bluuebunny/crossref_metadata_2025 huggingface dataset:
Deuterium Isotope Effects during HMX Combustion: Chemical kinetic burn rate control mechanism verified
Authors: Shackelford S. A. , Goshgarian B. B. , Chapman R. D. , Askins R. E. , Flanigan D. A. , Rogers R. N.
Published: December 2004

The appearance of a significant deuterium isotope effect during the combustion of the solid HMX compound verifies that the chemical reaction kinetics is a major contributor in determining the experimentally observed or global burn rate. Burn rate comparison of HMX and its deuterium labeled HMX‐d8 analogue reveals a primary kinetic deuterium isotope effect (1° KDIE) at 500 psig (3.55 MPa) and l000 psig (6.99 MPa) pressures and selectively identifies covalent carbon‐hydrogen bond rupture as the mechanistic step which ultimately controls the HMX bum rate under the static combustion conditions of this experiment. The 1° KDIE value further suggests the rate‐limiting CH bond rupture occurs during the solid state HMX decomposition/deflagration portion of the overall combustion event and is supported by other independently published studies. A possible anomalous KDIE result at 1500 psig (10.4 MPa) is addressed. This condensed phase KDIE approach illustrates a direct link between lower temperature/pressure thermal decomposition and deflagration processes and their potential applicability to the combustion regime. Most importantly, a new general method is demonstrated for mechanistic combustion investigations which selectively permits an in‐situ identification of the compound's burn rate‐controlling step.
Synthesis of Polynitrocompounds from Nitroguanidine
Authors: Yongzhong Yu , Zhuang Su , Baoru Duan , Fubo Chen
Published: December 2004

The reactions of nitroguanidine (NG) with urotropine or formaldehyde have been studied. The following compounds are synthesized from NG:

6‐nitroimino‐1,3,5‐trinitro‐1,3,5‐triazacyclohexane [2] and a number of itsderivatives;

bis(nitroguanidino)methane [9], a valuable intermediate for preparing some high explosives;

1,5‐dinitro‐2,4‐dinitroimino‐1,3,5triazacyclohexane [10] and some of its derivatives via intramolecular cyclization of [9];

2‐nitroimino‐1,3‐diaza‐5‐oxacyclohexane [15], 1‐(nitroguanidinomethyl)‐2‐nitroimino‐1,3‐diaza‐5‐oxacyclohexyl [14], and bis(2‐nitroimino‐1,3‐diaza‐5‐oxacyclohexyl)methane [16] by reactions of [9] with formaldehyde.

Some detonation data of the above compounds are reported. Campounds [2] and [10] are powerful explosives but very unstable thermally and easily hydrolized. However, compounds [14], [15], and [16] possess a better stability than triazacyclic polynitrocompounds containing nitroimino groups, such as [2] and [10].
Condensed phase reaction of boron with potassium nitrate
Authors: Yano Yutaka
Published: December 2004

The reaction process of boron (B) and potassium nitrate (PN) was examined with a thermochemical analysis. The process consists of a three‐stage gasification reaction. A significant heat is produced in the first‐stage process which is caused by the reaction B + KNO3 → KBO2 + NO. In the second‐stage process, the remaining unreacted PN decomposes to produce gaseous oxidizing fragments. The KBO2 produced in the first‐stage process decomposes in the third‐stage process. Thc heat produced in the first‐stage process is correlated with the mass fraction of B mixed within the B/PN mixture.
Rheology of Emulsion Explosives: a Practical Method
Authors: Cartwright R. V.
Published: December 2004

The Laray viscometer has been found to be useful for rheological characterization of the type of invert emulsion currently being utilized in commercial explosives. Shear rate can be varied over a range which encompasses typical emulsion processing conditions. The viscometer is also relatively inexpensive and simple to operate. Emulsion rheology is distinctly non‐Kewtonian. Dependence of shear stress on shear rate is in accord with the power law, with shear rate exponents (n) varying from 0.3 to 0.6. Both n and the pre‐exponential factor τref depend on emulsion composition and processing history in a manner consistent with known emulsion rheology.
Calculation of Detonation Velocities from Hugoniot Data
Authors: Walker Franklin E.
Published: December 2004

A very different method for calculating detonation velocities of chemical explosives is presented which is based on the shock velocities of the constituent elements. This method is indicative of a fundamentally different concept of the detonation process, which involves atomic vibrational velocities and reaction dynamics.
Study of the explosive behavior of highly confined cast PBXs submitted to bullet impact
Authors: Kent R. , Pinchot J. L.
Published: December 2004

Since many years, SNPE is trying to get a better understanding of the mechanisms which govern the bullet impact reactivity of highly confined eastable plastic bonded high explosives. In a first part, the different research thrust lines and the principal results are presented. In a second part are presented some results of bullet impact tests performed with instrumented small scale warheads which can be open after test without hazard. These small scale warheads are filled with disks of explosive and inert material. The presence of this inert material, which has the same mechanical properties that the explosive, allows to reduce the level of reaction and then, it is possible to:

measure the stresses induced by the impact,

localize the ignition points,

assess the amount of damage,

determine the amount of explosive having recated.
Combustion of Black Powder. Part III: Hot stage microscopy studies
Authors: Hussain G. , Rees G. J.
Published: December 2004

A hot‐stage unit, operating over the temperature range from ambient to 1000°C has been used to study the combustion of black powder. Direct observation of heating of mixtures was supplemented by 35‐mm photomicrography. Results are presented for black powder supplied and mixture prepared in the laboratory.
Modeling Hydrodynamic Behaviors in Detonation
Authors: Tang P. K.
Published: December 2004

A multistage reaction model developed for general use from initiation through detonation of heterogeneous high explosives is used to specifically simulate the interface vclocimetry and plate push experiments of a triamino‐trinitrobenzene‐based explosive in detonation. A simplification of the unified model leads to a rate relation that ineludes only two dominant stages: a fast one that represents the major portion of reaction dictated by propagation and decomposition, and a slow one that reflects probably the formation of large carbon molecules. The apparent more energetic behavior of the equation of state near the detonation front is actually due to the slow reaction process.
Analysis of a shaped charge jet with the double‐orthogonal‐synchro‐streak technique
Authors: Held Manfred
Published: December 2004

Recording the trajectory of a fully‐particulated shaped charge jet at two different positions along its flight path, in two mutually orthogonal planes at each recording station, allows the decomposition of the overall transverse velocities of the particles into two components. This can be done by analysing the differences in the deviations observed at the two stations. The overall transverse velocities are composed of the vector sums of those lateral‐ or off‐axis velocities which are intrinsic to the collapse process, and additional increments that are superimposed later as a result of particulation itself. In this paper the “IEPG Shaped Charge” has been used as an example to demonstrate the Double‐OSST measurement technique.

In these experiments, the overall transverse velocities derived are clearly larger than those seen between the collapse line and the first observation station. On the “Z” diagram (dispersion to the charge axis), the measurements made on this shaped charge do not exhibit random radial dispersion in all direction, but rather the particles spread out into a fan which expands more or less within one quadrant.
Electrolytic coloration of lithium‐doped strontium fluoride crystals
Authors: Song Cuiying , Gu Hongen , Han Li , Wu Yanru
Published: December 2004

Lithium‐doped strontium fluoride crystals were successfully colored electrolytically, and a lot of F, M (F2), M+ (F2+) and unidentified color centers were effectively produced in the colored crystals, which should mainly benefit from the appropriate impurity doped in the crystals, coloration temperature and electric field strength.
Growth of In2O3 thin films on silicon by the metalorganic chemical vapor deposition method
Authors: Kim Nam Ho , Myung Ju Hyun , Kim Hyoun Woo , Lee Chongmu
Published: December 2004

We have deposited indium oxide (In2O3) films on silicon substrates by the metal organic chemical vapor deposition (MOCVD). We have investigated the effect of substrate temperature on growth and structural properties of films in the range of 200–300 °C. The films had a preferred orientation along [111] direction, with the X‐ray diffraction (XRD) full width at half‐maximum (FWHM) of less than 0.4°.
The fluorination of the surface of elemental carbon. II—Deposition and stability of florine‐containing species: X‐ray photoelectron spectroscopic studies of flourinated graphite
Authors: Cadman P. , Scott J. D. , Thomas J. M.
Published: December 2004

X‐ray photoelectron spectroscopy (XPS) has been used to investigate the interaction of fluorine‐containing intermediates with the basal plane of freshly cleaved graphite. A polymeric film of polytetrafluoroethylene (PTFE) on the carbon surface was formed on the basal plane by the interaction of microwave discharged hexafluoroethane and tetrafluoroethylene at 0.1 Torr pressure. Photolysis of tetrafluoroethylene near the graphite deposited submonolayer quantities of PTFE on the basal surface. Similar photolysis of hexafluoroacetone produced a reaction of trifluoromethyl radicals with carbon atoms in the graphite surface.
Quantitative secondary ion mass spectrometry: A review
Authors: Werner H. W.
Published: December 2004

Quantitative analysis in general aims at determining the value of a selected physical or chemical property of a given sample. With SIMS, in particular, the parameters to be determined are the concentration of a given element and also its distribution, both in depth and along the surface. Every measurement is affected by a given overall uncertainty due to statistical fluctuations in the measured signal and to systematic errors related to the experimental conditions. A discussion is devoted to the experimental conditions which influence the reproducibility of the measured signal and give rise to systematic errors, e.g. charging effects, matrix effects, selective sputtering and mass‐dependent transmission, etc. The various methods used to derive the desired elemental concentration and its distribution in the sample from the raw measured data are evaluated, namely the use of calibration curves, relative sensitivity factors, fitting parameter methods and first‐principle methods. Finally, the question is considered of how representative is the value determined from the (usually small) volume with respect to the composition of the bulk of the sample (sampling error).
Low energy nitrogen implantation profiles in cobalt using AES
Authors: Malherbe J. B. , Hofmann S.
Published: December 2004

Using AES in combination with argon depth profiling, low energy (0.5–5 keV) nitrogen implantation profiles were determined. The profiles show reasonable agreement to the Schulz‐Wittmaack model of ion collection during sputtering when the effect of the finite escape depth of the Auger electrons is taken into account. The projected ranges of nitrogen in cobalt obtained when using this model shows reasonable correspondence with the LSS‐calculated ones.
Chemical and structural characterization of epitaxial compound semiconductor layers using X‐ray photoelectron diffraction
Authors: Evans Stephen , Scott Michael D.
Published: December 2004

The application of angle‐resolved X‐ray photoelectron spectroscopy (X‐ray photoelectron diffraction) to characterize thin layers of compound semiconductors grown on single crystal substrates is described. In studies of ZnSe grown on (100) GaAs, confirmation of the epitaxial character of the growth, together with a quantitative estimate (±5%) of the stoichiometry of the ZnSe layer, were achieved by means of a single experiment. The techniques described are equally applicable to very thin layers (<10nm) which cannot easily be characterized by established methods.
The inelastic mean free paths of auger electrons in thin films of copper and nickel
Authors: Burke M. A. , Schreurs J. J.
Published: December 2004

The inelastic mean free paths of 600–1000 eV Auger electrons have been determined in Cu and Ni films. Thin films of known thickness were produced by the vapor deposition of Cu on Ni substrates and vice versa. The strengths of the characteristic Auger signals of Cu and Ni were monitored as a function of film thickness. Values of the mean free paths are presented and compared to values previously published by other workers. By monitoring the strengths of the Auger signals from the condensate, it is concluded that backscattering factors for a Ni substrate carrying a Cu film are higher than the backscattering factors for a Cu substrate carrying a Ni film.
Analysis of polymer surfaces by SIMS. 2—fingerprint spectra from simple polymer films
Authors: Briggs D.
Published: December 2004

Seven polymers (low density polyethylene, polypropylene, polystyrene, polymethylmethacrylate, poly(methacrylic acid), Nylon‐6 and poly(ethyleneterephthalate)) have been studied by SIMS. Very good signal: noise spectra up to mass 250 have been obtained using low damage conditions (i.e. ion current densities ∽1 nA cm−2) and electron beam charge neutralization. The spectra are highly characteristic and fairly easily interpreted using fragmentation data from electron impact mass spectrometry.
Determination of metallic impurities in a‐Si:H by SIMS
Authors: Scilla G. J. , Ceasar G. P.
Published: December 2004

Secondary ion mass spectrometry (SIMS) has been employed to characterize the metallic impurities introduced into ion beam deposited a‐Si: H. For quantitative results, this type of characterization normally requires a specific standard for each element of interest. Ion implantation has been the method of choice for providing these types of standards in Si. The problem with this approach is the time and cost required in obtaining implants for each element to be analyzed. In this study, we describe the application of the local thermal equilibrium (LTE) model of SIMS quantitation to the analysis of metallic impurities in an a‐Si: H matrix. This method circumvents the need for specific standards for each element. Our results indicate that useful quantitative data can be obtained using the LTE method calibrated with one boron implant into c‐Si wafer.
The interaction of imidazole, benzimidazole and related azoles with a copper surface
Authors: Tompkins H. G. , Sharma S. P.
Published: December 2004

Azoles such as benzotriazole and benzimidazole are used as corrosion inhibitors, particularly for copper. The purpose of this work is to further illuminate the bonding and film growth for benzimidazole‐like structures. The interaction of imidazole, benzimidazole, 2‐methylbenz‐imidazole and benzotriazole with copper surfaces is studied with a quartz crystal oscillator microbalance and with X‐ray photoelectron spectroscopy. The copper surface is etched by imidazole in water and in CH3OH and by benzimidazole in CH3OH. A very thin film, probably a monolayer or less, is left behind after etching. Thicker films, 500 to 1000 AÅ, are formed by benzimidazole in water and by 2‐methylbenzimidazole in both water and CH3OH. Mechanisms of bonding and film formation for the thin and the thick films are discussed.
Ion sputtering in the surface analysis of practical surfaces
Authors: Keenlyside M. , Stott F. H. , Wood G. C.
Published: December 2004

The routine analysis of many practical, engineering specimens utilizing sputter‐etch, in‐depth profiling, coupled with a surface‐analysis technique, is severely restricted by the roughness of the surface under study. Limitations imposed by the irregularities in such surfaces have been examined and a method of relating the subsequent degradation of the in‐depth profile to the specimen roughness is described. This method has been used to assess the value of in‐depth profiling for surfaces produced in practical situations. In addition, the importance of specimen‐incident sputtering‐beam geometry in optimizing the uniformity of etching over a rough specimen surface, using a number of different arrangements, is evaluated.
Barrier‐Type anodic films on aluminium in aqueous borate solutions: 1—Film density and stopping power of anodic alumina films for alpha particles
Authors: Skeldon P. , Shimizu K. , Thompson G. E. , Wood G. C.
Published: December 2004

Stopping powers of an anodic film, formed on aluminium in aqueous ammonium pentaborate solution, have been measured experimentally for α particles, over the energy range 0.7–2.3 MeV. Comparison between the measured stopping powers and theoretically calculated values shows that Bragg's Rule may be applied, with reasonable accuracy (∼5%), to predict the stopping powers of anodic alumina. The density of the barrier‐type film was determined by Rutherford backscattering spectroscopy to be 3.10±0.15 × 103 kg m−3.
Study of emission and sputtering yields in some alloys and oxide by glow discharge optical spectrometry: Quantification of analysis
Authors: Pons‐Corbeau J.
Published: December 2004

In an analysis by glow discharge optical spectrometry (GDOS) the relation between the intensity of spectral emission of an element and its concentration at the surface of the sample is fundamental for interpreting the results. The different factors which occur in this relation are systematically investigated for different materials such as metallic alloys, oxidized matrices or matrices submitted to ionic implantation. The measurements show that the emission yield of an element is independent of the matrix although particular phenomena can affect the apparent experimental values. The simplification which results in the interpretation of experiments in GDOS is evident and a few examples of applications are presented.
Edge effects and image contrast in scanning Auger microscopy: A theory/experiment comparison
Authors: El Gomati M. M. , Prutton M. , Lamb B. , Tuppen C. G.
Published: December 2004

The contribution of surface roughness to the artefacts present in images and line‐scans from Scanning Auger Microscopes have been explored by Monte Carlo modelling and by experiment. The samples chosen for these studies are metal lines with sharp rectangular cross‐sections deposited upon silicon substrates. The Monte Carlo simulation reveals shadowing effects due to the analyser/sample geometry and the obstruction due to the height of the overlayer line; forward scattering effects through the sidewall of the overlayer which lead to edge enhancements in the overlayer and substrate Auger signals; back‐scattering effects which show up as an apparent broadening of the overlayer lines and substrate signal peaks appearing in the otherwise forbidden shadowed region. All of these effects are visible in the experimental results obtained for Si substrates with Al and with Au lines upon them. The experimental edge enhancement artefact is compared with the results of the simulation and good agreement is obtained. The difficulties which arise in the separation of topographical and chemical contrast are discussed and some suggestions for removal or reduction of the magnitude of these effects are outlined.
Elastic electron backscattering for quantitative elemental analysis of laser diode structures
Authors: Szostak D. J. , Thomas J. H.
Published: December 2004

A backscattered electron technique has been used to improve the spacial resolution and elemental sensitivity beyond that obtained from standard Auger microprobe electron spectroscopy. The elastically backscattered electron peak amplitude has been measured on a five‐layer laser structure of GaAs/AlGaAs with a CMA detector operating in the beam brightness modulation mode (BBM). Variations in elastic peak amplitude across these layers have been calibrated by standards to determine variations in aluminium concentration with 6% accuracy in areas as small as 0.25 μm diameter at atomic sensitivity of better than 1%. These results represent a significant improvement over the spatial resolution and elemental sensitivity available from standard Auger analysis in which backscattering contributions make the total analyzed area larger than the primary beam size.
The correlation of chemical structure and electrical conductivity in polypyrrole films by x‐ray photoelectron spectroscopy
Authors: Zeller M. V. , Hahn S. J.
Published: December 2004

X‐ray photoelectron spectroscopy was used to track chemical structure changes in conducting polypyrrole films which were electrochemically grown at various current densities. The film structures were correlated to changes in the film electrical conductivities. High resolution spectra of the C 1s, N 1s and O 1s regions were recorded. Concentrations of the charge compensating counter‐ions used in the growth of the film were also monitored and correlated to electrical performance. Results indicated that the films grown at low current densities contained hydroxide anions and deprotonated nitrogen species, while films grown at high current densities contained no hydroxide ions or deprotonated nitrogens and exhibited higher charge removal from the pyrrole ring. At medium current densities, the amount of incorporated dopant anion was maximized.
Surface analysis of Ti6Al4V adhesive bonding systems
Authors: Clearfield H. M. , Cote G. O. , Olver K. A. , Shaffer D. K. , Ahearn J. S.
Published: December 2004

Titanium surfaces that have been prepared for adhesive bonding are difficult to characterize because they exhibit micro‐rough and, in some cases, macro‐rough morphologies, Errors can arise in the interpretation of sputter depth profiles obtained from such surfaces dur to the analysis geometry, i.e. large sampling probes and shadowing of the ion etching beam. This can be avoided either by scanning Auger microscopy or by x‐ray photoelectron spectroscopy to obtain estimates of the surface layer composition and thickness. We illustrate the utility of both techniques by studying the mechanisms of failure in adhesive bonds formed at Ti6Al4V surfaces before and after exposure to air at 330°C for 165 hours.
Auger electron spectroscopy and x‐ray photoelectron spectroscopy of the biocorrosion of copper by gum arabic, bacterial culture supernatant and Pseudomonas atlantica expolymer
Authors: Jolley John G. , Geesey Gill G. , Hankins Michael R. , Wright Randy B. , Wichlacz Paul L.
Published: December 2004

Thin films (3.4 nm) of copper on germanium substrates were exposed to 10% gum arabic aqueous solution, 1% bacterial culture supernatant (BCS) (aqueous and simulated sea water solutions) and 0.5% Pseudomonas atlantica exopolymer (aqueous and simulated sea water solutions). Pre‐ and post‐exposure characterization were done by Auger electron spectroscopy and x‐ray photoelectron spectroscopy. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrate. Results indicate that the copper was oxidized by the gum arabic and BCS, and some was removed from the Cu/Ge interface by all three polymers and incorporated into the polymer matrix. Thus, biocorrosion of copper was exhibited by the gum arabic, BCS and Pseudomonas atlantica exopolymer.
Secondary electron emission characteristics of oxidized beryllium cathodes
Authors: Ritz Victor H. , Thomas Richard E. , Gibson John W. , Klebanoff Joseph
Published: December 2004

Oxidized beryllium surfaces are used in a number of microwave crossed‐field amplifier (CFA) tubes as secondary electron emission cold cathodes. During operation the cathode surface is subjected to electron and ion bombardment in a complex process which produces both erosion and replenishment of the oxide surface, in addition to a significant build‐up of amorphous carbon. The result is a general degradation of tube performance. Special techniques were developed to opoen an evacuated tub and transfer the cathode to a UHV surface analysis system with minimal contamination from the atmosphere. Three CFA tubes with various histories of operation were examined and measurements from made of the secondary electron emission (delta), first crossover, voltage at delta maximum, and the surface chemical composition by AES at several points on each cathode. Significant differences were found which reflected their number of hour of operation, as well as variations in manufacturing procedures. A generalized linear cofrrelation between secondary electron emission and the surface carbon atomic fraction was obtained when the data for all the tubes was combined and analyzed. The deleterious effects of carbon in operated CFA tubes were confirmed and suggest that reduction of potential sources of carbon contamination in the tube during manufacture, processing, and operation should improve overall performance.
Characterization of surface pretreatments of carbon fiber–polyimide matrix composites
Authors: Moyer Denise J. D. , Wightman J. P.
Published: December 2004

Various surface pretreatments of carbon fiber–polyimide matrix composites have been studied by XPS, ISS, PASFTIR (photoacoustic Fourier transform infrared spectroscopy) and high‐resolution SEM. Reduction of fluorocarbons from release cloth contamination and increase in carbon–oxygen‐containing functional groups was observed on the surface of composite samples treated in an oxygen plasma. These plasma‐treated samples also showed differences in surface topography, but no change in the photoacoustic infrared spectra when compared to a methanol‐washed sample.
The deconvolution of sputter‐etching surface concentration measurements to determine impurity depth profiles
Authors: Carter G. , Katardjiev I. V. , Nobes M. J.
Published: December 2004

The quasi‐linear partial differential continuity equations that describe the evolution of the depth profiles and surface concentrations of marker atoms in kinematically equivalent systems undergoing sputtering, ion collection and atomic mixing are solved using the method of characteristics. It is shown how atomic mixing probabilities can be deduced from measurements of ion collection depth profiles with increasing ion fluence, and how this information can be used to predict surface concentration evolution. Even with this information, however, it is shown that it is not possible to deconvolute directly the surface concentration measurements to provide initial depth profiles, except when only ion collection and sputtering from the surface layer alone occur. It is demonstrated further that optimal recovery of initial concentration depth profiles could be ensured if the concentration‐measuring analytical probe preferentially sampled depths near and at the maximum depth of bombardment‐induced perturbations.
Quantification of SIMS on titanium carbides
Authors: Brault G. , Moncoffre N. , Pivin J. C. , Rautureau G.
Published: December 2004

Ion implantation and Rutherford backscattering are combined to study:

the effects of caesium doping and caesium bombardment on SIMS emission yields,

the carbon emission yield as a function of its concentration in Ti1−xCx films. Quantitative analysis by SIMS of such films can be performed with an accuracy of 5%.
Measurements of the magnitude of crystalline effects in Auger electron spectroscopy
Authors: Bishop H. E.
Published: December 2004

Diffraction of both the primary electron beam and the excited Auger electrons are known to have an influence on the measured peak intensities in Auger electron spectroscopy (AES). In this work, crystalline effects have been measured for a number of single‐crystal materials under conditions commonly used for AES, in an ESCALAB Mk II (VG Scientific, Ltd) fitted with a goniometer stage. Large variations in Auger peak intensity with crystal orientation were observed, reflecting both the symmetry and structure of the surface. It is shown that under normal operating conditions the diffraction of the primary electron beam is mainly responsible for the observed intensity variations but that diffraction of the Auger electrons cannot be neglected entirely. The significance of crystalline effects to quantitative AES is discussed.
Energetics of nickel and palladium
Authors: Finley C. W. , Ferrante J.
Published: December 2004

We present several model calculations involving nickel and palladium using the embedded atom method. Adhesion in the crystalline form of these substances is studied by calculating surface energy as a function of separation of a solid along a crystalline plane, and slip barrier height as a function of displacement. We also investigate a bulk property, Poisson's ratio, as a function of tensile strain. In addition, we examine the equilibrium configuration of metal clusters by finding the minimum energy configuration of clusters consisting of a small number (N = 2–6) of nickel atoms.
An Auger sputter profiling study of nitrogen and oxygen ion implantations in two titanium alloys
Authors: Barton B. D. , Pope L. E. , Wittberg T. N.
Published: December 2004

Samples of two titanium alloys, Ti–6Al–4V and Ti–15V–3Cr–3Sn–3Al, were ion implanted with a combination of nitrogen (N+) and oxygen (O+). For each alloy, implantation parameters were chosen to give implanted nitrogen concentrations of ∼10 or 50 at.%, from a depth of 100 nm to a depth of 400 nm. In all but one case, dual energy (200 keV and 90 keV) implantations of nitrogen were used to give a relatively uniform nitrogen concentration to a depth of 300 nm. In each case, oxygen was implanted at 35 keV, following the nitrogen implantation, to give an oxygen‐enriched region near the surface. The implanted samples were then examined by Auger electron spectroscopy (AES) combined with argon ion sputtering. In order to determine the stoichiometry of the nitrogen‐implanted regions, it was necessary to determine the N KVV contribution to the overlapping N KVV and Ti LMM Auger transitions. It was also necessary to correct for the ion‐bombardment‐induced compositional changes that have been described in an earlier study of titanium nitride thin films. The corrected AES depth profiles were in good agreement with theoretical predictions.
Aluminum surface mobility on two types of silicon oxide during ionized cluster beam deposition
Authors: Levenson L. L. , Swartzlander A. B. , Usui H. , Yamada I.
Published: December 2004

An ionized cluster beam (ICB) source was used to deposit A1 onto two types of silicon oxides. One was a thermal oxide generated by steam oxidation of Si at 900°C. The other was a P‐doped oxide deposited on Si at 425°C. During Al deposition, 60 μm diameter wires were held at the substrates to serve as masks. After A1 deposition, the wires were removed and the masked areas were examined by scanning electron microscopy (SEM) and by scanning Auger microprobe (SAM). The ICB source was operated at 0, 3 and 6 kV accleration voltages. The substrates were held at 80, 200 and 400°C during A1 depositions. The A1 deposition rate averaged 24 nm min.−1 The chamber pressure during deposition was 3 × 10−4 Pa. The diffusion distance of A1l under a mask edge was determined from the SEM micrographs and SAM line scans. The maximum diffusion distance occurred at 200°C for both substrates, with the exception of the 0 kV A1 beam deposited on the low‐temperature oxide (LTO). On the high‐temperature oxide (HTO), the maximum diffusion distance was 29 μm at 6 kV acceleration voltage. The minimum diffusion distance was 8 μm at 70–80°C on the LTO for acceleration voltages of 0 and 3 kV.
XPS study of the Y/SiOx interface at room temperature
Authors: Reichl R. , Gaukler K. H.
Published: December 2004

The reducing reaction of vapour‐deposited yttrium layers on silicon oxide was measured by XPS at room temperature. The redox reaction was confined essentially to the deposition period. The thickness of the insulating SiOx layer decreases by ∼0.2–0.3 nm. No further reaction during the 8 h following deposition could be observed.
In situ X‐ray photoelectron spectroscopy of surfaces at pressures up to 1 mbar
Authors: Ruppender H. J. , Grunze M. , Kong C. W. , Wilmers M.
Published: December 2004

In this article we describe an x‐ray photoelectron spectrometer that can either be used as an ultra‐high vacuum instrument (p < 10−10 mbar) or, after insertion of a movable aperture, to analyse materials at ambient pressures up to 1 mbar. We will describe the basic design of the instrument, and the methods used to determine the pressure at the location of photoelectron ejection. One way to estimate the pressure is by attenuation of the substrate signal by the gas phase and comparing experimental with published ionization cross‐sections; the second method uses condensation isobars. Examples are given for gas‐phase spectra. Application of the instrument in surface science studies is demonstrated by two examples where surfaces were analysed under high‐pressure conditions as a function of temperature, showing that the instrument allows steady‐state equilibrium measurements of surface composition.
Method for the alignment of samples and the attainment of ultra‐high‐resolution depth profiles in Auger electron spectroscopy
Authors: Hunt C. P. , Seah M. P.
Published: December 2004

The need to align the electron beam, the electron spectrometer axis and the ion beam all at the same point on the sample surface in sputter‐depth profiling using Auger electron spectroscopy is crucial to the attainment of efficient high‐resolution profiles. In this study we develop a method that allows these axes to be set to ±25 μm in concentric hemispherical analyser systems. Then, using the coincidence of the electron beam and spectrometer axes, samples may be repositioned repeatedly to ±25 μm and the point of analysis on the sample to within ±40 μm of the centre of the ion‐sputtered crater. The method is illustrated in the characterization of a second batch of tantalum pentoxide on tantalum reference material. New resolutions of 1.51 and 1.60 nm are achieved for the 31.1 and 95.8 nm thick oxides, respectively, when using the standard conditions of 2 keV argon ions and monitoring the oxygen Auger electrons. If the ion energy is reduced to 1.5 keV and the tantalum low‐energy peaks are used, the resolution for the 95.8 nm oxide may be reduced to 0.82 nm.
XPS determination of the thickness of adsorbed mouthrinse components on dental enamel
Authors: Busscher H. J. , Van der Mei H. C. , Genet M. J. , Perdok J. F. , Rouxhet P. G.
Published: December 2004

In this paper, the stationary charging voltage of human dental enamel samples due to photoelectron ejection in an x‐ray photoelectron spectrometer is related to the amount of material adsorbed from commercially available mouthrinses and the adsorbed layer thickness. A clear relationship was observed between the charging voltage versus the C/Ca elemental surface concentration ratio, taken as a measure of the amount of adsorbed material. Consequently, a similar relationship was found between charging versus adsorbed layer thickness.
Contributions of surface analysis to corrosion science: Selective dissolution and oxidation phenomena in alloy corrosion
Authors: Landolt D.
Published: December 2004

The role for corrosion kinetics of corrosion‐induced surface composition changes on alloys is discussed and illustrated with surface analytical (AES, XPS, SIMS) and electrochemical (polarization behaviour) results from the author's laboratory. In situ oxidation of FeCrMo alloys, anodic dissolution in the active state of binary noble metal alloys (AgPd) and anodic dissolution in the passive state are compared. It is shown that selective oxidation and dissolution phenomena and differences in the transport rate of cations in thin oxide films control the chemical composition of the surface region and thus greatly affect the corrosion rate.
The effect of atomic‐scale etch pit formation on depth resolution in sputter profiling
Authors: Carter G. , Nobes M. J. , Katardjiev I. V.
Published: December 2004

A very simplified model of atomic‐scale etch pitting during sputtering erosion for composition depth profiling is used to modify the Benninghoven–Hofmann approach to layer‐by‐layer sputtering. It is shown that analytically tractable defining equations result, with solutions that indicate that etch pitting slightly worsens depth resolution as the probability of producing deep etch pits increases.
The ageing of Li implants in cadmium mercury telluride
Authors: Blackmore G. W. , Courtney S. J. , Astles M. G. , Shaw N.
Published: December 2004

Secondary ion mass spectrometry (SIMS) requires the preparation and measurement of standard samples in order to be considered a quantitative technique. This normally can be achieved by the production of ion‐implanted specimens in the matrix to be studied. The measured SIMS depth profile then can be integrated and compared with the known implanted dose in order to produce quantitative results. This paper reports a potential source of error in this method, discovered by studying the ageing of a lithium‐implanted cadmium mercury telluride (CMT) specimen over a six‐year period. Lithium has been shown to be a mobile impurity in CMT.

It is shown that the original implant produced a satisfactory profile shape, but that room‐temperature diffusion subsequently degraded its shape over a period of five years. This finding is confirmed by the further action of annealing the implanted specimen at 250°C and studying the resulting profile. The change in the shape of the implant profile is discussed in relation to diffusion theory. SIMS images are shown to demonstrate the spatial inhomogeneity of the sample.
Depth analysis of nickel thin films on silicon by glow discharge spectroscopy: The interface region
Authors: Weiss Zdeněk
Published: December 2004

Depth profiles of nickel thin films on silicon obtained with a Grimm glow discharge lamp operating at various conditions were compared. The best conditions for the profile analysis are: high argon pressure, high discharge current and low discharge voltage. The signal response at the interface was described quantitatively using piecewise linear model functions. Influence of the discharge parameters on the signal response at the interface was discussed. Interface broadening was confirmed to be caused by the crater effect, with a non‐uniform removal rate distribution across the analysed spot that does not depend on the total sputtered depth in the analysis of a homogeneous sample.
XPS analysis of thin oxide films on chemically treated aluminum alloy surfaces using a high‐energy Mg/Zr anode
Authors: Allgeyer Daniel F. , Pratz Earl H.
Published: December 2004

A method for determining the aluminum oxide and aluminum metal atomic concentrations on complex aluminum alloy surfaces using a high‐energy Mg/Zr x‐ray source (1253.6 and 2042.4 eV, respectively) was discussed. XPS analysis of chemically processed aluminum surfaces using an Mg or Mg/Al anode limits the analysis of aluminum to the Al 2s and Al 2p photoelectron lines. Analysis of aluminum surfaces using the Al KLL Auger transition and the Mg or Mg/Al x‐ray source is accomplished with the bremsstrahlung radiation. The utility of the high‐energy Mg/Zr x‐ray anode is realized by offering the ability to qualitatively and quantitatively analyze aluminum using the Al KLL Auger region at 1374–1405 eV kinetic energy. The Al KLL Zr excited Auger transition provides a clear separation between the aluminum oxide and metal transitions (6.0 eV).
Identification of subnanometre surface layers on polymer films by surface‐enhanced infrared transmission spectroscopy
Authors: Nishikawa Yuji , Ito Yoshiaki , Yamakami Noriko , Fujiwara Kunihiro , Shima Tetsuo
Published: December 2004

Identification of subnanometre surface layers on polymer films, which are only analysable by x‐ray photoelectron spectroscopy (XPS) or secondary ion mass spectrometry (SIMS), have been demonstrated by the use of transmission surface‐enhanced infrared absorption (SEIRA) spectroscopy with the use of silver island films: 1.0 nm thick polydimethylsiloxane (PDMS) or 0.5 nm thick polymethylphenylsiloxane (PMPHS) surface layers, which are semisolid materials, on polyethyleneterephthalate (PET) films were successfully identifiable with the use of transmission SEIRA by measuring the PDMS or PMPHS that was transferred onto the silver‐deposited BaF2 substrates under pressure. This approach completely eliminates strong spectral interference from PET films by measuring the transferred surface layer and greatly improves the signal‐to‐noise ratio of the surface layer absorption with the use of silver island films. The detection limit of PDMS surface layers on PET films is ∼0.2 nm. The present method gives a considerable amount of information about surfaces, such as chemical composition and chemical structure. This is a highly promising method for analysiing subnanometre surface layers which consist of liquid or semisolid materials, such as oil, lubricant, plasticizer and surface‐active agent on polymer materials.
Quantitative Auger analysis of metal oxides
Authors: Zagorenko A. I. , Zaporozchenko V. I. , Ivanova O. P.
Published: December 2004

Compositional changes of the surfaces of oxides ZnO, Al2O3, Y2O3, SiO2, GeO2, NiO and Nb2O5 induced by 3 keV Ar+ were quantitatively characterized by AES and XPS. The accuracy of Auger analysis based on the first‐principle calculation was estimated for the stable oxides. The results obtained enabled the most accurate algorithm for quantitative analysis of oxides to be selected. The measuring error was reduced to <3%. It was shown also that sputter‐induced compositional changes of oxide surfaces can be analysed satisfactory by AES.
The structure of pumice: An XPS and 27Al MAS NMR study
Authors: Venezia A. M. , Floriano M. A. , Deganello G. , Rossi A.
Published: December 2004

In order to investigate the surface structure of pumice, an amorphous aluminosilicate, samples of pumice and of standards of silica and alumina have been studied by x‐ray photoelectron spectroscopy (XPS). The effect of a mild acid leaching was also considered. The analysis of the Si 2p, Al 2p and O 1s photoelectron peaks and the Si KLL and O KLL Auger peaks indicated that pumice is formed by tetrahedral silica with some units being replaced by aluminate, AlO2−. The acid treatment decreases the alkali and the aluminate ions. X‐ray photoelectron spectra of the valence band of pumices and of standards of Al2O3 and SiO2 agree with the core‐level results. To support the conclusions from the XPS study, magic angle spinning (MAS) 27Al nuclear magnetic resonance (NMR) of pumice was used. The spectrum is indicative of tetrahedrally coordinated aluminium.
The influence of the oxide/metal interface composition on the adherence of oxide layers on metal substrates
Authors: Schmutzler H. J. , Viefhaus H. , Grabke H. J.
Published: December 2004

Well adherent and corrosion‐protecting oxide layers are of great importance for high‐temperature alloys. The adherence of the oxide layers is affected by the morphology and the chemical composition of the oxide/metal interface. In this study scanning Auger microscopy (SAM) is used to investigate the oxide/alloy interface of oxidized FeCrAl alloys (undoped or doped with Ti, Ce and Y) after partly removing the oxide layer by in situ bending. The metal surface shows individual voids and rugged parts, indicating imprints of the removed oxide. For the undoped alloy poor adherence of the oxide layer is observed. Sulphur is strongly enriched at the surface of the voids. In several areas of the rough interface no sulphur was detected. On the Ti‐containing alloys the oxide layer is again poorly adherent. Sulphur is strongly enriched at the surface of the voids and at a lower but constant level at the rough area. On Y‐ and Ce‐containing alloys the oxide layer is well adherent and no sulphur enrichment is detectable beneath the scale. The poor adherence of the oxide layers on undoped and Ti‐doped FeCrAl alloys is correlated to the presence of sulphur at the alloy surface. Sulphur enrichment is explained by sulphur segregation to the free alloy surface for the undoped alloy and additional sulphide formation for Ti‐containing alloys. The positive effect of Y and Ce on the adherence of the oxide layer is explained by sulphide precipitation, preventing sulphur segregation to the free alloy surface.
Interfacial analyses of copper corrosion by acrylic and methacrylic acids using XPS, auger and grazing angle FTIR spectroscopy
Authors: Yang D. Billy , Wolf David
Published: December 2004

We have observed that methacrylic acid (MA) is far more corrosive than acrylic acid (AA) on copper surfaces when copper was exposed to the vapor of these two acids at ambient temperature and environment. With the aid of modern surface‐sensitive instrumentation, which included grazing angle Fourier transform infrared (FTIR), XPS, x‐ray‐induced Auger electron and SEM/energy‐dispersive spectroscopies and white light stereo and metallurgical microscopy, we are reporting our results of an extensive study of the roles that MA and AA have in this unusual phenomenon of copper corrosion.

By grazing angle FTIR analysis we demonstrated that copper carboxylate salt formation is very rapid upon short contact with the vapor of both acids, and the acids showed no evidence of polymerization. We have also demonstrated by XPS and x‐ray‐induced Auger electron spectroscopy that copper surfaces exposed to the MA vapor contains mainly Cu(II) species. However, the oxidation state of the copper exposed to AA vapor will depend on exposure time and environment. With limited exposure to the air, the copper surface remained shiny for up to 12 months test time. The spectrum obtained from the shiny area of the AA/Cu surface shows that it contains mainly Cu(I) mixed with some copper (II). When the spectrum was taken from a dull area of AA/Cu surfaces, the Cu(II) state was found to be predominant. These results strongly indicate that when the shiny AA/Cu surface changed to a dull color, the oxidation state of the copper also changed from +1 to +2. The molecular structure of the Cu(II)–AA salt is also believed to be altered.

Both stereo microscopic and SEM/energy‐dispersive spectroscopy techniques were also used to perform the visual and microanalysis of the surface texture and elemental compositions of the corroded surfaces, respectively. The presence of oxygen was also found to play an important role in the overall corrosion processes. The differences in molecular structure of copper carboxylate salts of different oxidation states are discussed and are believed to be responsible for this unusual phenomenon. We believe that this finding will provide a good explanation for the cause of drastic differences of copper corrosion by acrylic and methacrylic acids.
Determination of the surface coverage of Mo/Al2O3 catalysts
Authors: Sazo Virginia , Gonzales Lilian , Goldwasser José , Houalla Marwan , Hercules David M.
Published: December 2004

The surface coverage of a series of Mo/Al2O3 catalysts prepared by the equilibrium adsorption method was measured by CO2 chemisorption, low‐temperature CO adsorption and ion scattering spectroscopy (ISS). Comparable values were obtained from ISS and CO adsorption. The results correspond to Mo cross‐sections of 22.2 Å2 Mo−1 (CO) and 20 Å2 Mo−1 (ISS).

The Mo coverages obtained by CO adsorption and ISS were compared with those estimated from CO2 chemisorption. The resuls indicated that, irrespective of the approach used to measure the coverage from CO2 chemisorption (volumetric method or from the decrease of the IR peaks attributed to bicarbonate and ‘free’ carbonate species), the CO2‐based method signficantly overestimates the coverage.