bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acidity of the outer surface of dealuminated mordenites as studied by X‐ray photoelectron spectroscopy of chemisorbed ammonia
Authors: Remy M. J. , Genet M. J. , Lardinois P. F. , Notté P. P. , Poncelet G. 
Published: May 2005

AbstractChemisorption of ammonia on the acid sites located at the outer surface of dealuminated mordenites has been investigated by x‐ray photoelectron spectroscopy. The N 1s level of chemisorbed ammonia results from the overlapping of three components occurring near 402.4, 400.5 and 399.1 eV. From the N 1s binding energy of NH4+− exchanged mordenite and values reported in the literature for pyridine adsorbed on Brönsted and Lewis acid sites, the components at 402.5 and 399.1 eV are assigned to ammonia in interaction with Si–OH–Al framework groups and with Lewis acid sites, respectively. Based on XPS N/Al ratios and infrared results, the component at 400.5 eV is attributed to ammonia chemisorbed on silanol groups. The surface concentration of the three types of acid sites is estimated from the decomposition of the N 1s peaks. Evidence for the presence of surface extra‐framework Al in dealuminated mordenites is provided and the influence of these Al species on the outer surface acidity is discussed.
Atomic mixing, surface roughness and information depth in high‐resolution AES depth profiling of a GaAs/AlAs superlattice structure
Authors: Hofmann Siegfried 
Published: May 2005

AbstractHigh‐resolution AES depth profiling of a GaAs/AlAs superlattice structure with 8.8/9.9 nm single‐layer thickness by sputtering with 1.0 keV and 0.6 keV Ar+ ions at an incidence angle of 80° resulted in optimum depth resolution values for 0.6 keV Ar+ ions of Δz = 2.0 nm for the low‐energy Al (68 eV) intensity profile and of Δz = 2.0 nm for the high‐energy Al (1396 eV) intensity profile. A simple model description of the influence of atomic mixing (w), surface roughness (σ) and Auger electron escape depth (λ) was applied to calculate the measured profiles. An excellent fit is obtained by a reasonable set of these parameters: for 0.6 keV Ar+ ion sputtering, w = 1.0 nm, σ = 0.6 nm, λ (Al 68 eV) = 0.4 nm and λ (Al 1396 eV) = 1.7 nm.
The formation of the copper/polyphenylquinoxaline interface: An HREELS study
Authors: Grégoire C. , Pireaux J. J. , Cros A. , Caudano R. 
Published: May 2005

AbstractThe interaction of copper with the surface of polyphenylquinoxaline is investigated with high resolution electron energy loss spectroscopy. The metal deposition is found to affect several features, in particular the elastic peak and the CH vibrational modes associated with the aromatic groups. Diffusion of copper to the bulk is observed upon thermal treatment.
The use of XPS valence band spectra in the study of plasma‐deposited polymeric films of tetramethyldisiloxane or hydroxyethylmethacrylate
Authors: Garbassi F. , Morra M. , Occhiello E. , Pozzi L. 
Published: May 2005

AbstractThin polymeric films were deposited from tetramethyldisiloxane (TMDSO) and hydroxyethylmethacrylate (HEMA) plasma. X‐ray photoelectron spectroscopy (XPS) and XPS valence band (XPS‐VB) analyses were performed to detect the effect of the deposition conditions on the structure of the plasma‐deposited films. In both cases XPS‐VB spectra were found strongly affected by the deposition conditions. Furthermore, XPS‐VB analysis can be used to obtain information on the structure and performances of these classes of plasma‐deposited polymer films.
Comparison between pulsed laser and ion irradiation of hydrogenated amorphous carbon films
Authors: Compagnini G. , Reitano R. 
Published: May 2005

AbstractHydrogenated amorphous carbon films were irradiated at room temperature both with ion beams and laser pulses. Ion irradiation was performed with 300 keV Ar+ ions at current densities of about 1 μA cm−2 and the average density release was of about 1024–1025 eV cm−3, while laser irradiation was performed with a Ruby laser (0.694 μm) with an energy flow of 0.1–1.2 J cm−2 and an energy release of about 1022 eV cm−3.The electronic and atomic structure of irradiated layers were investigated by optical measurements in the range 1–6 eV and Raman spectroscopy in the region of CC stretching modes (1000–2000 cm−1).It was found that laser irradiation shows a stronger efficiency with respect to ion beam bombardment in the modification of the film structure. Moreover Raman spectroscopy shows a progressive growth of the trigonal carbon component with respect to the tetrahedral one with increasing energy deposited inside the sample.The differences between ion and photon energy release mechanisms and a comparison with thermal processes are discussed in terms of primary interaction with the molecular constituents of the samples.
Degradation of polymers by hyperthermal atomic oxygen
Authors: Vered R. , Matlis S. , Nahor G. , Lempert G. D. , Grossman E. , Marom G. , Lifshitz Y. 
Published: May 2005

AbstractDegradation of polymers by hyperthermal species (e.g. atomic oxygen (ATOX)) occurs in a variety of practical systems including external surfaces of spacecraft in low earth orbits (LEO), for which the impact with the residual atomic oxygen (impact energy 3–7 eV) results in significant erosion. In the present work the effects of hyperthermal species on two polymers commonly used for space applications (Kapton H and Teflon FEP) were investigated. The polymers were exposed to 30 eV O+ and Ne+ fluences of 1015–1019 ions cm−2. The phenomena investigated included total mass loss and changes of surface morphology (SEM and AFM) and surface chemical composition (XPS). The relative significance of the collisional and chemical degradation processes was evaluated by comparing the effects of O+ and Ne+ bombardment. AFM analysis was found very powerful in studying the damage from its initial atomic scale (roughness of ∼ 1 nm) to its final macroscopic scale (roughness > 1 μm).
Application of electron spectroscopies aided by the pattern recognition method for quantitative analysis of solid surfaces
Authors: Jablonski A. , Lesiak B. , Zommer L. , Bilinski A. , Józwik A. 
Published: May 2005

AbstractQuantitative analysis of solid surfaces by AES or XPS involves determination of intensity of selected spectral features, usually the most pronounced, recorded for the constituents of a given sample. Such experiments are frequently accompanied by intensity measurements of the same features on standard samples. Differences between the spectra shapes corresponding to samples with different concentrations are neglected within this procedure. Much less frequently, the quantitative analysis is based on variation of the shape of the selected feature in the energy spectra. An attempt is made in this article to perform the quantitative analysis by relating the spectra shapes to composition using routines of the pattern recognition method. The proposed approach is also based on the set of standards, i.e. a set of samples with known composition. The photoelectron or the Auger electron peaks recorded for all standards, with height normalized to a constant value, create the ‘experience’ of a computer for the identification of samples with unknown composition. It has been found that one of the algorithms of the pattern recognition method, the so called k‐nearest‐neighbour (kNN) rule, can be effectively used in the calculations. An extensive user‐friendly expert system has been developed to facilitate the calculations. Performance of the proposed method is demonstrated on a set of AuPd alloys.
Glancing incidence X‐ray analysis: Forgotten or to be discovered?
Authors: v.d. Hoogenhof W. W. , de Boer D. K. G. 
Published: May 2005

AbstractMany analysis methods can be used to characterize surfaces and interfaces of thin layered materials. Glancing incidence x‐ray analysis (GIXA) has the potential of being one of the most powerful and versatile analysis methods that can be used because it combines x‐ray reflectivity (XRR) and x‐ray fluorescence (XRF). This technique enables the non‐destructive determination of layer thickness, interface roughness and elementary depth profile. Sophisticated laboratory instrumentation is described which enables materials to be characterized in detail using newly developed analysis algorithms.
The design and development of a time of flight fast atom/ion scattering spectrometer
Authors: Giles R. , Sullivan J. L. , Pearce C. G. 
Published: May 2005

AbstractThis paper describes the design and development of a time of flight fast atom/ion scattering spectrometer. The instrument allows sample irradiation with a monoenergetic pulsed beam of either atoms or ions and energy and intensity analysis of scattered atoms or ions simultaneously or separately. In addition, primary incident, scattered exit, azimuthal and scattering angles may all be varied independently. For surface analysis this instrument promises to overcome many of the problems associated with conventional LEISS. In addition, greatly improved fundamental understanding of surface charge exchange mechanisms is possible through measurements unique to the instrument. In this paper we give details of the instrument, summarize its capabilities and discuss its potential for future fundamental and practical investigations.
Auger imaging from rough, chemically inhomogenous, materials
Authors: Crone M. , Barkshire I. R. , Prutton M. , Kenny P. G. 
Published: May 2005

AbstractSurface analysis of practical materials often presents a challenging situation in Auger spectroscopy and imaging because the yield of Auger electrons depends not only on the composition of the surface but also upon the local surface inclination (the topography) and the composition of the material below the surface. The use of simultaneous imaging of the same area of a sample with an electron spectrometer and four quadrants of a backscattered electron (BSE) detector has been demonstrated previously to be very useful for the separate correction of either topographical contrast or sub‐surface composition effects. In this work the possibility is tested of using BSE detector images to correct simultaneously acquired Auger images for the presence of both topographical and sub‐surface composition effects in the same sample. Measurements on model samples with known topography and sub‐surface composition are used. The samples are formed from anisotropically etched Si(100) coated in some places with a thick Au film and then overcoated everywhere with either a thin film of CuSn alloy or partially coated with a thin film of Au. The correction process is successful in reducing the artefacts everywhere and the extent of this correction is discussed.
Experimental determination of attenuation lengths of photo‐ and augerelectrons in silicon dioxide and in silicon nitride in the energy range 500 eV < Ekin < 3100 eV
Authors: Ebel M. F. , Ebel H. , Hofmann A. , Svagera R. 
Published: May 2005

AbstractAttenuation lengths (AL) of photo‐ and Augerelectrons in SiO2, Si3N4 and Si in the energy range 500–3100 eV have been determined by XPS with variable emission angle. The results are compared to published theoretical data on inelastic mean free paths (IMFP). The measured AL responses versus electron energy are approximately 10% smaller than the IMFP responses. This is in agreement with Monte‐Carlo calculations performed on Si. Thus, our results provide an electron spectroscopic confirmation of the data for SiO2, Si3N4 and Si given in the literature.
Computer programs for surface analysis by SIMS and SNMS
Authors: Fitzgerald A. G. , Watton H. L. L. , Storey B. E. , Colligon J. S. , Kheyrandish H. 
Published: May 2005

AbstractPrograms which have been developed to enable the rapid identification and quantification of elemental and molecular ions in SIMS and SNMS (Sputtered Neutral Mass Spectrometry) are described. The efficiency of these programs in identifying elemental species and quantifying concentration has been tested with amorphous silicon nitride films. Silicon doped with boron by ion implantation and a range of cobalt‐silicon alloys have been used to test quantification in SIMS by the ‘relative sensitivity factor’ (RSF) method and quantification in SNMS respectively. The concentration obtained for boron in silicon by the RSF method gave good agreement with the concentration obtained from the ion implantation flux. Accurate quantification results were also obtained from the SNMS data.
Quantitative analysis of REELS spectra of ZrO2: Determination of the dielectric loss function and inelastic mean free paths
Authors: Yubero F. , Sanz J. M. , Trigo J. F. , Elizalde E. , Tougaard S. 
Published: May 2005

AbstractThe dielectric loss function of ZrO2 over 0–80 eV has been determined from a quantitative analysis of reflection electron energy loss spectra (REELS) at different primary energies. From this, the inelastic electron mean free path for 200–2000 eV electrons in ZrO2 has been calculated. The inelastic mean free path (IMPF) is found to depend on the depth from which the electron is backscattered. For great depths, the IMFP approaches a constant value which is the same as that which would be obtained within a model that ignores the effects of the surface. The derived IMFP values have been compared to different formulae presented in the literature and the TPP2 formula due to Tanuma et al. is found to give the best agreement with the present results.
Auger electron spectroscopy studies on TiNx
Authors: Haupt J. , Baker M. A. , Stroosnijder M. F. , Gissler W. 
Published: May 2005

AbstractA new method for the determination of N/Ti ratio for TiNx samples has been proposed. High energy resolution Auger spectra recorded of the Ti L3M23M45 peak have shown that on nitridation of Ti to TiNx a second peak, labelled the L3M23Hybrid peak, emerges at 3.9 eV below the L3M23M45 peak in the raw data, which grows with the grade of nitridation. After a simple Shirley background correction a linear dependence between the ratio of the L3M23Hybrid/L3M23M45 peak height of the raw data and the N/Ti ratio was found. This relation can be used directly to evaluate the nitrogen content of an unknown TiNx compound by recording only the Ti L3M23M45 region. The changes of the L3M23M45 peak structure have been interpreted and compared with earlier DOS calculations for Ti and TiN. Good agreement between experiment and theory was found, enabling a discussion of the valence electronic structure changes for Ti on nitridation.
Growth of cobalt overlayers onto Si(100)
Authors: Benitez G. , Carelli J. L. , Heras J. M. , Viscido L. 
Published: May 2005

AbstractThe growth of evaporated Co overlayers onto Si(100) at 350 K was studied using Auger electron spectroscopy. Cobalt 5N was evaporated at a rate of ≈0.4 monolayers/min from a filament. The amount deposited was monitored with a quartz crystal microbalance with a resolution of 0.2 monolayers. The changes in the L23VV Si as well as in the cobalt LMM and MVV Auger transitions were followed. The growth mode of Co onto Si(100) surface depends strongly on the presence of oxygen. Without oxygen a diffusion front of Co is found after deposition of ≈4 monolayers. In the presence of oxygen (5 × 10−10 mbar), Si atoms diffuse to the surface, the adsorbed oxygen acting as the driving force with possible building of CoSi and Co2Si. The admitted oxygen does not cause detectable oxidation of the Si surface nor of the Co overlayer. A thin layer of SiO2 can be formed on the Si surface by O2+ bombardment, acting as a diffusion barrier to Co overlayers.
The chemical environment of nitrogen in the surface of carbon fibres
Authors: Alexander M. R. , Jones F. R. 
Published: May 2005

AbstractThe electrolytic oxidation of Type AU carbon fibres in an ammonium bicarbonate electrolyte was used as a model for the surface treatment of commercially available Type AS fibres. XPS and ToF SIMS of a range of fibre treatment levels was used to obtain information on the chemical changes at the fibre surface resulting from this treatment. The chemical state of the nitrogen determined by XPS to be presen ton the surface of Tyep AU fibre was identified as a protonated amine from the N1s peak position. Nitrogen was introduced into the surface of the Type AU fibre as a result of the electrolytic oxidation process. From a combination of XPS and ToF SIMS it it postulated that this was present as either an aromatic imide or urethane. On the basis of this information and composite strength measurements by other authors it is postulated that the chemical contribution to the increase in fibre‐epoxy bond strength was provided solely by the introduced oxygen functionalities. It is proposed that chemical reaction of the protonated amine present on the untreated fibres with the epoxy resin was responsible for the high ILSS of untreated Type A fibre‐expoxy composites relative to fibres with no surface nitrogen such as Type I.
Insulator surface analysis
Authors: Le Gressus C. , Blaise G. 
Published: May 2005

AbstractCharging an insulator hampers surface analysis techniques from working properly and over a long time has been considered as a spurious effect. Actually it is a physical phenomenon of major importance because its parameters are also those used to describe the macroscopic properties of insulators. This paper explains trapping/detrapping mechanisms where the important points are the calculation of the trap energy and of the energy stored in a charged dielectric material. Experimental techniques are developed for determining the insulator intrinsic properties. It is shown that measurements of permitivity, detrapping activation energy, trapping rate, detrapping space charge field, and power coefficient in the law describing the relationship between the insulator size and the detrapping field, are obtained with an electron beam. Another important finding is that charging significantly modifies the free energy of the sample. The consequence of the dielectric relaxation is investigated. It has been found that electron beam damages is not related to stimulated desorption but to the release of the polarization energy. This new approach to charging and related phenomena is applied to material science. It is shown that many phenomena such as breakdown, friction, fracture, which were believed to be very different are actually all related to dielectric processes. One consequence of the dielectric relaxation is the exoemission of various particles including neutrons in appropriate materials. The enormous energy released during charge detrapping or during polarization switching in ferroelectrics has been used elsewhere to produce electron and ion sources and nuclear fusion.
Electron spectroscopy of porous silicon layers. Indirect detection of hydrogen by elastic peak electron spectroscopy
Authors: Gergely G. , Gruzza B. , Bideux L. , Bondot P. , Jardin C. , Vázsonyi É. 
Published: May 2005

AbstractEfficient visible luminescence from porous Si (PSi) layers is associated with the quantum size and the presence of hydrogen as a passivaant on the inner surface. The increase of the amount of H was performed by wet chemical etching in HF, producing the increase of photoluminescence intensity. The detection of H is not possible by AES or XPS and is difficult even with EELS. Elastic peak electron spectroscopy (EPES) showed a large decrease of the elastic reflection coefficient re appearing in the elastic peak, and measured with a retarding field analyser (RFA). The effective elastic backscattering coefficients of a monolayer of H, Si, O were calculated for the RFA angular window and resulted in reasonable agreement with literature data available. They were completed for the 50–100 eV range. Experiments on a Si(111) wafer verified calculations. A dramatic decrease of re was found on HF‐etched PSi (a factor of 3–10) in the 50–100 eV range. Above 200 eV, effects are shadowed by the contribution of deeper layers of the substrate and reduced attenuation of the H adlayer. This indicates the formation of high H coverage on the porous inner surface. Experiments are interpreted by multiple elastic reflection and attenuation of electrons by the H‐covered porous surface. Detailed AES and EELS studies made with a hemispherical analyser resulted in Si and SiO2 bond on the surface.
Automatic matching of dissimilar SAM‐images
Authors: Böhmig S. D. , Reichl B. M. , Eisl M. M. , Störi H. 
Published: May 2005

AbstractAn important step in analysing multispectral image data—measured at different times or at slightly differing positions of the sample—is the matching of these data. The matching process consists of two steps: registration, which restores image differences induced by varying detector positions, and comparison, which follows image analysis and makes it possible to overlap different images and to detect and classify differences of the image contents.1–3We present a new technique for registering uni‐ and multispectral image data, which is independent of the underlying grey‐level distributions. This characteristic property is achieved by first transforming the representation of the image into a set of connected regions with homogeneous grey levels by means of a k‐means classification algorithm. The idea is to compare the geometric extensions of overlapping regions instead of single pixel values of images for a given geometric transformation. The transformation which yields the best similarity is then chosen to restore the data.The method was applied to several different uni‐ and multispectral scanning Auger microscopy (SAM) images and the results were judged according to accuracy and robustness.
In‐depth inhomogeneous photoluminescent properties of porous silicon layers
Authors: Parkhutik V. P. , Martinez‐Duart J. M. , Moreno D. , Albella J. M. , Gonzalez‐Velasco J. , Marcos M. L. 
Published: May 2005

AbstractChemical composition and photoluminescence of free‐standing porous silicon (PS) layers produced by anodization of p‐Si in aqueous HF solutions at high current densities (Ja = 50–250 mA cm−2) are studied. It is shown that the PS layers are enriched in oxide phase, presumably due to silicic acid formation during the pore growth. Chemical composition of PS films produced at current densities about 100–150 mA cm−2 is non‐uniform: internal faces of PS samples contain more silicon atoms than external. Their luminescent properties are also asymmetrical: the external face of the PS layer emits less light than the internal one. The samples grown at current densities above 200 mA cm−2 do not exhibit asymmetry of chemical composition and luminescence. The obtained results are considered based on existing models for PS luminescence and it is shown that the quantum confinement and siloxene‐based models may fit the present data.
XPS investigations of electrochemically modified porous silicon layers
Authors: Jeske M. , Jung K. G. , Schultze J. W. , Thönissen M. , Münder H. 
Published: May 2005

AbstractThe effect of electrochemical modifications like anodic oxidation, polymer deposition and electrodeposition of Cu and Ni on porous silicon are investigated with XPS and sputter depth profiling. It is shown that after the anodic oxidation small amounts of Si0 remain in the porous layer. The deposition of polymers as well as of metals takes place not only at the surface, but also in the porous layer.