bluuebunny/crossref_metadata_2025 huggingface dataset:
A computational study of a fluorescent photoinduced electron transfer (PET) sensor for cations
Authors: De Silva S. A. , Kasner M. L. , Whitener M. A. , Pathirana S. L.
Published: August 2004

Ab initio molecular orbital theory and density functional theory with the 6‐31G(d,p) basis set have been used to calculate the structural parameters of a fluorescent photoinduced electron transfer (PET) sensor for cations and its zinc complex. The optimized geometries are compared with the X‐ray crystal structures of N‐(9‐anthracenylmethyl)–N‐[(2‐pyridinyl)methyl]‐2‐pyridinemethanamine and [N‐(9‐anthracenylmethyl)‐N‐[(2‐pyridinyl‐κN)methyl]‐2‐pyridinemethanamine‐κN1, κN2]dichlorozinc. Although the X‐ray studies are based on solid‐phase structures and the computational studies are based on gas‐phase structures, comparisons of the data show significant agreement between the two sets of geometric parameters. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical study of adsorption of methyltert‐butyl ether on the substituted tetrahedral surface of dickite
Authors: Michalkova A. , Gorb L. , Zhikol O. A. , Leszczynski J.
Published: August 2004

The adsorption of methyltert‐butyl ether (MTBE) on the substituted tetrahedral surface of dickite has been studied using the n‐layered integrated molecular orbital and molecular mechanics (ONIOM) approach and Becke's three‐parameter exchange functional and the gradient‐corrected functional of Lee, Yang, and Paar (B3LYP)/6‐31G(d):PM3 approximation. Two Si atoms of the tetrahedral side were substituted by Al atoms in three different mutual arrangements (1,2‐, 1,3‐, and 1,4‐substitution). The negative charge of the layer originating from the substitution was compensated by the exchangeable Mg2+cation. Initially the Mg2+cation was placed above the center of the six‐member ring with the tetrahedral structure of the mineral fragment. The Mg2+cation plays a crucial role in the adsorption of MTBE on the substituted surface of dickite. Methyl tert‐butyl ether is adsorbed due to the formation of a chemical bond between the oxygen atom of MTBE and the Mg2+cation and due to the formation of multiple weak C‐H…O hydrogen bonds between the C–H groups of MTBE and the surface oxygen atoms. The adsorption results in changes in the structural parameters of MTBE that are the most significant in the case of the 1,3‐substituted system. The interaction energies of MTBE adsorbed on the substituted surface of dickite corrected by basis set superposition error were predicted. The values of adsorption energies range from −42.8 kcal/mol (1,2‐substitution) to −45.9 kcal/mol (1,3‐substitution) to −47.2 kcal/mol (1,4‐substitution). © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Elemental distributions around the oxide scales/alloy interfaces by SIMS and GDOES analyses
Authors: Horita Teruhisa , Xiong Yueping , Yamaji Katsuhiko , Kishimoto Haruo , Sakai Natsuko , Yokokawa Harumi
Published: August 2004

The oxide scales formed on FeCr alloys in CH4H2O gas mixtures (at 1073 K for 3–1050 h) were precisely analysed by SIMS and GDOES. Depth profiles were compared between SIMS and GDOES. They were almost consistent with each other with some differences in minor elements. In depth profiles, the following three zones were identified from surface to internal oxides: Mn and Fe rich layer, Cr‐rich layer, and Si‐rich layer. The elemental distributions at different depths were investigated by the SIMS imaging technique. Concentration differences of some elements at grain and grain boundaries were imaged at the resolution of µms. The grain boundary diffusion of cations in the alloys was clearly visualized, and the grain boundary diffusion plays an important role in the formation of oxide scales. Copyright © 2004 John Wiley & Sons, Ltd.
Surface characterization of the oxide layer grown on TiNbZr and TiNbAl alloys
Authors: Gutiérrez A. , López M. F. , Jiménez J. A. , Morant C. , Paszti F. , Climent A.
Published: August 2004

The surface of the oxide layers formed after oxidation in air at 750°C of three titanium alloys has been characterized by several techniques. The investigated alloys were Ti7Nb6Al, Ti13Nb13Zr and Ti15Zr4Nb, with potential applications as biomaterials. XPS experiments showed that, after 24 h exposure, the surface of the Ti7Nb6Al alloy is mainly formed of Al2O3, with a minor presence of TiO2, and absence of Nb oxide. On the other hand, the surface of both TiNbZr alloys is mainly composed of TiO2, with some amount of ZrO2 and Nb2O5. An enrichment of the Nb signal is observed in both samples with respect to the bulk composition. The topography and surface morphology of the oxidized alloys were investigated by atomic force microscopy. A more regular surface topography was observed for the Ti7Nb6Al alloy than for the TiNbZr alloys and, consequently, a higher potentiality in biomedical applications. Finally, in order to get in‐depth information of the oxide scale, Rutherford backscattering spectroscopy experiments were also performed. The results obtained with this technique confirm those obtained by XPS, and can help to understand the mechanism and kinetics of the oxide film formation. Copyright © 2004 John Wiley & Sons, Ltd.
Viscosity effect on GaInSn studied by XPS
Authors: Scharmann F. , Cherkashinin G. , Breternitz V. , Knedlik Ch. , Hartung G. , Weber Th. , Schaefer J. A.
Published: August 2004

Viscosity measurements of GaInSn eutectic alloys were performed in a homebuilt device for low (9%) and high (95%) relative humidity for shorter (450 min) and longer (1800 min) time periods. At constant exposure time a characteristic increase of viscosity is observed with increasing humidity. For high humidity, high viscosity is obtained after a short time.

Assuming that the measured viscosity change is strongly related to the absorption of oxygen, XPS was applied to the chemical and quantitative analysis of differently prepared samples. In all cases, Ga is predominantly oxidized at the surface whereas Ga atoms in the metallic state are located deeper inside. Besides Ga2O3 (the most stable oxide phase), the less stable Ga2O is detected. Indium and tin are almost stable in their metallic state. With increasing humidity the thickness of the oxide film increases in our case from about 19 Å to 25 Å, assuming a layer‐by‐layer model. The presented results confirm our assumption of the increase in viscosity of the GaInSn system as a consequence of the preferential oxidation of gallium in the near‐surface region. Copyright © 2004 John Wiley & Sons, Ltd.
AES characterization of thin oxide films growing on Al foil during oxygen plasma treatment
Authors: Mozetic M. , Zalar A. , Cvelbar U. , Babic D.
Published: August 2004

The oxidation phenomenon during exposure of an Al foil to a low‐pressure weakly ionized oxygen plasma was studied by Auger electron spectroscopy (AES). We used a high‐purity Al foil with a thickness of 10 µm. Prior to plasma experiments the samples were analysed by AES depth profiling. The surface composition slightly varied between samples but, generally, a native impurity film with a thickness of approximately 2.5 nm was found on the Al surface. The surface film consisted of Al, O and C. The chemical state of aluminium was determined from the Al (68 eV) and Al (51 eV) peaks. The samples were exposed to weakly ionized oxygen plasma for various periods up to 300 s. Plasma parameters were measured with Langmuir and optical fibre catalytic probes. The electron temperature was about 70 000 K, the density of charged particles was about 1 × 1016 m−3, and the density of neutral oxygen atoms 2.4 × 1021 m−3. The AES depth profiles of plasma exposed samples showed that even after a short exposure to oxygen plasma a thin but stoichiometric Al2O3 layer was formed. With further exposure to oxygen plasma the thickness of the oxide layers and broadening of the oxide/Al interface increased which was explained by thermal effects. Copyright © 2004 John Wiley & Sons, Ltd.
Ellipsometric and XPS study of the initial oxidation of zirconium at room temperature
Authors: Lyapin A. , Jeurgens L. P. H. , Graat P. C. J. , Mittemeijer E. J.
Published: August 2004

The initial oxidation of polycrystalline zirconium has been investigated with XPS and in situ spectroscopic ellipsometry. Oxidations were performed at room temperature at partial oxygen pressures (pO2) of 1.3 × 10−7, 1.3 × 10−6 and 1.3 × 10−5 Pa. Analysis of the measured Zr 3d XPS spectra revealed the presence of a Zr‐enrichment in the oxide contiguous to the metal/oxide interface, as well as at the oxide surface. Investigation of the oxide‐film growth kinetics at various values of pO2, as determined from both the XPS and the ellipsometry measurements, showed the occurrence of an initial regime of very fast, electric‐field controlled growth, followed by a much slower oxidation stage, ending up with a non‐stoichiometric oxide film of ‘limiting’ thickness. Copyright © 2004 John Wiley & Sons, Ltd.
The oxidation of PbTe(100) surface in dry oxygen
Authors: Yashina L. V. , Tikhonov E. V. , Neudachina V. S. , Zyubina T. S. , Chaika A. N. , Shtanov V. I. , Kobeleva S. P. , Dobrovolsky Yu. A.
Published: August 2004

The oxidation of PbTe(100) surface in dry oxygen was studied by means of XPS. The appearance of a Te+4 component in the Te 3d spectra and an additional component shifted 1.1 eV towards higher binding energies in the Pb 4f spectra was observed. It was revealed that the oxidation mechanism does not change in the range of oxygen exposure 1011–1015 L. The oxidation product stoichiometry is close to PbTeO3. Quantum chemical modelling of the interaction of the small cluster (PbTe)4 with one oxygen molecule was performed by employing the hybrid DFT B3LYP method. It was revealed that PbO (2.22–2.43 Å) and TeO (1.97 Å) bonds are formed during the energetically favourable chemisorption process, giving rise to the increase of Pb and Te effective Mulliken charges by +0.18–0.31e and +1.11e, respectively. These changes are in good correlation with the observed binding energies for additional components in the XPS spectra of the oxidized surface. Copyright © 2004 John Wiley & Sons, Ltd.
SO2 adsorption at room temperature on Ni(111) surface studied by XPS
Authors: Galtayries A. , Cousi C. , Zanna S. , Marcus P.
Published: August 2004

The aim of this work was to investigate the initial stages of the SO2 interaction with Ni(111) surfaces. SO2 adsorption was performed at 1 × 10−7 mbar, at room temperature, in a preparation chamber attached to the XPS analysis chamber. After each adsorption, the S 2p and O 1s core levels were analysed. Various S‐containing adsorbed species were observed: S(ads) located at 162.0 ± 0.2 eV, and SO3(ads) at 166.7 ± 0.2 eV. A weak signal at 163.8 ± 0.3 eV is tentatively assigned to a small amount of SO(ads). The data provided by the O 1s core level spectra have been used to confirm the nature of S‐containing adsorbed species. Changes in the surface concentrations of the different adspecies as a function of exposure indicate that, first, SO2 dissociates into S(ads) and O(ads), then SO2 can either dissociate or combine with the available O(ads) to form SO3(ads). The surface saturation is reached after 12 L. Copyright © 2004 John Wiley & Sons, Ltd.
Epitaxial growth of BaO film on a Ti buffered MgO(100) surface using low‐energy neutral scattering
Authors: Kawanowa Hitoshi , Mori Daisuke , Gotoh Yoshihiko , Souda Ryutaro
Published: August 2004

The atomic structure of the BaO film formed on the Ti buffered MgO(100) surface has been investigated by low‐energy neutral scattering spectroscopy (LENS). The LENS was developed for surface structure and composition analyses particularly of highly insulating materials. The polar angle dependences of scattered He0 intensities indicate that the Ba and O atoms in the BaO unit locate on the missing Ti site and on top of the Ti atom, respectively, in the TiO2 unit formed on the MgO(001) surface and the spacing between the BaO and TiO layers is about 0.15 nm, which is smaller than that of BaTiO3 (c/2 = 0.20 nm) by 0.05 nm. Copyright © 2004 John Wiley & Sons, Ltd.
Characterization of iron oxide thin films
Authors: Aronniemi Mikko , Lahtinen Jouko , Hautojärvi Pekka
Published: August 2004

Iron oxide thin films were grown with gas‐phase deposition on a glass substrate in order to study the effects of the deposition temperature and time on the film properties. Characterization of the samples was performed using x‐ray photoelectron spectroscopy, x‐ray diffraction, and atomic force microscopy. It was observed that the film deposited at 350°C consisted of γ‐Fe2O3 whereas films produced at temperatures between 400°C and 500°C could be identified as α‐Fe2O3. Increasing the deposition temperature resulted in an increase of the grain size at temperatures between 350°C and 450°C. When the deposition time was decreased, a part of the iron ions were observed to be in the divalent state. Copyright © 2004 John Wiley & Sons, Ltd.
Preparation of ultrathin HfO2 films and comparison of HfO2/SiO2/Si interfacial structures
Authors: Tan R. Q. , Azuma Y. , Fujimoto T. , Fan J. W. , Kojima I.
Published: August 2004

Stoichiometric HfO2 films were successfully prepared using both thermal oxidation of Hf metal film and direct reactive sputtering deposited on native SiO2/Si wafer. Angle‐resolved x‐ray photoelectron spectroscopy, Auger depth profiling and grazing incident x‐ray reflectivity have been exploited to study the interfacial structures of the generated HfO2 films. A thinner interface (about 1.2 nm) of Hf‐rich silicates is formed using thermal oxidation, while the reactive sputtering deposition leads to a thicker (about 3.2 nm) Si‐rich interface. The results of binding energy, chemical composition, thickness and density all indicate that both interfaces have a graded structure where the concentration of Hf in the silicate interlayer decreases gradually along the depth. Copyright © 2004 John Wiley & Sons, Ltd.
Oxidation behaviour of Al‐alloyed ductile cast irons at elevated temperature
Authors: Kiani Rashid A. R. , Edmonds D. V.
Published: August 2004

The oxidation resistance of ductile irons alloyed with aluminium in the range from 0.08 to 6.16 wt.% has been investigated by heating at 550°C for periods up to 1270 h. Examination by light and SEM microscopy and EPMA indicated that two quite distinguishable layers of oxide were established at the surface. It was found that, in alloys containing aluminium, a very thin and adherent film of aluminium oxide is produced after a short period of heating, which protects the bulk of the alloy from further attack. It is believed that the oxidation resistance can be improved by increasing the aluminium content: an increase in aluminium content led to a decrease in the average thickness of the iron‐rich oxide layer. It was also found that the Al addition improved decarburization resistance; after long times at 550°C a nodular iron with a 6.16% Al content was free of decarburization. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of the oxidation kinetics of modified α‐iron substrate: correlation between TGA and AES
Authors: Grosseau‐Poussard J. L. , Panicaud B. , Dinhut J. F. , Lahaye M. , Silvain J. F.
Published: August 2004

A conversion phosphating treatment has been performed on polycrystalline α‐iron in order to modify its thermal oxidation behaviour. This has been studied by means of in situ thermogravimetric experiments and line profile nanoscale AES of the phosphated surface layer, both before and after the oxidation experiments. Modifications of the α‐iron oxidation mechanisms and their correlations with the evolution of the oxidation kinetics of α‐iron under the influence of phosphate films are evidenced in this work. Copyright © 2004 John Wiley & Sons, Ltd.
Reproducible XPS on biopolymers: cellulose studies
Authors: Johansson Leena‐Sisko , Campbell J. M.
Published: August 2004

The development of ‘user‐friendly’ surface analytical instrumentation has expanded the application of x‐ray photoelectron spectroscopy (XPS) towards softer and more complex composite materials. However, the knowledge of fundamental phenomena in practical, interdisciplinary applications is dearly needed. In the case of polymers and polymer‐based or ‐reinforced composites, the analytical problems are not only related to detection limits and resolution; indeed, the effects of contamination and experimental artefacts on interpretation of the carbon signal are often the more crucial challenge.

As a biopolymer, natural cellulose fibres provide an interesting model system for polymer studies. Numerous published XPS studies on lignocelluloses highlight both the possibilities and the problems of the surface analytical probes in analysis of air‐exposed organic materials.

We report XPS experiments of cellulosic natural fibre materials, discussing the effects of sample storage, UHV exposure, radiation doses, charging and data analysis. Based on a large body of experimental data we also propose that clean paper specimens could be used as an in‐situ reference in polymer studies. Copyright © 2004 John Wiley & Sons, Ltd.
Labelling techniques for the chemical analysis of polymer surfaces
Authors: Holländer Andreas
Published: August 2004

The labelling of functional groups for the surface analysis of polymers has been developed to become a useful tool. We briefly review examples which show the power improvement of a number of instrumental techniques for the analysis of chemically complex surfaces.

The application of labelling techniques to some real‐world samples is demonstrated with some examples. The relation between labelling for XPS and for a fluorescence determination is shown with an oxygen plasma treated polyethylene. It was reacted with diaminoethane (DAE) and with fluorescamin or with dansyl hydrazine. The sensitivity of the fluorescence labelling is about two orders of magnitude higher. The robustness of the fluorescence labelling technique is shown by an orthogonal coupling. The subsequent coupling of two types of dyes to two different functional groups does not influence the fluorescence intensity of each dye. Copyright © 2004 John Wiley & Sons, Ltd.
Surface characterization of plasma‐treated PTFE surfaces: an OES, XPS and contact angle study
Authors: Vandencasteele N. , Reniers F.
Published: August 2004

PTFE surfaces have been exposed to neutral atoms and molecules, and to electrons originating from a modified RF nitrogen plasma, able to filter out the cations. The changes in surface energy of the modified polymer, determined by the water contact angle, are linearly related to the increase of the nitrogen concentration at the surface, determined by XPS. The deconvolution of the spectral envelope of the C 1s photoelectron peak shows a strong modification of the nature of the chemical groups on the surface, depending on the treatment time and on the plasma power. Electrons are postulated to be mainly responsible for the appearance of the CF3 group, while the major functions induced by nitrogen seem to be CN, CN and a possible FCN group. Copyright © 2004 John Wiley & Sons, Ltd.
Interface analysis and compositional depth profiling by XPS of polymer coatings prepared using ultra‐low‐angle microtomy
Authors: Hinder Steven J. , Watts John F. , Lowe Chris
Published: August 2004

Conventional rotary microtomy in combination with high‐precision, ultra‐low‐angle sectioning blocks have been used to produce cross‐sectional, ultra‐low‐angle tapers in polymeric coating systems. Tapered samples produced by ultra‐low‐angle microtomy (ULAM) have been employed in the investigation of intercoat bonding interfaces in multilayer polymeric coatings and for the compositional depth profiling of polymer/polymer + additives systems.

X‐ray photoelectron spectroscopy (XPS) cross‐sectional analysis of a poly(vinylidene difluoride) (PVdF) based topcoat and a poly(urethane) based primer interface exposed by ULAM processing indicates diffusion of fluorine‐containing components of the PVdF topcoat formulation into the uppermost nanometres of the underlying poly(urethane) primer. It is demonstrated that a ULAM exposed, cross‐sectional multilayer interface, with a taper of <0.05°, investigated by high‐resolution XPS employing a 15 µm spot‐size enables the interface region to be probed at a depth resolution of <20 nm.

Depth profiling characterization by XPS of a polyamide powder coating with an organosilane adhesion promoter reveals a silicon concentration gradient within the cured polymer. This result demonstrates that the organosilane preferentially segregates to the surface regions of the cured polymer coating system. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of viologen‐containing poly(vinylidene fluoride) redox‐sensitive membranes
Authors: Liu X. , Neoh K. G. , Kang E. T.
Published: August 2004

Thermally induced graft co‐polymerization of 4‐vinylbenzyl chloride (VBC) with ozone‐preactivated poly(vinylidene fluoride) (PVDF) was carried out in N‐methyl‐2‐pyrrolidone solution to produce VBC‐g‐PVDF co‐polymers. The resulting VBC‐g‐PVDF co‐polymers with different VBC graft concentrations were cast into microfiltration membranes by phase inversion. Viologen moieties were introduced by the di‐quaternization of 4,4′‐bipyridine with the VBC‐g‐PVDF membranes and VBC through a two‐step reaction in ethanol. The viologen‐containing membranes were characterized by x‐ray photoelectron spectroscopy, elemental analysis, and thermogravimetric analysis. Surface morphology was studied by scanning electron microscopy. It was demonstrated that the permeability of the viologen‐containing membrane can be regulated by redox reactions. This technique of fabricating viologen‐containing membranes represents a relatively simple and effective approach for achieving membranes with redox‐sensitive permeation properties. Copyright © 2004 John Wiley & Sons, Ltd.
Fast atom beam treatment of ultra‐high molecular weight polyethylene
Authors: Tóth A. , Ujvári T. , Bertóti I. , Szilágyi E. , Keszthelyi T. , Juhász A.
Published: August 2004

Ultra‐high molecular weight polyethylene (UHMWPE) was surface treated by beams of various inert and reactive atoms in the low keV range. Sum frequency generation (SFG) spectroscopy showed the complete destruction of ordered packing at the topmost surface. Rutherford backscattering (RBS) and elastic recoil detection analysis (ERDA) revealed a strong surface dehydrogenation. Depth‐sensing nano‐indentation and nanoscratch measurements testified to alterations in the nanomechanical properties. A correlation has been established between the scratch resistance and the plasmon loss energy of the C 1s XPS peak. Copyright © 2004 John Wiley & Sons, Ltd.
Optical and mechanical properties of polypropylene modified by metal oxides
Authors: Kruenate J. , Tongpool R. , Panyathanmaporn T. , Kongrat P.
Published: August 2004

Films of polypropylene (PP)/SiO2, PP/ZnO and PP/SiO2ZnO nanocomposites have been prepared. SiO2 and ZnO were prepared by the sol–gel method and mixed with dispersant (Efka) and coupling agent (thiocyanatopropyltriethoxysilane) before being introduced to melted PP in an internal mixer. The transmission of UV, visible light and NIR radiation of the nanocomposite films was less than that of the PP films. Efka and silane made the film clearer to all rays since they hindered the particle agglomeration. PP/ZnO film had a unique property as it blocked UV while transmitted visible light better than PP/SiO2. The modulus of PP mixed with metal oxide increased whereas the elongation to break decreased, indicating that the metal oxides increased the film strength and brittleness. The PP/SiO2 gave higher tensile strength and modulus than the PP/ZnO due to the greater hardness of SiO2. The silane improved the tensile strength and modulus of PP/SiO2. Copyright © 2004 John Wiley & Sons, Ltd.
Surface and interface characterization of smart membranes
Authors: Zhai Guang‐Qun , Ying Lei , Kang E. T. , Neoh K. G.
Published: August 2004

Multistimuli‐responsive microfiltration (MF) membranes were fabricated from blends of poly(N‐isopropylacrylamide) (PNIPAm) and poly(vinylidene fluoride) (PVDF) grafted with poly(acrylic acid) (PAAc) and poly(4‐vinylpyridine) (P4VP) side‐chains (PVDF‐g‐PAAc/PNIPAm and PVDF‐g‐P4VP/PNIPAm, respectively) by phase inversion in aqueous media. Elemental and XPS analyses indicated that both the bulk and surface concentration of PNIPAm in the PVDF‐g‐PAAc/PNIPAm and PVDF‐g‐P4VP/PNIPAm blend membranes increased with increasing PNIPAm concentration in the blend used for the casting solution. Surface enrichment of the PNIPAm chains occurred in both types of membrane, leading to a surface concentration ten times that of the bulk. SEM results showed that the porous morphology of the membranes could be regulated by the pH and temperature of the coagulation bath. Actual measurements revealed that the pore size of the PVDF‐g‐P4VP/PNIPAm blend membranes increased with the increase in temperature and the decrease in pH of the aqueous casting bath. The flux through the PVDF‐g‐PAAc/PNIPAm and PVDF‐g‐P4VP/PNIPAm blend membranes exhibited simultaneously temperature‐ and pH‐dependent behaviour. Copyright © 2004 John Wiley & Sons, Ltd.
The influence of the ion distribution on interfacial effects in oligoether functionalized poly(p‐phenylene) based mixed ionic electronic conductors
Authors: Wenzl F. P. , Suess C. , Poelt P. , Mauthner G. , List E. J. W. , Bouguettaya M. , Reynolds J. R. , Leising G.
Published: August 2004

We report on surface composition studies of thin spin‐cast films of a polymeric mixed ionic electronic conductor (PMIEC). The polymeric constituent consists of a hydrophobic conjugated poly(p‐phenylene) (PPP) backbone functionalized with hydrophilic oligo(ethylene oxide) (OEO) side‐chains to supply the electronically conducting conjugated polymer with an ion transporting functionality. In particular a lithium salt (lithium trifluoromethanesulfonate), the prototype salt applied in solid‐state electrolytes, was chosen for the investigations.

Identification of the elements and their quantification was done by XPS for different salt concentrations in order to address the still open question of surface‐induced effects on the ion distribution in thin films of solid‐state electrolytes. No enrichment or depletion of the ionic species at the free surface could be observed for the concentrations investigated within the error of the measurement given. Copyright © 2004 John Wiley & Sons, Ltd.
Surface excitation of selected conducting polymers studied by elastic peak electron spectroscopy (EPES) and reflection electron energy loss spectroscopy (REELS)
Authors: Gergely G. , Menyhard M. , Sulyok A. , Orosz G. T. , Lesiak B. , Jablonski A. , Tóth J. , Varga D.
Published: August 2004

Electrons impinging into a solid surface produce excitations in the surface layer. The elastic reflection coefficient of a solid (i.e. elastic peak) is reduced by surface losses. Selected conducting polymers were studied with elastic peak electron spectroscopy (EPES) and reflection electron energy loss spectroscopy (REELS). The electron inelastic mean free path (IMFP) was determined using EPES with Ag and Si references and corrected for surface excitations, characterized by the surface excitation parameter Pse(E). A new procedure was developed for experimental determination of the parameter Pse(E), a further development of Tanuma's work. It is based on comparison of experimental and calculated integrated elastic peak ratios of sample and reference. Another procedure was based on the REELS method. Pse(E) of selected polymers were determined for E = 0.2–2.0 keV using a HSA analyser. Experiments were evaluated by Monte Carlo simulation using NIST elastic scattering databases. The IMFP values for polymers were calculated by Gries, Cumpson and TPP‐2M formulae. Material parameter data, ach, using Chen's approach for selected polymers, and IMFPs of polyethylene corrected for surface excitation are presented. Copyright © 2004 John Wiley & Sons, Ltd.
Polymerization of aniline in the channels of micro‐ and mesoporous materials
Authors: Márquez F. , Roque‐Malherbe R. , Ducongé J. , del Valle W.
Published: August 2004

Preparation of conducting polymers incorporated within porous materials, that is, zeolites and mesoporous materials, is an attractive methodology to obtain composite materials where the organic polymer may exhibit an increased mechanical and chemical performance compared to the pure polymer. For any application, a crucial issue is the polymer content of the resulting composite material. In fact, a major limitation of the use of hosts has been up to now the low loading of conducting polymer that has been achieved. Based on the composition of related composite materials, a weight percentage of the organic polymer of at least 25% should be attained. We now report the polymerization of aniline within the pores of aluminosilicates and the characterization of the encapsulated polymer/host composites. These composites have potential as stable molecular wires and their applications in the design of batteries and systems to accumulate electric charge are currently being developed. Copyright © 2004 John Wiley & Sons, Ltd.
Wettability and interfacial reactions in Al/TiO2
Authors: Sobczak N. , Stobierski L. , Radziwill W. , Ksiazek M. , Warmuzek M.
Published: August 2004

The effects of temperature and testing procedure on the wetting properties of molten Al on polycrystalline TiO2 substrates were studied by a sessile drop method in vacuum at 1173–1373 K. For the common contact heating procedure, oxidized molten Al wets titania at T > 1210 K. The removal of the oxide film from the Al drop by means of a capillary purification procedure makes the Al/TiO2 couple wettable at 1173 K. The structure and chemistry characterization of Al/TiO2 interfaces shows that molten Al reacts with TiO2 to form fine alumina particles and Ti, which subsequently is dissolved in the Al drop. However, this reaction is remarkable at 1373 K only and much higher temperatures are required for successful reactive synthesis of Al/Al2O3 composites. Copyright © 2004 John Wiley & Sons, Ltd.
Influence of doping on the surface feature and formation of PbI2 polytypes
Authors: Soudmand M. , Habibi S.
Published: August 2004

A study of phase transformation at elevated temperature has been undertaken on single crystals of lead iodide grown in gel. The crystals of the polytype 2H, which is known to be the common modification of PbI2 at room temperature, have been found to transform into well‐ordered crystals of the polytype 12R after heating for nearly 8 h at 150°C. During the intermediate period of heating the crystals show features of disorder, viz. streaking, arcing, or both, on their x‐ray diffraction photographs. On the other hand, the higher polytypes do not show any change in cell dimensions even after prolonged heating. In addition, it was found that if silver iodide is added in extremely minute quantities as an impurity during crystallization the process of phase transformation in the as‐grown crystals appreciably accelerates. Inspection by optical microscopy of these crystals has revealed the existence of a wide variety of growth features on their basal surfaces. The results have been discussed in detail. Copyright © 2004 John Wiley & Sons, Ltd.
Chemical speciation of N‐(phosphonomethyl)glycine in solution and at mineral interfaces
Authors: Ramstedt Madeleine , Norgren Caroline , Sheals Julia , Shchukarev Andrei , Sjöberg Staffan
Published: August 2004

The chemical speciation of the zwitterionic compound N‐(phosphonomethyl)glycine (PMG) was studied in solution and at the mineral/water interface at different pH. Results from vacuum techniques such as XPS were compared with previously published conventional batch experiments. It was shown that by keeping the samples frozen during XPS analyses it was possible to keep a water interface. The frozen interface enables studies of the protonation of the nitrogen group which has previously been difficult using XPS. The protonation in frozen solutions was compared with literature data and the differences discussed. Furthermore, the speciation of PMG at the surface of manganite (γ‐MnOOH) and goethite (α‐FeOOH) was studied. It was found that at least one of the protonation constants for surface‐bound PMG differs significantly from the protonation constants in a pure PMG solution. The formation of different surface complexes is discussed together with differences between the sorption capacities of PMG onto the minerals studied. Copyright © 2004 John Wiley & Sons, Ltd.
Surface composition of CuAu single crystal electrodes determined by a coupled UHV–electrochemical approach and a Monte‐Carlo simulation
Authors: Pace S. , Van Hoof T. , Hou M. , Buess‐Herman C. , Reniers F.
Published: August 2004

Recent papers show that copper could act as an electrode capable of electrocatalysing the reduction of carbon dioxide, a major greenhouse gas. However, no fundamental studies on single crystals have been related, and although the presence of surface oxides seems to be important, little is known about the mechanism.

Single crystal electrodes of Au, Cu and AuCu alloys (1, 10, and 20 at.% gold) and a 50 at.% gold polycrystal alloy have been synthesized and characterized by AES and cyclic voltammetry (CV). The segregation equilibrium was studied experimentally (using the low‐energy Auger peaks of Cu and Au after deconvolution) and theoretically (with classical thermodynamics and a Monte‐Carlo Metropolis approach). All the alloy electrodes show a surface enrichment in gold. The electrochemical characterization reveals that the dilution of copper by gold delays the oxidation of the electrode to more positive potentials with respect to pure copper, whereas simultaneously the reduction of protons occurs at more negative potentials than pure gold. Thanks to an electrochemical–UHV transfer system, we show that the surface composition of the electrode drastically depends on the working potential. Copyright © 2004 John Wiley & Sons, Ltd.
The connection between hydrogen diffusion through a steel membrane and mechanism of the hydrogen evolution reaction
Authors: Tsygankova L. E. , Vigdorovich V. I. , Vigdorovich M. V.
Published: August 2004

The kinetics of the hydrogen evolution reaction (HER) on Armco iron and carbon steel have been studied in the C2H4(OH)2H2OHCl system. The addition of 5–10% water or 1–10 mM Na2HAsO4 to the ethylene glycol solutions of HCl causes a transition from the Volmer rate determining step (rds) to the Tafel rds in the HER mechanism. According to experimental data, the rate of hydrogen diffusion through the carbon steel membrane does not depend on the rds nature of the HER. Theoretical analysis of the peculiarities of the Tafel rds has been carried out in which a recombination step was represented as a set of successive reactions. An expression has been obtained which determines the balance of surface processes and the hydrogen permeation into the bulk of the metal. It has been confirmed experimentally. Copyright © 2004 John Wiley & Sons, Ltd.
Calibration of various analytical methods with heavy‐ion ERDA
Authors: Bohne W. , Lindner S. , Röhrich J. , Strub E.
Published: August 2004

Heavy‐ion ERDA (elastic recoil detection analysis) can be used to characterize thin solid layers. Absolute concentrations of the chemical elements can be detected as well as the layers' thickness and depth profiles. For the measurement, the sample is irradiated with a heavy‐ion beam. Atoms of the sample are recoiled and detected with an energy and mass dispersive spectrometer. Since the ERDA principle is based on the classical Rutherford scattering theory, the expected yields for the given conditions can be calculated exactly. Therefore, ERDA is a standard‐free method. Absolute concentrations can be determined for all detected chemical elements simultaneously. By comparison with ERDA measurements an FT‐IR (Fourier transform–infrared) spectrometer, routinely used to determine the stoichiometry of ZnO layers, was calibrated. Artefacts in SIMS (secondary ion mass spectrometry) data for the characterization of chalcopyrite based solar cell absorbers are ruled out. Copyright © 2004 John Wiley & Sons, Ltd.
AES analysis of nitride layers on steel with target factor analysis
Authors: Vandendael I. , Steenhaut O. , Hubin A. , Vereecken J. , Prince P. , Reniers F. , Segato T.
Published: August 2004

Industrially nitrided steel samples are analysed with AES. The aim of this work is to optimize the quantification of nitrogen and to extract the chemical information hidden in the shape of the measured Auger peaks with Target Factor Analysis (TFA).

To optimize the use of TFA, reference samples of pure components are necessary. These components are made in a laboratory reactor in which pure iron is nitrided. The resulting nitride layer is identified with X‐Ray Diffraction (XRD). Afterwards their AES spectra are taken as input for the TFA of the industrial layers. In this paper, the preparation and the characterization of a γ′‐Fe4N standard is discussed, as well as the correction of the sensitivity factors used for the quantification of nitrogen. Finally, the application of TFA on an industrial nitride layer is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Experimental measurements of the surface excitation parameters of Cu, Au, Ni, Ag, Ge and Pd based on Si and other reference standard materials
Authors: Gergely G. , Menyhard M. , Gurban S. , Toth J. , Varga D.
Published: August 2004

Surface excitation in electron spectroscopy is characterized by the surface excitation parameter Pse. In electron spectroscopy, the total surface excitation is observed for electrons impinging and reflected elastically (elastic peak electron spectroscopy, EPES) or for backscattered (REELS) electrons. Surface excitation reduces the intensity of the elastic peak and affects the REELS spectra. Experimental determination of the total Pse from EPES spectra is made by measuring the ratio of integrated elastic peak intensities for the sample Iese and reference material Iere. This paper presents further development of Tanuma's work for this ratio. Pser of the reference was calculated with the formula and material parameters of Chen. Monte Carlo simulations were based on the NIST elastic scattering and Tanuma's IMFPs database for the reference samples. This work deals with Cu, Au, Ag, Ni and Pd metals and Ge, used also as standards for electron spectroscopy. Experiments were made with a high‐energy resolution spectrometer (HSA), and with a DESA 100 spectrometer (Staib Ltd) with large solid angle for E = 0.2–2 keV. Surface excitation correction factors have been developed for the above metals and Ge, used for reference samples. Their application reduced the differences in IMFPs from Tanuma's values for the uncorrected rms errors Δλu (% values) to Δλc (corrected) data for Si/Ag (from 21.2 to 6.7%), for Si/Ni (11.4 to 9.8%), and for Si/Cu (13.5 to 5%). A similar improvement was found for Si/Au, Ag/Ni, Ag/Cu and Ag/Au experimental results, using surface excitation correction. Copyright © 2004 John Wiley & Sons, Ltd.
Instrument for thin film diagnostics by UV spectroscopic reflectometry
Authors: Urbánek M. , Spousta J. , Navrátil K. , Szotkowski R. , Chmelík R. , Buček M. , Šikola T.
Published: August 2004

This paper describes the principles, design and testing of an instrument for the UV/Vis‐optical‐reflectance monitoring of homogeneity of the optical properties of thin films developed in our group. A 200 µm reflection probe, miniature fibre optic spectrometer and a home‐built computer controlled x–y mapping stage together with original data fitting software are the principal parts of the instrument. The results achieved show the usability of this instrument for the post‐production testing of samples of various optical thin films prepared by different technologies. By this instrument the gradients and other inhomogeneities of thickness and spectral optical constants (n, k) of thin films can be monitored. Copyright © 2004 John Wiley & Sons, Ltd.
The effect of bias voltage on the measurement of local barrier height
Authors: Yoshitake Michiko , Yagyu Shinjiro
Published: August 2004

The effect of experimental conditions on local barrier height (LBH) measurement with the STM technique was examined based on Simmons' formula. It has been revealed that the effect of bias voltage on LBH has to be measured under constant tip–specimen separation, not under constant tunnel current as normally used, because tip–specimen separation varies with bias voltage under constant current condition. We propose to start LBH measurement with I–V curve measurement and vary bias voltage along the I–V curve so that the tip–specimen distance is kept constant. We also propose to use the I–V curve to choose an equation suitable for LBH calculation in a specific bias voltage. The formula applicable for each bias voltage has been given. Copyright © 2004 John Wiley & Sons, Ltd.
Distinguishing the dependence of the apparent local barrier height on measurement conditions
Authors: Yagyu Shinjiro , Yoshitake Michiko
Published: August 2004

We have investigated a method for finding the dependency of the apparent local barrier height (LBH) on measurement parameters (tunnelling current, bias voltage and tip–sample separation). The validity of the method is demonstrated by measuring the LBH on an Au(111) surface. This method enables comparison of LBH values on various surfaces. Copyright © 2004 John Wiley & Sons, Ltd.
Multivariate characterization of ultra‐thin nanofunctional plasma polymer films using ToF‐SIMS analysis
Authors: von Gradowski M. , Wahl M. , Förch R. , Hilgers H.
Published: August 2004

Octadecanethiol self‐assembled monolayers (SAMs) on gold substrates have been exposed to an allylamine plasma for different plasma times ranging from 0 to 9 min. Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) positive spectral fragmentation patterns of SAM‐allylamine plasma films of varying allylamine deposition times were analysed using multivariate techniques (PCA and PLS). Multivariate data analysis permits the exploration of the entire spectrum by forming the best linear combination of the principal components which describes the maximum amount of variance of the sample set. PLS‐models have been calculated correlating spectral parameters to sample properties such as layer thickness and atomic concentration of selected ions. The predicted sample properties were in good agreement with the experimental results showing that the combination of ToF‐SIMS analysis with multivariate techniques is an efficient way of sample characterization and interpretation of spectral data and should be the method of choice for future spectral data analysis. Copyright © 2004 John Wiley & Sons, Ltd.
Optimization of x‐ray monochromating systems: application to LiF(220) crystal with Johansson geometry for Cu K (8047.78 eV)
Authors: Moslemzadeh N. , Watts J. F. , Tsakiropoulos P. , Beamson G. , Haines S. , Weightman P.
Published: August 2004

The design of monochromated x‐ray sources for high‐energy XPS is of particular importance. Prediction of the final result and the effect of the experimental parameters is very important if optimum performance is to be obtained in practice. A computer program has been written to calculate crystal reflectivity, collection solid angle and integrated beam intensity for any singly and doubly bent crystal diffractor. The intensity profile, size and shape of the image‐spot produced by the diffracted x‐rays on any arbitrary plane are then predicted by ray tracing. The application of the program to optimize a LiF(220) crystal with Johansson geometry for Cu K (8047.78 eV) will be demonstrated. Copyright © 2004 John Wiley & Sons, Ltd.
Modified chromatographic thin layer surface as an interface to couple thin layer chromatography with ToF‐SIMS
Authors: Oriňák Andrej , Arlinghaus Heinrich F. , Vering Guido , Oriňáková Renáta
Published: August 2004

The goal of our research is the development of a new interface to combine thin layer chromatography (TLC) with time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). The direct combination of the simple separation technique (TLC) with the highly selective identification unit (ToF‐SIMS) requires a modification of common TLC material to reduce the background signal in SIMS spectra. The background signal is caused either by the stationary phase or by the residual mobile phase (solvent). The aluminium back of the TLC layer has been modified to get a universal porous TLC–ToF‐SIMS interface. Functionality of this novel interface has been tested with a Methyl Red indicator as a representative analyte to visualize its transport through the chromatographic layer and interface. From ToF‐SIMS results it was found that the indicator molecule fragments at the diazo double bond NN. Copyright © 2004 John Wiley & Sons, Ltd.
Electron beam irradiation of hydrogenated amorphous carbon films
Authors: Calliari L. , Filippi M. , Laidani N.
Published: August 2004

The effect of electron irradiation on hydrogenated amorphous carbon (a‐C:H) films is investigated on both as‐deposited and thermally annealed films and is compared to the effect of thermal annealing. As for the as‐deposited film, both electron irradiation and thermal annealing result in a change in the film structure from diamond‐like to graphite‐like. In the case of electron irradiation, such a phase transformation proceeds in a logarithmic way as a function of the electron dose. No electron‐induced effect is observed on previously annealed films. Copyright © 2004 John Wiley & Sons, Ltd.
Sol–gel synthesis and characterization of iron oxide–silica nanocomposites
Authors: Tongpool R. , Jindasuwan S.
Published: August 2004

The films of iron oxide–silica nanocomposites have been prepared using the sol–gel process and spin‐coating technique. The film morphology was dependent on precursors, additives, ageing duration and the molar ratios between iron (Fe) and silicon (Si) of the coating solution. Hematite was derived from iron oxide sol while those obtained from silica and iron oxide–silica sols were relatively amorphous, indicating that crystallization and particle growth of hematite were inhibited by the silica network. Hydroxypropylcellulose (HPC) was found to reduce cracks successfully. It increased the film porosity and did not interrupt the crystallization of the host. The film containing a Fe:Si:HPC ratio of 50:50:0.005 showed the smoothest surface. Copyright © 2004 John Wiley & Sons, Ltd.
Epitaxial growth of sub‐nanometre thick tin dioxide films on sapphire substrates by pulsed atomic layer chemical vapour deposition
Authors: Takeuchi Toshio , Doteshita Isao , Asami Seiji
Published: August 2004

Sub‐nanometre thick tin dioxide (SnO2) films were grown on both amorphous Pyrex glass and crystalline CZ sapphire substrates using pulsed atomic layer metal‐inorganic chemical vapour deposition. The source materials, SnCl4 and H2O, were introduced by pulsed doses as reactants into the cold reactor, and doses were separated by pulse doses of inert purge gas doses. Depositions took place at a reduced pressure 2.5 × 10−2 Torr at the temperature range 400°C to 500°C. X‐ray diffraction analysis (XRD), ultraviolet photoelectron spectroscopy (UPS), XPS and spectrophotometry were used to characterize the films. The crystal structure of the grown films were rutile type, as with the single crystals. During the one growth operation, films with a SnO2(100) crystal surface were epitaxially grown on the sapphire(0001) substrates and films with a SnO2(101) crystal surface were epitaxially grown on the sapphire(1‐102) substrates at the same deposition processes. Copyright © 2004 John Wiley & Sons, Ltd.