bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surface and optical characterization of yttrium hydride films deposited on regular glass to be used as switchable mirrors
Authors: Velásquez P. , Castañer R. , de la Casa‐Lillo M. A. , Sánchez‐López M. M. , Mallavia R. , Moreno I. , Gutiérrez A. , Mateos F. 
Published: October 2002

AbstractYttrium and palladium thin films deposited on glass have been characterized by means of XPS depth profiling, SEM, energy‐dispersive x‐ray spectroscopy and ultraviolet–visible spectroscopy. These films allow optical windows of variable transparency to be obtained based on the formation of yttrium hydride by hydrogenation, with the palladium film working as a barrier against yttrium oxidation but being permeable to hydrogen. The transformation of yttrium into its hydride is concomitant with a metal–semiconducting transition that changes the physical properties of the material, especially its optical behaviour: the transmittance in the visible range goes from 0% for the metallic state to 30–70% for the hydrogenated state. In this work, the preparation conditions of optical windows using low‐cost regular glass as substrate have been optimized, both regarding the deposition and the hydrogenation. Uniform films free of impurities, such as oxygen and carbon, have been obtained under ultrahigh vacuum conditions of ∼10−7 Pa. Deposition has been performed by electron bombardment of the material, using palladium and yttrium of high purity. Copyright © 2002 John Wiley & Sons, Ltd.
Microchemical and micromorphological features of gunshot residue observed by combined use of AFM, SA‐XPS and SEM + EDS
Authors: D'Uffizi M. , Falso G. , Ingo G. M. , Padeletti G. 
Published: October 2002

AbstractMicrochemical and micromorphological analytical methods have been used by law enforcement agencies to ascertain whether or not an individual has been involved recently in a firearm shooting by determining the presence of gunshot residue (GSR).In the present work, the microchemical and micromorphological features of the GSR particles deposited on the bullet and on the firing hands, collected using double‐sided tape, have been studied by means of the combined use of scanning electron microscopy + energy‐dispersive spectroscopy (SEM + EDS), atomic force microscopy (AFM) and selected‐area x‐ray photoelectron spectroscopy (SA‐XPS).The results indicate that this advanced approach could disclose new micromorphological and microchemical features that could be useful for considerably increasing the confidence level of such determination. Copyright © 2002 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy study of thin oxide layers formed on (001)‐oriented β‐NiAl single‐crystal surfaces
Authors: Frémy Nicolas , Maurice Vincent , Marcus Philippe 
Published: October 2002

AbstractQuantitative XPS data complemented by low‐energy electron diffraction (LEED) and scanning tunnelling microscopy (STM) results of the very first stages of oxidation of an NiAl(001) single‐crystal surface are reported. The thickness, stoichiometry and alloy composition at the oxide/alloy interface and, when possible, the structure have been analysed after oxidation at room temperature and 750°C and under 10−7, 10−5 and 200 mbar of oxygen. The growth of alumina layers is essentially two‐dimensional in the initial stages. Thin oxide films grown up to 50 Å show an oxygen enrichment that decreases with increasing thickness. The competition between the segregation of aluminium and its consumption by oxygen in the growth kinetics of the oxide layers is evidenced by the variation of the stoichiometry of the oxide films and alloy composition at the oxide/alloy interface. Copyright © 2002 John Wiley & Sons, Ltd.
Investigation of surface structure and composition ofin situannealed Fe–Mn binary alloy samples using RHEED and electron spectroscopy
Authors: Martínez C. , Cremer R. , Neuschütz D. , Servais J. P. , Loison D. 
Published: October 2002

AbstractThe formation of oxides at the surface of Fe–1.5%Mn and Fe–0.6%Mn binary alloys was investigated as a function of the conditions of the heat treatments. Both the influence of temperature and the atmosphere under which the experiments were performed were studied. The range of annealing temperatures was adjusted to 800°C. The atmosphere consisted of a mixture of N2–5%H2and traces of water vapour, with different fixed dew points ranging from −10°C to −30°C. The state of the annealed surfaces was determined usingin situanalytical devices attached to the annealing reactor in order to avoid surface contamination or the formation of native oxides after the experiments due to contact with air. The structure and composition of the surfaces were determined by reflection high‐energy electron diffraction (RHEED) and electron spectroscopy (XPS, AES). Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of hydrous manganite (γ‐MnOOH) surfaces—an XPS study
Authors: Ramstedt M. , Shchukarev A. V. , Sjöberg S. 
Published: October 2002

AbstractCrystalline manganite (γ‐MnOOH) has been synthesized and characterized using x‐ray diffraction and high‐resolution transmission electron microscopy techniques. The surface composition was studied with XPS between pH 0.4 and 11. Special pre‐cooling procedures were developed to keep the manganite/water interface intact before and during XPS measurements. The O/OH group ratio differs between pH 6 and 11, in agreement with the acid/base characteristics of the surface. Below pH 6, on the other hand, drastic changes can be seen in the O 1s spectra due to dissolution of manganite. Possibly the interaction of OH groups with H+ in acidic suspensions is a first step leading to dissolution. The surface charge arising at high and low pH is compensated by the counter‐ions Na+ and Cl−, respectively. The XPS spectra are presented and discussed in terms of the mechanisms for surface complexation and dissolution processes. Copyright © 2002 John Wiley & Sons, Ltd.
Use of spectroscopic ellipsometry to study Zr/Ti films on Al
Authors: Laha P. , Schram T. , Terryn H. 
Published: October 2002

AbstractSpectroscopic ellipsometry in the spectral range between the near‐ultraviolet and the near‐infrared (250–1700 nm) (SE) and the mid‐infrared (2–23 µm) (IR‐SE) have been used for the characterization of various thin coatings on aluminium. Both SE and IR‐SE provide information concerning the morphological features of the coating, but owing to the presence of characteristic absorptions IR‐SE also reveals the chemical composition. This paper discusses the application of the developed optical models for the characterization of the more complex Zr/Ti‐based passivation coatings. The results obtained indicate that these coatings consist of a complex hydrated Zr/Ti/Al oxyfluoride. Copyright © 2002 John Wiley & Sons, Ltd.
Study of the NiTi/SiO2 interface: analysis of the electronic distributions
Authors: Jarrige Ignace , Jonnard Philippe , Frantz‐Rodriguez Nadège , Danaie Kamran , Bosseboeuf Alain 
Published: October 2002

AbstractWe present a study of the interface between a NiTi film deposited by magnetron d.c. sputtering and a SiO2 film obtained by thermal oxidation. Electron‐induced X‐ray emission spectroscopy (EXES) is used to characterize the physicochemical environment around the Si atoms at the NiTi/SiO2 interface, and to obtain information about the interfacial reactivity. From analysis of the Si 3p valence states, the composition and the thickness of the interfacial zone before and after annealing are deduced. The composition of the passivation layer, located at the surface of the metallic film, is determined by EXES and X‐ray Photoelectron Spectroscopy. Copyright © 2002 John Wiley & Sons, Ltd.
Compositional and structural characterization of zirconia films with reticular structure obtained by spray pyrolysis
Authors: Martin F. , Ayouchi R. , Ruiz C. , Ramos‐Barrado J. R. , Leinen D. 
Published: October 2002

AbstractZirconia (ZrO2) films with reticular structure, to be used as support in catalysis, have been deposited on AISI‐304 stainless steel held at 473 K by spray pyrolysis using aqueous solutions of zirconyl chloride octahydrate (ZrOCl2·8H2O) as precursor. As‐deposited films and films annealed in air to different temperatures after deposition have been studied by x‐ray diffraction (XRD), SEM and XPS. It was found that the crystal structure of the ZrO2 films changes from amorphous to tetragonal and that the films were uniform and well adhered to the stainless‐steel substrate for annealing temperatures up to 773 K. However, films annealed to 873 K crack and peel off from the substrate owing to the growth of an interfacial oxide layer between the ZrO2 film and the stainless‐steel substrate. The fracture, which leads to delamination of the ZrO2 film, occurs through the interfacial oxide layer. XPS depth profiling revealed that this interfacial oxide layer is of varying composition (containing iron, chromium and nickel) with depth. Copyright © 2002 John Wiley & Sons, Ltd.
Surface chemical changes induced by low‐energy ion bombardment in chromium nitride layers
Authors: Bertóti I. , Mohai M. , Mayrhofer P. H. , Mitterer C. 
Published: October 2002

AbstractIn this work three types of CrNx layers—one close to Cr2N, the other to CrN and a third with high nitrogen content CrN1+x—were prepared by reactive magnetron sputtering. The samples were subjected to bombardment by Ar+ and N2+ ions applied in sequence. The relative atomic concentration and the chemical states of the elements in the surface layer were determined by x‐ray photoelectron spectroscopy. Alternate bombardment with Ar+ and N2+ ions (1–2 keV) resulted in significant compositional and chemical state changes. Although prolonged Ar+ bombardment did not decrease the nitrogen content of Cr2N below the nominal (CrN0.5) composition, it decreased the nitrogen content of the closely stoichiometric CrN appreciably, to about CrN0.8. At bombardment with N2+ ions nitrogen could be implanted into the Cr2N films, changing its composition up to about CrN0.8. It was shown that extra nitrogen could be incorporated also into the CrN samples, increasing the nitrogen content above the stoichiometric composition up to about CrN1.2. The CrN1+x‐type sample showed high stability towards Ar+ bombardment. Two significantly different chemical states of nitrogen were determined for the two types of nitrides: the N 1s peak at 397.5 ± 0.1 eV binding energy was characteristic of N in Cr2N and the peak at 396.5 ± 0.1 eV of N in the CrN state. The effect of Ar+ and N2+ bombardment on the surface composition discussed in this paper may provide information for elaboration of deposition conditions for CrNx coatings with predetermined chemical composition and structure. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of ultrathin Cr layers on PET by RBS and XRF
Authors: Draxler M. , Zoister S. , Kastner F. , Bergsmann M. , Bauer P. 
Published: October 2002

AbstractWe studied the characterization of thin metallic layers vacuum‐deposited by magnetron sputtering onto commercial polyethylene terephthalate (PET) films in an industrial web coater. Because the technology of metal coating for technical films tends more and more towards nanotechnology, quantitative surface and interface analysis are required to optimize the metallization procedures. An important factor is the thickness of the thin coated layers. A powerful tool to characterize chemical composition and layer thickness of such nanofilms quantitatively is low‐energy Rutherford backscattering spectroscopy (LE‐RBS); it is, however, not suitable for production control. A standard industrial tool for these measurements at higher layer thickness is x‐ray fluorescence spectroscopy (XRF). This method is highly sensitive and reproducible but needs calibration standards.We show that the thickness of chromium layers in the subnanometre range can be determined by means of LE‐RBS without deterioration of the PET film. We further show that a set of layers of different thickness can be measured by LE‐RBS with sufficiently high accuracy to serve as calibration standards for XRF or optical density measurement. From the correlation of the results obtained by RBS and XRF, we learn about the uncertainties induced by the production process (lateral uniformity) and by the analytical techniques. Copyright © 2002 John Wiley & Sons, Ltd.
Monolayers of simple organic molecules on silicon studied by surface tools
Authors: Scandurra A. , Renna L. , Cerofolini G. , Pignataro S. 
Published: October 2002

AbstractSimple organic molecules such as 1‐octadecene, 1‐tetradecene, 1‐dodecyne and 1,13‐tetradecadiene have been grafted to hydrogenated B‐doped silicon (100) surfaces. Such substrate has been obtained by etching commercial native oxide‐capped flat crystal silicon wafers with procedures involving dilute HF aqueous solutions, but also by hydrogenation with a new method involving treatment of the wafer in an oven with H2 gas. The functionalization of such a surface has been done by using described wet methodologies involving pure liquids or solutions with thermal activation of the hydride. Contact angle, ESCA, atomic force microscopy (AFM) and time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS) measurements have been carried out to characterize the above systems. Particular emphasis is devoted to the interpretation of the ToF‐SIMS spectra, seldom used until now to characterize organic monolayers. Copyright © 2002 John Wiley & Sons, Ltd.
Combined application of ion beam slope cutting and SEM/EDX for investigation of the surface layer system on tungsten microwires after tribological treatment
Authors: Hauffe W. , Pannicke S. , Däbritz S. , Schade P. 
Published: October 2002

AbstractThe surface layer system on tungsten wires developed after different technological processing steps and depending on the tribological treatment during the production technology has been investigated. The ion beam slope cutting (IBSC) technique in combination with scanning electron microscopy (SEM) and energy‐dispersive x‐ray (EDX) analysis has been applied for full three‐dimensional determination of the phase and grain microstructure of the border zones of tungsten wires. The IBSC technique was changed for wire‐shaped samples and modified by additional ion beam processing steps to characterize the near‐surface regions of microwires. Transversal and longitudinal cuts through the border zones of the microwires have been performed for SEM observation and EDX microanalysis of the cut areas. The inhomogeneous three‐dimensional distribution of tungsten oxide and graphite (as a lubricant) as well as the fine‐grained tungsten structure could be determined with SEM resolution. Copyright © 2002 John Wiley & Sons, Ltd.
Quantitative XPS analysis of aluminium in the presence of copper
Authors: Hazell Leonard B. 
Published: October 2002

AbstractQuantification of aluminium in the presence of copper is a fundamental problem in XPS analysis due to peak overlap. This article presents and demonstrates the utility of a simple approach to alleviate this difficulty based on measurement of the P : S combination peak area ratio. It is particularly appropriate for inclusion in this Festshrift edition of the journal dedicated to Professor Jim Castle, who has worked extensively on copper–aluminium alloys throughout his long career. Incorporation of the method into commercial data systems and, particularly, an expert system is recommended so that the analyst can be alerted to the likely presence of aluminium and provided with a means to quantify the amount. Copyright © 2002 John Wiley & Sons, Ltd.
Surface evolution of Ni–V transparent oxide films upon Li insertion reactions
Authors: Zanoni R. , Decker F. , Coluzza C. , Artuso F. , Cimino N. , Di Santo G. , Masetti E. 
Published: October 2002

AbstractA detailed picture is reported of the nature of an Li insertion Ni–V mixed‐oxide electrode and of its evolution upon prolonged intercalation/deintercalation cycles. A combination of bulk and surface‐sensitive techniques is used, including electrochemical analysis (cyclic voltammetry, impedance spectroscopy), atomic force microscopy (AFM) and XPS. The Ni–V oxide film, obtained by r.f. sputtering as a thin film on conductive glass for use as a transparent electrode in electrochromic windows, is an Li insertion material with high charge capacity, very good reversibility and a surface morphology characterized by a low initial roughness. Its surface composition shows an initial Ni enrichment. The nominal Ni–V stoichiometry is recovered already after ten cycles. Extended Li charge–discharge cycles induce progressive changes in the electrode reversibility (capacity fading) and in the reaction kinetics (increase of impedance). The surface evolution consists of the progressive accumulation of an Li carbonate layer, with thickness and roughness increasing with the number of cycles. The constancy of the core level and Auger peaks of Ni and V after 100 cycles excludes major changes in the electronic structure of the host oxide. However, electrochemical and AFM experiments performed after 1000 cycles indicate that the carbonate deposition on the electrode progresses further, therefore the surface layer is unable to yield a permanent electrode passivation and stabilization. Copyright © 2002 John Wiley & Sons, Ltd.
Surface chemistry of cement pastes: a study by x‐ray photoelectron spectroscopy
Authors: Baeta Neves Maria Inês , Oliva Victor , Mrabet Béchir , Connan Carole , Chehimi Mohamed M. , Delamar Michel , Hutton Simon , Roberts Adam , Benzarti Karim 
Published: October 2002

AbstractTwo cement pastes commonly used in concrete formulations were characterized by XPS before and after coating with an epoxy resin and a hardener. The XPS allowed the surface chemistry change induced by the organic coating to be monitored. In particular, the C 1s spectra were peak fitted in order to deduce the contribution of the organic materials to the total carbon content on the surface. Inspection of the N 1s peak at the cement/hardener interface indicates a certain degree of donor–acceptor interaction, where the aminated hardener plays the role of the Lewis base (donor) and the cement acts as the Lewis acid.A relationship has been established between the dispersive contribution to the surface free energy (γSd) of the cement pastes and the surface chemical composition. A substantial decrease in the surface energy (from 65 to ∼30 mJ m−2) of the materials has been observed for a higher surface content in organic materials or, alternatively, for a more homogeneous organic coating even at a lower mass loading of the resin or hardener. Copyright © 2002 John Wiley & Sons, Ltd.
Degradation during ARXPS measurements of polystyrene treated with an oxygen plasma
Authors: Paynter R. W. 
Published: October 2002

AbstractThin polystyrene films, deposited on glass substrates, were exposed to an oxygen / helium plasma for 3s, 7s, 15s or 30s. Following exposure to air for four weeks, the samples were analyzed by ARXPS in a VG ESCALAB 220i X‐ray photoelectron spectrometer and in a VG Theta Probe instrument. Comparison of the results obtained demonstrates the effect of the oxygen loss during analysis in the VG ESCALAB 220i, which flattens the angle‐resolved profiles obtained and leads to the calculation of an oxygen depth profile which extends deeper into the surface and in which the oxygen concentration is lower. A simple procedure for the correction of the data obtained in the VG ESCALAB 220i is only partially successful at reconciling the derived oxygen depth profile with that calculated from the Theta Probe data. Copyright © 2002 John Wiley & Sons, Ltd.
Estimation of the area under the ROC curve
Authors: Faraggi David , Reiser Benjamin 
Published: October 2002

AbstractThe area under the receiver operating characteristic curve is frequently used as a measure for the effectiveness of diagnostic markers. In this paper we discuss and compare estimation procedures for this area. These are based on (i) the Mann–Whitney statistic; (ii) kernel smoothing; (iii) normal assumptions; (iv) empirical transformations to normality. These are compared in terms of bias and root mean square error in a large variety of situations by means of an extensive simulation study. Overall we find that transforming to normality usually is to be preferred except for bimodal cases where kernel methods can be effective. Copyright 2002 John Wiley & Sons, Ltd.
Role of the Data and Safety Monitoring Committee (DSMC)
Authors: Wilhelmsen Lars 
Published: October 2002

AbstractThe Data and Safety Monitoring Committee (DSMC) is a committee independent of both the Steering Committee (SC) and any sponsor. It advises these bodies on continuation or stopping based upon safety and efficacy considerations. The primary objective is to assure safety for the patients in the trial. Blinding of the DSMC regarding type of treatment is usually avoided. The DSMC is composed of three to five members and should include one or two clinicians knowledgeable in the field of the trial, one or two statisticians and in some situations a pharmacologist and an ethicist. It is important that the members have experience from other trials and have high integrity. Rules for the statistical analyses have to be set up in the beginning of the trial. However, the DSMC cannot rely only upon statistical rules. Information from other sources may cause stopping before the scheduled end of the trial. The DSMC has to check that the overall quality of the data is good. Of special importance is that the Endpoint Committee is current with classification of endpoints. Timing of the DSMC meetings is dependent on several factors: (i) the incidence of events; (ii) the power of the study design; (iii) the effectiveness of the intervention. Legal requirements to report serious adverse events to legal authorities may be taken over by the DSMC, which ideally is the only body that has access to unblinded data. Copyright © 2002 John Wiley & Sons, Ltd.
Evaluating the costs and effectiveness of cardiovascular therapies: who cares about economic analyses?
Authors: Califf Robert M. 
Published: October 2002

AbstractThe field of cardiovascular medicine is providing important insights about how the costs and effectiveness of diagnostic and therapeutic technologies are managed. As health‐care budgets have taken up more of the economy and as employers and patients have become concerned about the escalating costs of health care, we have entered an era in which individual practitioners must become concerned with the costs of a service relative to its benefits. Further, increasing numbers of effective therapies in a time when finances are notably constrained, we clearly cannot use all effective therapies in all patients. Increasingly, therefore, we must assess the value derived from spending incremental money on health care products and services. This exercise has been termed cost‐effectiveness analysis. The case of the platelet glycoprotein IIb/IIIa inhibitor, abciximab, is used to illustrate many of the issues surrounding the collection, interpretation, and (mis) application of cost‐effectiveness data. Copyright © 2002 John Wiley & Sons, Ltd.