bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect on surface texture of material addition and removal processes
Authors: Zipin Richard B.
Published: December 2004

Over the past few years there has been a continuing study of the effects of various sorts of manufacturing processes on the texture of engineering surfaces. It has been shown that surface profiles contain a history of the processes used to create them, and that the history is revealed when the cumulative distributions of the height of the surface profiles are plotted on normal probability co‐ordinates. These plots reveal various strata within the profiles which may be related to the creation processes and, in many cases, the parameters of the processes may be determined.

Earlier work has considered two‐strata surfaces created by processes which either add material to the peaks or to the valleys of a surface profile or remove material from them, and three‐strata surfaces created by processes which displace material within a profile. The present work considers the three‐strata surfaces which are created by material addition or removal processes such as plating and etching which act on the surface profile as a whole. It thus completes the classification scheme for surface profiles which was originally outlined at the beginning of these efforts.

The analytical technique described in this work and the earlier work on this subject are the surface metrologist's analogs to the techniques used by geologists and archeologists. They also determine history by an examination of the strata evidenced by the surfaces which they study.
Vapour development of PMMA resists under x‐ray exposure
Authors: Lehockey E. M. , Reid I.
Published: December 2004

Poly (methyl methacrylate) PMMA films of approximately 3 μm thickness have been irradiated with Al x‐rays. The amount of vapour development is shown to increase as the initial molecular weight decreases and the rate of vapour development is shown to decrease with increasing dose. A model to describe this behaviour is presented. This model indicates that unlike the vapour development of poly (olefin sulphones), the vapour development characteristics of PMMA are not consistent with an unzipping mechanism as in the depolymerization process. Despite this there is shown to be connections between depolymerization and vapour development. Poly (methyl acrylate) PMA which has a higher depolymerization temperature is shown to vapour develop less than PMMA. Consistent with the view that irradiating reduces the depolymerization temperature, irradiated PMMA is shown to vapour develop further if it is heated after the irradiation. If the irradiation dose is high enough however (12–16 μA min cm−2), this enhanced vapour development is found to decrease. This decrease is in a dose region in which the radiation damaging process is believed to be dominated by cross‐linking. XPS analysis of the irradiated PMMA shows that, with irradiation, the oxygen content of the PMMA initially increases and then decreases. The oxygen increase is consistent with the formation of hydroxyl groups at the surface and the decrease in the oxygen content is shown to occur preferentially from the COCH3 sites of PMMA.
XPS and IR (ATR) analysis of Pd oxide films obtained by electrochemical methods
Authors: Tura Josep M. , Regull Pere , Victori Lluís , de Castellar M. Dolors
Published: December 2004

Palladium oxide was detected by XPS and IR (Attenuated Total Reflection) analysis of the surface of a Pd electrode which was polarized in the medium 1 M KOH. This oxide set a peak of Pd 3d5/2 shifted 3.5 eV with respect to the metal which is a much higher value than those reported and obtained for PdO and PdO2. An IR absorption band of 535 cm−1 was found to be different from those reported in the literature of PdO and PdO2. The presence of this oxide is in agreement with results obtained using electrochemical methods where the existence of PdO3 has been assumed.
SIMS depth profiling of Si/SiO2/Si layers by using self‐sputtered Ga+ from a gallium liquid metal ion source
Authors: Licciardello Antonino , Torrisi Alberto , Pignataro Salvatore
Published: December 2004

SIMS depth profiles of Si/SiO2/Si systems have been carried out using a Ga+ primary beam tracing the Ga+ yield. This ion is found to be a good marker for thin oxide layers at an Si/Si interface. In the case of thicker (7–85 nm) buried SiO2 layers, various peaks are observed for Ga+ yield. The influence of primary beam energy on the observed profiles has been investigated. A qualitative model is proposed that explains the observed profiles in terms of phenomena, such as radiation‐induced segregation, occurring in the same depth range of the cascade collision.
Study of SIMS argon ion gun for quantitative surface analysis
Authors: Zhanping Li , Jianhua Wang , Youzhe Li , Pijin Chen
Published: December 2004

A new appartus for measuring the energy distribution of an axial ion beam is decribed in this paper. Because this apparatus is combined with an ion gun exit aperture, the assembly error has been decreased. Hence, it is possible to measure an energy spread as low as 0.36 eV. In addition, the total and axial energy distribution of the ions from the ion source and the lenses of the Kornelsen gun are measured.

The variation of ion beam current, ion beam density and minimum beam diameter with a change of pressure in the ion source and ion energy have also been described.

Also, a semi‐empirical formula for the relation of ion beam diameter d with ion energy E and ion source pressure P is given as
X‐ray photoelectron spectroscopy on radioactive materials using a McPherson ESCA‐36 equipped with an SSL position‐sensitive detector
Authors: Gerwing A. F. , Doern F. E. , Hocking W. H.
Published: December 2004

A McPherson ESCA‐36 instrument has been upgraded extensively to achieve greatly enhanced x‐ray photoelectron spectroscopy (XPS) performance. An SSL position‐sensitive detector (PSD) has been retrofitted to the spectrometer in place of the standard exit slit and channel electron multiplier. A DEC LSI‐11/73 computer and a Tektronix colour‐graphics terminal with ink‐jet plotter have been substituted for the original PDP 8/e computer and peripherals. The system vacuum quality also has been significantly improved by installation of modern cryosorption and turbomolecular pumps. A self‐contained software package, based on interactive program modules, has been developed for XPS surface analysis, comprising instrument control, data acquisition and data processing. Photoelectron spectra are recorded in the non‐retardation scanning mode, utilizing the output from the central 200 channels of the 256‐channel PSD. High spectrometer resolution has been maintained by accounting for energy dispersion to second order. Calibration of the spectrometer energy scale and intensity–energy response function is discussed. The suitability of the upgraded ESCA‐36 for XPS studies of highly radioactive materials, such as used CANDU fuel, is illustrated.
Charge distribution and local and non‐local screening effects studied by means of the Auger parameter and chemical state plots
Authors: Moretti G. , Porta P.
Published: December 2004

Copper‐ and zinc‐containing compounds, as well as other 3dn transition metal compounds, are characterized by making use of two concepts introduced first by Wagner: the Auger parameter, α = EB (photoelectron) + EK (Auger), and the so‐called chemical state plots (EK vs. EB, with the binding energy in the negative direction on the abscissa and the Auger parameter on a diagonal grid with slope equal to +1). These are useful tools to obtain information on: (1) the relative initial state charge distributions; and on (2) the relative extra‐atomic relaxation energy in the final state.

In the present paper, for the first time, we show that the Auger parameter can also be helpful in the analysis of the screening mechanism in transition metal compounds.

The position in the chemical state plots of different classes of compounds is discussed. The constancy of the Auger parameter for Cu(II) compounds is interpreted as further evidence of the electronic nature of the 2p3/2 final state. It can be represented by a 2p53d10L electronic structure, a local screended final state, where a charge transfer from the ligand valence orbitals toward localized d‐orbitals allows screening of the core‐hole. For copper, this relaxation energy is similar to the screening energy in the metallic state.

For Cu(I) compounds, as in the case of Zn(II) compounds (d10 electronic configuration), a large dependence of the Auger parameter on the chemical nature of the ligands suggests a non‐local screening mechanism in the final state, i.e. a strong influence of electronic polarizability of the ligands on the relaxation energy. In this case, the extended s‐p cation orbitals are involved in the screening process.

The charge distribution in the initial state can be studied analytically or by using chemical state plots. For example, Cu(II) compounds have about a constant Auger parameter (they fall on the same diagonal line with slope equal to +1), with the more ionic compounds at higher 2p3/2 binding energy and lower (L3M45M45, 1G) Auger kinetic energy.

It appears that the Auger parameter and the chemical state plots permit an accurate characterization of the ground‐state electronic structure of cations in transition element compounds and of the screening mechanism in the final state.
An ESCA method for determining the oxide thickness on aluminum alloys
Authors: Strohmeier Brian R.
Published: December 2004

A simple method for estimating the oxide thickness on aluminum alloys using ESCA was investigated. The method is based on a uniform overlayer model and requires only a single ESCA measurement per sample. Expressions are shown which relate the experimental intensity ration of the oxidic and metallic Al 2p ESCA peaks to the oxide thickness, for both MG and Al x‐ray sources. The method does not require ion etching or separate calibration procedures. Several practical examples that illustrate the usefulness of this method are presented. The method can also be applied to other thin film (i.e. <∼ 100 Å) metal oxide/metal systems. The maximum oxide thickness that can be measured using the method is limited to approximately three times the inelastic mean free path of the appropriate photoelectrons within the material of interest.
Raman studies of laser‐ablated ETFE (tefzel®) films
Authors: Siperko L. M. , Creasy W. R. , Brenna J. T.
Published: December 2004

An ethylene–tetrafluoroethylene (ETFE) copolymer film exposed to 266 nm radiation from a Nd: YAG laser (fourth harmonic) shows visible evidence of damage to the film surface in the form of blackened areas. Evidence for backbone damage to the polymer is indicated by Raman spectroscopy. MicroRaman spectroscopy of the blackened areas yields the spectrum of a carbonaceous structure superposed on the spectrum of the polymer film. Surface‐enhanced Raman spectroscopy (SERS) allows the spectrum of the damaged area to be obtained without spectral interference from the underlying film, with the resultant spectrum similar to SERS spectra of graphite fibers. The carbonaceous layer is not electrically conductive, and scanning electron microscopy shows the ablated areas to be severely cracked and discontinuous.
Determination of amino and silanol functional groups on glass via chemical derivatization and ESCA
Authors: Dang Tuan A. , Gnanasekaran Ramaswamy
Published: December 2004

The ESCA analysis of surface silanol (Si‐OH) and amino (NH2) functional groups on glass is either not possible or very ambiguous. These functional groups can be identified positively by using chemical derivatization in conjunction with ESCA. In addition to specificity, the technique also offers a significant decrease in detection limit. The NH2 was derivatized using penta‐fluorobenzaldehyde (PFB) and the Si‐OH was silylated with tridecafluoro‐1,1,2,2‐tetrahydrooctyl‐1‐trichloro‐ silane (TDFS). Quantification of the NH2 group can be accomplished with PFB derivatization. Only a relative comparison of the silanol group on glass can be carried out in TDFS silylation owing to the uncertainty in the completion of this reaction in the ESCA sampling depth.
Influence of ion mixing, ion beam‐induced roughness and temperature on the depth resolution of sputter depth profiling of metallic bilayer interfaces
Authors: Cirlin Eun‐Hee , Cheng Yang‐Tse , Ireland Philip , Clemens Bruce
Published: December 2004

To study the factors limiting the depth resolution of sputter depth profiling, we have examined the influence of ion mixing, ion beam‐induced roughness and temperature on the interface resolution of metallic bilayers consisting of Pt on top of Ni or Ti. We studied Pt/Ni and Pt/Ti interfaces because Ni and Ti have similar ballistic properties, including atomic mass and number, but the heat of mixing, ΔHm of Pt/Ni and Pt/Ti are significantly different, ‐7 and ‐122 kJ g‐1 at.‐1, respectively. We observed that the measured interface width for Pt/Ti is ∼2.5 nm wider than that of Pt/Ni under identical experimental conditions, indicating the importance of the heat of mixing during ion mixing. Furthermore, for the given sputtering geometry we found that the interface widths were proportional to the square root of the Pt layer thickness. This thickness dependence was absent when the sample was rotated during sputtering, suggesting that the thickness dependence was largely due to roughness caused by unidirectional sputtering. We also investigated the influence of substrate temperature and found a small (0.7 nm) decrease in interface width at 150 K relative to that at 300 K, which may be due to reduced preferential sputtering and a smoother surface. Our studies show the importance of thermodynamic parameters in low‐energy ion mixing and support our earlier conclusion that diffusion in a thermal spike is a dominant mechanism in low‐energy ion mixing, just as it is at high energies in these systems.
Oxidation of an NiTi alloy
Authors: Chan C.‐M. , Trigwell S. , Duerig T.
Published: December 2004

In this study, the oxidation of the surface of a 50/50 (at.%) NiTi alloy was studied by XPS, AES and SEM. Samples of the NiTi alloy were oxidized at 23°C and high temperatures at an oxygen pressure of 10−4 Torr and in atmosphere. At 10−4 Torr of O2 and 23°C, titanium was oxidized preferentially while nickel remained in the metallic form even after 40 min of exposure. At the same oxygen partial pressure and 400°C, a mixture of TiOx, Ti2O3 and TiO2 was formed, and nickel remained metallic. Eventually, after 40 min of O2 exposure, the whole surface was covered with a layer of TiO2. In atmosphere and at 23°C, titanium again was oxidized preferentially, but NiO was detected on the surface after the first minute of air exposure. At a higher temperature of 450°C, areas comprising a mixture of NiO and TiO2, and areas consisting of TiO2 only were found. Below the top surface layer, a complete layer of TiO2 was detected. Underneath the TiO2 layer, a nickel‐rich layer was present.
XPS study of the state of oxygen on a chemically treated glass surface
Authors: Mohai M. , Bertóti I. , Révész M.
Published: December 2004

The O 1s line of an ordinary, untreated glass surface and of a glass surface in its dealkalized state were studied by XPS. One single O 1s peak was detected on the dealkalized sample at a binding energy (BE) of 532.5 eV while on the alkali‐containing sample, and also on the dealkalized sample after alkali solution treatment, a second peak at 531.1 eV BE also could be detected. Experimental data were backed by semi‐empirical quantum chemical calculations. The observed low BE component of the O 1s line, according to the outlined experimental evidence, is connected with the presence of alkali ions. This clearly contradicts earlier publications, interpreting the O 1s line as originating from oxygen atoms in bridging and non‐bridging positions.
Influence of surface melting treatment by laser on the segregation of sulphur, nitrogen and chromium on the surface of a single‐crystal FeCrNi alloy
Authors: Moulin G. , Larere A. , Marcus P.
Published: December 2004

After melting the (100) surface of a FeCrNi single crystal by a CWCO2 laser, a quasi‐epitaxial regrowth of the melted zone takes place2 within a misorientation of ∼4°. Three distinct areas are obtained: unaffected, heat affected and melted surfaces. On all areas, the segregation of sulphur alone occurs at high temperature, while there is a cosegregation of sulphur and nitrogen at T < 700°C. The thermodynamic interpretation of the segregation results is reported.

For the surface segregation of sulphur, no interactions are noted with other alloy elements, except with chromium on the unaffected surface. The difference between the free enthalpies of segregation of sulphur on the untreated and treated surfaces is associated with the evolution of the defect content.

When sulphur and nitrogen cosegregate on the surface of the untreated alloy, a repulsive coefficient of interaction between sulphur and nitrogen (i.e. βSN) of the order of 20 ± 5 kJ mol−1 is calculated. For the laser‐treated surfaces, the chromium content increases on the surface. Then, the regular solid solution model is applied to the CrNS ternary system. The calculated βSN coefficient is now 45 ± 5 kJ mol−1 and agrees with the experimental data obtained from the experimental evolution of ΔG versus YN (with ΔG = free energy of segregation of S and data YN = nitrogen concentration on the surface). More complex interactions are also discussed, especially for nitrogen, on account of the site competition between N and S and the influence of the vacancy content on the treated surfaces.
Optimization of the dynamic range of SIMS depth profiles by sample preparation
Authors: von Criegern R. , Weitzel L. , Zeininger H. , Lange‐Gieseler R.
Published: December 2004

The dynamic range is one of the most important figures of merit of SIMS measurements and equipment. The term refers to the concentration range of an analysed element—its concentration being high near the surface but decreasing with increasing depth—that can be measured by depth profiling. The state of the art is such that, under favourable conditions, 5–6 orders of magnitude are possible (measured on ion‐implanted boron in silicon). It is shown that with special sample preparation techniques (removal of the sputter crater environment) the dynamic range can be extended to 7 orders of magnitude. Experimental details of the preparative methods are given together with a critical evaluation of the methods.
An AES study of the room‐temperature oxidation of TaSix after bombardment with Ar+ ions of different energies
Authors: Clement M. , Sanz J. M. , Martínez‐Duart J. M.
Published: December 2004

Tantalum silicide films of ∼200 nm thick and composition TaSi2 were obtained by co‐sputtering in a Varian 3120 S‐gun magnetron system. The films were then introduced in an AES spectrometer and bombarded with Ar+ ions of different energies in order to obtain surfaces of different compositions as a consequence of preferential sputtering effects and their dependence on the energy of the primary ions. Lowering the energy of the Ar+ ions resulted in surfaces very rich in tantalum. The interactions of these surfaces with oxygen at low pressures (10−8−10−5 Torr) and at room temperature then have been studied comparatively by Auger electron spectroscopy. Reference experiments with pure Si and Ta allowed the comparison with those of the different silicide surfaces. It is found that the oxygen uptake depends on the Ta content so that the richer in Ta the surface is, the higher the O2 incorporation. Furthermore, the uptake rate at the different TaSix surfaces resembles better the measured rate for pure Ta than that observed for pure Si. It has been observed also that the oxidation of Si is enhanced over that of pure silicon in all the surfaces studied here. Besides, the enhancement depends on the tantalum content.
Determination of the sputtering rate of electroless nickel layers with a glow discharge lamp
Authors: Böhmer R. G. , Nel J. T.
Published: December 2004

Grimm glow discharge spectrometry was used to analyse electroless nickel coatings on a steel substrate. Because of poor depth resolution at the coating/metal interface, it was necessary to determine the sputtering rate of the layer itself at different power settings and to calculate the sputtering rate per power unit. The penetration time for layers with different thicknesses was also determined for different power settings. By comparing sputtering rates per power unit, it was found that the best results were obtained if the penetration time was equated to the time needed for the nickel signal to reduce to half its original value.
Surface characterization of chemically modified chrysotile asbestos by particle‐induced desorption mass spectrometry
Authors: Bennett J. A. , Schweikert E. A. , Poisson D. , Jolicoeur C.
Published: December 2004

252‐Cf particle‐induced desorption mass spectrometry (PDMS) has been used to follow the modification of chrysotile asbestos fiber with organosilane compounds. Monitoring changes in the peak area ratios of Si+, Mg+ and SiOH+ ions in PDMS and atomic ratios from XPS, the formation of organosiloxane polymers vertical to the surface is suggested. Changes in the ratios also indicate differing coverages of the modifiers, owing in part to steric effects associated with the different organic substituents. The fibrous, non‐conductive nature of the sample did not impair the analysis with 252‐Cf PDMS. This application lends further support to the belief that PDMS is a surface‐sensitive technique.
Investigation of gallium arsenide multilayer structures using a tunnelling microscope combined with a UHV‐SEM
Authors: Albrektsen O. , Salemink H.
Published: December 2004

Analysis of semiconductor multilayers in an ultrahigh vacuum (UHV) environment is performed using a tunnelling microscope built into a UHV‐SEM with an Auger facility. The GaAs (110) surface is investigated with tunnelling spectroscopy and topography. As this cleavage plane is perpendicular to the preferential 〈001〉 growth direction, several material properties along the growth direction can be monitored with atomic resolution. The system is equipped with an interlocked preparation chamber for UHV cleavage of samples and for preparation of tunnelling tips, which subsequently are transferred into the scanning tunnelling microscope (STM). The SEM is used to select the sample area for the STM, with a resolution of 25 nm. Examples of results are the tracing of p‐n junctions in (Al)GaAs heterostructures and the valence band alignment in GaAs/AlGaAs interfaces. Typically, these results are obtained with a spatial resolution of 1.0–1.5 nm and are compared with results from conventional experiments (luminescence or C–V measurements), which pertain to much larger sample areas. Finally, we discuss recent results on cross‐sections of MBE‐grown (Al)GaAs multilayers, with atomic resolution in the epitaxial layers and in their interfaces.
EELS and low‐energy electron emission of clean and oxygen‐exposed tantalum
Authors: Palacio C. , Martínez‐Duart J. M.
Published: December 2004

The electron energy‐loss spectra (EELS) associated with 4f and 5p excitations, and the secondary electron spectra (SES) have been used to study the oxidation of a clean polycrystalline tantalum surface. For the clean and oxygen‐exposed surfaces, the EELS results are discussed in terms of bulk and surface plasmons as well as interband transitions to unoccupied states above the Fermi level (EF). The secondary electron spectra have been used as a fingerprint for the density of unoccupied states above EF. The changes observed in the EEL spectrum upon oxygen exposure are explained as being due to oxide formation, in agreement with previous results by XPS and AES. The features observed above the NVV and OVV Auger transitions, in both the clean and oxidized surfaces, are described as auto‐ionization emission due to the decay of electrons that have been excited resonantly from the 4f and 5p levels to states well above the states well above the Fermi energy. The excitation process has been identified also in the EEL spectra.
Intercomparison of surface analysis of thin aluminium oxide films
Authors: Olefjord I. , Mathieu H. J. , Marcus P.
Published: December 2004

A round robin test organized by the European Federation of Corrosion (EFC) Working Party on Surface Science and the Mechanisms of Corrosion and Protection, supported by the European Community Bureau of References (BCR), and further extended under VAMAS (Versailles Project on Advanced Materials and Standards), has been performed. The aim of the test was to study the reproducibility of surface analyses in different laboratories on well‐documented samples by ESCA and Auger spectroscopy. The reference material is aluminium, oxidized at 250°C in oxygen. Test samples were distributed to 22 laboratories in Europe, North America and Japan. Data have been received from 20 laboratories.

The test results collected are: peak positions, intensities, chemical shifts. The reference energies of the ESCA spectrometers are 84.0 eV for Au 4f7/2 and 932.7 eV for Cu 2p3/2. The binding energies of the metallic states of Al 2p and Al 2s are 73.0 (±0.1) eV and 118.0 (±0.2) eV, respectively. The chemical shifts of Al3+ in the oxide layer are 2.8 (±0.1) eV and 2.5 (±0.1) eV. The oxygen content of the oxide layer, measured by nuclear reaction analysis, is 16.3 × 1015 atoms cm−2. This corresponds to an oxide thickness, d, of 23 (±1) Å. The value of d/λ (λ is the attenuation length) calculated from the measured ESCA intensities is 1.13 (±0.03) for Al 2p with an Mg Kα x‐ray source, taking into account the take‐off angle. The values of the attenuation length obtained for Al2O3 are λ(Al3+) Mg Kα = 20.2 (±2.0) Å and λ(Al+3) Al Kα = 24.8 (±3.3) Å. The ratios of the photoelectron yields of oxygen and aluminium are Y(O1s)/Y(Al2p) = 6.2 (±0.8) and Y(O1s)/Y(Al2s) = 5.4 (±0.8) with an Mg Kα x‐ray source and Y(O1s)/Y(Al2s) = 6.6 (±0.6) and Y(O1s)/Y(Al2s) = 4.9 (±0.5) with an Al Kα x‐ray source.

The LMM and KLL AES energies of Al in Al2O3 are 53.4 (±2.8) eV and 1389.4 (±3.5) eV, respectively. The corresponding values for aluminium metal are 66.4 (±2.7) eV and 1394.4 (±4.0) eV. For thin films where the attenuation length is of the same order of magnitude as the film thickness, an exponential fit of the experimental depth profile is proposed. The ratio of the sputtering rates of Al2O3 and Ta2O5 is thus found to be 0.72 (±0.14).

The consistency between measurements performed in the different laboratories is excellent in many instances but certain problems are identified, which would deserve further work.
Quantitative AES and XPS: Determination of the electron spectrometer transmission function and the detector sensitivity energy dependencies for the production of true electron emission spectra in AES and XPS
Authors: Seah M. P. , Smith G. C.
Published: December 2004

For the use of published general or theoretical sensitivity factors in quantitative AES and XPS, the energy dependence of both the spectrometer transmission function and the detector sensitivity must be known. Here, we develop simple procedures that allow these dependencies to be determined experimentally. Detailed measurements for a modified VG Scientific ESCALAB II, the metrology spectrometer, operated in both the constant ΔE/E and constant ΔE modes, are presented and compared with theoretical estimates. It is shown that an exceptionally detailed electron‐optical calculation, involving proprietary information, would be required to match the accuracy of the experimental procedures developed. Removal of the spectrometer transmission function and the detector sensitivity terms allow the measured spectrum to be converted to the true electron emission spectrum, irrespective of the mode of operation. This provides the first step to the provision of reference samples to calibrate the transmission functions and detector sensitivities of all instruments so that they, in turn, may produce true electron emission spectra. This is vital if: (1) all instruments are to give consistent results; (2) theoretical terms are to be used in quantifying either AES or XPS; (3) reference data banks are to be established for AES or XPS.
Correcting the depth profiles broadened by the crater effect: A numerical procedure
Authors: Weiss Zdeněk
Published: December 2004

Concentration–depth profiles which are distorted by the crater effect exhibit a special relationship between the concentration vs. depth distribution and the measured signal vs. time response. This relation is given by a linear Volterra integral equation of the first kind with the kernel which can be experimentally evaluated. A numerical procedure is described for the profile correction by solving that equation, along with discussion of existence, uniqueness of the solution and convergence of the approximations to the original profile.
Optimization of rotational Auger depth profiling
Authors: Tanemura M. , Aoyama S. , Okuyama F.
Published: December 2004

The dependence of depth resolution on the rate of sample rotation in rotational Auger depth profiling was systematically investigated for Cu/Fe multilayer films, using 1–3 keV Ar+ and Xe+ ions as projectiles. Except for Xe+ ion bombardment at 1 keV, the depth resolution was invariably improved by increasing the rate of rotation up to a critical value. The resolution improvement was more pronounced for Ar+ sputtering, but at and above the critical rate the resolution was nearly constant, independent of the sputtering conditions. The critical rotation rate depended on ion species and energy, decreasing with lowering ion energy and increasing ion mass. For 1 keV Xe+ the depth resolution obtained without rotation was comparable to that obtained with sample rotation, indicating that sample rotation was not the sole means to attain high depth resolution. As confirmed by scanning electron microscopy, highly resolved depth profiles for rotated samples were due mainly to reduced surface roughening. Evidence is also presented that at the critical rate of rotation the depth resolution was limited by the intrinsic interface roughness.
Performance of MgO/Au cermet films as secondary electron emission cold cathodes
Authors: Ritz Victor H. , Shih Arnold , Sobocinski Brian
Published: December 2004

The performance of MgO/Au cermet films as secondary electron emission cold cathodes was tested in a crossed‐field amplifier (CFA) tube until it showed signs of cathode insufficiency. Only 5–25% of the original cermet thickness (4000 Å) was left. Although heavy C coverage was observed, which degraded the secondary electron emission (delta), the primary cause of tube failure was the erosion of the cermet film under electron and ion bombardment. The mechanism and dissociation rate for MgO was determined in electron‐stimulated desorption measurements. A threshold for O+ ion desorption at the Mg 2p level demonstrated that MgO dissociates by the Knotek‐Feibelman mechanism with a yield of 1 × 10−7 O+ ions desorbed per incident electron. Various aspects of cathode erosion during CFA operation were considered and evaluated using a combination of experimental data and theoretical calculations. The results indicate that electrons and ions are both important sources of film erosion and limit the use of MgO/Au cermet films in practical CFA tube applications.
Determination of arsenic distribution across SiO2/Si interfaces with secondary ion mass spectrometry, using Ar+ bombardment and the internal indicator method
Authors: Michiels F. , Butaye L. , Adams F. , Simons D.
Published: December 2004

The quantification of arsenic in SiO2/Si interfaces is hindered by matrix effects that influence the sensitivity of the impurity elements in the interface. Moreover, ion‐ and electron‐enhanced segregation, charging effects and mass interferences further complicate the analysis. The suitability of the internal indicator method to account for the variation of the sensitivity of arsenic while profiling through SiO2/Si interfaces was evaluated. Although the method does not provide a comprehensive answer to all problems, the feasibility of the methodology was demonstrated. Arsenic was foundd to be enriched in the Si phase by a factor of ∼4000.
Small‐area XPS and XAES study of early iron metallurgy slags
Authors: Ingo G. M. , Scoppio L.
Published: December 2004

A group of slags dating back to Iron Age II (Aramean Period, 800–720 BC), which appeared to be iron‐smelting by‐products, has been found at Tell Afis (Northwestern Syria). The chemistry of these materials has been studied by means of small‐area x‐ray photoelectron spectroscopy and x‐ray‐induced Auger electron spectroscopy. The results indicate that the slags can be associated with an iron smelting process and show the presence of large amounts of FeO1−x′, Fe3O4 and FeOOH mixed with different aluminium and silicon compounds. As evidenced by the Wagner two‐dimensional chemical‐state plots of silicon and aluminium, these latter consist essentially of quartz and various silicates, such as wollastonite, Mg[SiO4] or Mg[SiO6] compounds, melilite and other complex aluminosilicates. Chemical information agrees with the predictions of the model of early iron‐making furnaces and is used to elucidate some aspects of the early iron‐making process.
The depth distribution function in Auger/XPS analysis
Authors: Dwyer V. M. , Richards J. M.
Published: December 2004

An analysis of a recent three‐exponential approximation of the depth distribution function (DDF) for quantitative Auger/XPS analysis is presented and a comparison is made with an exact DDF obtained for an analytical solution to the Boltzmann transport equation in the transport approximation. Several problems with the approximate DDF are identified and, using the derived analytical form, an alternative two‐exponential DDF is suggested.
In situ measurements of the porosity on thin oxide films by IR emission spectrometry
Authors: Pigeat P. , Pacia N. , Weber B.
Published: December 2004

Observation of the normal spectral emissivity is used as a method of in situ surface investigation. This technique has been used here to follow tungsten oxidation during reactions performed under 1.3 Pa of oxygen both above and below the temperature of the phase transition: ortho‐rhombic αWO3 → tetragonal α′WO3.

We show that the difference between the observed radiative behaviour is due to the difference between the morphology of these oxides (αWO3 is homogeneous and α'WO3 is porous).

From this difference, with an optical model using an effective medium theory (Bruggeman equation), we show that it is possible to describe correctly the experimental measures and to calculate the value of the porosity of the film during its growth. In this model, we show that the best value of the depolarization factor for the oxide particles is 1/3. This is precisely the value that characterizes a porous deposit where the particles (here, oxide particles) are spherical; it is also a good approximation for particles deprived of a particular shape (geometrically isotropic) and disposed at random, such as what we have effectively observed by scanning electron microscopy.
Analysis of polymer surfaces by SIMS 17. An assessment of the accuracy of the mass assignment using a high mass resolution ToF‐SIMS instrument
Authors: Reichlmaier S. , Hammond J. S. , Hearn M. J. , Briggs D.
Published: December 2004

The prospects for obtaining highly accurate mass assignments in polymer surface studies using state‐of‐the‐art time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) have been investigated systematically. For a thick film of poly(ethylene terephthalate) (PET), the reproducibility of mass measurement in both positive ion (range m/z = 0–600) and negative ion (range m/z 0–350) modes has been studied in statistical fashion over a period of several months. Glyceryl monostearate, representing a typical polymer additive, was studied both on PET and as a very thin film on aluminum in order to compare the behavior of insulating and conducting samples. The effect of different mass calibration strategies (including use of atomic and molecular species), mass interferences and metastable peaks on mass accuracy also have been investigated. Finally, the importance of peak intensity for mass resolution and achievable mass accuracy has been determined. The results show that a useful mass accuracy of better than 20 ppm can be achieved over a mass range m/z = 0–600 for these polymer film surface studies under routine operating conditions.
The infinite velocity method: A new method for SIMS quantification
Authors: Van Der Heide P. A. W. , Zhang Min , Mount G. R. , McIntyre N. S.
Published: December 2004

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. Likewise, the resulting concentration profiles of the implant materials analysed agreed well with concentration profiles calculated via the integration method. Thus, samples can be quantified by this procedure without the requirement for matrix‐matched calibration materials. Theoretical implications and the assumptions used in the calculations are also discussed.
High‐resolution XPS studies of superconducting Ag/(Bi0.9Pb0.1)2.3Sr2.0Ca1.9Cu3.0O10+x tapes and wires
Authors: Hoad D. R. C. , Flavell W. R. , Male S. E. , Fletcher I. W. , Beamson G.
Published: December 2004

Investigations were carried out on superconducting Ag/(Bi0.9Pb0.1)2.3Sr2.0Ca1.9Cu3.0O10+x (BSCCO) wires and tapes using high‐spatial resolution x‐ray photoelectron spectroscopy. Chemical maps at the interfacial region between the sheath and the superconducting core of the wire samples and also of the core of the tape after peeling were produced using the VG ESCASCOPE, which is capable of sub‐10 μm resolution. Linescans across the Ag/BSCCO interface were produced using the SCIENTA ESCA 300 instrument, which combines high energy resolution with a lateral resolution of ∼25 μm. A series of heat‐treated BSCCO pellets of the same composition as the wire core were also studied. Characterization by x‐ray diffraction, vibrating sample magnetometry and energy‐dispersive analysis by x‐rays showed that the amounts of 2212 and 2223 phases present are a function of the number of heat treatments. Core‐level photoemission studies using the SCIENTA showed changes in the Bi 4f and O 1s peak shapes, which correlate with the change in the proportion of the two phases.
Novel model system to study the influence of rubber compound formulation on the structure and composition of the rubber–brass interphase
Authors: Holtkamp D. , Elschner A. , Müller G. , Pieroth M.
Published: December 2004

A model system was developed to study the influence of the rubber formulation and/or the aging conditions on the adhesion between brass and rubber. The bonding compounds were vulcanized on thin, homogeneous brass layers that had been prepared by sputtering onto special polymeric substrates; some of these compounds were steam‐aged under controlled conditions subsequently. After the separation of the polymeric film, combined analytical electron microscopy (transmission electron microscopy/energy dispersive spectroscopy; TEM/EDS) and sputter neutral mass spectrometry (SNMS) analyses were performed. While the TEM/EDS studies offer a detailed insight into the morphological structure of the interphase, the SNMS depth profiles allow a rapid and reliable differentiation between various rubber formulations. With these model samples the beneficial effect of boric acid esters on the adhesion of cobalt‐containing bonding compounds, which is observed in a typical short‐term adhesion test after steam‐aging, can be explained: boric acid esters act with cobalt salts as corrosion inhibitors for brass, preventing the growth of a thick intermediate ZnO/Zn (OH)2 layer that is the starting point for delaminations.
Evaluation of in‐depth resolution in grimm‐type glow discharge optical emission spectrometry from differentiated depth profiles
Authors: Hamada Takahiro , Wagatsuma Kazuaki , Hirokawa Kichinosuke
Published: December 2004

Depth profiling of surface coatings is the most significant field in analytical applications of glow discharge optical emission spectrometry. This paper suggests a method for evaluating the depth resolution of the profiles. For this purpose, the emission intensities that are differentiated as a function of sample depth can be used. The differentiated intensities follow a characteristic curve at the coating/substrate interface. The analyses of the differential curve provide useful knowledge about the depth resolution interface.
Influence of surface treatments of hot‐dip galvanized steels on their acid–base properties and on their reactions with some organic compounds
Authors: Gaillard F. , Peillex E. , Romand M. , Verchère D. , Hocquaux H.
Published: December 2004

The surface of hot‐dip galvanized steels is a complex system highly dependent upon the composition of the galvanization bath and upon surface treatments such as degreasing, alkaline etching and chromate conversion. In this study, industrial zinc‐coated samples are subjected to degreasing, alkaline etching and chromating and then characterized by XPS and Fourier transform infrared spectroscopy (FTIR). Their surface reactivity is studied by vapourphase adsorption of probe molecules, either basic (pyridine) or acidic (phenol), and FTIR analysis. The reactivity enhancement following the alkaline etching is clearly evidenced by this technique. In order to gain information upon the reactivity of the hot‐dip galvanized steel surface towards some organic components of epoxy resins, dicyandiamide adsorption was performed at 180°C on the chemically treated substrates. As suggested by the results obtained with probe molecules, alkaline etching of galvanized steels allows a dicyandiamide–zinc reaction leading to the formation of a defined complex. In addition, the study of the interaction of model substrates (pure zinc and aluminum‐contaminated pure zinc) with dicyandiamide clearly shows that surface contamination of galvanized steels by aluminium is responsible for the inhibition of the dicyandiamide–zinc reaction.
Effect of low‐power air plasma treatment on the mechanical properties of carbon fibres and the interfacial shear strength of carbon fibre—epoxy composites
Authors: Farrow G. J. , Atkinson K. E. , Fluck N. , Jones C.
Published: December 2004

A low‐power plasma treatment has been adapted to work on a pilot plant scale to continuously treat a tow of carbon fibres. This treatment successfully increases fibre–resin adhesion to levels comparable if not higher than those obtained by commercial electrochemical treatments. One advantage is that the plasma treatment does not appear to affect the tensile properties of the fibre, unlike the electrochemical oxidation.

We have also shown that the chemical groups introduced during air plasma treatment play a significant role in fibre–resin adhesion whereas those introduced by electrochemical oxidation do not. A possible explanation for this is that plasma treatments introduce chemical groups onto the immediate surface of the fibres that have the potential to react with the resin, whereas electrochemical oxidation occurs predominantly at the edge sites and proceeds into the sublayers of the fibre. The vast majority of the functional groups are therefore inaccessible to the resin. This type of plasma treatment, however, is unlikely to remove all of the weakly bound layers as in the case of electrochemical treatment because the sputtering capability of the plasma is very low.

The fact that these conclusions can be drawn from both the single‐fibre fragmentation test and the short‐beam shear test is encouraging and goes to prove that both these tests are suitable for looking at trends in fibre–resin adhesion.
Effects of low‐power plasma treatment on polyethylene surfaces
Authors: O'Kell S. , Henshaw T. , Farrow G. , Aindow M. , Jones C.
Published: December 2004

This paper describes the effects that a low‐power plasma (<1 W) has on the chemistry, topography and surface energy of polyethylene (PE) film. The gases used for treating the film were air and nitrogen. The plasma cell was attached directly to the preparation chamber of an x‐ray photoelectron spectrometer, enabling the immediate effects of the plasma on the chemical nature of the films to be monitored. Significant amounts of chemical functionality were introduced onto the surface using both plasmas even after a few seconds of treatment. Carbon/oxygen functionality dominates surfaces treated with an air plasma. Nitrogen plasma treatment, as expected, introduced amines, imines and amides. Exposing the treated surfaces to air results in oxygen adsorption, the amount of oxygen pick‐up being time dependent. This ageing of the treated polymer films is thought to occur via two processes: short‐term hydrolysis of the amines and gradual oxidation of the polymer chain itself.

The topographical changes were studied using atomic force microscopy, which was performed after the films had been exposed to air. Both plasmas caused the polymer surface to roughen, with nitrogen plasma treatment having a more pronounced effect. The surface energy of the film was increased from 37 dyn cm−1 (untreated) to 47 and 46 dyn cm−1 after 20 s of exposure to air and nitrogen plasmas, respectively. After 1 min of treatment, the polar surface energy component of the film treated with a nitrogen plasma (12 dyn cm−1) was much higher than that treated with an air plasma (7 dyn cm−1). This is supported by the XPS results in that the concentration of chemical groups introduced onto the surface after nitrogen plasma treatment was greater than that for air.

The greater changes in polymer surface properties observed for nitrogen plasma treatment were not reflected in the values obtained for the level of polymer/metal adhesion. Only air plasma‐treated samples showed significant improvement in the adhesion between polyethylene and aluminium and we conclude that the presence of oxygen‐containing functional groups plays a major role in this improvement.