bluuebunny/crossref_metadata_2025 huggingface dataset:
A rapid method to determine plasma homocysteine concentration and enrichment by gas chromatography/mass spectrometry
Authors: Valerio Anna , Baldo Goretta , Tessari Paolo
Published: January 2005

Homocysteine is an independent risk factor for cardio‐ and/or cerebrovascular diseases. Many methods are used to measure plasma homocysteine levels in physiological fluids. Current gas chromatographic/mass spectrometric (GC/MS) methods allow determination not only of plasma homocysteine concentration, but also of its turnover. However, they have some methodological limitations due to the reduction of disulfide bonds between homocysteine and other thiols or proteins often requiring the use of several very toxic compounds or multi‐step procedures that are particularly time‐consuming, and/or utilize expensive instruments. Herein is described a rapid and precise GS/MS method to determine homocysteine turnover from a relatively low volume of plasma (200 μL). First disulfide bonds were reduced by 2‐mercaptoethanol, which allows the maintenance of the reduced status preventing the rebuilding of the disulfide bond. Then the sample was derivatized to form the bis‐tert‐butyldimethylsilyl derivative. A deuterated internal standard, DL‐[3,3,3′,3′,4,4,4′,4′‐2H8]‐homocystine, was employed to account for losses associated with each analytical step. To evaluate the ‘in vivo’ homocysteine metabolic turnover, [1‐13C]‐methionine was infused and the derived [1‐13C]‐homocysteine quantitated. So a standard curve of [1‐13C]‐homocysteine was prepared by the decomposition of the [1‐13C] methionine. The ions at m/z 325 and 326 were monitored, corresponding to the unlabeled [12C]‐homocysteine and to labeled [13C]‐homocysteine, respectively. The ion at m/z 325 ([M–114)]+) probably resulted from the loss of one derivatizing group to regenerate a free amino group. The intra‐assay coefficient of variation (CV‐intra%) was consistently less than 1.06%, the inter‐assay (CV‐inter%) less than 1.05%. The method described here seems to be simpler, more rapid, and less toxic than those published so far. In particular, its main strength appears to be the degree of precision obtained. We suggest applying this method to the measurement of the ‘in vivo’ rate of production of homocysteine (by the plasma 13C‐homocysteine enrichment) from its precursor (13C‐methionine). Copyright © 2005 John Wiley & Sons, Ltd.
Accurate mass measurement in nano‐electrospray ionization mass spectrometry by alternate switching of high voltage between sample and reference sprayers
Authors: Satomi Yoshinori , Kudo Yoichiro , Sasaki Kyoko , Hase Toshiharu , Takao Toshifumi
Published: January 2005

An electrospray dual sprayer, which generates separate sample and reference sprays by alternately switching the high voltage between the two sprayers, is described. The technique permits accurate mass measurements in nano‐electrospray ionization mass spectrometry (ESI‐MS) to be obtained using a quadrupole/orthogonal acceleration time‐of‐flight mass spectrometer (Q‐TOF). Similar to the method employed with a dual ESI source (Wolff JC et al., Anal. Chem. 2001; 73: 2605), the two sprays are orthogonal with respect to each other, but can be independently sampled without any baffle between these sprays. The reference sprayer is used in the original configuration of the ESI source and was optimized for a 1–2 μL/min flow, whereas the sample sprayer can be either a conventional glass capillary or a borosilicate tip of the type used for nano‐ESI. Both sprayers can be positioned close to the cone so as to give maximum ion currents. The sample and reference sprays are independently generated by raising the potentials on the sample and reference sprayers to 1.4 and 3.0 kV, respectively; the high voltages can be rapidly turned on and off in ca. 1 ms. A nano‐ESI‐MS or nano‐flow LC/ESI‐MS experiment using a Q‐TOF coupled with the above system gave mass accuracies within 3 ppm for measurements of ions up to m/z 1000 using subpicomole samples. Copyright © 2005 John Wiley & Sons, Ltd.
Tandem mass spectrometry of multiply phosphorylated forms of a ‘histidine‐tag’ derived from a recombinant protein kinase expressed in bacteria
Authors: Du Ping , Loulakis Pat , Xie Zhi , Simons Samuel P. , Geoghegan Kieran F.
Published: January 2005

When a histidine‐tagged form of the protein kinase Aurora‐2 was expressed in Escherichia coli, the purified product carried four to nine phosphate groups, although many fewer were expected. The amino‐terminal tag had the sequence GSSHHHHHHSSGLVPRGSHMK‐. Tryptic digestion of the product followed by analysis by liquid chromatography/mass spectrometry (LC/MS) and tandem mass spectrometry (MS/MS) showed that phosphorylation could occur on the five serine residues of the tag. Mono‐, bis‐, tris‐, tetra‐ and pentaphosphorylated forms of the tag were detected, and their behavior in MS/MS was studied using a quadrupole/time‐of‐flight mass spectrometer. The MS/MS spectra were dominated by the products of neutral loss events (in 98 Da increments, each equivalent to loss of H3PO4), but sufficient b‐ and y‐type sequence ions were detected to allow the locations of the phosphates to be specified in some cases. The assignment of phosphorylation sites for incompletely phosphorylated forms of the tag peptide was challenging, but it appeared that Ser‐10 and Ser‐11 of the tag were more likely to be phosphorylated than Ser‐2 and Ser‐3. Copyright © 2005 John Wiley & Sons, Ltd.
Investigation of the metabolic fate of 2‐, 3‐ and 4‐bromobenzoic acids in bile‐duct‐cannulated rats by inductively coupled plasma mass spectrometry and high‐performance liquid chromatography/inductively coupled plasma mass spectrometry/electrospray mass spectrometry
Authors: Jensen Berit Packert , Smith Christopher J. , Bailey Christopher J. , Rodgers Colin , Wilson Ian D. , Nicholson Jeremy K.
Published: January 2005

Inductively coupled plasma mass spectrometry (ICPMS) has been used to determine the rate and routes of excretion of bromine following the intraperitoneal administration (50 mg kg−1) of 2‐, 3‐ and 4‐bromobenzoic acids to male bile‐duct‐cannulated rats. Analysis of urine and bile for 79/81Br using ICPMS showed that all three bromobenzoic acids were rapidly excreted (82–98%) within 48 h of dosing, primarily via the urine. High‐performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS) was then used to obtain metabolite profiles for bile and urine. These profiles revealed that extensive metabolism had taken place, with the unchanged bromobenzoic acids forming a minor part of the total of compound‐related material detected. Concomitant MS studies, supplemented by alkaline hydrolysis, enabled the identification of the major metabolite of all three of the bromobenzoic acids as a glycine conjugate. Ester glucuronide conjugates were also identified, but formed only a small proportion of total. Copyright © 2005 John Wiley & Sons, Ltd.
Comparison of primary monoatomic with primary polyatomic ions for the characterisation of polyesters with static secondary ion mass spectrometry
Authors: Van Royen Pieter , Taranu Anca , Van Vaeck Luc
Published: January 2005

Static secondary ion mass spectrometry (S‐SIMS) emerges as one of the most adequate methods for the surface characterisation of polymers with an information depth of essentially one monolayer. The continuing search for increased analytical sensitivity and specificity has led to exploring the use of polyatomic primary ions as an alternative to the traditionally applied monoatomic projectiles. As part of a systematic investigation on polyatomic bombardment of organic and inorganic solids, this paper focuses on selected polyesters. Mass spectra and ion yields are compared for layers deposited on silicon wafers by spincoating solutions with different concentrations of poly(ε‐caprolactone) (PCL), poly(butylene adipate) (PBA) and poly(ethylene adipate) (PEA). Accurate mass measurements have been used to support the assignment of the ions and link the composition of the detected ions to the analyte structure. Use of polyatomic projectiles increases the yield of structural ions with a factor of ±15, ±30 and ±10 for PCL, PBA and PEA, respectively, in comparison to bombardment with Ga+ primary ions, while the molecular specificity is improved by the detection of additional high m/z ions. Copyright © 2005 John Wiley & Sons, Ltd.
Management of the “skills inventory” in times of major change
Authors: Winch Graham W.
Published: January 2005

Times of major change can pose extra‐ordinary challenges to any organisation. Case studies investigating how companies had faced the challenges of a major change in the previous four or five years, and especially how they attempted to prepare their managers for their new roles, revealed that many were ill‐equipped to face the task. One particular result suggested that firms that had relied only on their existing management team and/or on internal promotions had not fared as well as those for whom circumstances permitted the recruitment of new managers to key posts. This observation seems to run counter to the management dictum that firms should always endeavour to hold onto their experienced staff. A simple system dynamics model of a firm's “skills inventory” sheds light on this apparent paradox. The model indicates that in times of stability or slow/incremental change, retaining existing staff is indeed very important. However, in times of major change, as the obsolescence rate of the firm's existing skill base increases rapidly, importing critical skills with new recruits may be the only realistic way of boosting the skill‐base to the necessary levels. This situation is likely to have important competitiveness consequences for firms with traditionally low staff attrition rates, where growth is not creating new post opportunities, or in areas where the external recruitment market offers only limited access to new appointees with advanced skills. Copyright © 2001 John Wiley & Sons, Ltd.
Rerum cognoscere causas: Part I — How do the ideas of system dynamics relate to traditional social theories and the voluntarism/determinism debate?
Authors: Lane David C.
Published: January 2005

This is the first half of a two‐part paper which deals with the social theoretic assumptions underlying system dynamics. The motivation is that clarification in this area can help mainstream social scientists to understand how our field relates to their literature, methods and concerns. Part I has two main sections. The aim of the first is to answer the question: How do the ideas of system dynamics relate to traditional social theories? The theoretic assumptions of the field are seldom explicit but rather are implicit in its practice. The range of system dynamics practice is therefore considered and related to a framework—widely used in both operational research (OR) and systems science—that organises the assumptions behind traditional social theoretic paradigms. Distinct and surprisingly varied groupings of practice are identified, making it difficult to place system dynamics in any one paradigm with any certainty. The difficulties of establishing a social theoretic home for system dynamics are exemplified in the second main section. This is done by considering the question: Is system dynamics deterministic? An analysis shows that attempts to relate system dynamics to strict notions of voluntarism or determinism quickly indicate that the field does not fit with either pole of this dichotomous, and strictly paradigmatic, view. Part I therefore concludes that definitively placing system dynamics with respect to traditional social theories is highly problematic. The scene is therefore set for Part II of the paper, which proposes an innovative and potentially fruitful resolution to this problem. Copyright © 2001 John Wiley & Sons, Ltd.
Experiences and reflections on the transition from classroom to practice
Authors: Haslett Tim
Published: January 2005

Translating university‐based learning to a real‐world context preoccupies many academics. For the systems modelling group at Monash University, the aim is to establish a community of system dynamics practitioners in business and government. System dynamics modelling has been taught at Masters level for the past five years, during which time various methods have been used to affect this translation. These involved varying formats for the major piece assessment, including individual organization‐based projects, case‐study projects and group organization‐based projects. The advantages and disadvantages of these approaches are discussed and some of the insights gained from student feedback and reflection by the teaching staff are presented. Copyright © 2001 John Wiley & Sons, Ltd.
Model‐based scenarios for the epidemiology of HIV/AIDS: the consequences of highly active antiretroviral therapy
Authors: Dangerfield Brian C. , Fang Yongxiang , Roberts Carole A.
Published: January 2005

A system dynamics model of HIV/AIDS epidemiology is employed to simulate the effects of triple combination antiretroviral therapy in the treatment of HIV/AIDS. The epidemic data on homosexual men in the UK (1981‐‐1998) have been used to fit the baseline model. The new combination therapies, which supplanted antiviral mono and dual therapy in 1996, are proving to be the most effective prophylaxis yet for halting viral replication in vivo, but many uncertainties still surround their use. A range of model‐generated scenarios are created as a means of considering these uncertainties. Possible futures for the HIV/AIDS epidemic are constructed. Copyright © 2001 John Wiley & Sons, Ltd.
Anomalous strain effect on magnetic properties of La1−xBaxMnO3 epitaxial thin films
Authors: Zhang Jun , Tanaka Hidekazu , Kanki Teruo , Kawai Tomoji
Published: January 2005

We report an anomalous strain effect on magnetic properties in La1−xBaxMnO3 (LBMO) thin films. Epitaxial LBMO films grown on SrTiO3(100) (STO) single‐crystal substrate by pulsed laser deposition suffer strains due to the lattice mismatch between LBMO and STO. For films with x = 0.1 and x = 0.2, tensile strain enhances the ferromagnetic state, resulting in the ferromagnetic Curie temperature TC increasing significantly compared with the corresponding bulk materials. However, for x = 0.3 and x = 0.33, TC decreases in thin films. These results are very different from the previous reported strain effect in other colossal magnetoresistance manganite thin films, and can be interpreted by considering the strain‐induced modification of orbital eg stability. Copyright © 2001 John Wiley & Sons, Ltd.
On the anomalous SIMS transient of B in Si: the influence of surface conditions
Authors: Alkemade P. F. A. , Liu Z. X.
Published: January 2005

The SIMS 11B+ signal from a homogeneously boron‐doped silicon sample was measured with a 1 keV O2+ beam at 60° incidence without oxygen flooding. Stationary levels of boron secondary ions were reached only at a depth of ∼40 nm. In vacuo rotation of the analysed samples during interruption of the profiling revealed that there is no relation between the anomalous long boron transient and the formation of surface ripples by the ion beam. In contrast, removal of the native oxide by HF prior to the SIMS analysis resulted in a reduction of the boron transient to a normal value of ∼6 nm. This work shows that for accurate dynamic SIMS analysis the initial surface condition can be important. Copyright © 2001 John Wiley & Sons, Ltd.
X‐ray photoelectron spectroscopy studies of Ti–Al and Ti–Al–V alloys using Cr Kβ radiation
Authors: Diplas S. , Watts J. F. , Tsakiropoulos P. , Shao G. , Beamson G. , Matthew J. A. D.
Published: January 2005

High‐energy and conventional x‐ray photoelectron spectroscopy (XPS) using Cr Kβ (hν = 5946.7 eV) and Al Kα (hν = 1486.6 eV) radiation, respectively, were employed to study the alloying behaviour of Ti with Al and V in Ti–Al (Al = 10, 20 and 30 at.%), V–50at.%Al, Ti–35at.%Al–15at.%V, Ti–40at.%Al–20at.%V, Ti–25at.%Al–25at.%V and Ti–50at.%V alloys. The differences of the initial and final state Auger parameters of the elements of interest between unalloyed and alloyed conditions were used to interpret possible charge transfer/redistribution between the elements and to explain subsequent electronic changes occurring upon alloying. The spectroscopic studies were related to thermodynamic predictions and the microstructures of the alloys. The large negative shift of the Al Auger parameter indicated that Al atoms are better screened in the pure metallic environment than in the alloy. This shift was attributed also to the ordering tendency in the Ti–Al and Ti–Al–V alloys, shown by thermodynamic modelling and microstructural studies. Variations of the initial state Auger parameter indicated that initial state effects are significant and may indicate charge transfer from the Al sites towards the transition metal sites. The Auger parameter variations of the transition metals were small, which is in agreement with previous studies. Copyright © 2001 John Wiley & Sons, Ltd.
Characterization of Ge δ‐doped Si(111) with RBS channelling
Authors: Yuhara J. , Morita K. , Falta J. , Müller B. H. , Horn‐von Hoegen M.
Published: January 2005

The crystalline quality of the Si cap layer, the lattice location and the depth distribution of δ‐doped Ge layers in Si(111) crystals grown by molecular beam epitaxy at low and high temperatures have been studied by means of double‐grazing‐angle Rutherford backscattering spectrometry (RBS), RBS channelling and atomic force microscopy. The crystalline quality of the Si cap layer grown at high temperature is excellent, but there are some lattice defects in the interface or in the cap layer grown at low temperature. The RBS channelling measurements show that most of the Ge atoms occupy the Si substitutional sites. The full width at half‐maximum in the depth distribution of δ‐doped Ge in the Si(111) crystal is determined to be 13 ± 5 Å. Copyright © 2001 John Wiley & Sons, Ltd.
The chemical state vector: a new concept for the characterization of oxide interfaces
Authors: Barranco A. , Yubero F. , Espinós J. P. , González‐Elipe A. R.
Published: January 2005

For certain metal oxides deposited as a thin film on the surface of another oxide, changes may occur in the binding energy (BE) of the photoelectron peaks as well as in the kinetic energy (KE) of the Auger peaks of the deposited cation and consequently in its Auger parameter. These changes are illustrated here for the systems formed by SiO2 deposited onto TiO2 and Al2O3. Shifts by −1.3 and −1.0 eV in the Si 2p BE and by 2.3 and 0.7 eV in the KE of the Si KLL Auger peak are found for these two systems when comparing the values obtained for small amounts of SiO2 directly interacting with the support with those of a thick film of this material.

The different values of these electronic parameters obtained for increasing amounts of SiO2 can be represented in a Wagner plot. The tendency and magnitude of the changes are similar to those found for Si in phyllosilicate or zeolite compounds with different Si/Al ratios.

To systematize these changes in the electronic parameters of the deposited phase the new concept of ‘chemical state vector’ is proposed. It is defined as the vector that connects the two extreme points of a Wagner plot dot graph where the BE of photoelectron peaks is represented versus the KE of the Auger peaks for a cation M of a given MO/M′O interface. The possibilities and limitations of this concept are discussed with regard to the SiO2/TiO2 and SiO2/Al2O3 interface systems reported in this paper and the data for other MO/M′O systems taken from previous works. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitative AES IX and quantitative XPS II: Auger and x‐ray photoelectron intensities and sensitivity factors from spectral digital databases reanalysed using a REELS database
Authors: Seah M. P. , Gilmore I. S. , Spencer S. J.
Published: January 2005

An extension has been made of previous analyses of peak area intensities for elemental spectra in digital Auger and x‐ray photoelectron databases. The intensities, instead of being analysed after removal of a background derived from the Tougaard Universal cross‐section, are now analysed after removal of the extrinsic characteristic loss background calculated by deconvolving the relevant angle‐averaged reflected electron energy‐loss spectroscopy (REELS) spectrum. The angle‐averaged REELS data for each element are calculated from a digital REELS database using a recently defined scaling of the measured characteristic losses from the elastic peak. The new background removal procedure leads to an improvement in the correlation between experiment and theory for intensities in both AES and XPS. Analysis of these correlations shows that a systematic divergence remains for each element, which is the same for XPS as for AES. This divergence is attributed to an inadequacy either of the angle‐averaged REELS method or of the material‐to‐material dependence of the TPP‐2M equation used in the calculation of the inelastic mean free paths. Correction for this is possible in a new matrix‐less quantification formulation using average matrix sensitivity factors. This leads to correlations between experiment and theory with scatter factors of ×/÷1.08 and ×/÷1.11 for AES and XPS, respectively, for a wide range of elements and peaks. These scatter factors are much better than for previous correlations and underpin the choice of formulae to calculate the relevant theoretical intensity predictions. These calculations lead directly to values of average matrix sensitivity factors, appropriate for use with spectrometers giving true spectra or with those spectrometers that may be calibrated to provide such spectra. © Crown Copyright 2001. Published by John Wiley & Sons, Ltd.
Optical characterization techniques for process monitoring
Authors: Pickering C.
Published: January 2005

The aim of this special issue is to bring to the attention of the surface science community the potential and application of optical techniques. This paper gives an overview of the major optical characterization techniques and the subsequent papers. Where possible, links with other surface science techniques are discussed and the use of optical methods for process monitoring and control is emphasized. © Crown Copyright 2001. Published by John Wiley & Sons, Ltd.
Reflection anisotropy spectroscopy: a new probe of metal surfaces
Authors: Martin D. S. , Weightman P.
Published: January 2005

Reflection anisotropy spectroscopy (RAS) is a non‐destructive optical probe of surfaces capable of operation within a wide range of environments. The RAS technique was developed to study semiconductor growth and more recently has been used to probe the optical properties of metal surfaces. Surface sensitivity has been demonstrated with the detection of reconstruction, adsorbate interaction and the observation of transitions involving surface‐localized electronic states. The RAS technique has non‐ultrahigh vacuum (UHV) environment capability and thus opens up the study of metal surfaces in catalytic and corrosive environments at high pressure and at the solid/liquid interface. The combination of RAS with a full range of surface science techniques applied to the study of well‐defined surfaces aids in the interpretation of RAS spectra. The focus of this article will be on well‐characterized metal surfaces prepared and studied under UHV conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Spectroscopic ellipsometry for monitoring and control of surfaces, thin layers and interfaces
Authors: Pickering C.
Published: January 2005

Spectroscopic ellipsometry can provide information non‐destructively on layer thickness, composition, refractive index, crystallinity and surface/interface roughness. This article discusses its use for ex situ/in‐line monitoring and in situ/real‐time control. Examples are given based on silicon epitaxial surfaces, GaN nucleation layers, SiGe/Si and other multilayer structures. Real‐time data analysis methods are discussed and in situ spectroscopic ellipsometry is shown to provide insights into surface effects during SiGe epitaxial growth. © Crown Copyright 2001. Published by John Wiley & Sons, Ltd.
Surface photovoltage spectroscopy of semiconductor structures: at the crossroads of physics, chemistry and electrical engineering
Authors: Kronik Leeor , Shapira Yoram
Published: January 2005

The possibility of obtaining a detailed picture of the electronic structure makes surface photovoltage spectroscopy (SPS) eminently suitable for bridging the gap between the chemical, physical, optical and electrical properties of semiconductors. In SPS, changes in band bending (both at the free semiconductor surface and at buried interfaces) are monitored as a function of external illumination. Surface photovoltage spectroscopy can provide detailed, quantitative information on bulk properties (e.g. bandgap and type, carrier diffusion length and lifetime) and can be used for complete construction of surface and interface band diagrams, including the measurement of energy levels in quantum structures. A particular strength is that a comprehensive analysis of surface and bulk defect state distributions and properties is made possible. Measurements using SPS are contactless and non‐destructive. In addition, they can be performed both in situ and ex situ, at any reasonable temperature, on any semiconducting material, at any ambient and at any lateral resolution down to the atomic scale. This review starts with an overview of SPS‐related surface and interface theory, describes the SPS experimental set‐up and presents applications for surface and interface characterization of a wide variety of materials and structures, cross‐correlating them with other methodologies. Copyright © 2001 John Wiley & Sons, Ltd.
Raman spectroscopy of GaN, AlGaN and AlN for process and growth monitoring/control
Authors: Kuball M.
Published: January 2005

The use of micro‐Raman spectroscopy to monitor non‐invasively GaN, AlGaN and AlN material parameters for process and growth monitoring/control is demonstrated. Concepts to determine the crystalline quality, the stress, the free carrier concentration, the aluminium composition and the temperature from the Raman modes are reviewed. Raman monitoring of processing and growth is illustrated on selected examples: the high‐temperature processing of ion‐implanted and non‐implanted GaN layers, the Raman monitoring of AlGaN/GaN heterostructure field‐effect transistors and the in situ Raman monitoring of GaN growth at elevated temperatures. Ultraviolet Raman spectroscopy has been employed to characterize material properties of GaN surface layers and GaN/AlGaN interfaces. Raman mapping is illustrated on bulk AlN crystals to investigate stress fields related to growth striations and defects. Copyright © 2001 John Wiley & Sons, Ltd.
Optical testing techniques for new semiconductor processes and new materials
Authors: Reader A. , Moore C. , Brinker R. , Hennessy J.
Published: January 2005

Industrial semiconductor manufacturing—and therefore industrial semiconductor metrology—is being faced with a new generation of processes and materials coming out of development laboratories worldwide. These need careful monitoring, particularly in the early stages of manufacture. Many metrology challenges are well met by optical techniques, and the article discusses three such techniques that have transferred to industrial production process control. Laser ellipsometry brings high precision to ultrathin 25 Å gate oxide measurements and can analyse many types of (transparent) new materials. Impulsive stimulated thermal scattering is a new opto‐acoustic technique and therefore is covered more fully here—it complements laser ellipsometry by analysing single and bilayer metal (opaque) films after these have been exposed to a variety of semiconductor processes. Photoluminescence is invaluable for analysing compound semiconductors, where it measures directly the quality of epitaxial layers and so helps to understand and reduce defect mechanisms and improve yields. The article concludes by discussing industrial requirements for integrating the measurement system into a deposition system for in situ process control. Copyright © 2001 John Wiley & Sons, Ltd.
NESSPIOM—Network for enhanced semiconductor surface processing through in situ optical monitoring
Authors: Pemble Martyn E.
Published: January 2005

The activities of the Network for Enhanced Semiconductor Surface Processing through In situ Monitoring (NESSPIOM), based in the UK and funded through the Engineering and Physical Sciences Research Council, are described. This group, consisting of academics and industrialists, is evaluating the potential benefits that may accrue from the use of optical monitoring methods during semiconductor surface modification, both from a fundamental and an applied perspective. The findings of the network to date are presented. Interferometry, light scattering techniques and diode laser spectroscopy are highlighted as methods that may result in improved materials or processes, whereas other techniques such as reflectance anisotropy spectroscopy, spectroscopic ellipsometry, surface photoabsorption and second harmonic generation are found to provide more fundamental information. The future for the application of methods such as this within both the academic and industrial communities is discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Manipulation experiments on Si(111)7 × 7 by scanning tunnelling microscopy
Authors: Kraus A. , Hanbücken M. , Koshikawa T. , Neddermeyer H.
Published: January 2005

We describe our results on atomic‐scale manipulation of clean and H‐covered Si(111) surfaces by using scanning tunnelling microscopy. In particular, we focus on the manipulation of surface atoms by using a well‐defined distance decrease between sample and tip, with the sample‐tip voltage switched off. For comparison we also applied voltage pulses to the tip and recorded the tunnelling current simultaneously. For H‐covered Si(111) surfaces the desorption of H is associated with a dramatic current increase. For Si(111)7 × 7, the removed Si adatom very often is found in a neighbouring 7 × 7 unit cell half, where it fluctuates above rest atom sites already at room temperature. Copyright © 2005 John Wiley & Sons, Ltd.
Novel structures of carbon layers on a Pt(111) surface
Authors: Fujita Tomohiro , Kobayashi Wataru , Oshima Chuhei
Published: January 2005

The growth behaviour of carbon layers formed on a Pt(111) surface has been investigated by means of scanning tunnelling microscopy. A carbon layer with a ($\sqrt{19}$ × $\sqrt{19}$)R23.4° structure was grown by benzene exposure of 3 L at 1000 K. After exposure of >10 L, graphene islands with hexagonal shapes appeared in the surface terraces. The graphene islands grew beyond step edges, and their growth often caused bunching of the step edges by Pt atom migration. Copyright © 2005 John Wiley & Sons, Ltd.
Electronic structures of nanostructured transition metals on the Au(788) surface
Authors: Fujisawa H. , Shiraki S. , Nantoh M. , Kawai Maki
Published: January 2005

The electronic structures of nanostructured transition metals (Fe, Co, Ni) grown by step decoration of the Au(788) surface are investigated by normal emission angle‐resolved photoemission spectroscopy (ARPES). As the coverage of the transition metals is increased, the intensity of Au 5d valence bands decreases but the peak positions do not change, suggesting that the mixing between Au 5d and 3d of transition metals is negligibly weak. The coverage dependences of ARPES spectra near the Fermi level (EF) for Fe, Co and Ni are discussed and compared with the photoemission results on bulk materials. In the higher coverage regions, we identify the observed 3d peaks near EF as ferromagnetic exchange splitting bands with similar exchange energy to the bulk. In contrast, at lower coverages, the exchange splitting vanishes for Fe and Co and becomes small for Ni. The origins of this behaviour are attributed to atomic volume, structural dimensionality and finite temperature effects. Copyright © 2005 John Wiley & Sons, Ltd.
Characteristics of ion‐beam‐synthesized tantalum silicide film
Authors: Liang J. H. , Ruan W. M.
Published: January 2005

This paper deals with the characteristics of ion‐beam‐synthesized tantalum silicide film on different substrates as a function of annealing conditions. An implantation of 2 × 1017 40 kV Ta ions cm−2 was performed using an ion implanter of metal vapour vacuum arc. Silicon wafers of <100> and <111> orientation were chosen as representatives of different substrates. Rapid thermal annealing conditions included annealing temperatures of 550–1000 °C and annealing times of 5–90 s. Annealing‐induced variations in microstructure, composition, resistivity and diffusion in the tantalum silicide film were analysed by means of x‐ray diffractometry, Rutherford backscattering spectrometry, resistometry and secondary ion mass spectrometry, respectively, in order to compare the as‐implanted and as‐annealed specimens. The results revealed that tantalum silicide film possesses the most optimum properties when annealed at 850 °C for 30 s in both the <100> and <111> specimens. Copyright © 2005 John Wiley & Sons, Ltd.
Abnormal electron emission from MgO thin film under ion irradiation
Authors: Tsujita T. , Nagatomi T. , Takai Y.
Published: January 2005

Energy distributions of secondary electrons from an MgO thin‐film surface under ion irradiation were investigated. The abnormal ion‐induced secondary electron emission was observed in addition to the normal emission. The abnormal emission observed in the present study is found to be a kind of self‐sustained emission because it continued after stopping ion irradiation. The energies of the abnormal secondary electrons are lower than the vacuum level at the MgO surface by ∼7–10 eV and its energy distribution is close to the profile of the density‐of‐states of the valence band of MgO. The results strongly suggested that the abnormal electron emission observed in the present study is due to field emission of the valence electrons of MgO through a mechanism other than the Malter effects or the Townsend Avalanche effect. Copyright © 2005 John Wiley & Sons, Ltd.
Diffusion phenomena at the interface between dielectric films and compound semiconductors
Authors: Shiramizu T. , Tanimura J. , Kurokawa H. , Sasaki H. , Abe S.
Published: January 2005

The diffusion phenomena at the interface between dielectric films and compound semiconductors under two kinds of condition (humid or dry thermal) have been studied by means of secondary ion mass spectrometry (SIMS). Under the humid condition—the pressure cooker test at 121 °C, 100% relative humidity and 2 atm—we confirmed that oxygen diffused into dielectric films of SiNx or SiOxNy from the surface and that both Ga and As diffused into films from GaAs substrates simultaneously. Because such diffusion phenomena did not occur under the dry thermal condition at 120 °C, the diffusion was assumed to be influenced by the existence of water vapour. In addition, we investigated the selective diffusion of Ga from AlGaAs into SiOx under the dry thermal condition with rapid thermal annealing. We found that the diffusion velocities depended on the SiOx growing method and the diffusion into SiOx deposited by sputtering was more remarkable than that by plasma chemical vapour deposition Copyright © 2005 John Wiley & Sons, Ltd.
Effects of BaTiO3 overlayers deposited on SrTiO3(001) on its 105 K phase transition
Authors: Matsushita Kyohiko , Kitahara Amane , Sakaue Kiyoshi , Takahashi Isao , Terauchi Hikaru , Doi Syuichi
Published: January 2005

We investigated effects of a BaTiO3 overlayer deposited epitaxially on an SrTiO3(001) surface on the 105 K phase transition of SrTiO3. With the use of x‐ray reflectivity and Bragg reflection we observed the critical behaviour of the 105 K phase transition in the interfacial region and in the bulk. For T < Tc(Tc = 105 K), rocking‐curve‐widths of x‐ray reflectivity and of Bragg reflections are found to exhibit power law behaviour (Tc − T)2β, where β obtained by x‐ray reflectivity (βINTERFACE) is almost the same as that obtained by Bragg reflection (βBULK = 0.34 ± 0.02). The present result shows a sharp contrast to the critical behaviour of SrTiO3 having free SrTiO3(001) surfaces, where 2βSURFACE ≈ βBULK is reported. In this study, we find that the critical behaviour of the BaTiO3/SrTiO3 interface is influenced significantly by the surface condition generated by the epitaxial cap layer. It is likely that a change of dimensionality and/or tensile stress at the interface could affect the critical behaviour of this interfacial region. Copyright © 2005 John Wiley & Sons, Ltd.
Electronic stopping of keV nitrogen ions interacting with a Pt(110)(1 × 2) surface—a tool to characterize electronic surfaces
Authors: Robin A. , Postnikov A. V. , Heiland W.
Published: January 2005

Ion channeling is used to investigate the electronic density corrugation at surfaces by analysing the electronic stopping behaviour of ions scattering grazingly off a clean single crystalline Pt(110)(1 × 2) surface. We use the fact that under these conditions the elastic contribution can be separated from the inelastic energy‐loss processes, which are closely related to the electronic density sampled along the projectiles trajectories. Therefore, we have a direct probe of the surface electronic density structure. Here, experiments and their theoretical interpretation for N+ ions at primary ion energies of 1–10 keV are presented. Multi‐peak features of the energy spectra, depending on the azimuthal surface orientation, are attributed to different particle trajectories. A detailed analysis of trajectory calculations affords an unambiguous assignment of the observed peak structures to three trajectory classes, each sampling specific energy losses. The comparison of the experimental energy‐loss values with results obtained from a surface‐adapted energy‐loss model for ion scattering that includes the electron density allows us to investigate the electronic surface of the sample. The results are compared with calculated surface electron density contours. Reasonable agreement is obtained, showing that the presented method is suitable to characterize the electronic density structure at crystalline surfaces. Copyright © 2005 John Wiley & Sons, Ltd.
Angle‐dependent neutralization of low‐energy alkali ions scattered from alkali‐covered Si surfaces
Authors: Kan T. , Yasue T. , Koshikawa T.
Published: January 2005

An angle‐resolved ion scattering apparatus has been developed to observe the charge exchange process between low‐energy ions and surfaces. The incident angle‐dependent neutralization was observed for Li+ ions scattered from a Cs‐adsorbed Si(111) surface. The shadowing effects have an important role in the neutralization efficiency. The azimuthal angle dependence of the neutralization efficiency of D2+ ions scattered from a clean Si(100) surface also showed minima along the crystallographic orientations. This anisotropy is explained by the blocking effects of the outgoing particles scattered in the bulk. It is suggested that the crystallographic information has to be considered to explain the angle‐dependent neutralization efficiency, and it is shown that the depth information is also important to understand the neutralization efficiency. Copyright © 2005 John Wiley & Sons, Ltd.
High‐resolution Auger depth profiling by sub‐keV ion sputtering
Authors: Inoue Masahiko , Shimizu Ryuichi , Lee Hyung Ik , Kang Hee Jae
Published: January 2005

Auger electron spectroscopy depth profiling of a GaAs/AlAs superlattice sample was performed with Ar+ ions of 100–500 eV using a compact floating‐type low‐energy ion gun. The practical etching rate of >1.5 nm min−1 was ensured in the energy region beyond 150 eV. High depth resolutions of 1.3, 1.6, 1.8 and 2.0 nm (84 − 16%) were obtained with Ar+ ions of 100, 150, 200 and 300 eV at the leading edge of Al LVV depth profiles, respectively.

At the sputtering energy of 100 eV, remarkable improvement of the depth resolution at the leading edge (Δzl = 1.3 nm) has been observed but this is followed by considerable deterioration at the trailing edge (Δzt = 2.7 nm). Dynamic Monte‐Carlo simulation for sputtering energies of 150–300 eV was performed for comparison. Although the Monte‐Carlo simulation overestimates the depth resolutions by ∼0.6 nm larger than the relevant experimental values, it describes the energy dependence of the depth resolution with considerable success. Copyright © 2005 John Wiley & Sons, Ltd.
Multilayer mirrors for µ‐XPS using a Schwarzschild objective
Authors: Takenaka Hisataka , Ichimaru Satoshi , Nagai Koumei , Ohchi Tadayuki , Ito Hisashi , Gullikson E. M.
Published: January 2005

The development of highly reflective multilayer mirrors for use in the wavelength region around 6 nm has made it possible to use a multilayer‐coated Schwarzschild objective for micro‐x‐ray photoemission spectroscopy. For this purpose, CoxCr1−x/C and W/C multilayers were fabricated by magnetron sputtering and the soft x‐ray reflectivities were measured. The peak reflectivity of the Cr/C multilayer was found to be the highest with ∼18.9% at a wavelength of 6.42 nm and an incident angle of 88°. It is believed that a Cr/C multilayer will provide sufficient performance for use on a Schwarzschild mirror for x‐ray photoemission spectroscopy using 6 nm x‐rays. Copyright © 2005 John Wiley & Sons, Ltd.
Depth profiling of polycrystalline layers under a surface using x‐ray diffraction at small glancing angle of incidence
Authors: Fujii Y. , Komai T. , Ikeda K.
Published: January 2005

An analysis method for evaluating a polycrystal structure under a surface using x‐ray diffraction at small glancing angle incidence was studied. Intensities of the diffracted x‐rays on a polycrystalline iron surface were measured at various incidence angles, and the dependency of the incidence angles was investigated by analysing the intensity of x‐ray propagation in surface layer materials characterized by a complex refractive index that changes continuously with depth. The dependence of the diffracted x‐ray intensities on the glancing angle was analysed and the depth profile of the polycrystalline layers of oxidized iron was evaluated to an accuracy of the order of nanometres. Copyright © 2005 John Wiley & Sons, Ltd.
Development of the spin‐polarized atom‐surface scattering method for characterizing surface magnetism: detection efficiency of the microchannel plate
Authors: Ikedo Y. , Sueyoshi Y. , Shimizu T. , Hirose E. , Hori H. , Torikai E.
Published: January 2005

The energy, charge and angle dependence of the detection efficiency of the microchannel plate (MCP) for caesium (Cs) atoms and ions was studied for measuring the spin asymmetry of the ionization probability in the atom‐surface scattering process. Based on the model of a spin‐dependent scattering of a spin‐polarized and energy‐tunable Cs atomic beam at a magnetic surface, we have developed a new experimental method for characterizing surface magnetism. Copyright © 2005 John Wiley & Sons, Ltd.
Characterization of electrically inactive arsenic atoms in heavily arsenic‐doped Si
Authors: Kikuchi Y. , Goto Y.
Published: January 2005

The origin of electrically inactive arsenic (As) atoms in heavily As‐doped Si(100) wafers after rapid thermal annealing has been studied by using several advanced techniques. Direct experimental evidence linking the formation of As–vacancy complexes to the inactive As atoms is shown. Approximately 78% of the As atoms sit on the Si substitutional sites in spite of their inactivity, However, the local strain relating to the implanted As atoms is higher than expected for the implanted As concentration. In addition, the Si lattice constant expanded as the As concentration increased. The results indicate that most of the As atoms in the heavily doped region exist in a uniform layer of As–vacancy complexes combined with substitutional As atoms. Copyright © 2005 John Wiley & Sons, Ltd.
Electrical conductivity measurements of a multi‐walled carbon nanotube
Authors: Shimizu Tetsuo , Abe Hidekazu , Ando Atsushi , Nakayama Yoshikazu , Tokumoto Hiroshi
Published: January 2005

We present a new method for fabricating a multi‐walled carbon nanotube (CNT) probe using a low‐melting‐point alloy as the connecting material. In particular, we constructed a CNT bridge structure connected by the alloy and measured current–voltage (I–V) characteristics exhibiting a resistance of <450 kΩ, which is low enough to compare with the tunnelling gap resistance of scanning tunnelling microscopy. Furthermore, to investigate the electrical conductivity of the CNT bridge structure in detail, we assembled a special holder to manipulate the CNT within a scanning transmission electron microscope. We then fabricated a CNT bridge structure and measured its I–V characteristics in the microscope using TiNi nanoparticles (with an average diameter of 100 nm) as the connecting material between the CNT and the electrode. The resistance of the CNT bridge structure showed an ideal quantum resistance, indicating that TiNi nanoparticles can be considered as one of the ideal connecting materials. This success demonstrates the usefulness of the holder that we assembled. We believe that this holder will contribute to the fabrication of conductive CNT probes and the realization of CNT‐based electrical devices. Copyright © 2005 John Wiley & Sons, Ltd.
Photoluminescence characterization of nano‐size defects in sub‐surface region of silicon wafers
Authors: Tanahashi Katsuto , Yamada‐Kaneta Hiroshi
Published: January 2005

The sub‐surface defects in annealed wafers with an oxide layer are characterized by ultraviolet‐excited photoluminescence spectroscopy and mapping. Two types of defects are detected as a reduction of band‐edge emission in the region determined to be defect‐free by laser scattering tomography (LST): an interface gap state between silicon and the oxide layer, and a nitrogen‐related defect (which is below the detection limit of LST). Copyright © 2005 John Wiley & Sons, Ltd.
Improvement of angle‐resolved electron energy analyser for high‐performance x‐ray photoelectron diffraction measurements
Authors: Mamishin Shuichi , Mochizuki Hidehiro , Ishii Hideshi , Kobayashi Hideo , Iwai Hideo , Watanabe Katsumi , Taguchi Masami , Owari Masanori , Nihei Yoshimasa
Published: January 2005

For more precise and rapid x‐ray photoelectron diffraction (XPED) measurements, we have improved an angle‐resolved electron energy analyser developed a ±1.4° diffraction plane aperture mode, and a novel high‐speed 64‐channel detector. In this study, a large number of photoelectrons from a newly developed diffraction plane aperture mode were detected by a novel high‐speed detector, facilitating rapid and precise XPED measurements. The Ti 2p XPED patterns from an SrTiO3(001) surface also revealed the performance of this improved analyser. In addition, high‐speed XPS measurements from an Ag polycrystal were performed for several milliseconds. Copyright © 2005 John Wiley & Sons, Ltd.
Structural analysis of Co thin films grown on Ge(111) at room temperature by x‐ray photoelectron diffraction
Authors: Tsuruta A. , Chu W. G. , Tamura K. , Ishii H. , Owari M. , Nihei Y.
Published: January 2005

The thickness dependence of the structure of ultrathin Co films grown on Ge(111), using molecular beam epitaxy at room temperature, was studied via low energy‐electron diffraction (LEED) and x‐ray photoelectron diffraction. Cobalt deposition led to a surface phase transition from a c(2 × 8) reconstruction to a (1 × 1) structure. The (1 × 1) LEED pattern was gradually degraded with increased Co coverages, implying partial loss of long‐range order. Experimental and theoretical XPED studies revealed that 0.7 and 1.5 ML Co deposition resulted in the formation of a reacted surface layer mostly composed of a partly ordered orthorhombic CoGe2 phase, whereas 5 and 10 ML deposition resulted not only in this surface phase but also in the formation of a partly ordered bcc Co metal on top. The formation mechanism of these structures in the ultrathin Co/Ge(111) films was elucidated in the light of the Effective Heat of Formation model and lattice mismatch. Copyright © 2005 John Wiley & Sons, Ltd.