking probability of water molecules on the aluminium surfaces. The observed temperature dependence of the oxidation kinetics is likely to be due to a precursor mechanism of water desorption. Copyright © 2001 John Wiley & Sons, Ltd.

The oxidation of thin-film Au- Al alloy, as well as pure Al, has been studied using XPS across a wide range of water vapour and air exposures (0.1 L to 1 × 1014 L). The alloys and the pure Al all undergo a similar set of oxide growth kinetics. In addition to the three stages of early growth kinetics identified for Al in previous studies, a fourth stage is identified at air exposure doses of >109 L. During this stage, the average composition of the film changes from Al2O3 to Al2O3·H2O. The Al 2p lineshapes for the oxides grown on pure Al and Au-Al alloy are different; the origins of this appear to result, in part, from a change in the Fermi level as the oxide thickens. The Al L2,3 X-ray absorption near-edge structure (XANES) furthermore provides a complementary probe of the different oxide structures on alloy and Al metal. Thus, their chemical characteristics are affected also by the presence of the gold. This difference in oxide structure is detected at the interface and not through the oxide generally. Copyright © 2001 John Wiley & Sons, Ltd.

The morphology of a surface imaged by dynamic force mode atomic force microscopy is obtained through an interaction between the probe tip and surface features. When the tip is contaminated and the size of the contaminant is comparable to the size of the features on the sample surface, artifacts attributable to the contaminant are observed to dominate the image. To reduce the possibility of effects from such artifacts, the tip performance should be checked by scanning a reference sample of known surface morphology. We demonstrate a simple and effective method of evaluating tip performance by the imaging of a commercially available biaxially oriented polypropylene (BOPP) film, which contains nanometer-scale-sized fibers. This sample is appropriate for use as a reference because a contaminated tip will not detect the fiberlike network structure. In addition, BOPP has a soft, highly hydrophobic surface of low surface energy, thus ensuring that the tip will not be damaged or contaminated during the evaluation ...

Using atomic force microscopy we have examined the surface morphology of sequentially biaxially oriented polypropylene (BOPP) films. The surface was shown to be dominated by a nanometer-scale fiber-like network structure, the configuration of which was found to be determined by the relationship between the draw ratios used in the bi-directional stretching processes [machine draw (MD) and transverse draw (TD)]. For the film fabricated with MD and TD ratios of 5.2:1 and 9:1, respectively, preferential orientation of fine fibers to the TD direction and larger veins to the MD direction were observed. When MD and TD ratios became similar, no predominant TD direction fiber alignment and no larger veins were observed. We have shown that the residual effects of the first stretching of the film surface can provide information on the way in which morphological development of the BOPP occurs.

The oxidation kinetics of Mg-, Si- and Fe- implanted aluminum has been studied at room temperature and a water vapour pressure of 2.0◊10'6 Pa using X-ray photoelectron spectroscopy. The elements Mg, Si and Fe were implanted into pure aluminum at low ion doses from 6.0◊1012 to 3.6◊1013 ions cm'2. Secondary ion mass spectrometry (SIMS) depth profiles have shown that the element distributions of Mg and Fe in aluminum are consistent with the theoretical depth profiles calculated using a TRIM program. The implanted elements are distributed in the near surface region with their maximum concentration at a depth of ~50 nm. In the case of implanted Si, however, the SIMS depth profile shows no maximum concentration peak, and the near-surface concentration is much higher than that calculated. This is ascribed to diVusion of Si toward the surface during implantation. The oxidation kinetics of implanted aluminum have shown that surface concentrations of implanted Si, as low as 40 ppm, cause an increase in the Al oxidation rate compared to the pure metal. By contrast, equivalent concentrations of implanted Mg in aluminum result in a lowered oxidation rate until the oxide reaches a thickness of 3 monolayers, after which a rapid increase in oxidation occurs. Implanted Fe in the same concentration range does not cause any change in oxidation rate of aluminum. These oxidation kinetics can be explained on the basis of metal vacancies in the defect structure of aluminum thin oxide films. The eVects of surface damage caused by ion beam during the implantation experiment were also determined by measurements of oxidation kinetics. © 1999 Published by Elsevier Science B.V. All rights reserved.

Surface analysis techniques, including x-ray photoelectron spectroscopy with small-spot analysis (down to 100 μm 2 ) capabilities, field emission scanning Auger microscopy, electron energy-loss spectroscopy in association with these two techniques and micro-Raman spectroscopy, have been used to collect surface information on specific facets of commercially available submillimetre-sized cubic boron nitride (cBN) crystals. With the freedom of choosing a specific facet with a known orientation relative to the probing beam and detector, it is possible to obtain accurate information on the surface compositional structure of a cBN crystal before and after a surface reaction.

The three-way parallel factor analysis (PARAFAC) has been used to decompose a set of XPS (X-ray photoelectron spectroscopy) spectra which result during the oxidation of aluminium surfaces by water vapour. Al(2p) and O(1s) core-level photoelectron lines have been used to follow oxide film growth on clean aluminium surfaces as a function of exposure time and pressure of water vapour. The PARAFAC solution provides new information on elemental processes in the very initial stages of oxidation kinetics, showing new components in the XPS spectrum, as well as their evolution through the range of time and pressure variables. Reaction of H2O vapour with aluminium results in attenuation of the metallic peak, binding energy (BE) at 72.87±0.05 eV, and increase of the oxidic peak, BE at 75.80±0.05 eV. An additional factor is identified, which suggests the formation of an interface metal hydride, with BE at 72.4(4) eV, as well as a concomitant oxide peak at 75.4(3) eV. At pressures above 1.3×10−5 Pa this factor is diminished; this is presumably due to the increase in recombination of atomic hydrogen.

Chemical reactions of the surface of a polypropylene (PP) film in the presence of various combinations of ultraviolet light and ozone gas (UVO) conditions were studied. Exposure of the polymer surface was carried out in a laboratory-scale UVO reactor in which the following parameters could be varied: ozone concentration, wavelength of ultraviolet (UV) radiation, pulsed operation of the UV lamps, the treatment distance between the PP film and the lamps, and water vapor concentration. Advancing and receding contact angle measurements were used to monitor surface energy changes imparted by the treatment. Two spectroscopic techniques, X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance–Fourier transform infrared spectroscopy (ATR–FTIR), were used to monitor changes in the polymer surface chemistry. Oxidation of the PP surface is proposed to occur through two alternate mechanisms: (1) insertion of an O (1D) atom to form ether linkages, or (2) hydrogen abstraction by O (3P), followed either by crosslinking or by reaction with oxygen species to form carbonyl and/or carboxyl functional groups. It was found that reaction 1 dominates initially, but that its rate is reduced by the formation of products from reaction 2. It appears that the ether functional groups produced by reaction 1 are responsible primarily for increased surface energy. Carbonyl, carboxyl, and hydroxyl groups formed in reaction 2 appear to have little additional effect on surface energy; it is proposed that these groups are involved strongly in intramolecular hydrogen bonding, thereby decreasing their availability to contribute to increased surface energy. High-energy UV radiation was found to play only a minor role in the surface modification of PP. Of the narrow range of ozone concentrations studied, no clear relationship was found to exist between ozone concentration and rate of modification of the surface; thus, the concentration of ozone must not affect the relative concentrations of products from the competing reactions. Increased surface oxidation and decreased contact angles were observed when the lamp-to-sample distance was minimized. The presence of water vapor during UVO treatment was found to lead to greater oxygen uptake after short-term treatments but did not result in increased surface energy. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2489–2501, 1999