bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical effects in Auger electron spectra of aluminium
Authors: Timmermans B. , Vaeck N. , Hubin A. , Reniers F. 
Published: October 2002

AbstractThe bonding and electronic structure of surface atoms is most often studied by XPS, where the energy shift of a photoelectron peak can be ascribed to a change in the chemical environment. Because three atomic levels are involved in the Auger emission process, the use of Auger spectroscopy to obtain this information from peak positions and lineshape is more difficult. However, new progress in signal analysis techniques makes the extraction of chemical information intrinsically present in the Auger spectra possible. The advantage of AES over XPS is its higher lateral resolution, allowing study of the surface distribution of the elements (Auger mapping). This, combined with modern computational methods, opens up new opportunities in surface analysis.In order to try to correlate the changes in the Auger peak energies with the changes in the chemical environment, we performed a full experimental and theoretical study of the Auger KLL lines of aluminium in several compounds (Al2O3, AlN, AlB2 and AlF3) by AES and x‐ray‐induced AES, the peak position for AlB2 being reported for the first time. The inner‐shell KLL peaks of Al show large energy shifts, depending on the chemical environment. The experimental results are compared to ab initio calculations based on a new cluster model including chemical, structural and relaxation effects. Copyright © 2002 John Wiley & Sons, Ltd.
How to measure accurately mass transport in thin films by AES
Authors: Girardeaux C. , Clugnet G. , Erdélyi Z. , Nyéki J. , Bernardini J. , Beke D. , Rolland A. 
Published: October 2002

AbstractIn this paper, we show that AES is a powerful technique to determine mass transport in thin films with model metal/metal thin‐layer structures (for systems without any compound formation). We show the conditions where grain boundary and/or bulk diffusion coefficients can be determined accurately at unusually low temperatures by monitoring the surface segregation kinetics of an impurity through a nanocrystalline film using the Hwang–Balluffi approach (systems with total solubility), and the dissolution of ultrathin deposits in a matrix using a model based on Martin's kinetic deterministic equations (systems with total solubility). Copyright © 2002 John Wiley & Sons, Ltd.
Simultaneous processing of plasma carburization and carburization prevention by hollow cathode discharge
Authors: Urao R. , Khoo K. P. , Kuramochi Y. , Takeuchi H. , Funaki Y. , Takeuchi M. 
Published: October 2002

AbstractA simultaneous treatment for carburization and carburization prevention by hollow cathode discharge was carried out with methane and hydrogen mixing gas for preheating, carburization and diffusion treating in the same chamber simultaneously. The hardness, carbon distribution and microstructure of carburized chromium–molybdenum steel were investigated after the treatment of simultaneous plasma carburization and carburization prevention. It was found that the simultaneous treatment of carburization and carburization prevention depended on the methane content in the mixing gas, the flow rate of the mixing gas and the treating temperature. The experimental results indicate the possibilities for simultaneous treatment of plasma carburization and carburization prevention. Copyright © 2002 John Wiley & Sons, Ltd.
Surface passivation of gallium selenide by nitrogen implantation
Authors: Márquez F. , Segura A. , Muñoz V. , González G. 
Published: October 2002

AbstractIn this paper we report on the characterization of nitrogen‐implanted single‐crystal GaSe samples. Nitrogen atoms were implanted at 80 keV, with doses ranging from 4 × 1013 to 1015 N+ ions cm−2. Next, samples were aged in open air and characterized by small‐area XPS, together with an unimplanted clean surface, in order to quantify the effects of the nitrogen implantation. In general, we found that the oxidation was fully prevented in N+‐implanted samples. Copyright © 2002 John Wiley & Sons, Ltd.
Combined use of GDOES and SEM + EDS for the microchemical study of oxide layers grown at high temperature on Nimonic 80 A nickel‐based superalloy
Authors: Ingo G. M. , Angelini E. , Calliari I. , Dabalà M. , De Caro T. 
Published: October 2002

AbstractThe microchemical structure of the oxide scale grown on a polycrystalline Nimonic 80 A nickel‐based superalloy as a function of the air high‐temperature treatment (up to 950°C) has been studied by means of the combined use of glow discharge optical emission spectrometry (GDOES), scanning electron microscopy with energy‐dispersive spectrometry (SEM + EDS) and x‐ray diffraction (XRD). The results disclose the morphology, the microchemical structure and the in‐depth elemental chemical composition of the oxide layers and their variation as a function of the temperature of the air thermal treatment. Furthermore, GDOES, SEM + EDS and XRD results show the different oxidation behaviours of both main alloying and minor reactive elements that induce the formation of a stratified oxide structure. Copyright © 2002 John Wiley & Sons, Ltd.
Micro‐ and nanocomposites of Keggin heteropolymetalates in cellulose esters
Authors: Oliveira Francílio de C. , Schneider José , Siervo Abner , Landers Richard , Plepis Ana M. G. , Pireaux Jean‐Jacques , Rodrigues‐Filho Ubirajara Pereira 
Published: October 2002

AbstractComposites of Keggin heteropolymetalates have been prepared and characterized by SEM, XPS, 31P‐magic angle spinning/nuclear magnetic resonance and differential scanning calorimetry. The phosphotungstic acid and phosphomolybdic acid form nanocomposites where the oxocluster structure is preserved and is highly dispersed over the material, probably inserted between the polymeric chains. Phosphovanadotungstic clusters suffer partial decomposition during composite formation, resulting in a biphasic microcomposite. The decomposition product, phosphotungstic acid presents surface segregation as shown by comparison of XPS and nuclear magnetic resonance results. Copyright © 2002 John Wiley & Sons, Ltd.
UHV–liquid cell transfer system for Auger electron spectroscopy on electrodes
Authors: Reniers F. , Rooryck V. , Pace S. , Buess‐Herman C. 
Published: October 2002

AbstractMany chemical reactions take place at the liquid/solid interface that are responsible for dramatic environmental, industrial and economic problems. For a long time, these reactions have been studied by conventional electrochemical techniques and the influence of most of the macroscopic parameters involved in the reaction (solution pH and composition, redox potential, etc.) are known for many systems. The resulting oxidized surface is often analysed by XPS and AES, but the measurements are performed after air exposure and thus after surface contamination or post‐oxidation. Most of the time, no direct information on the surface composition at the liquid/solid interface is available because of the lack of in situ available techniques for chemical analysis.In order to combine the intrinsic advantage of electrochemical techniques (superior for the study of the redox reactions in solution) and the power of surface analysis techniques such as XPS and AES used under ultrahigh vacuum (UHV), we have designed, built and validated an original versatile UHV–electrochemical cell transfer system. This system allows the preparation of a clean electrode surface under UHV and its characterization by low‐energy electron diffraction and AES before its transfer to an electrochemical cell under a controlled atmosphere (no oxygen, no contamination). The study of model electrochemical reactions can take place and is followed by transfer of the electrode back to the UHV chamber for surface analysis by AES, without exposure to air. The transfer procedure takes 4 min.Model systems were used to validate the system:

Bromide ions were electrochemically adsorbed on gold at various electrode potentials, inducing different surface compositions. Evolution of the Br content on the surface as a function of the electrode potential, estimated after transfer by AES, is in good agreement with the Br surface excess extracted from the electrochemical data, indicating that the transfer process induces no significant alteration of the surface, despite the weak bonding of bromide on gold and the brutal transfer from liquid to UHV. Results were compared with the literature.
Aluminium was taken as a standard to study the residual oxidation due to the composition of the atmosphere during the transfer process. The residual contamination (carbon) induced by the transfer process was also analysed. Carbon‐free transfer procedures were established.
In conclusion, such a transfer system combines the unique advantages of electrochemical methods to study corrosion processes with the power of a UHV technique such as AES. Copyright © 2002 John Wiley & Sons, Ltd.
Adsorption of cationic ‘gemini’ surfactants at the TiO2/solution interface
Authors: Ardizzone S. , Bianchi C. L. , Quagliotto P. , Viscardi G. 
Published: October 2002

AbstractAdsorption isotherms of cationic pyridinium surfactants at the solid/liquid interface were obtained on aqueous dispersions of titanium dioxide as a function of the electrification features of the adsorbent. The surfactants, prepared in the laboratory, were a symmetric ‘gemini‐like’ dimer (1,1′‐bidodecyl‐4,4′‐bipyridinium chloride) and its related simple monomeric salt (1‐dodecyl‐4‐methylpyridinium chloride). X‐ray photoelectron spectroscopy analyses were performed both on the bare adsorbent and in the presence of the adsorbates. The XPS regions of Ti 2p, O 1s, N 1s and C 1s were specifically investigated. The nature of the interactions supporting the adsorption and the molecule orientation/co‐area are discussed in the light of the different experimental evidence. Copyright © 2002 John Wiley & Sons, Ltd.
In situ spectroscopic ellipsometry as a sensor for hard coatings and steel nitriding
Authors: Bonanni A. , Stifter D. , Hingerl K. , Störi H. , Werner W. S. M. , Brenner J. , Weithaler C. , Gruska B. , Prunel G. , Delaire V. , Sanvito T. 
Published: October 2002

AbstractIn this work, where the major emphasis has been given to in situ and on‐line measurements, we extend the available experience in the field of spectroscopic ellipsometry to plasma‐assisted chemical vapour deposition (PACVD) hard coatings and diffusion layers on steel, namely TiN, TiCN, TiAIN and FexNy. Furthermore, Auger electron spectroscopy was carried out in order to correlate the spectroscopic ellipsometry data on an absolute scale to their composition. It could be shown that monitoring of whole standard industrial processes (up to 24 h) for the control of nitriding/deposition processes is easily achievable. Thus, the formation of compound layers, the effectiveness of sputtering and the nitriding process as well as the composition of hard coatings (TiN and compounds) can be determined in real time in order to control and tune on‐line the fabrication of PACVD hard coatings. Copyright © 2002 John Wiley & Sons, Ltd.
Study of InP(100) surface nitridation by x‐ray photoelectron spectroscopy
Authors: Bideux L. , Ould‐Metidji Y. , Gruzza B. , Matolin V. 
Published: October 2002

AbstractIon beam nitridation of indium phosphide (100) substrates was studied using x‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). Argon ion bombardment of the InP(100) surface removes the native oxides and induces the formation of three‐dimensional indium clusters. After cleaning, the samples were nitrided in an ultrahigh vacuum chamber using a home‐made radiofrequency plasma source (13.56 MHz) that allows nitridation at low pressures (10−4 Pa). We have studied the influence of temperature on the nitridation mechanisms. For low temperature (T < 200°C), no variation of the metallic indium droplets was observed; for high temperature (T > 270°C), the first layers of the substrate were damaged. The optimal temperature for the nitridation of InP(100) was found to be 250°C. Copyright © 2002 John Wiley & Sons, Ltd.
Electron spectroscopic studies of iron and iridium silicides
Authors: Probst M. , Denecke R. , Whelan C. , Kinne M. , Borgmann D. , Steinrück H.‐P. 
Published: October 2002

AbstractThe formation of iron and iridium silicides was studied by means of highly resolved photoelectron spectroscopy of core and valence levels as well as by means of low‐energy electron diffraction (LEED). The experiments were carried out at BESSY II in Berlin using synchrotron radiation for the photoemission studies. After evaporation of seven monolayers of Fe on Si(111) at room temperature and annealing to 410 K for 420 s, an ordering of the surface structure and the formation of an (1 × 1) LEED pattern is observed. Upon further heating to 500 K a strong change in both UPS and XPS spectra occurs. This behaviour is attributed to the formation of FeSix (1 ≤ x ≤ 2). After annealing of a thin Ir layer on Si(100) to 1130 K, a p(2 × 2) LEED pattern with respect to the silicon substrate is observed, which indicates the formation of a well‐ordered surface compound. Comparison with the literature shows that the formation of an IrSi species is well known, but only an amorphous and a polycrystalline modification have been described upto now. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of the boundaries of thin films of TiO2 by atomic force microscopy and optical methods
Authors: Franta D. , Ohlídal I. , Klapetek P. , Pokorný P. 
Published: October 2002

AbstractIn this paper slight roughness of the upper boundaries of TiO2 thin films prepared on substrates formed by single‐crystal silicon is studied. Atomic force microscopy (AFM) and an optical method based on combining variable‐angle spectroscopic ellipsometry and near‐normal spectroscopic reflectometry are used for this purpose. It is shown that the values of the basic statistical quantities characterizing this roughness depend quite strongly on the values of the thicknesses of these films (they increase with increasing thickness). Differences observed between the values of the basic statistical parameters determined by AFM and the optical method are explained. It is also shown that the TiO2 films exhibit an inhomogeneity represented by a profile of the complex refractive index. Copyright © 2002 John Wiley & Sons, Ltd.
Spatially resolved microchemical analysis of chromate‐conversion‐coated aluminum alloy AA2024‐T3
Authors: Jaime Vasquez M. , Kearns J. R. , Halada G. P. , Clayton C. R. 
Published: October 2002

AbstractThe corrosion of aerospace aluminum alloys has been linked to the electrochemical behavior and chemical composition of constituent intermetallic compounds (IMCs). In this study, secondary ion mass spectrometry (SIMS), x‐ray photoelectron spectroscopy (XPS), synchrotron infrared microspectrometry (SIRMS) and x‐ray absorption near‐edge structure spectroscopy (XANES) were used to characterize chromate conversion coatings (CCCs) formed on AA2024‐T3 sheet and cast IMC analogs. The nascent surface film formed on IMC and matrix surfaces was characterized to reveal the influence of microstructure on CCC structure and composition. Copper‐rich regions were found on the outermost CCC surface. Intermetallic compounds rich in Cu were found to be surface depleted of Cr and enriched in CN from the ferricyanide present in the CCC as an accelerator compound. By distinguishing particle morphology and chemistry, SIMS data demonstrated that heterogeneities in CCC composition were associated with IMCs. Copyright © 2002 John Wiley & Sons, Ltd.
Size isn't everything
Authors: Hampton J. R. 
Published: October 2002

AbstractClinical trials now often involve thousands of patients, and statisticians emphasize the importance of trial size in ensuring that ‘correct’ answers are obtained. However, when a good treatment appears for a disease that was hitherto untreatable – for example, oranges for scurvy or streptomycin for tuberculosis – only a small trial is needed. Large trials are only needed to demonstrate small effects. The meta‐analysis of small trials is often misleading, and may hide undesirable effects of individual drugs. The concept of equivalence between treatments is important, and while a statistically adequate equivalence trial may have to be very large, many clinicians will question the need for extreme statistical propriety. Clinical trials often do not reflect ‘real world’ practice, and the clinical relevance of a trial is more important than its size. Copyright © 2002 John Wiley & Sons, Ltd.
Collaboration with the local community
Authors: Jackson Michael L. , Cherrey Cynthia 
Published: October 2002

AbstractColleges and universities continually search for ways to enhance the safety and security of their educational programs and physical plant. This chapter examines how the University of Southern California and other institutions are using collaborative efforts with the local community to enhance their mutual safety and security through dynamic partnerships and expanded service learning, volunteer, and teaching experiences for students, faculty, staff, and campus neighbors.
Some issues related to the feedback control of a baffled plate
Authors: Preumont A. , De Man P. , François A. 
Published: October 2002

AbstractThis paper addresses a few issues related to the active structural acoustic control (ASAC) of a baffled plate. The first part proposes a feedback control strategy according to which a SISO control system is built by using a volume displacement sensor and a set of actuators driven with a single amplifier. The location of the actuators is then optimized to achieve an open‐loop transfer function with alternating poles and zeros, as for systems with co‐located actuators and sensors. This important feature allows the use of low‐order controllers. The second part of the paper discusses the volume displacement sensor; the spatial aliasing of a discrete array sensor is first demonstrated and a new electrode design is proposed, which makes it possible to tailor the effective piezoelectric properties of PVDF films. This electrode is used to design a volume displacement sensor. Copyright © 2002 John Wiley & Sons, Ltd.
Experimental study on the behaviour of aluminium panels for seismic energy dissipation
Authors: Foti D. , Nobile R. 
Published: October 2002

AbstractThe aim of this work is to provide the results of a series of experimental tests to study the behaviour of frames equipped with energy‐dissipating devices. The frame has been mounted on a shaking table and subjected to increasing seismic actions. Energy‐dissipating devices are built by assembling panels in aluminium and steel, designed in such a manner that the local plasticization allows seismic energy dissipation. Two different types of panels have been considered, which differ in plate junction technology. The dissipation capacities are evaluated by measuring the change of the dynamic characteristics of the frame. Copyright © 2002 John Wiley & Sons, Ltd.
Repolarization of the presynaptic action potential and short‐term synaptic plasticity in the chick ciliary ganglion
Authors: Poage Robert E. , Zengel Janet E. 
Published: October 2002

AbstractStimulation‐induced increases in synaptic efficacy have been described as being composed of multiple independent processes that arise from the activation of distinct mechanisms at the presynaptic terminal. In the chick ciliary ganglion, four components of short‐term synaptic plasticity have been described: F1 and F2 components of facilitation, augmentation, and potentiation. In the present study, intracellular recording from the presynaptic calyciform nerve terminal of the chick ciliary ganglion revealed that the late repolarization and afterhypolarization (AHP) phases of the presynaptic action potential are affected by repetitive stimulation and that the time course of these effects parallel that of facilitation. The effects of these changes in the presynaptic action potential time course on calcium influx were tested by using the recorded action potential waveforms as voltage command stimuli during whole‐cell patch‐clamp recordings from acutely isolated chick ciliary ganglion neurons. The “facilitated” action potential waveform (slowed repolarization, decreased AHP amplitude) evoked calcium current with slightly but significantly greater total calcium influx. Taken together, these results are consistent with the hypothesis that activity‐dependent changes in the presynaptic action potential are one of several mechanisms contributing to the facilitation phase of stimulation‐induced increases in transmitter release in this preparation. Synapse 46:189–198, 2002. © 2002 Wiley‐Liss, Inc.
Wrapping and Inclusion of Organic Molecules with Ultrathin, Amorphous Metal Oxide Films
Authors: Ichinose Izumi , Kunitake Toyoki 
Published: October 2002

AbstractIn this review, we overview metal oxide nanostructures in which organic molecules play important roles as templates, as structural units, and, in some cases, as hosts. Their structural precision and diversity are discussed from the viewpoint of the topology of a metal‐oxygen network. Supramolecular capsules of metal oxides are prepared by the self‐assembly of polyoxometalates. Zeolites and mesoporous materials are synthesized by using organic molecules with their assemblies acting as templates. The topological networking of silsesquioxanes makes it possible to produce novel nanocomposites and microporous materials. In the final section, we demonstrate our recent studies into molecular imprinting, the encapsulation of a fluorescent dye, and the wrapping of individual polymer chains. Ultrathin, amorphous metal oxide films can retain the shape of organic molecules and can be used to create molecular composites by precisely wrapping individual molecules. These films are also effective in insulating molecular functions from external environments. The advantages of amorphous metal oxides are discussed in relation to the properties of the corresponding crystalline metal oxides and their potential prospects in nanotechnology. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 339–351, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10032
Enzymatic Radical Catalysis: Coenzyme B12‐Dependent Diol Dehydratase
Authors: Toraya Tetsuo 
Published: October 2002

AbstractA peculiar function resides in a peculiar structure. Coenzyme B12 or adenosylcobalamin, a naturally occurring organometallic compound, serves as a cofactor for enzymatic radical reactions. How do the enzymes form catalytic radicals at the active sites? How do the enzymes utilize and control the high reactivity of the radicals for catalysis? Recently, three‐dimensional structures of several radical‐containing or radical‐forming enzymes including B12 enzymes have been reported, enabling the analysis of the fine mechanisms of the action of these interesting enzymes. Our biochemical, mutational, and crystallographic studies as well as theoretical calculations on diol dehydratase, an adenosylcobalamin–dependent enzyme, revealed that its structure is adapted for its function—that is, activation of the CoC bond toward homolysis, abstraction of a specific hydrogen atom from the substrate and its recombination to a particular product, and transition state stabilization in the hydroxyl group migration of a substrate‐derived radical. The functions of K+ and the active‐site amino acid residues in enzyme catalysis are also investigated. Based on the results, the fine mechanism of the enzyme and the energetic feasibility of enzymatic radical catalysis are described here. © 2002 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 2: 352–366, 2002: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.10035