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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.

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.

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.

(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.

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.

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.

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.

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 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 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.

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

Three-way parallel factor analysis (PARAFAC) has been used to decompose a set of x-ray photoelectron spectroscopy (XPS) spectra that result during the oxidation of aluminium surfaces. The Al 2p 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. In this paper, a fine peak structure of the XPS Al 2p spectrum has been extracted using PARAFAC. 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 a range of time and pressure variables. As expected, the reaction of water vapour with aluminium results in attenuation of the metallic peak at binding energy (BE) 72.87±0.05 eV and an increase of the oxidic peak at BE 75.80±0.05 eV. However, an additional factor is also identified, which suggests the formation of an interfacial metal hydride at BE 72.4(4) eV, as well as a concomitant oxide peak at 75.4(3) eV. Both are ascribed to products of the hydrolysis of adsorbed water molecules at the aluminium interface. At pressures above and below 1.3×10−5 Pa this factor is diminished; in the case of higher pressure, this is ascribed to an increase of the recombination of atomic hydrogen. Copyright © 1999 John Wiley & Sons, Ltd.

The oxidation kinetics of Mg-, Si-, and Fe-implanted aluminum has been studied at room temperature and a water vapor pressure of 2.0 {times} 10{sup {minus}6} Pa using X-ray photoelectron spectroscopy. The elements Mg, Si, and Fe were implanted into high-purity aluminum at low ion doses from 6.0 {times} 10{sup 12} to 3.6 {times} 10{sup 13} ions {center_dot} cm{sup {minus}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 (transport of ions in matter) program. The implanted elements are distributed in the near-surface region with their maximum concentration at the depth of {approximately} 50 nm. In the case of implanted Si, however, SIMS depth profile shows no maximum concentration peak and the near-surface concentration is much higher than that calculated. This is ascribed to diffusion of Si toward the surface during implantation. 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, implanted Mg, surface concentration from 20 to 120 ppm, results in a lowered oxidation ratemore » until the oxide reaches a thickness of {approximately}0.55 nm, and after that a rapid increase in oxidation occurs. Implanted Fe does not cause any change in the 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 effects of surface damage caused by the ion beam during the implantation experiment were also determined by measurements of oxidation kinetics.« less

The surface oxidation behavior at room temperature of two thin films of the alloys Al2Au and Au2Al was investigated using X-ray photoelectron spectroscopy (XPS). Relatively large chemical shifts of both Au4f and Al2p photoelectron lines with the alloy composition assist the identification of additional alloy phases. The spectral resolution has been improved by the use of the Maximum Entropy Method which removes the external contributions to the photoelectron linewidth. In the case of Au2Al, as much as 80% of the surface phase is transformed into two new alloy phases. This is equivalent to a transformed layer thickness of 10 nm. For the Al2Au, oxidation also results in a partial phase transition to a gold-enriched alloy, but the transition region extends only to an estimated depth of 2 nm.

Three-dimensional (3D) SIMS images of secondary ion distributions in a solid volume can be produced from a stack of individual images acquired sequentially at different depths during depth profiling of the solid. While it is often possible to obtain visual correlations of large-scale features that occur in several images in the stack, the correlation of less-obvious features requires a more mathematical approach. We present here two cases where image cross-correlatiob spectroscopy (ICCS) can be used to clarify the presence or absence of organized structure in a 3D depth profile. In one example, the images of deuterium distribution in a zirconium oxide thin film were confirmed to exhibit order over a series of images, thereby suggesting the existence of continuous pores in the material. In a second example, the apparent clustering of gold distributions in a 3D profile of an arsenopyrite mineral was shown to be uncorrelated and likely an artefact of data collection.

The maximum entropy method (MEM) is applied to the deconvolution of x-ray photoelectron spectra. This method provides the least-biased estimate of the unbroadened spectrum by using the Shannon information content as the regularizing functional. The large-scale, non-linear optimization problem is solved using a robust variable metric sequential-quadratic programming (SQP) algorithm implemented on a personal computer (PC). The program is tested on simulated spectra and then shown to provide reliable resolution enhancement of measured spectra by unfolding a measured instrumental resolution function. Typical resolution enhancements of 50% are achievable in < 15 min of computer time.

The maximum entropy method (MEM) is a new procedure for deconvoluting exciting line width and instrument resolution contributions from XPS spectra. MEM has been used to obtain additional detail from XPS 2p spectra collected from pyrite, marcasite and arsenopyrite surfaces which have been exposed by fracturing under UHV conditions. The resultant spectra have line widths that are nearly 50% narrower than the original spectra. Deconvoluted S 2p and Fe 2 p 3 2 spectra are shown to contain contributions from species located in disrupted lattice sites near the fracture surface as well as species on the outermost fracture surface. Iron 2p spectra are also found to exhibit fine structure which is attributed to multiplet splitting.

The diffusion of D 2 O into and through oxide films on Zr-Nb alloys was investigated using secondary ion mass spectrometry (SIMS) image analysis. In preparation for this, the microscopic structures of the oxide were studied in relation to the grain structures in the underlying alloy. On alloys containing low concentrations of niobium (1-2.5 wt.%), the oxide was found to exhibit more localized growth, particularly above grain boundaries in the alloy. Such oxide regions appeared to be considerably more porous to D 2 O ingress. By contrast, the oxide film on the Zr 20 wt.% Nb alloy was found to be the most resistant to D 2 O ingress; no local regions of higher porosity could be found.

X-ray photoelectron spectroscopy (XPS) has been used to follow oxide film growth on pure magnesium and pure aluminum surfaces across 12 orders of magnitude exposure to water vapour and humid air. Both Mg and Al exhibited logarithmic-type oxide growth kinetics. Oxide film growth was observed to continue well into the ambinent exposure range, suggesting the possibility for modifying the oxide film chemistry while still under atmospheric conditions. The chemistry of the films was monitored as a function of exposure by examining the changes in the core-level O 1s spectra and the associated oxidised metal/oxygen stoichiometry. It was observed that both Mg and Al surfaces initially formed partially hydrated oxide surfaces which became progressively more hydrated at longer exposures.

A number of binary oxides, sulphide compounds and complex minerals have been analysed by x-ray photoelectron spectroscopy to give the relative intensities of major photoelectron lines. Where possible, compound surfaces were prepared by fracturing in vacuo or in inert gas to avoid contamination. Alternatively, some of these compounds have undergone a mild thermal treatment in vacuo to remove much of the surface contamination which normally affects such intensity measurements. The experimental line intensity ratios were corrected only by their particular photoelectron cross-section and inelastic mean free paths. For most oxides and complex minerals studied, good agreement is obtained with the expected stoichiometry, particularly when using photoelectron lines of higher kinetic energy. This tends to support the use of a simple background approximation when measuring specifically with those oxides involving non-transition elements. The sulphides studied mostly involved transition metals ; agreement between calculated and actual stoichiometry was only modest. Some differences in measured surface stoichiometry occurred as a result of the ambient conditions within which the fracture was made ; fracture in vacuo produced a different S/M ratio than did fracture in an inert gas environment.

The gas phase downstream products of an air glow discharge have been measured, using absorption and emission spectroscopies, as a function of plasma power, air flow rate, and distance from the plasma. In addition, the reaction of these products with a linear low density polyethylene (LLDPE) polymer surface has been followed using x-ray photoelectron spectroscopy (XPS). At higher air flow rates (>300 sccm), the primary reactive species is confirmed to be O( 3 P) atomic oxygen. Some O( 3 P) is generated in the plasma itself, but more appears to be formed in the downstream region, because of dissociation of molecules in their excited states. At low flow rates, the concentration of O( 3 P) is strongly depleted at the sample position, but other atomic oxygen states become more prominent. O( 5 S) and O( 3 S) are two states which are identified. XPS studies of the polyethylene surface reacted at high flow rates shows oxygen functionalities that are likely the result of an initiation by hydrogen abstraction. At low flow rates, the products suggest initiation by oxygen insertion. Thus, changes in flow rate can result in major changes to the polymer surface chemistry.

X-ray photoelectron spectroscopy (XPS) was used to examine the corrosion films formed on nanocrystalline (nc) and amorphous Ni-P alloys in 0.1 M H 2 SO 4 . Neither the nc nor the amorphous alloys were found to exhibit passivity. An enrichment of elemental P compared to Ni was observed at the surface of both materials, suggesting that Ni is preferentially dissolved during anodic polarization. The high volume fraction of grain boundaries and triple junctions on the nc specimens resulted in enhanced dissociative adsorption of oxygen and hydroxyl species from solution. The films formed were, however, non-protective because the defective nc surfaces also facilitated atom dissolution and oxidation of surface P atoms from hypophosphite to soluble phosphate anions. At higher applied potentials, the thick, porous films formed on the nc specimens provided a small kinetic barrier to further dissolution, resulting in slightly lowered anodic current densities compared with amorphous Ni-P.

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.

Factor analysis (FA), the multivariate statistical technique, has been used to extract chemical bonding information from SIMS secondary ion energy distributions. The method is outlined in detail and shown to be capable of constructing quantitative profiles for the chemical states of zirconium present in ZrO2/Zr and ZrNx/Zr structures. In addition, a truncated data collection procedure wherein secondary ion intensity values are collected at a fixed number of emission energy values during the depth profile is outlined. This method, which enables data to be collected in a shorter time and from a smaller sample volume, is subsequently shown to yield reliable results, as confirmed by FA of Auger depth profiles on similar specimens.

This report illustrates, in a stepwise fashion, the application of a new method for quantifying SIMS results (termed the infinite velocity method) to the depth profile analysis of multilayered samples. The two samples analysed comprised a silicon substrate implanted with cobalt and a silicon substrate bearing an oxide layer implanted with boron. Concentrations were extracted by: sampling the secondary ion emissions over several kinetic energies during the depth profile; correcting the resulting intensities for instrument transmission and sputter yield effects, so that these may be plotted against the inverse of the velocity; and referencing the point at which the resulting curves intersect with the intensity axis (intensity at infinite velocity) to an element whose concentration is known, or to the sum of all major element intercept data. Characteristic velocity data obtained from each cycle of the depth profiles were also used to illustrate a new method for defining the position of the interface. To illustrate the validity of these results, peak concentrations were compared with those calculated via the integration method as well as Auger depth profile analysis

Twelve elements spanning a mass range of 197 atomic mass units from five standard reference materials and three implant materials were analysed to ascertain the validity of a new method, termed the infinite velocity method, for quantifying the negative monatomic secondary ion emissions resulting from Cs-bombarded surfaces. This method extracts quantitative data by extrapolating secondary ion yield versus kinetic energy data to the infinite velocity limit. Extrapolation to infinite velocity is done because matrix effects are theoretically predicted to be removed at this limit. Plotting the extrapolated data against known concentrations for the homogeneous standard reference materials yielded linear standardization curves for all elements analysed, indicating that the matrix effect is indeed removed, i.e. sensitivity factors were not required

The room temperature interaction of water vapour with polycrystalline magnesium specimens deliberately contaminated with very low levels of iron (120 to 700 ppm by weight) has been examined using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). The initial adsorption and subsequent reaction of the water molecules with the iron-containing specimens was shown to be retarded during the very early stages. The influence of iron on the uptake of oxygen on magnesium surfaces was not found to be a clear function of iron concentration. This was likely due to the fact that the solubility limit of iron in magnesium ( ~ 55 wt ppm) was exceeded in each specimen, suggesting that iron in magnesium solid solution strongly influences the oxidation process. The oxide growth rate at longer exposures, during the bulk thickening regime of the oxidation process, was found to be unaffected by the iron content. Segregation of iron into the oxide film was, however, detected by static secondary ion mass spectrometry (SSIMS). Finally, the saturated oxide films formed on Fe-containing magnesium specimens were shown by XPS to be more “defective” than those formed on pure magnesium.

The room temperature interaction of water vapour with two polycrystalline MgAl alloy surfaces, Mg-3.0wt%Al and Mg-8.5wt%Al, has been examined in detail using Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). By using calibrated doses of deuterated water vapour, three stages of early oxide growth were recognised: dissociative chemisorption during low exposures (up to ≈ 0.5 langmuirs (L)); oxide nucleation and island growth during intermediate exposures (≈ 0.523.0 L); and slow, diffusion-controlled bulk oxide thickening after coalescence of the oxide islands. AES lineshape analysis indicated that water vapour dissociates on MgAl surfaces, leading to the simultaneous adsorption of oxygen atoms on both Mg and Al atoms present on the surface. Modelling results suggested that the rate of oxide nucleation and growth was enhanced on MgAl surfaces compared to on pure Mg surfaces, particularly at higher Al contents. In addition, it was found that magnesium oxide islands were preferentially nucleated at Mg-rich regions and subsequently grew to cover the mixed MgA-O chemisorbed precursor layer. At longer exposures, XPS indicated that Al 3+ ions were incorporated into the growing oxide film, resulting in an increased activation energy for ion movement and a pronounced decrease in the rate of bulk thickening. The surface concentration of aluminum was observed to decrease slowly during the bulk thickening regime. The results have been interpreted based on the Cabrera-Mott theory of low temperature oxidation.

Four tinplate specimens with different corrosion properties were studied using secondary ion mass spectrometry (SIMS) image analysis. The continuity of the structure of the interfacial iron-tin alloy was able to be examined using a volume rendition computer program, which generated a three-dimensional representation of the stack of ion images. The surface coverage of tinplate was found to vary widely on some specimens; those exhibibiting poor corrosion characteristics were found to have little or no elemental tin covering the raised regions between the rolling grooves

The room temperature interaction of water vapour with magnesium surfaces irradiated with Ar + ions in the dose range θ = 10 to 2000 ions/surface atom and ion energy range 1 to 5 keV has been systematically studied by Auger electron spectroscopy (AES). The character of the kinetics of water interaction with irradiated surfaces has been found to be dependent upon the total ion bombardment dose and the ion energy and to change with the level of water exposure. The effect of ion bombardment was found to be most pronounced in the oxide nucleation and growth stage of the oxidation process. The dissociative chemisorption and final bulk thickening regimes were only weakly affected by prior irradiation. The results have been interpreted based on the assumption of competition between the effects of radiation defects (vacancies, vacancy clusters, dislocation loops) and implanted argon atoms on the oxidation process. The effect of vacancy-type defects was speculated to be the provision of adsorption sites of high sticking probability and nucleation sites of reduced activation energy for place exchange and subsequent island growth. The effect of implanted argon atoms was speculated to be the blocking of adsorption and nucleation sites and interference with oxide island ordering. At relatively high water exposures (20 L) there was enhanced penetration of oxygen into the magnesium lattice postulated to occur along dislocation emergence points. No such enhanced penetration was observed for shorter water exposures (0.3 L). The limiting thickness of the oxide layer formed on magnesium at room temperature was not found to be affected by the level of prior ion bombardment.

This work explores the use of time-of-flight secondary ion mass spectrometry to characterize films on Monel 400 steam generator tubing that has been subjected to simulated CANDU reactor start-up conditions. The results are compared with those obtained using more traditional techniques, including scanning Auger microscopy and x-ray photoelectron spectroscopy. Copyright © 2002 John Wiley & Sons, Ltd.