bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accurate local density photoionization cross sections by LCAO Stieltjes imaging approach
Authors: Stener M. , Lisini A. , Decleva P. 
Published: January 2005

AbstractPhotoionization cross sections are evaluated at the local density level avoiding any potential shape approximation by employing the Stieltjes imaging (ST) technique in conjunction with large (STO) basis LCAO calculations. The ST technique proves accurate in comparison with full continuum calculation on the noble gases ionization. Several choices for the final‐state potentials, including different exchange‐correlation potentials, are tested on the noble gases, as well as in H2O and CO. Finally, several molecules are investigated employing the transition‐state xα potential and the results compared with available experimental data and previous calculations. The accuracy of the proposed approach appears quit comparable to the ab initio static‐exchange level, removing spurious resonances associated to the muffin‐tin approximation, and should prove useful in the analysis and interpretation of cross‐section data for large systems, where it is shown that basis‐set requirements become less stringent. The accuracy obtainable for the cross‐section profiles allows close comparison with experimental data, which, although showing good general agreement for the shape of the cross‐section profile, indicates the need of a further refinement of the theoretical model. © 1995 John Wiley & Sons, Inc.
Interpretation of the high‐energy band within the photoelectro spectra of alkanes both in terms of appropriate orbitals and on the basis of chemical structure
Authors: Gineityte V. 
Published: January 2005

AbstractTwo generalized interpretations of the high‐energy band (HEB) within the photoelectron spectras (PES) of alkanes, usually referred to as the C2s band, have been suggested. The quantum chemical one consists of attributing to the HEB of any alkane (CnH2n+2) the chain of n similiar orbitals ηk (k = 1…n), each of them containing mainly one 2sc AO and some contributions of another four orbitals from its nearest environment. The structure of each orbital ηk has been shown to be similar to that of the lowest totally symmetric MO of methane. The chemical interpretation of the same band involves relating it and the definite subspectrum of the full chemical graph of alkane, associated mainly with its C skeleton. The interrelation of these two complementary interpretations follows from the one‐to‐one correspondence between the orbitals ηk and the CH2(CH3) groups in alkane. © 1995 John Wiley & Sons, Inc.
Cubic‐grid Gaussian basis sets for electron scattering calculations. I. Definition and construction
Authors: Čársky Petr , Hrouda Vojtéch , Michl Josef 
Published: January 2005

AbstractWe propose a new type of Gaussian basis sets for use in calculations of electron scattering by molecules. Instead of locating the basis‐set functions on the atomic centers of the target molecule, we place primitive s‐type Gaussians at the positions of a cubic lattice with a regular grid. The grid and the Gaussian exponent are fixed so as to give the best representation of the plane‐wave function. Plane‐wave functions and Green functions obtained by means of the cubic‐grid basis set are tested graphically against exact functions and functions expressed by means of a conventional Gaussian basis set. © 1995 John Wiley & Sons, Inc.
Variational calculations for the hydrogen atom confined in spaces with paraboloidal and spheroidal boundaries
Authors: Cruz S. A. , Ley‐Koo E. , Marín J. L. , Taylor‐Armitage A. 
Published: January 2005

AbstractVariational calculations for the lowest‐energy states of the hydrogen atom confined in (A) semi‐infinite spaces with paraboloidal boundaries, (B) symmetrical boxes with paraboloidal surfaces, and (C) prolate spheroidal boxes were performed with geometry‐adapted trial wave functions. Comparisons of variational energies with the exact energies available for the respective geometries provide indications on the reliability of the trial wave functions. This is a necessary and preliminary step to investigate atoms with several electrons in the corresponding confining geometries. © 1995 John Wiley & Sons, Inc.
On master equations, spectral resolutions, and self‐energy fields in propagator theories for quantum open systems
Authors: Bochicchio Roberto C. , Grinberg Horacio 
Published: January 2005

AbstractMaster equations for propagators in quantum open systems and their spectral resolutions are derived. The Zwanzig partitioning scheme along the superoperator algebra are used to derive equations of motion for partitioned operators in a Liouville space. The reservoir influence on the dynamical evolution of operators is shown to lead explicitly to dissipative effects arising from memory terms in the evolution equations of such operators. It is also shown that spectral representations may be written in a self‐consistent analytic way by means of the self‐energy fields for transition energies of the system by taking into account the lack of the complete knowledge about the reservoir. A kinematic fluid interpretation of the resultant equations is given and an explicit form of the “collision” superoperator is obtained. Finally, a simple example to illustrate the determination of self‐energy fields for the system–reservoir interaction corrections is given. © 1995 John Wiley & Sons, Inc.
A new boundary treatment: HF surface potential model applied to solid‐state cluster calculations
Authors: Liu Hong‐Lin , Chen Nian‐Yi , Ladik Janos J. , Otto P. 
Published: January 2005

AbstractA new boundary treatment, a Hartree–Fock (HF) surface potential model, is proposed to deal with the surface effect in the solid‐state cluster calculations using the LCAO–MO–SCF ab initio method. The surface potential arises from one or more atoms, which have no basis function and are added to the calculated cluster system. These atoms are placed in such sites so that the HF potential field of the calculated system should possess a point‐group symmetry. The surface potential could be found by the corresponding HF potential using a symmetry operator. The fact that a rather symmetric electronic structure of the asymmetric cluster YBa2CuZn2O7 is obtained using the HF surface potential shows that the surface effect in the cluster calculations could be neutralized to a great extent. © 1995 John Wiley & Sons, Inc.
Accurate energy eigenvalues for enclosed hydrogen atom within spherical impenetrable boxes
Authors: Aquino A. Norberto 
Published: January 2005

AbstractWe study the hydrogen atom confined within spherical impenetrable walls. The potential in the box is the Coulombian potential and outside the box the potential is infinite. To compute the energy eigenvalues of the Schrödinger's equation, we use a method proposed few years ago by Campoy and Palma to solve free quantum systems. The energy eigenvalues are computed with great accuracy for different box sizes, in addition we also compute few position expectation values that are related with the hyperfine splitting, nuclear magnetic shielding, polarizability, and pressure. Our results are more accurate than the literature calculations. © 1995 John Wiley & Sons, Inc.
Direct solution of the many‐body Schrödinger equation in the hyperspherical formalism: Application of the CFHH–GLF method to a set of He‐like systems
Authors: Bian Wensheng , Deng Conghao 
Published: January 2005

AbstractWe apply the CFHH–GLF method, a modified version of our HH–GLF method, to directly solve the three‐body Schrödinger equation for a set of He‐like systems, including H−, He, Li+, Be2+, and B3+. Correlation functions with no adjustable parameters are determined from the cusp condition of the wave function. Our calculational results exhibit very fast and good convergence with hyperspherical harmonics (HH) and a generalized Laguerre function (GLF) and substantial improvement over the HH–GLF method. With only 36 HH and 6 GLF, we obtained the ground‐state energy of −2.90371, −7.27988, −13.6555, and −22.0308 au for He, Li+, Be2+, and B3+, respectively. This compares with −2.89361, −7.26131, −13.6253, and −21.9859 au, respectively, by the HH–GLF method and Pekeris' results of −2.90372, −7.27991, −13.6556, and −22.0310 au, respectively. So, the inclusion of 36 HH and 6 GLF has yielded the precision of a few parts in 106 for He, Li+, Be2+, and B3+. However, our calculational results for H− are not so good. We analyzed the cause of this kind of exception and improved our calculations in this respect by using a slightly different correlation function. We finally obtained the ground‐state energy of −0.527754 au for H− with 36 HH and 15 GLF, which is very near Pekeris' result of −0.527751 au and of the same order of precision as those achieved for other He‐like ions. © 1995 John Wiley & Sons, Inc.
Newton–Raphson optimization of the explicitly correlated Gaussian functions for the ground state of the beryllium atom
Authors: Zhang Zhenghong , Adamowicz Ludwik 
Published: January 2005

AbstractExplicitly correlated Gaussian functions have been used in variational calculations on the ground state of the beryllium atom. In such calculations on systems with more electrons, it becomes imminent and essential to develop effective strategies for optimizing the parameters involved in the basis functions. The theory of analytical first and second derivatives of the variational functional with respect to the Gaussian exponents and its computational implementation in conjunction with the Newton–Raphson optimization technique is described. Some numerical results are presented to illustrate the performance of the method. © 1995 John Wiley & Sons, Inc.
Backscattering effects in Auger electron spectroscopy: A review
Authors: Jabłoński Aleksnder 
Published: December 2004

AbstractQuantitative Auger electron spectroscopy requires knowledge of a factor correcting for backscattering effects. This paper discusses the definition of the backscattering correction and reviews the experimental and theoretical methods for determining this correction. The values of the backscattering factor reported in the literature are compiled, and the dependence of the backscattering factor on the primary beam incidence angle and the solid composition is also briefly discussed.
Surface characterization and adhesive bonding of stainless steels: II—The Steel/Adhesive Interface
Authors: Gettings M. , Kinloch A. J. 
Published: December 2004

AbstractIn part I of this study the surfaces of three steels were characterized prior to the application of adhesives. In this part of the study the interface region between a silane‐based primer and the surface of the three chemically etched stainless steels was analyzed using a verity of surface‐specific techniques to investigate the chemistry of the primer/metal interaction. These studies were correlated with joint durability studies. It was found that polymerization of the primer was limited and the variation in durability of the joint could be directly related to the amount of interaction between the silicon in the primer and the surface oxide. It appears that the primer/metal interaction was influenced by surface topography and morphology.
Adventitious carbon—the panacea for energy referencing?
Authors: Swift P. 
Published: December 2004

AbstractA brief historical review has been made of the values assigned to the binding energy of C1s electrons from hydrocarbon contamination on sample surfaces. The particular energy calibration technique used for each electron spectrometer on which the C1s determination was made has been identified. There are notable variations in the C1s electron binding energy for a hydrocarbon contamination layer with respect to the substrate on which it was measured. The possible source and nature of adventitious carbon have been discussed, as have factors which can affect its C1s binding energy value. Sodium phosphate salts have been used to illustrate the relative merits of using an internal energy reference line rather than the C1s electrons from the adventitious carbon layers of these salts. Alternative energy referencing techniques, which include deposition of soot from a candle flame and deliberate ‘in situ’ condensation of a volatile organic compound onto the sample surface, have been compared with the method under review. Another possible method is the mixing of powdered samples with reference compounds (e.g. graphite). It is concluded that, although the use of C1s electrons from adventitious carbon layers is often a convenient method of energy referencing, interpretation of binding energy data obtained should be treated with caution.
Surface studies of keratin fibers and related model compounds using ESCA. I—intermediate oxidation products of the model compound 1‐cystine and their hydrolytical behaviour
Authors: Setiawan L. D. , Baumann H. , Gribbin D. 
Published: December 2004

AbstractThe intermediate oxidation products of 1‐cystine, namely cystine S‐monoxide, cystine S,S‐dioxide and cysteine sulphinic acid have been synthesized according to the procedures of other workers. Attempts to prepare cystine trioxide and cystine tetroxide have also been carried out. The stability of cystine S‐monoxide, cystine S,S‐dioxide and cysteine sulphinic acid in aqueous solutions both under mild hydrolytical conditions (2 h, 25 °C) at different pH values and under the conditions of acid hydrolysis (6 N HCl, 105 °C, 1–20 h, 24 h) have been studied. Cystine, its oxidation products and the disproportionation products are identified by ESCA (C 1s, O 1s, N 1s, S 2p). Both cysteine sulphinic acid and cysteic acid exist mainly as Zwitterions due to the fact that in the carbon spectra of each of them an additional peak shifted to about 1.4 eV (relative to the hydrocarbon peak) has been observed, which is attributed to carbon bond to protonated nitrogen. In addition, only in the cases of cysteine sulphinic acid and cysteic acid an increasing of the nitrogen binding energy of about 1 eV compared with those of cystine and its corresponding oxides has been found indicating of protonated nitrogen. Both the monoxide and the dioxide are relatively unstable in aqueous solutions (2 h, 25 °C, pH 1–10). However the monoxide is more stable than the dioxide under these conditions. Cysteine sulphinic acid is stable under this mild hydrolytical condition. Even in 6 N HCl at 105 °C for 1–20 h in vacuo cysteine sulphinic acid is moderately stable. After 24 h it cannot be detected at all. The results achieved from these studies are discussed in detail in conjunction with previous results reported by other investigators concerning the hydrolytical behaviour of cystine intermediate oxidation products.
Application of elastic peak electron spectroscopy (EPES) to determine inelastic mean free paths (IMFP) of electrons in copper and silver
Authors: Doliński W. , Nowicki H. , Mróz S. 
Published: December 2004

AbstractElastic peak electron spectroscopy (EPES) is used for determination of inelastic mean free paths in silver and copper for electrons with energy of 250, 500, 1000 and 1500 eV. Namely, the elastic scattering coefficient ηe is measured with a retarding field analyser (LEED optics) and calculated by computer simulation for different values of the inelastic mean free path λ. A value of λ giving the best fit for the measured and calculated ηe is taken as the experimental inelastic mean free path. Results obtained are in agreement with those known from the literature. Equivalency between the values of ηe obtained by analytic calculation and by computer simulation is found.
Evaluation and measurement of changes in intensity of the characteristic lines and background of Auger electron spectra due to crystalline effects. Application to an aluminium target bombarded with electrons
Authors: Akamatsu B. , Henoc P. , Maurice F. , Le Gressus C. , Raouadi K. , Sekine T. , Sakai T. 
Published: December 2004

AbstractWe evaluated and measured the influence of channelling on changes in intensity of the characteristic lines and background of Auger electron spectra by performing calculations and experiments on an aluminium single crystal.Propagation of the incident beam in the crystal was calculated by the dynamic theory of electron diffraction, while the Monte‐Carlo method was used to simulate electron paths in the material as a function of experimental conditions.We measured the contrasts of the Al LVV (68 eV) and Al KLL (1396 eV) lines in both channelling and abnormal absorption positions and we recorded the background of the En(E) curves for different electron accelerating voltages and for some strong reflections.The theoretical and experimental results are consistent, revealing the magnitude of crystalline effects in AES. These effects, although they are a hindrance in routine analysis, can be used to study changes in the surface layer composition of metals and ceramics.
Charge compensation and high‐resolution TOFSIMS imaging of insulating materials
Authors: Briggs D. , Hearn M. J. , Fletcher I. W. , Waugh A. R. , McIntosh B. J. 
Published: December 2004

AbstractA charge compensation system, based on a pulsed lowenergy electron flood source, designed for the 1X23S time‐of‐flight secondary ion mass spectrometry (TOFSIMS) instrument is described. Its performance in the non‐imaging mode is illustrated by spectra from polytetrafluoroethene (PTFE). High‐resolution (∼1 pm) imaging of challenging insulating samples under near‐static SIMS conditions is demonstrated for the first time.
Determination of peak positions and areas from wide‐scan XPS spectra
Authors: Turner N. H. , Single A. M. 
Published: December 2004

AbstractIt has been found that by taking transforms of both Gaussian and Lorentzian line shapes into polynomial representations, it is possible in many instances to determine peak position, peak intensity and the full‐width at half‐maximum (FWHM) from wide‐scan XPS spectra that have a low number of data points per electron‐volt. This approach was tested with several samples, ranging from an insulator, Al2O3, to an excellent conductor, sputter‐cleaned gold. Several data sets were constructed from narrow‐scan spectra with points selected about 1 eV apart to simulate wide‐scan spectra. Then, comparisons were made between values calculated with a non‐linear least‐squares fit that used all of the data points from a given spectrum, and the polynomial procedure with the simulated wide‐scan data. It was found that the peak positions usually agreed to within 0.1 eV between the methods. The FWHM and intensities agreed to ∼20%. The area ratios usually were within ∼10%. Comparisons between actual and simulated wide‐scan data showed similar area ratio agreement. However, there appeared to be a systematic difference in the peak position of ∼0.5 eV, which was due to the spectrometer used in this study. Thus, in many cases, estimates of the relative atomic amounts can be made with those results from the polynomial procedure that would be comparable to those obtained from non‐linear least‐squares analysis of narrow‐scan data. The effects of such factors as baseline, overlapping peaks, computational techniques and line shape on the use of the polynomial method are discussed also.
Ion microprobe for studying cluster ion decay reactions
Authors: Bekkerman A. D. , Dzhemilev N. Kh. , Rotstein V. M. 
Published: December 2004

AbstractIn the present paper, an ion microprobe is used to study the fragmentation regularities of Aln+ and Sin+ cluster ions sputtered under ion bombardment. The results have shown that the ions formed during cluster fragmentation, along the path from the target to the detector, transform the mass spectra of both charged and neutral components and the energy distribution of the parent cluster and monomer ions.
Escape depth of photoelectrons
Authors: Jablonski Aleksander 
Published: December 2004

AbstractThe sampling depth of electron spectroscopies, AES and XPS, is frequently directly associated with the value of the inelastic mean free path (IMFP). Owing to elastic scattering of signal electrons, a separate parameter, the escape depth (ED), should be used to describe the analysed volume. There is no simple relation between the ED and the IMFP. In the present work, extensive Monte Carlo calculations were performed to calculate the ED for photoelectrons emitted from gold (Au 4s, Au 4p3/2, Au 4d5/2 and Au 4f7/2). All XPS configurations within a plane normal to the surface were considered. It has been found that the anisotropy of photoelectron emission is strongly reflected in the angular dependences of the ED. Furthermore, the value of ED divided by the cosine of the detection angle, which is equivalent to the attenuation length (AL) described by one of the definitions, may considerably exceed the IMFP, in contrast with common expectations. This occurs at large detection angles and/or in experimental configurations with the direction of x‐rays close to the direction towards the analyser. A simple and accurate parameterization was proposed in the present work, taking into account the anisotropy of photoemission, from which the ED can be predicted for photoelectrons considered and for any XPS configuration.
Potential applications of hyperthermal atomic oxygen for treatment of materials and structures
Authors: Kleiman J. I. , Iskanderova Z. A. , Gudimenko Y. I. , Tennyson R. C. 
Published: December 2004

AbstractMany polymer‐based materials degrade in low earth orbit (LEO), mainly due to the damaging environmental effects of hyperthermal or fast atomic oxygen of energy E ∼ 5 eV and solar vacuum ultraviolet radiation. Fast atomic oxygen fluxes of similar energies are generated now in ground‐based facilities that are used for accelerated testing of materials.This paper presents a brief overview of the effects of interaction of fast atomic oxygen fluxes with polymer‐based materials in the LEO space environment and in ground‐based simulators, and discusses a few possible applications of fast atomic oxygen fluxes. Such applications can lead to considerable advantages over plasma treatment, aimed at improvement of adhesion‐related and optical properties of polymer‐based materials, high‐quality precise photoresist etching and passivative oxidation of advanced semiconductor materials, and modified or entirely new surface properties of biomaterials and chemical sensors.
NIST oxide‐marker‐layer standard reference material (SRM 2136) for depth profile analysis
Authors: Fine Joseph , Navinsek Boris 
Published: December 2004

AbstractA chromium thin‐film structure containing thin oxide layers was developed specifically for secondary ion mass spectrometry calibration of sputtered depths and erosion rates. Information on its structure and characterization is summarized. It is available from NIST as Standard Reference Material 2136.