bluuebunny/crossref_metadata_2025_split huggingface dataset:
Physico‐chemical modifications of solid surfaces by interaction with ion beams
Authors: Pignataro Salvatore 
Published: December 2004

AbstractThe physico‐chemical processes occurring in the particle (ion, photon) bombardment of a surface are reviewed, with particular emphasis on the ion beam–solid interaction. The main factors influencing the chemical reactions which occur by ion bombardment will be discussed in terms of Lindhard–Scharff–Schiøtt (LSS) theory on the basis of experimental data obtained on both organic and inorganic simple systems as well as on polymers. Some typical reaction schemes will be reporte and the modification of the physical properties of the bombarded surface will be shown to be connected with the chemical nature of the products formed as a consequence of the energy deposition of the ion beam. A few examples showing the importance of the above phenomena in the field of surface and interface analysis will be given.
Chemical changes in titanate surfaces induced by Ar+ ion bombardment
Authors: González‐Elipe A. R. , Sanz J. M. , Espinós J. P. , Fernandez A. , Munuera G. 
Published: December 2004

AbstractThe reduction effects and compositional changes induced by 3.5 keV Ar+ bombardment of several titanates (i.e. SrTiO3, Al2TiO5 and NiTiO3) have been quantitatively investigated by XPS.In all the samples studied here the original Ti4+ species were reduced to lower oxidation states (i.e. Ti3+ and Ti2+), although to a lesser extent than in pure TiO2. On the contrary, whereas Sr2+ and Al3+ seem to remain unaffected by Ar+ bombardment, in agreement with the behaviour of the respective oxides (i.e. SrO and Al2O3), Ni2+ appears more easily reducible to Ni0 in NiTiO3 than in NiO. In addition, other specific differences were observed between the titanates, which reveal the existence of interesting chemical effects related to the presence of the different counter‐ions in the titanates.In the case of Al2TiO5, its Ar+‐induced decomposition to form TiO2 + Al2O3 could be followed by XPS.
Electron‐irradiation‐induced effects on high‐Tc superconductors analysed by high‐resolution Auger electron spectroscopy
Authors: Seibt E. W. , Zalar A. 
Published: December 2004

AbstractThe change in the surface and bulk compositions of high‐Tc BiPbSrCaCuO and YBaCuO system superconductors caused by electron beam irradiation at room temperature have been investigated using high‐resolution Auger electron spectroscopy (AES). Electrons of energies between 5 and 15 keV were used to study energy‐dependent decomposition phenomena for a wide range of electron radiation doses up to a maximum value of above 1028 electrons m−2. Additionally, irradiations with focused electron beams were carried out on silver‐sheathed Bi1.7Pb0.3Sr2Ca2Cu3O10.2/10 wt.% Ag tape samples with relatively high critical current densities [jc(0 T, 77 K) = 3.3 × 108 A m−2] in order to investigate the radiation‐induced effects on surface and bulk compositions by AES multiplex and sputter depth‐profiling techniques. The results indicate that there are significant changes in composition of the BiPbSrCaCuO samples up to concentration values of about 10 at.% for oxygen and about 12 and 15 at.% for calcium and copper respectively, whereas only small irradiation‐induced decomposition effects are observed for YBaCuO single–crystal and thin film superconductors.
Oxidation of metals by an oxygen ion beam in the MBE process
Authors: Shimizu T. , Nonaka H. , Arai K. 
Published: December 2004

AbstractX‐ray photoelectron spectroscopy was used to study the oxidation of Cu by oxygen plasma generated from a Kaufman ion gun. It was found that Cu was much less oxidized in co‐evaporation with Ba or Nd compared to Cu‐only evaporation when the total flux density of supplied metals and the oxygen plasma conditions were similar. It was also found that elemental Ba or Nd deposited on a CuO film at room temperature deoxidized the CuO.
Correlation of hydrogen content with properties of oxidic thin films
Authors: Ottermann C. R. , Bange K. , Wagner W. , Laube M. , Rauch F. 
Published: December 2004

AbstractHydrogen and hydrogen‐containing species (H2O, OH etc.) play a dominant role in the various properties of glass surfaces and technical oxidic thin films deposited on glass. The amount of hydrogen and its distribution with depth are influenced by preparation and production processes, film materials, density and voids, etc. The 15N nuclear reaction technique, which works quantitatively and non‐destructively, was used to investigate glass surfaces and thin films of TiO2, Ta2O5 and SiO2 produced by sol‐gel processes, reactive evaporation, sputtering and ion plating on glass substrates. An increase or decrease in hydrogen content influences optical and mechanical properties such as the refractive index and adhesion of the films.
Study of the phase composition of iron‐containing Langmuir–Blodgett layers before and after thermal and chemical treatment
Authors: Meisel W. , Gütlich P. 
Published: December 2004

AbstractIron‐containing Langmuir–Blodgett mono‐ and multilayers were prepared by depositing ferric stearate onto silicon wafers. Particular care should be taken in order to avoid the presence of alkali ions, which may replace iron ions in the deposited film. By a subsequent heating in air, the fatty acid chains were thermodesorbed. This results in a rather homogeneous coating of the samples by an iron oxide, most probably in the form of crystalline and amorphous γ‐FeOOH, as found by conversion electron Mössbauer, photoelectron and microprobe studies. By a subsequent heating in hydrogen gas or exposure to nascent hydrogen, a partial reduction of the iron oxide layer is possible up to the metallic state (α‐Fe). The Mössbauer spectra show the formation of a mixture of different iron species (Fe3+, Fe2+, Fe0) depending on the reductive treatment.
Surface and in‐depth chemical characterization of sputter‐deposited CrSiO layers by XPS and AES techniques
Authors: Bertóti I. , Tóth A. , Czermann M. , Menyhárd M. , Sulyok A. , Zsoldos E. 
Published: December 2004

AbstractRF‐sputtered CrSiO cermet films deposited without and with a bias (200 V) have been studied by XPS and AES. Samples as deposited, etched by HF solution as well as annealed at temperatures up to 600°C have been considered. XPS results showed that the surface of the as‐received samples were depleted in Cr and enriched in O with respect to the target composition. Silicon and Cr were present in both oxidized and reduced forms in the surface layer. Ar+ ion sputter profiles revealed that the composition of the subsurface approached that of the target and that Cr was present in the subsurface in reduced and Si in both oxidized and reduced states. AES in‐depth profiling resulted in element concentration trends similar to but element ratios different from those observed by XPS. This was attributed to preferential sputtering coupled with the significantly different sampling depths of the two techniques. Cr3Si was identified by x‐ray diffraction in samples treated at 600°C, but not even traces of it could be detected by this method below 400°C. The Si Auger parameter determined by XPS proved to be more sensitive in identifying silicide‐type bonds in the CrSiO layers studied.
Changes induced in the surface characteristics and catalytic activity of amorphous Cu‐Zr by hydrogen pretreatment
Authors: Katona T. , Molnár Á. , Perczel I. V. , Kopasz Cs. , Hegedűs Z. 
Published: December 2004

AbstractHydrogen‐treated amorphous Cu61Zr39 alloy ribbon exhibits the development of characteristic formations (hemispheres) in a circular arrangement (as revealed by SEM) on both sides of the ribbon, in parallel with copper enrichment (determined by AES) and partial crystallization (determined by differential scanning calorimetry). The extrusion of pure copper is considered to be caused by hydrogen diffusing into the bulk through existing surface defects. As a consequence of the surface and structural changes, steady increases in both the copper surface area and the catalytic activity (dehydrogenation of alcohols and isomerization of allyl alcohol and 2‐propyloxirane) are demonstrated.
Use of model depth resolution functions for the deconvolution of depth profiling data
Authors: Makarov V. V. 
Published: December 2004

AbstractThe problem of deconvolution of SIMS depth profiles with model depth resolution function, which may differ from the true resolution function, is considered. The concept of residual depth resolution function is introduced to describe mathematically the result of the deconvolution. The consequences of using a model depth resolution function of double exponential form are explored and the range of exponents over which a deconvolution might give useful information is derived analytically.It is shown how a depth resolution function of double exponential form distorts the initial profiles of different types. The analytical expressions are obtained for rectangular and exponential initial profiles. It is shown that the convolution of the initial exponential profile with a double exponential resolution function leads to a linear combination of exponential functions containing separately either exponential parameters of the resolution function or that of the initial profile. The resultant inverse of the exponential slope cannot be calculated by direct summation of the characteristic lengths of the initial profile and those of the resolution function.The asymptotic behaviour of the convolution of the initial Gaussian profile with a double exponential resolution function is explored analytically.
AES study of Si LVV bonding states in various substoichiometric oxide environments
Authors: Lang B. , Khellafi M. 
Published: December 2004

AbstractAuger electron spectroscopy has been applied to a study of chemical structure effects in silicon oxides caused by changes of the surface or bulk stoichiometry. Ion‐damaged SiO2, vacuum‐deposited SiOx (1 < × < 2) and Si/SiO2 interfaces were investigated. Silicon enrichment causes not only the growth of the elemental Si peak, but also a broadening of the main oxide peak. Detailed comparison of the Si LVV spectra in the three types of samples suggests that the elemental Si component occurs with the same local structure as in bulk silicon.
Si LVV Auger lineshape analysis to study the oxygen chemisorption on TaSi2 thin film
Authors: Sharma J. K. N. , Chakraborty B. R. , Bera Santanu 
Published: December 2004

AbstractThe Si LVV Auger lineshapes of the single‐crystal Si(100) surface and the oxygen chemisorbed and clean TaSi2 surfaces are studied by observing the three Auger transitions that have different final states in the valence band. It is seen from the Si and Ta Auger fingerprints that both Si and Ta form oxides due to chemisorption of oxygen on the silicide surface at room temperature. The variations in the Si LVV fingerprint in silicide and the oxygen‐exposed silicide are explained in term of surface effects and the behaviour of the 3s orbital in the bondings involved. Electron energy‐loss spectroscopy is used to understand the different shallow‐level transitions in Ta and the silicide. The electron impact autoionization spectra for TaSi2 and oxygen‐exposed TaSi2 are also presented and analysed, along with the Ta NNN fingerprint to show the oxidation in Ta.
Sloping shirley‐type inelastic line shapes
Authors: Végh János 
Published: December 2004

AbstractA simple modification to the Shirley‐type inelastic line shape is proposed. The modification results in a sloping background contribution (‘tail’) and a non‐infinite inelastic tail area. Far from the photopeak the present tail shows Tougaard‐type behaviour, but in the vicinity of the photopeak it deviates significantly from the Tougaard‐type tail. Using the ‘universal’ constants derived in the frame of the Tougaard model, universal ‘tail height’ and ‘tail slope’ parameters are derived.
Photoemission study of an AuPdAu(111) multilayer grown by MBE
Authors: Cole R. J. , Evans J. A. , Gregory D. A. C. , Unsworth P. , Weightman P. , Greig D. , Walker M. J. , Beamson G. 
Published: December 2004

AbstractAn au/Pd/Au(111) multilayer system grown by molecular beam epitaxy has been studied by high‐resolution x‐ray photoelectron spectroscopy. An analysis of the dependence of the relative intensity of the Au and Pd core‐level XPS lines on the take‐off angle indicates that the thickness of the Pd sandwhich layer is ∼5 monolayers. The photoelectron spectra show the presence of more than one chemical environment for each element and suggest that the core‐level photoelectron spectra of Pd atoms in the interfacial layers and the inner layers of the Pd sandwich are split by ∼0.6 eV. The photoelectron spectra of the valence band show that the Pd sandwich retains the high density of states at the Fermi energy that is characteristic of Pd metal.
Preliminary results from the development of a transmission x‐ray photoelectron spectrometer
Authors: Jenkins S. N. , Castle J. E. 
Published: December 2004

AbstractThere is an increasing demand to obtain XPS analyses from smaller sample areas. The development of a transmission x‐ray photoelectron spectrometer eventually will allow spectrum acquisition and imaging with a lateral resolution of 1 μm2. The principle is based on back‐foil excitation, originally described by Cazaux, where thin samples are placed on an aluminium anode. Electron irradiation of the anode produces a local source of x‐rays and thus a local source of photoelectrons from the opposite side of the sample.In this work a VG MA500 spectrometer was modified to give the 180° geometry for transmission x‐ray photoelectron spectroscopy. A hemispherical analyser with a high magnification lens replaced the cylindical mirror analyser of Cazaux's original work. The high magnification ensured a large solid angle of photoelectron collection and the hemispherical analyser gave the, previously unobtainable, energy resolution necessary to obtain chemical state information. Following Cazaux the aluminium anodes, either foils or evaporated directly onto the bulk side of the sample, were scanned by an electron beam. The maximum photoelectron lateral resolution obtainable is determined by the x‐ray excitation volume. This is reliant on the electron beam diameter, the accelerating voltage and the sample and anode thickness.We believe the local production of x‐rays by a scanning electron beam to be the ideal way of examining the microtomed sections through interfaces and soft composite materials. Hard materials require the use of ion beam thinning. Samples must be of submicrometre thickness (300 nm to 1 μm ideally).
XPS study of laser‐annealed ion‐implanted GaAs
Authors: Krastev V. , Marinova Ts. , Karpuzov D. , Kalitzova M. , Vitali G. , Rossi M. 
Published: December 2004

AbstractData on the effects of 140 keV Zn+ implanation of (100)GaAs and the consequent low‐power pulsed laser annealing (LPPLA) on the composition of the surface layers are presented. The implantation does was 1014 cm −2 and the sample temperature was kept at 110 ± 10°C. THE LPPLA was carried out by 10–30 pulses of a Q‐switched ruby laser (λ = 694.3 nm, τ = 25 ns and P0 = 4–6 MW cm−2) equipped with a spatial homogenizer. The crystal surface was studied by XPS analysis combined with depth profiling with the use of 1 keV Ar+.The results presented include the depth redistribution of oxygen and the As/Ga ratio as well as the oxide thickness for (a) virgin, (b) as‐implanted and (c) implanted and then annealed samples.
Chemical bonding studies on UV/ozone‐ and (NH4)2S‐treated InP(001) surfaces by x‐ray photoelectron spectroscopy and x‐ray induced Auger electron spectroscopy
Authors: Streubel P. , Peisert H. , Hesse R. , Chassé T. , Szargan R. 
Published: December 2004

AbstractX‐ray photoelectron spectroscopy (XPS) and x‐ray‐induced Auger electron spectroscopy (XAES) have been applied to characterize the surface chemistry of InP(001) after ex situ treatment with ozone or with (NH4)2S solution. Both high‐resolution chemical shifts and the Auger parameter concept were used for the identification of chemical species.After UV/ozone exposure, indium oxide and two phosphate types (orthophosphate and metaphosphate) were found on the InP surface. Upon annealing the phosphates desorb first, followed by the oxide. On (NH4)2S‐treated InP surfaces three sulphur species were observed and identified as two different sulphides and as a polysulphide (SS bond). The thermally most stable sulphur species was attributed to a sulphide with sulphur on a phosphorus site in the uppermost subsurface layer. Changes of surface Fermi energy position accompanying the surface sulphurization were established to correlate with the annealing behaviour of the polysulphidic species found at the InP surface.
Information on compositional depth profiles conveyed by angle‐resolved XPS
Authors: Seelmann‐Eggebert M. , Keller Robert C. 
Published: December 2004

AbstractThe technique of retrieving depth profiles from angle‐resolved x‐ray photoelectron spectroscopy (ARXPS) data is analysed with respect to its depth resolution and its potential to differentiate compositional zones. The usable range of polar angles is shown to have an non‐obvious limitation at grazing electron escape owing to the peculiar way the ARXPS signal depends on the probing depth. This limitation along with the experimental error in the measurement introduces ambiguities in two respects. First, these experimental limitations lead to a considerable depth (broadening) uncertainty which confines the number of resolvable depth zones to about 10. Second, the space of functions (over the accessable range of probing depths), which includes all possible ARXPS signals, is of very low dimension. Within an assumed experimental error of 1%, the class of all possible ARXPS signal functions is shown to be contained in a subspace spanned by just five basis functions. Therefore, the information obtainable for each single ARXPS signal is confined to a maximum of five parameters. Almost all ARXPS signals of a single component (except for a few very special cases) can be interpreted in terms of a depth profile consisting of just three zones with constant composition and with two optimized interface positions. However, the number of resolvable compositional zones increases with the number of XPS components. A lower limit for this number can be assessed by a factor analysis that also yields unambiguous information on the composition of the zones. Elastic scattering effects and local variations of the electron escape length are expected to have little influence on these results, because they simply lead to a rescaling of the depth and the concentration scale of the retrieved profile.
Electrochemical behavior and surface chemistry of non‐equilibrium aluminum–tantalum alloys: Solute‐rich interphase mechanisms
Authors: Davis G. D. , Shaw B. A. , Rees B. J. , Pecile C. A. 
Published: December 2004

AbstractThe electrochemical behavior and surface chemistry of sputter‐deposited non‐equilibrium stainless Al–Ta alloys have been investigated. These alloys exhibit enhanced passivity over a pH range of 2–12 even though the passive film chemistry varies considerably over this range. This enhanced passivity can be explained by the solute‐rich interphase mechanism (SRIM), which states that formation and passivation of occluded cells are controlled by localized concentrations of solute. The higher concentrations of solute at the metaloxide interface and around occluded cells stabilize the passive‐film from continued Cl− attack and dissolution.
Melt rheology of vinyl chloride‐vinyl acetate copolymers
Authors: Hollister Edward H. 
Published: December 2004

AbstractMelt flow behavior of vinylchloride‐vinyl acetate copolymers is measured and expressed as melt viscosity, shear rate and shear stress—information useful to the plastics engineer in formulation, design, and processing. Copolymer of comparable I.V. to homopolymer PVC requires less energy to process. Good compounding techniques are required to realize the potential of ultra‐clear profile extrudates.
Rheology of flexible PVC compounds. Part II: Verification of the crystallinity concept
Authors: Hookanson S. H. , Smith D. L. , Irvine J. L. 
Published: December 2004

AbstractIt has been proposed that changes in elasticity associated with the processing of PVC are influenced by the crystallinity of the resin. In the early stages of processing, crystallites melt and elasticity decreases. As grains fuse together, new crystallites are formed in the previously unoccupied grain boundaries and the elasticity increases. A theoretical curve combining the percent of crystallinity with the developing boundary volume has been developed. This curve can be used to predict how elasticity changes with time. Experimental observations detailing the changes in elasticity with respect to processing verify these predictions.
Spectroscopic studies of ligand exchange reactions in alkyl‐ and estertin PVC stabilizers
Authors: Burley J. W. , Dworkin R. D. 
Published: December 2004

AbstractIt has long been appreciated that mercaptoester/Cl exchange equilibria in mono‐ and dialkyltin mercaptoester/chlorides are important in understanding the stabilization of PVC by alkyltin mercaptoesters (1–3). More recently, IR studies have demonstrated the existence of similar equilibria in mixed mono‐/dialkyltin systems; it has been suggested that these exchange reactions may be the source of synergism in the mixed mono‐/dialkytin mercaptoester stabilizers (4). The ability to study these systems by IR and NMR methods is based upon the phenmenon of carbonyl to Sn coordination in these compounds and its sensitivity to molecular environment, principally the electronegativity of the tin atom. Our previous studies have now been extended to include estertin (β‐carboalkoxyethyltin) mercaptoesters and mercaptoester/chlorides. In contrast to the simple alkyltin systems, the position of the respective mercaptoester/Cl exchange equilibria are dominated by carbonyl to Sn coordination from the ester group of the β‐carboalkoxyethyl moiety. Based on the same phenomenon of carbonyl to tin coordination, the nature of alkyl‐ and estertin mercaptoesters containing alkyltin sulfides has been looked at to a very limited extent.
An evaluation of the effects of antimony and tin stabilizer on the fusion characteristics of PVC dryblends
Authors: Clark Dane L. , Hollo Brenda J. , Tornstrom Paul K. , Turnbull Robert E. , Woodley Tom R. 
Published: December 2004

AbstractAlthough the classification of lubricants can be misleading, the classification of their actions is not only possible but very useful. By considering the basic actions which affect PVC dryblend fusion, a better understading of the characteristics and advantages of additives can be realized. The antimony and tin stabilizers used in this study have been characterized by the affects on PVC dryblend fusion. Production extrusion results confirm the laboratory classifications.
The effect of grain shape on the properties of PVC resins and compounds
Authors: Schwaegerle Paul R. 
Published: December 2004

AbstractThe properties of PVC resin grains have been shown to influence the bulk density and flow properties of PVC resins and powder compounds. Bulk densities of PVC resins and powder compounds are highly dependent on grain shape. Lower bulk density has been related to more irregular grain shape. Flow properties of PVC resins and powder compounds improve with increased grain size. Twin screw extrusion rates are directly proportional to the compound bulk density in the feed throat.