bluuebunny/crossref_metadata_2025 huggingface dataset:
A spin polarization analyzer attachment to a scanning auger microprobe
Authors: Welkie David G.
Published: May 2005

A new, compact electron spin polarization analyzer attachment to a scanning Auger microprobe has been described. Its operation and present performance has been demonstrated using the SEMPA technique to image the surface magnetic microstructure of three different types of magnetic samples. The unique advantages of SEMPA have been identified previously; those that were illustrated in these applications are: (1) the tecnique is surface sensitive; (2) the magnetic structure is imaged independently of the surface topography; (3) the contrast and signal are large; and (4) all three components of the polarization can be determined and therefore the surface magnetic vector can be mapped. Additionally, high spatial resolution can be achieved.
Comparison of electron attenuation lengths and escape depths with inelastic mean free paths
Authors: Jablonski A. , Ebel H.
Published: May 2005

It is shown that calculations of electron attenuation lengths and escape depths would require modification of definitions proposed in the literature, since these definition are not universally applicable. Exemplary experimental arrangements are indicated for which more general definitions are necessary, and such definitions are proposed. A Monte Carlo program has been developed with which it is possible to estimate attenuation lengths and escape depths. A comparison of these parameters is made for photoelectrons arising from s levels.
Differential reflectometry and its application in materials science
Authors: Hummel Rolf E.
Published: May 2005

The differential reflectometer is briefly described, Its use as a fast, simple, and non‐destructive surface analytical instrument is stressed and several examples are provided. Among them are a study of the electronic structure of alloys, the identification and evaluation of surface films in situ, and some investigations which elucidate the damage which is inflicted on semiconductor materials and electronic devices by ion implantation and other means.
Surface characterization by means of photoemission of adsorbed xenon (PAX)
Authors: Wandelt K. , Markert K. , Dolle P. , Jablonski A. , Niemantsverdriet J. W.
Published: May 2005

Photoemission of adsorbed xenon (PAX) is a very sensitive probe towards the local work function. This is shown with three selected examples, namely a bimetallic Ag/Ru(001) surface, a trimetallic (Ag + Au)/Ru(001) surface and an oxygen exposed Si(111)7 × 7 surface, which prove PAX to be a powerful technique for the qualitative and quantitative characterization of surface heterogeneities on an almost atomic scale.
Atom‐Probe analysis of grain boundary segregation
Authors: Nordén H. , Andrén H. O.
Published: May 2005

Atom‐probe micronalysis has a very high spatial resolution and equal detectivity for all elements, including the lightest. It is therefore well suited for the study of grain boundary segregation. In this paper the accuracy and spatial resolution of atom‐probe analysis are discussed, as well as the advantage of and limitations to the method. Specimen preparation methods are descibed, in particular controlled preparation using electron microscopy and pulse electropolishing. Three examples of atom‐probe studies of grain boundary segregation are given: cobalt segregation to carbide grain boundaries in cemented carbide materials; boron grain boundary segregation in austenitic stainless steels; and nickel segregation to grain boundaries in tungsten.
Grain boundary segregation in inconel 600
Authors: Caceras P. , Ralph B. , Allen G. C. , Wild R. K.
Published: May 2005

Inconel 600 is a nickel‐based superalloy which has been shown to exhibit stress corrosion cracking under certain conditions. In general the stress corrosion cracking (SCC) is intergranular in nature and hence attention has been focused on the grain boundary microstructure. A series of model alloys was produced with a range of impurity levels. Initially a high‐purity base alloy was prepared to which boron, carbon, silicon and phosphorus was added. Alloys were then examined in the mill‐annealed state and after a standard thermal ageing treatment. The grain boundary interface was analysed using scanning Auger microscopy (SAM) with the grain boundaries being exposed, only after hydrogen embrittlement, using an in situ tensile stage. The segregation of phosphorus and boron to the grain boundary surface was studied and a number of particles identified at grain boundaries. The effect of the segregants on the mechanical properties of this alloy is discussed.
Analytical study on the Fe/Ti interface in titanium‐clad steels
Authors: Kurosawa Fumio
Published: May 2005

The precipitates on the Fe/Ti interface in a rolled titanium‐clad steel was investigated by the potentiostatic etching with non‐aqueous electrolyte (SPEED method) followed by SEM observation and chemical analysis using a computer‐aided X‐ray microanalyser (CMA). Titanium‐clad steel (CP‐Ti/0.01% C steel) was annealed between 700 and 1000 °C for 0.5–100 h in vacuum. The cross‐section of the annealed clad steel was etched by the SPEED method and the morphology and the chemistry of the precipitates were investigated in relation to the interface by using SEM and CMA.

Film‐like titanium carbide, intermetallic compunds (Fe2 Ti, FeTi) and β‐Ti containing Fe were observed on the Fe/Ti interface.

The shear strength depends on the quantity of film‐like titanium carbide on Fe/Ti interface but intermetallic compunds and β‐Ti have slight influence.

Thus it is considered that the embrittlement of the Fe/Ti interface was caused by (1) diffusion of carbon in steel towards the titanium layer, (2) precipitation of film‐like titanium carbide at the interface, and (3) fracture at the film.
Oxygen‐Containing species on amorphous Fe80B20 and Fe40Ni40B20 alloys during chemisorption of CO and H2
Authors: Zsoldos Z. , Schay Z. , Guczi L.
Published: May 2005

Our study was conducted to determine the forms of the oxygen chemisorbed during the interaction of CO and H2 with FeNiB and FeB alloys in both amorphous and crystallized states using photoelectron spectroscopy. Four different kinds of oxygen were observed to exist on the samples based upon O Is binding energies (B.E.), that is, 530.1 ± 0.2 eV, 531.0 ± 0.2eV, 531.5 ± 0.2 eV and 532.0 ± 0.2 eV. The first peak is probably related to bulk iron oxide while the last one correlates directly with the occurrence of boron oxide species. The second peak is believed to be the signal of a weakly chemisorbed surface oxygen species in atomic state covering the surfaces after room temperature and low pressure (10−4Pa) oxygen adsorption. It can be the possible precursor for deep oxidation of metal. The third peak may be assigned to the oxygen species stuck to the boron‐metal interfaces having migrated from the metal surface to the surrounding boron atoms. Thereby small metal ensembles can be stabilized. In an ealier work it was established that the highest catalytic activity in the CO + H2 reaction can be related to the partially crystallized FeNiB alloys. It was supposed to be due to a special surface structure hindering the formation of the inactive graphitic species. In the light of the present study his structure can be stabilized by this boron oxide.
Equilibration processes at NiO surfaces
Authors: Nowotny J. , Sloma M. , Weppner W.
Published: May 2005

Work function (WF) measurement were performed to monitor defect processes at the surface of NiO single crystals during re‐equilibration at elevated temperatures using gas atmospheres of controlled oxygen activities. The WF data are reported for isothermic redox experments performed at 780°C within an oxygen activity ranging between 1.74 × 102 and 4.3 × 10−4Pa.

Determination of the WF is based on the measurements of the contact potential differences by the Kelvin probe. Pt was applied as a reference level. Y‐stabilized zirconia was used for calibration of the reference electrode under experimental conditions.

The WF data obtained for a NiO single crystal are evaluated in terms of point defect equilibrai in the nearsurface region. It is shown that the ideal defect model is applicable for a freshy cleaved NiO surface within about 20 h of treatment at 780°C. At longer times the near‐surface defece defect model becomes more complicated involving strong defect interactions. The complications are mainly produced by segregation of bulk extrinsci defects. The outer crystal layer of the studied NiO material becomes signficantly enriched with Ca which segregates to surfaces and presumably to grain boundaries.

The impact of the experimental data of the kinetics of high temperature heterogeneous processes is discussed.
Selective oxidation and chemical state of Al and Ti in (Ti, Al)n coatings
Authors: Hofmann Siegfried , Jehn Hermann A.
Published: May 2005

(Ti, Al)N hard coatings are a promising alternative to TiN owing to an improved resistance to oxidation. In order to study the oxidation process in more detail, (Ti, Al)N coatings reactively sputter‐deposited on high speed steel substrates from a target composed of Ti:Al = 50:50 (at%) were annealed in air and in vacuum at temperatures between 500 and 800 °C. Auger electron spectroscopy (AES) sputter depth profiling as well as X‐ray photoelectron spectroscopy (XPS) studies indicate a high stability of the Ti‐N bond, whereas Al has considerable mobility in the mixed nitride. The chemical shift of the Al 2p XPS and LVV AES peaks allow a distinction between oxide, nitride and metallic states of Al. Preferential sputterin during depth profiling with 3 keV Ar+ ions resulted in a relative depletion of Al in the surface layer. It is concluded, that the Al in (Ti, Al)N is only weakly bonded to nitrogen as compared to Ti.
EXAFS study of passive films on Ni and NiMo alloy electrodes
Authors: Bosio L. , Cortès R. , Delichère P. , Froment M. , Joiret S.
Published: May 2005

The specular reflectivity of x‐rays at sufficiently small grazing angles is absorption‐coefficient‐dependent so that the EXAFS technique can be used to probe the surface. This method allows in situ measurements. Applications to the study of passive films on nickel and nickel‐molybdenum alloy electrodes are presented. In both cases, the passive films is found to be composed of NiO entities probably ordered perpendicularly to the electrode. Molybdenum enrichment in the surface layer is confirmed by an increase of the Mo k edge signal.
A study of the development of tribological oxide protective films mainly by Auger electron spectroscopy
Authors: Sullivan J. L. , Saied S. O.
Published: May 2005

Since the importance of oxide film formation in the protection of contacting surfaces was recognized, there has been speculation and controversy on the nature and mechanisms of formation of such films. In this work films generated under different sliding conditions have been examined, mainly by Auger electron spectroscopy. The results show that there are two major mechanisms responsible for film formation, a homogeneous diffusion controlled mechanism and one due to agglomeration and compaction of smaller oxide particles and that system geometry is important in determining the dominant mechanism in any particular case. In both mechanisms the protective oxide film grows to critical thickness before becoming detached to form a wear particle.
Surface analysis in atmospheric environmental studies
Authors: Adams F. , De Waele J.
Published: May 2005

Surface analysis can now be applied on the microscopical level using a number of instrumental analytical techniques. A review is given of the field of air pollution and a brief description is presented of a number of examples from our laboratory practice concerned with the characterization of air particulates and emission samples or the surface characterization of pure and modified asbestos fibres.
Application of AES micro‐analysis to interface characterization in TiSi diffusion couples: 1—Phase analysis
Authors: Quenisset C. , Naslain R. , Demoncy P.
Published: May 2005

A detailed analysis of the silicides which are formed by diffusion at a titanium–silicon interface was performed by quantitative AES analysis. The diffusion couples were annealed in vacuum at temperatures ranging from 450 to 700°C. Semi quantitative AES spectrum/peak‐to‐peak height analytical mode was found to be not accurate enough to identify the titanium silicides particularly at low temperatures and short durations annealing. A quantitative method based on E · N(E) spectra and peak‐to‐background ratios, was used which led to more reliable results. Furthermore, the shape of the titanium Auger electron peaks were used to confirm the phase nature. After a diffusion treatment of moderate intensity, the interaction zone is mainly formed of two silicides, Ti5Si3 and TiSi2. On the contrary, under severe diffusion conditions, the disilicide phase is predominant. Finally, the growth of TiSi2 rejects oxygen (present in trace amounts in the titanium film) in the Ti‐rich side of the couple.
Auger electron spectroscopy from elemental standards. I: Theoretical calculations
Authors: Batchelor D. R. , Rez P. , Fathers D. J. , Venables J. A.
Published: May 2005

New calculations of electron impact ionization cross‐sections and back‐scattering correction factors have been undertaken for comparison with experiment. The ionization cross‐sections were obtained from ab initio Hartree–Fock–Slater calculations and the back‐scattering correction factors from the solution of the Boltzmann transport equation. The cross‐sections and correction factors have been calculated for the elements silicon, copper, silver and tungsten over the energy range 0.3–30 kV and the incident angle range 0–90°. These calculations are compared with previous calculations available in the literature.
A study of surface segregation in austenitic stainless steels—factors that control this segregation, its relation to grain boundary segregation and its usefulness for interpreting intergranular corrosion data
Authors: Briant C. L.
Published: May 2005

This paper reports a study of various factors that influence surface segregation in austenitic stainless steels. In particular four rather practical questions are addressed, all of which arose from various concerns about the corrosion behavior of these alloys. They are the following: (1) will significant segregation occur at temperatures below 500°C?; (2) is sulfur segregation affected by the presence of a strong sulfide former such as Mn?; (3) does silicon segregate to interfaces in these alloys?; and (4) do niobium additions affect phosphorus segregation in these alloys? The results show that at temperatures below 500°C, phosphorus, sulfur, nitrogen and silicon will all segregate, although at about 300°C the kinetics of segregation are becoming rather sluggish. Silicon will also segregate at temperatures at least up to 650°C. Manganese additions greatly lower sulfur segregation but niobium additions do not retard phosphorus segregation. In addition to the presentation of these results on surface segregation we consider what can be learned from them about grain boundary segregation and how they can be used to help interpret results on intergranular corrosion and stress corrosion cracking.
Lattice and grain boundary diffusion of oxygen in titanium subhydride studied by Auger sputter profiling
Authors: Wittberg T. N. , Wolf J. Douglas , Keil R. Gerald , Wang Pu Sen
Published: May 2005

Anodic TiO2 films were grown on titanium subhydride samples under galvanostatic conditions. The samples were heat treated at temperatures between 550 and 600°C and changes in the profile of oxygen concentration as a function of depth were monitored using Auger electron spectroscopy (AES). For TiH0.87 and TiH0.96 at 600°C, the lattice oxygen diffusivity, D1 is ∼5 × 10−15 cm2 s−1 and the grain boundary oxygen diffusivity, Db, is given by δDb ∼3 × 10−18 cm3 s−1 where δ is the grain boundary width in centimeters. Using electron energy loss spectroscopy (EELS) to measure the bulk plasmon loss energy it was possible to determine the stoichiometry of the titanium subhydride substrate. Samples of TiH0.87 foil were found to dehydride somewhat upon heating to 600°C.
The surface analysis of a plasma modified contact lens surface by SSIMS
Authors: Fakes D. W. , Davies M. C. , Brown A. , Newton J. M.
Published: May 2005

The oxygen glow discharge plasma modification of a contact lens material has been studied using SSIMS. SSIMS provides evidence at the molecular level for the conversion of surface organosiloxane species to inorganic silica functionalities with treatment time. These findings shown an excellent correlation with a dramatic increase in surface hydrophilicity, as derived from surface energy studies, on plasma treatment. This study further illustrates the potenial of SSIMS in the determination of the molecular changes at the surface during the plasma treatment process.
Core‐level shifts and the choice of Auger parameter
Authors: Rivière J. C. , Crossley J. A. A. , Moretti G.
Published: May 2005

The approximation that the change in the Wagner Auger parameter α* is equal to twice the change in the extra‐atomic relaxation energy depends on the assumption of equal core‐level binding‐energy shifts. It is shown from the available published data that, in general, this assumption is incorrect, and that α* cannot be used to estimate relaxation energies accurately. If accurate relaxation energies are required, then Auger parameters such as ζ of Hohlneicher et al., or ζ′ of Sodhi and Cavell, based on the generalized Auger parameter ζ of Lang and Williams, must be used. However, for purely empirical chemical state identification in metals and semi‐metals, the various versions of α* are perfectly adequate, and indeed it matters little which version is used, since the changes Δα* with chemical state are the same for all of them within experimental error. For non‐metals there are as yet insufficient data to be certain just how useful α* might be, but for those two elements, sulphur and phosphorus, for which there are adequate data, it seems that α* on its own may not be as helpful as for the metals. In the latter case there is much less ambiguity in identification if the Wagner ‘chemical state’ diagram is used; this is particularly so for sulphur, for which the α* and β variations with chemical state seem complex.
Structural characterization of III–V semiconductor surfaces by quantitative aes
Authors: González M. L. , Alonso M. , Soria F.
Published: May 2005

The main objective of the present work is to extend the use of Auger electron spectroscopy as a technique capable of providing information not only about the chemical composition of III–V semiconductor surfaces, but also on surface structure by using some atoms as markers. These atoms can be either the III or V surface atoms, or/and some foreign atoms (O2, Si) when the adsorption process is site‐specific. Thus, by the interaction of O2 and Si with differently prepared GaAs[111] surfaces, we have determined besides the chemical composition of the surface bilayer, the adsorption sites, occupation sequence and the nature of the vacancy sites of the surface layers. Moreover, we have also detected anomalously low attenuation lengths of the substrate atoms. This phenomenon, observed before by other authors in different systems, was never satisfactorily explained. We present experimental evidence that the anomalous attenuation lengths are related to the structural disorder of the adsorbed layers and, therefore, that the low values observed are not correct. Consequently, great care is recommended when using attenuation lengths given by the overlayer method.
Quantitative surface analysis using electron beam SNMS: Calibrations and applications
Authors: Wilson R. , Van Den Berg J. A. , Vickerman J. C.
Published: May 2005

A system of optics for electron impact post‐ionization sputtered neutral mass spectrometry (SNMS) has been designed and constructed. The design is based on an existing set of ‘Wittmaack‐box’‐type secondary ion mass spectrometry (SIMS) optics, commercially operational at UMIST. The system operates with ‘state of the art’ efficiency in the SNMS mode (a post‐ionization efficiency of 10−3–10−4), without significant degradation of the SIMS operation.

The development stages described demonstrate many of the practical problems in the design of an electron beam post‐ionizer, involving characterization of the energy analyser used and the conditions from the optics for best secondary ion and residual gas suppression in the SNMS mode.

Calibration of the SNMS mode of the system has been undertaken using standardized samples, cross‐calibrated by optical emission spectroscopy. (Typical spectra of standard stainless steel and some CuZn and CuAl alloys are presented.) These studies revealed a reproducibility of better than 10% in the relative sensitivity factors, which have been assigned to several elemental species. From these studies, a detection limit of better than 0.01 at.% was obtained for most elemental species under 10 μA Ar+ primary beam bombardment.

The effects of surface roughness on the efficiency of sputtered neutral collection are reported. Studies of CuZn alloys have revealed effects on the absolute calibration and on data analysis of multicomponent materials where the individual components have differing sputter yields. This study also revealed SNMS to be a useful tool in the measurement of the sputter yields of composite materials. Studies of InAsxP1−x have been used to demonstrate the linearity of SNMS for quantitative analysis, as well as revealing the homogeneity of the layers analysed.
A new lineshape for fitting x‐ray photoelectron peaks
Authors: Losev A.
Published: May 2005

A new asymmetric lineshape with four parameters is proposed for fitting x‐ray photoelectron peaks. Some of its properties are elucidated, as it is compared with previously used lines. A simple way of implementing a computer routine is suggested and examples of applications are presented.
Surface compounds and surface precipitates on single crystal surfaces
Authors: Uebing C. , Viefhaus H. , Grabke H. J.
Published: May 2005

The co‐segregation of chromium or vanadium with nitrogen or carbon to (100)‐, (110)‐ and (111)‐oriented surfaces of carbon‐ and nitrogen‐doped Fe–15%Cr, Fe–3%V and Fe–3%Si–0.04%V alloys has been investigated by applying AES, low‐energy electron diffraction and SEM.

Two‐dimensional epitaxially stabilized surface compounds CrN, CrC, VC and V(C, N) are formed in the temperature range 500–750°C on (100)‐oriented specimens. The surface compounds CrN, VC and V(C, N) are also formed on (110). The structures of the surface compounds are related to (100) and (110) planes of the corresponding three‐dimensional bulk compounds CrN, VC and V(C, N) and of a hypothetical bulk compoud CrC with a rock‐salt structure. In all cases, the lattice mismatch between the substrate surface and the corresponding crystallographic plane of the bulk compound is <3%. Upon surface compound formation, the (111) surface into (100) facets covered with the surface compounds.

At low temperatures and high non‐metal concentrations, heterogeneous nucleation facilitates the formation of three‐dimensional precipitates at the surface.
XPS studies on cerium, zirconium and yttrium valence states in plasma‐sprayed coatings
Authors: Ingo G. M. , Paparazzo E. , Bagnarelli O. , Zacchetti N.
Published: May 2005

X‐ray photoelectron spectroscopy (XPS) is used for investigating the valence state of the chemical elements present in 25.5 wt.% CeO2−2.5 Y2O3−72 ZrO2 plasma‐sprayed coatings as a function of the deposition temperature. Unlike the other chemical elements, cerium changes its valence state during and after the spraying process. The analysis of Ce 3d binding energies and satellite structures shows that CeO2 after spraying is either partially reduced to Ce(III) at low deposition temperature, or remains essentially unchanged at high deposition temperature. In both cases, the presence of ZrO2−x suboxides is found, which does not depend apparently on the cooling rate.
An XPS study of the kinetics of dissolution of ZrO2 in α‐Zr
Authors: Prieto P. , Galán L. , Sanz J. M. , Rueda F.
Published: May 2005

The dissolution of a 15 Å thick oxide layer into polycrystalline Zr at temperatures between 440 and 600 K and under non‐oxidizing conditions has been studied by XPS. The thickness of the oxide layer as a function of the annealing time shows a parabolic dependence. It is then concluded that the rate of dissolution is controlled by diffusion into the Zr substrate of oxygen atoms, which generate at the interface by decomposition of the oxide. In addition, the effective oxygen diffusion coefficient in the 440–600 K temperature range has been determined as D = 4.42 × 10−6 exp(−99.7/RT) cm2 s−1, with the activation energy in kJ mol−1.
XPS study of MnO2 minerals treated by bioleaching
Authors: Di Castro V. , Polzonetti G. , Contini G. , Cozza C. , Paponetti B.
Published: May 2005

XPS has been used to follow the change of the ore surface composition during bioleaching with a mixed culture of microorganisms. In the original sample, the presence of MnO2 together with silica and alumina is observed. During bioleaching, Mn(IV) is progressively reduced to Mn(II) and signals due to the presence of the microorganisms appear in the C 1s and N 1s spectra.

In the residual sample, a considerable amount of Mn associated with the cells of the microorganisms of reprecipitated in the from of the Mn(OH)2 is present on the surface of the ore. This Mn species can be removed completely by treatment with a dilute soultion of HCI.
Quantitative AES: Calibration of spectrometers for true spectral measurements—results of a VAMAS round robin and recommendations for acquiring reference data banks
Authors: Seah M. P. , Smith G. C.
Published: May 2005

As a result of careful calibration, a metrology spectrometer has been developed at the National Physical Laboratory (NPL) to give true spectra. This instrument has been used to measure the true spectra from three reference materials under defined conditions in AES. Measurements for these reference materials, on any other instrument, allow that instrument's intensity–energy response function to be calibrated so that that instrument, in turn, may produce true spectra. In a VAMAS interlaboratory assessment involving 38 respondees, these methods and data have been tested. The results show that AES instruments may be calibrated over the energy range 10–2500 eV to give true spectra to an accuracy in the range 1.5–3.0% in the direct mode and ∼12% in the differential mode. For the first time, all these instruments may be calibrated to give: (1) the same spectra; and (2) spectra in which the instrumental systematic intensity errors are reduced to the above levels.
Application of factor analysis to the AES and XPS study of the oxidation of chromium
Authors: Palacio C. , Mathieu H. J.
Published: May 2005

Auger electron spectroscopy (AES), x‐ray photoelectron spectroscopy (XPS) and factor analysis of the MVV Auger spectra and the Cr 2p XPS spectra were applied to study quantitatively the initial stages of the oxidation of polycrystalline chromium. Application of factor analysis allows the identification of up to three real factors. According to the previous works on chromium oxidation, the factors responsible for variations in data were identified as being due to pure metal, chromium oxide (Cr2O3) and chemisorbed oxygen, respectively. The very first stages of the oxidation, <1 L exposures, were found to be characterized by only two factors. Since two standard spectra are known (i.e. metal and chromium oxide spectra), the quantification of all three real factors mentioned above is possible by the application of target testing procedures.
XPS investigation on the corrosion behaviour of nickel in sea water
Authors: Arfelli M. , Ingo G. M. , Mattogno G. , Beccaria A. M.
Published: May 2005

The effect of hydrostatic pressure on nickel corrosion in sea water and in similar solutions has been investigated.

By increasing the hydrostatic pressure, the corrosion rate of nickel increases in 0.58 M NaCl and in 0.1 M Na2SO4 and decreases in 0.01 M Na2SO4 and in sea water.

This fact is explained by the different nature and composition of the corrosion film grown in these solutions, obtained by XPS, the results of which are compared with electrochemical data.
Surface modifications during Y zeolite dealumination
Authors: Merlen E. , Lynch J. , Bisiaux M. , Raatz F.
Published: May 2005

The external shell formed on a Y zeolite during steaming is shown by XPS to contain both Al and Si extracted from the framework. The progressive formation of SiOH defect groups during steaming and subsequent acid leaching may be followed by binding energy changes and by peak decomposition. The usefulness of the latter for characterization of the chemical environment in silica aluminas is, in this case, limited to suggesting a coherent framework for interpretation of binding energy shifts.
Chemical reactions induced in polymers by keV ions, electrons and photons
Authors: Marletta Giovanni , Catalano Salvatore M. , Pignataro Salvatore
Published: May 2005

Polyvinylcarbazole, polyvinylpyridine and polyethersulphone films have been bombarded with 150 keV Ar+ ion beams and the midified surfaces have been characterized chemically by ESCA and REELS (reflection electron energy loss spectroscopy).

In the explored fluence range (5 × 1012−1 × 1016 ions cm−2), several types of chemical reactions, such as dehydrogenation, loss of heteroatopms, loss of aromaticity via ring opening, reduction, etc., heve been shown to occur, depending on the chemical structure of the pristine system.

For the polyethersulphone, a comparison of the chemical effects produced by electrons, photons and ion beams of comparable energy (∼1 keV) and fluence (1015−10−16 ions cm−2) also has been reported.

The results are discussed in terms of energy deposition mechanisms, as well as chemical grounds. In particular, they allow a further assessment to be made of the field of chemical reactions induced by ion beams. Furthermore, they show that for a given dose the chemical modification of a polymer surface by an ion beam is much greater than that expected for electrons or photons.
XPS study of BN thin films deposited by CVD on SiC plane substrates
Authors: Guimon C. , Gonbeau D. , Pfister‐Guillouzo G. , Dugne O. , Guette A. , Naslain R. , Lahaye M.
Published: May 2005

BN films deposited from a BF3NH3 precursor, under chemical vapour infiltration conditions, on plane sintered α‐SiC substrates were analysed by XPS. The films are non‐stoichiometric with an N/B atomic ratio of <1. They also contain significant amounts of oxygen atoms, homogeneously distributed in the film and thought to replace partly the nitrogen atoms in the turbostratic hexagonal network. As a result, ternary BNxOy species are formed locally. Near the BN/SiC interface, the oxygen concentration increases owing to the occurrence of ternary SiNxOy species, thought to be the result of an oxinitriding reaction on the substrate surface with the gas phase containing residual oxygen, at the very beginning of the BN deposition process.
Electronic structure of metal–sapphire interfaces
Authors: Gillet E. , Ealet B. , Berlioz J. L.
Published: May 2005

We have investigated metal‐Al2O3 bonding by AES (Auger electron spectroscopy), EELS (energy electron loss spectroscopy) and XPS (x‐ray photoelectron spectroscopy). The metal–alumina interfaces were formed by in situ vapour deposition and we studied the early stages of metal condensation for Pd, Ni, Cr and Zn at room temperature on well‐defined (0001) and (1012) sapphire surfaces. Depending on the treatment, these surfaces exhibit different electronic structures. Upon increasing the metal coverage, new electronic features appear, which point out the role of surface defects (oxygen vacancies, dangling bonds, etc.) during the formation of the first metal monolayer.
Experimental and theoretical XPS study of model molecules for poly(methyl methacrylate)
Authors: Naves de Brito A. , Keane M. P. , Correia N. , Svensson S. , Gelius U. , Lindberg B. J.
Published: May 2005

High‐resolution C is and O is gas‐phase X‐ray photoelectron spectra of methyl isobutyrate, methyl methacrylate, methyl acrylate, acrylic acid, acetic acid and formic acid have been investigated as model compounds for solid poly(methyl methacrylate) (PMMA). Secondary chemical shifts, variations in peak shapes and intensities for the different core lines were observed. It is shown that asymmetries and differences in line widths of the component peaks should be considered for a correct analysis of the solid polymer spectra. The observed intensities of the different C 1s and O is peaks in the gas‐phase spectra do not follow stoichiometric ratios owing to different shake‐off/shake‐up probabilities. The gas‐phase core electron binding energies have been compared with ab initio ΔSCF calculations where the relaxation of the core‐hole state was included. Using a group shift argument, the relationship between the gas‐phase model molecule shifts and the solid PMMA shifts have been discussed and applied to the analysis of the PMMA spectra.
Mass spectrometry of secondary neutrals and ions for chemical analysis of salts
Authors: Fichtner M. , Lipp M. , Goschnick J. , Ache H. J.
Published: May 2005

Complete characterization of solid environmental samples requires sensitive chemical analysis, which includes quantitation of elements, identiflcation of compounds and determination of their spatial distribution. In order to investigate the possible contribution to an analysis of microparticles collected from the atmosphere, plasma‐based secondary neutral mass‐spectrometry (SNMS) and SIMS were examined using salt samples as these are frequent components of such environmental materials. Chlorides, carbonates, nitrates and sulphates were bombarded with high fluxes of argon ions to meet the dynamic conditions for depth‐resolved analysis. This first application of plasma‐based SNMS to salts revealed that their neutral secondary emission mainly consists of those atoms or elements that the bombarded sample is composed of. Thus, mass analysis of the emitted atoms enables the identification of all elements and an example shows that elemental quantitation can be performed with a moderate matrix dependence. A small fraction of binary clusters within the total neutral emission offers compound‐specific information of compounds owing to the emission of characteristic polyatomic ions. Quantitation of the stoichimetry of complex sulphur anions was found to be rather less matrix‐dependent using negative SIMS than SNMS. Although dynamic bombardment inevitably induces chemical reactions, the results demonstrate that depth‐resolved analysis of salt‐containing samples, including elemental quantitation and chemical speciation, can be performed using SNMS and SIMS.
XPS O 1s binding energies for polymers containing hydroxyl, ether, ketone and ester groups
Authors: López Gabriel P. , Castner David G. , Ratner Buddy D.
Published: May 2005

XPS spectra of nine model polymers containing oxygen functional groups are studied. The measured O 1s binding energies were 532.8 eV for ether and alcohol oxgens, 532.2 eV for ketone oxygens and 532.2 and 533.7 eV for the carbonyl‐ and ether‐type oxygens in ester groups, respectively. Comparison with previous experimental and theoretical O 1s binding energies for these groups is also presented. Absolute O Is binding energies of polymers are not in agreement with those published by other groups. However, with the exception of ketone oxygens, binding energy shifts observed for the various functional groups are comparable.
Secondary neutral mass spectrometry using a gallium ion probe
Authors: Bishop H. E. , Greenwood S. J.
Published: May 2005

An electron beam pos‐ionization cell has been fitted to the input optics of the quadrupole mass spectrometer of a gallium microprobe secondary ion mass spectrometry (SIMS) instrument. The use of gallium as the primary beam for secondary neutral mass spectrometry (SNMS) has been evaluated. Although much higher probe currents are required for SNMS than for SIMS, no problems have been encountered from gallium retained in the sample. Examples of quantitative analysis of insulating samples and of depth profiles are given.
Auger electron spectroscopy study of the surface segregation in silver–palladium alloys
Authors: Reniers F. , Jardinier‐Offergeld M. , Bouillon F.
Published: May 2005

An AES study of the surface composition of silver–palladium alloys is described. The influence of sulphur contamination, matrix effects and attenuation coefficients on the quantification of the first layer composition is discussed. The experimental Auger data are treated following the Pons et al. model. A weak silver segregation is observed and the results are compared with theoretical models and other experimental studies.
An X‐ray photoelectron spectroscopic investigation of the selectivity of hydroxyl derivatization reactions
Authors: Chilkoti Ashutosh , Ratner Buddy D.
Published: May 2005

The Selectivity of trifluoroacetic anhydride (TFAA), used for the vapor‐phase derivatization of hydroxyl groups in multifunctional oxygen‐containing polymeric surfaces, has been investigated by XPS studies on model epoxides systems. The reactivity of TFAA towards epoxides observed here is discussed in the context of the large amount of published literature implying high selectivity of this reaction towards hydroxyl groups. Acetyl chloride (AcCl) and heptafluorobutyryl chloride (HFBuCl), used to derivatize hydroxyl groups in the literature, were also examined, with regard to cross‐reaction with epoxides. Both AcCl and HFBuCl react with epoxides, forming chloroacetates and perfluorinated chloroacetates, respectively. Moreover, HFBuCl is shown to react with double bonds forming perfluorinated chloroacetates, while AcCl is unreactive towards them. The reactivity of HFBuCl to wards epoxides and unsaturation compromises its use as a derivatization reagent of hydroxyl groups. However, the unique reaction products formed by exposure of hydroxyls and epoxides to AcCl vapor may allow hydroxyl species to be distinguished from epoxides in multifunctional carbon‐oxygen polymeric surfaces.
Application of Tougaard background subtraction to Auger spectra. II. Ti and Co silicides
Authors: Bender H.
Published: May 2005

The application of the Tougaard algorthm for the calculation of the inelastic background of surface electron spectra to the investigation of titanium and cobalt silicides is disecussed. The differential inelastic scattering cross‐section is calculated based on optical or energy loss experiments, derived from REELS spectra or approximated by the ‘Universal cross‐section’. The signal‐to‐noise ratio, the sensitivity for small peaks and sensitivity factors are discussed.
Self‐induced floatability of sulphide minerals: Examination of recent evidence for elemental sulphur as the hydrophobic entity
Authors: Buckley A. N. , Riley K. W.
Published: May 2005

Recent evidence, based on spectrophotometric analysis of ethanol extracts, for elemental sulphur being present at the surface of sulphide minerals dry–ground in air has been re–examined. Analysis of ethanol and cyclohexane extracts of ground galena, and electron spectra of abraded galena surfaces, have revealed that while ethanol does extract or leach a sulphur species from galena, sulphur is not present in elemental from on a freshly ground mineral surface.
Low‐energy implantation and sputtering of TiO2 by nitrogen and argon and the electrochemical reoxidation
Authors: Wolff M. , Schultze J. W. , Strehblow H.‐H.
Published: May 2005

In this paper we report the investigation of the implantation and radiation damage during sputter profiles of 30 nm TiO2 layers on Ti with 3 keV N2+. The profiles are analysed by normal and angle‐resolved XPS measurements. Supplementary electrochemical reoxidants are performed, handling the sample without any contact to air during the whole process. Additional information is obtained by comparison with 4 keV Ar+ and 3 keV air sputter profiles.

At the beginning of a 3 keV N2+ sputter profile some TiO2 at the surface is converted to TiNxOy, which is only partially oxidizable by repassivation. A portion of the implanted nitrogen exists as molecular N2. After higher sputter dosed the composition changes drastically. Preferential sputtering reduces the oxygen concentration to an extent to allow TiNxO1−x and TiN formation. The TiNxOy changes its composition since it is now fully reoxidizable, as are all compounds with a Ti oxidation state of less than 4 +. N2 reacts with TiNxO1−x by recoil excitation and no longer exists. The occurrence of TiO, Ti2O3 and Ti3N4 is unlikely, but possible in small concentrations. The products of all electrochemical repassivations are TiO2 and N2.

Angle‐resolved XPS measurements show Ar‐ and N2‐attenuated surface layers. During Ar and air implantation these layers remain constant owing to an equilibrium between outgassing and implantation of new sputter gas. After nitrogen implantation the N2‐attenuated layers are constant in the beginning and increase when the N2 begins to react with TiNxO1−x until the N2 totally disappears.

An addition of oxygen to the sputter gas can decrease the surface roughening effect, which is often found after prolonged sputtering, XPS binding energies show that Ar and N2 gas do not occur in gas bubbbbles.
Sample rotation during depth profiling with secondary ion mass spectrometry
Authors: Vajo John J. , Cirlin Eun‐Hee
Published: May 2005

Depth profiles obtained using secondary ion mass spectrometry with O2+ primary ions and without sample rotation have been measured for Mg‐implanted GaAs, B‐ and 2H‐implanted bulk Mo, a deposited Ni/SiO2 interface and for a molecular‐beam‐epitaxy‐grown structure consisting of monolayers of AIAs in GaAs. For the Mg‐implanted GaAs sample profiled without rotation, secondary ion yield changes associated with the development of surface ripples distorted both the matrix an implant profiles. Rotation of the sample during profiling prevented the formation of; surface ripples and, therefore, the associated yield changes. For the bulk Mo sample, surface roughness developed for both rotated and stationary samples. However, with sample rotation, the roughness was considerable reduced and, consequently, depth resolution for the implant profiles was improved. Similarly, the resolution of the Ni/SiO2 interface was greatly increased using sample rotation. For the monolayer AIAs/GaAs sample, profiles were obtained with low primary ion primary ion energy and large angle of incidence with respect to the surface normal in order to optimize the depth resolution. Under these conditions without sample rotation, uneven sputtering by spatially averaging the ion current density, thereby providing good depth resolution of the AIAs monolayers almost without degradation.
Conversion of sputtering time into depth in depth profiles of oxidized CuNi alloys obtained by glow discharge spectroscopy
Authors: Tsuji Kouichi , Hirokawa Kichinosuke
Published: May 2005

Depth analyses of oxidized Cu–Ni alloys were performed in the constant voltage mode by glow discharge optical emission spectroscopy. A Cu‐rich oxide was segregated on the surface of Cu–Ni oxidized layer and, moreover, the discharge current varied strongly with the sputtering time. Therefore, it is presumed that the sputtering rate varied with the sputtering time. The dependence of the sputtering rate on the composition of samples was investigated for oxidized Cu–Ni layers in order to convert intensity vs. sputtering time to intensity vs. depth. The region of the Cu‐rich oxide layers in the corrected depth profiles was larger than that in the uncorrected sputtering time profile.
An XPS analysis of different SiO2 modifications employing a C 1s as well as an Au 4f7/2 static charge reference
Authors: Gross Th. , Ramm M. , Sonntag H. , Unger W. , Weijers H. M. , Adem E. H.
Published: May 2005

Four different silica modifications—thermally grown SiO2, quartz glass, silicalite and silica gel—have been investigated by XPS. Binding energies for Si 2p, Si 2s and O 1s were obtained by employing different methods of static charge referencing. In any case, a C 1s references was used as usual. In another experiment, deposited 20 nm gold particles were used to provide an Au 4f7/2 binding energy (BE) reference. The two different charging correction procedures result in essentially identical BE data. Furthermore, the results confirm that different modifications of silica give substantially the same relevant BEs in XPS. Though the investigated samples are characterized by quite different concentrations of silanol groups, no significant effect on the measured BEs has been found. On the other hand, the analysed silica samples are observed with quite different Si 2p and O 1s peaks widths. This effect is discussed in terms of differential charging.

A rather extensive compilation of XPS literature BEs of silica modifications is given.
Characterization of polycrystalline silicon thin‐film multilayers by variable angle spectroscopic ellipsometry
Authors: Snyder Paul G. , Xiong Yi‐Ming , Woollam John A. , Krosche Eric R. , Strausser Yale
Published: May 2005

Samples of polycrystalline silicon (poly‐Si) thin‐film multilayers were prepared by low‐pressure chemical vapor deposition. Analysis of these samples by cross‐sectional transmission electron microscopy (XTEM) revealed large changes in grain size between the undoped–as‐deposited and doped–annealed poly‐Si layers. Roughness at the top of the poly‐Si layers was also observed by XTEM. Non‐destructive variable angle spectroscopic ellipsometry (VASE) was used to characterize these structures and to determine the layer thicknesses and compositions. The poly‐Si and roughness layers were each modeled as physical mixtures, using the Bruggeman effective medium approximation, and incorporated into the appropriate multilayer fitting models. As a result, layer thicknesses and compositions, as well as the surface and interface roughnesses, were determined. The VASE‐obtained thicknesses compared well with those determined by destructive XTEM. The effects on the poly‐Si layer microstructure due to doping and annealing were also characterized.
X‐ray photoelectron spectroscopy and infra‐red studies of X‐ray‐induced beam damage of cellulose, ethyl cellulose and ethyl‐hydroxyethyl cellulose
Authors: Brown Norman M. D. , Hewitt Janet A. , Meenan Brian J.
Published: May 2005

The cellulose derivatives ethyl cellulose and ethyl‐hydroxyethyl cellulose (EHEC) have been studied by XPS in the form of solvent‐cast films. All the films, as well as a sample of cellulose used as a standard material, show significant surface degradation on irradiation in the time period consistent with XPS data acquisition. Under the experimental conditions employed here the four materials studied behave similarly, in that a reaction occurs in the cellulose skeleton, resulting in dehydroxylation of some of the pyranose units in the surface layers, with concomitant elimination of molecules of water.

An infrared (IR) analysis of the ethyl cellulose and high‐molicular‐weight EHEC films indicates the presence of a strong carbonyl band, no evidence for which is found in the XPS spectra. However, other features of the IR spectra support the proposed dehydroxylation mechanism. The origin of this inconsistency is nuclear but may be attributable to either differences in the surface and bulk degradation products formed or to the detection differences of the XPS and IR techniques.