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1.
Electrophoretic mobility measurements and X-ray photoelectron spectroscopy (XPS) analysis have been performed on several
lanthanum chromite powders with different dopants. Principal component analysis of both deconvoluted XPS data and differentiated
overall XPS spectra showed a clustering of the powders. From loading plots it was seen that high amounts of La and O on the
surface gave highest isoelectric points (IEP). Partial-least-squares, multivariate response modelling was used to calibrate
the IEPs from both deconvoluted XPS data and from differentiated overall XPS spectra. The best model was obtained when second-order
differentiated overall XPS spectra were used, with an average predictive error of pH ± 0.25. This is promising considering
that the IEP has been determined with an accuracy of pHIEP± 0.3. When deconvoluted data was used, the average predictive error rose to pH ± 1.1. It is therefore an advantage to use
multivariate data analysis which is a nonsubjective latent variable decomposing technique in contrast to deconvolution which
is an even more time-consuming method for calibration of IEP values from XPS.
Received: 8 October 1998 Accepted in revised form: 27 January 1999 相似文献
2.
As computer controlled instruments for surface analysis are in common use for many years, the problem of exchangeability
of analytical data has attracted interest in the surface analysis community. More and more examples for the development of
standarized data formats as the VAMAS format [1] and the Standard for Chromatography Data Communication from the AIA [2] have
been published. There are a few attempts to establish standardized “data dictionaries” e.g. the parameter lists describing
AES and XPS spectra pusblished in Surface Science Spectra [3, 4]. If several different analysis methods (such as AES, SAM,
XPS, SIMS, STM, AFM, EPMA, …) are applied to the same sample, a quite independent and open approach is needed to be able to
combine data of various instruments in a common data evaluation procedure. It could be the basic concept of real mutli-method
analysis. The public domain software package MAXMIND has been developed, as only a standardized data exchange and storage
format based on data dictionaries can guarantee a high level of independence of proprietary measurement systems.
Received: 16 January 1997 / Revised: 9 May 1997 / Accepted: 14 May 1997 相似文献
3.
As computer controlled instruments for surface analysis are in common use for many years, the problem of exchangeability
of analytical data has attracted interest in the surface analysis community. More and more examples for the development of
standarized data formats as the VAMAS format [1] and the Standard for Chromatography Data Communication from the AIA [2] have
been published. There are a few attempts to establish standardized “data dictionaries” e.g. the parameter lists describing
AES and XPS spectra pusblished in Surface Science Spectra [3, 4]. If several different analysis methods (such as AES, SAM,
XPS, SIMS, STM, AFM, EPMA, …) are applied to the same sample, a quite independent and open approach is needed to be able to
combine data of various instruments in a common data evaluation procedure. It could be the basic concept of real mutli-method
analysis. The public domain software package MAXMIND has been developed, as only a standardized data exchange and storage
format based on data dictionaries can guarantee a high level of independence of proprietary measurement systems.
Received: 16 January 1997 / Revised: 9 May 1997 / Accepted: 14 May 1997 相似文献
4.
Schülke M Paulus H Lammers M Kiss G Réti F Müller KH 《Analytical and bioanalytical chemistry》2008,390(6):1495-1505
Hydrogen storage in metal hydrides is a promising alternative to common storage methods. The surface of a metal hydride plays
an important part in the absorption of hydrogen, since important partial reaction steps take place here. The development of
surface contaminations and their influence on hydrogen absorption is examined by means of absorption experiments and surface
analysis, using X-ray photoelectron spectroscopy (XPS), thermal desorption mass spectrometry (TDMS) and secondary neutral
mass spectrometry (SNMS), in this work. All investigations were carried out on a modern AB2 metal hydride alloy, namely Ti0.96Zr0.04Mn1.43V0.45Fe0.08. Surface analysis (SNMS, XPS) shows that long-term air storage (several months) leads to oxide layers about 15 nm thick,
with complete oxidation of all main alloy components. By means of in situ oxygen exposure at room temperature and XPS analysis,
it can be shown that an oxygen dose of about 100 Langmuirs produces an oxide layer comparable to that after air storage. Manganese
enrichment (segregation) is also clearly observed and is theoretically described here. This oxide layer hinders hydrogen absorption,
so an activation procedure is necessary in order to use the full capacity of the metal hydride. This procedure consists of
heating (T = 120° C) in vacuum and hydrogen flushing at pressures like p = 18 bar. During the activation process the alloy is pulverized to particles of ∼20 μm through lattice stretches. It is shown
that this pulverization of the metal hydride (creating clean surface) during hydrogen flushing is essential for complete activation
of the material. Re-activation of powder contaminated by small doses of air (p ≈ 0.1 bar) does not lead to full absorption capacity. In ultrahigh vacuum, hydrogen is only taken up by the alloy after sputtering
of the surface (which is done in order to remove oxide layers from it), thus creating adsorption sites for the hydrogen. This
is shown by TDMS measurements with and without sputtering and oxygen exposure.
Figure Investigated metal hydride before and after activation 相似文献
5.
Silane coupling agents are commonly used to activate surfaces for subsequent immobilization of biomolecules. The homogeneity
and surface morphology of silane films is important for controlling the structural order of immobilized single-stranded DNA
probes based on oligonucleotides. The surfaces of silicon wafers and glass slides with covalently attached 3-glycidoxypropyltrimethoxysilane
(GOPS) have been characterized by using angularly dependent X-ray photoelectron spectroscopy (XPS), time-of-flight secondary-ion
mass spectrometry (ToF–SIMS), atomic force microscopy (AFM), scanning electron microscopy (SEM), and monochromatic and spectroscopic
ellipsometry. XPS and ToF–SIMS data provided evidence of complete surface coverage by GOPS. Data from angularly resolved XPS
and ellipsometry methods suggested that the GOPS films were of monolayer thickness. AFM and SEM data indicated the presence
of films that consisted of nodules approximately 50–100 nm in diameter. Modeling suggested that the nodules may lead to a
nanoscale structural morphology that might influence the hybridization kinetics and thermodynamics of immobilized oligonucleotides. 相似文献
6.
Numerical approximation of AR‐XPS spectra for rough surfaces considering the effect of electron shadowing
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D. Bianchi L. Katona J. Brenner G. Vorlaufer A. Vernes W. S. M. Werner 《Surface and interface analysis : SIA》2015,47(1):15-21
A computational scheme is presented that takes into account the topography, i.e. the shadowing and hence the local emission angle of the electrons when evaluating AR‐XPS data of macroscopic rough surfaces. The topography of the sample surface is supposed to be recorded by atomic force microscopy and/or optical microscopy. The emitted photoelectrons are simulated based on an extension of the Beer–Lambert law that includes the shadowing, the current local emission angle, and the geometrical instrument setup. The obtained angle‐resolved XPS spectra are optimized in accordance with experimental ones via a self‐consistent minimization algorithm that also allows one to determine the layer thicknesses of the corrugated sample. In order to validate the proposed numerical scheme, the simulation program simulation of electron spectra for surface analysis is used. An additional analysis is then performed considering only experimental data. The numerical scheme gives good agreement in simulation–simulation as well as simulation–experiment comparisons and permits a comprehensible interpretation of the measured data. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
Giovanni Di Nicola Cristiano Di Nicola Matteo Moglie Marco Pacetti 《Journal of Thermal Analysis and Calorimetry》2012,108(2):621-625
This study presents a new formula for the surface tension prediction of alkenes. As a first step, an analysis of the available
data of the experimental surface tension data for alkenes was performed. The experimental data were collected, after a careful
literature survey, for the following pure fluids: propene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-tetradecene, and 1-pentadecene.
Then, the experimental data were regressed with the most reliable semi-empirical correlating methods based on the corresponding
state theory existing in the literature. As a final step, an analysis of the available data of the experimental surface tension
data for alkenes was performed starting from the two recently proposed equations for the prediction of the surface tension
of refrigerants based on the corresponding states principle. To minimize the deviation between the predicted data and the
experimental data and to find the optimal equation coefficients for experimental data regression, a (μ + λ)-evolution strategy
was adopted. The analysis showed that the equation that gave the best results for the prediction of the surface tension of
alkenes was the one with a very limited number of parameters. The finally proposed equation is very simple and gives a noticeable
improvement with respect to the existing equations. It is based on the corresponding state principle, containing the acentric
factor, the critical temperature, and pressure. 相似文献
8.
Yongchang Fan Marcus R. Davidson James A. Cairns Graham J. Berry Alexander G. Fitzgerald 《Mikrochimica acta》2002,139(1-4):49-54
This study examines the thermal decomposition of 1,5-cyclooctadiene platinum (II) chloride organometallic films, deposited
by thermal evaporation. The thin film samples were annealed both in air and hydrogen with well-controlled temperature regimes.
After annealing, the decomposed thin films were examined by AFM and STM scanning probe, XPS and TEM microbeam analytical techniques.
The experimental results confirm that the thermal decomposition products on silicon substrates are composed predominantly
of metallic platinum. Annealing in hydrogen can reduce substantially the decomposition temperature of the material from around
250 to 160 °C but the surface morphology of the decomposed films is significantly different to those annealed in air. The
metallic nature of the thermally decomposed films was confirmed by bonding configuration recognition, electronic property
probing and microstructure analysis. 相似文献
9.
In this study, CO2 laser was used for treating cotton fabric to create surface effects which were found to vary with laser process parameters,
i.e. resolution and pixel time. The resolutions used were 40, 50 and 60 dpi while the pixel time used were 100, 110 and 120 μs.
Both physical and chemical properties at the surface of fabrics treated with different combinations of resolution and pixel
time were analysed by the Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy with Attenuated Total
Reflection mode (FTIR-ATR), and X-ray Photoelectron Spectroscopy (XPS). SEM investigation revealed the appearance of various
numbers of pores, cracks and fragments present on the fibre surface after laser treatment. FTIR-ATR spectra showed that the
laser-treated cotton fabric suffered changes in chemical structure with the hydroxyl (–OH) stretching group being oxidised
to carbonyl/carboxyl groups. The XPS analysis revealed a change in surface elemental composition after laser treatment. Furthermore,
the wicking property of the laser-treated cotton fabrics was evaluated. 相似文献
10.
The wetting of well-characterized heterogeneous surfaces of block copolymers has been studied by low-rate dynamic contact
angle measurements using axisymmetric drop-shape analysis. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy
(XPS) were used to investigate the roughness, the heterogeneity and the chemical composition of the surfaces. By changing
the block length of polysulfone and semifluorinated polyester segments in the block copolymers, the surface heterogeneity
of thin films prepared on silicon wafers could be controlled. Tapping-mode AFM measurements showed that soft, hydrophobic
domains of varying size on the submicrometer length scale were obtained on these surfaces (60–250 nm). The mean roughness
was of the order of several nanometers. The results of the contact angle measurements showed that neither roughness nor heterogeneity
had a significant effect on the advancing contact angle of water, at the scale of the features present; however, the contact
angle hysteresis increased with increasing percentage of the soft domains. We assume that liquid retention by the solid upon
retraction of the three-phase line is the main cause for the observed increase in contact angle hysteresis. Concerning the
molecular composition of these block copolymer surfaces, angle-resolved XPS analysis showed a surface segregation of fluorine
within the surface region. A direct correlation was found between the fluorine content of the block copolymer surfaces and
the advancing contact angle of water.
Received: 26 May 2000 Accepted: 3 January 2001 相似文献
11.
Malicka E Sitko R Zawisza B Heimann J Kajewski D Kita A 《Analytical and bioanalytical chemistry》2011,399(9):3285-3292
The paper presents possibilities and difficulties in nondestructive analysis of small multielement single crystals performed
by means of X-ray spectrometry techniques: micro-X-ray fluorescence spectrometry (μ-XRF), energy-dispersive electron probe
microanalysis (ED-EPMA), and X-ray photoelectron spectroscopy (XPS). The capability of the X-ray spectroscopy techniques in
elemental analysis is demonstrated with the single crystals of selenide spinels of the general formula M
x
N
y
Cr
z
Se4 (M+2 and N+3 are, for example, Zn+2, V+3, Ga+3, Cd+2, In+3, and Sb+3). The results of the nondestructive analyses (μ-XRF, ED-EPMA, and XPS) are compared with those obtained by inductively coupled
plasma optical emission spectrometry (ICP-OES) and wavelength-dispersive X-ray spectrometry (WDXRF) following sample digestion.
The present study shows satisfactory agreement between the results of μ-XRF analysis performed using the standardless fundamental
parameter method and the results obtained with the WDXRF and ICP-OES analyses. If the measured single crystal is precisely
positioned, the difference between μ-XRF and wet analysis (WDXRF and ICP-OES) does not exceed 5% rel. The reliable results
of ED-EPMA can be obtained only if the measured area is sufficiently large, i.e., of 200 × 300 μm. Even if this condition
is fulfilled, the relative difference between the ED-EPMA and the wet analysis may reach 10% rel. In case of the XPS analysis,
the accuracy of results depends on the proper preparation of the sample surface. It should be free of contamination that can
be obtained by scraping in situ in ultrahigh vacuum. The ion etching, commonly used for cleaning the surface, leads to preferential
sputtering; therefore, the reliable results cannot be obtained. 相似文献
12.
Angelo Boscolo Boscoletto Mario Gleria Roberto Milani Laura Meda Roberta Bertani 《Surface and interface analysis : SIA》2009,41(1):27-33
This paper investigates by means of XPS analysis the surface functionalization of soda‐lime and fused quartz glass substrates with hexachlorocyclophosphazene (HCCP), obtained by simple immersion in solutions of phosphazene in anhydrous solvents. Several experimental parameters like reaction solvent, temperature and treatment duration were studied, together with the influence of physisorbed water on the surface of the substrates. Phosphazene‐derived deposits resistant to tetrahydrofuran (THF) washing and vacuum drying were obtained. They presented P:N:Cl stoichiometric ratios close to 1:1:1 when the reaction and the final drying of the samples were performed at room temperature; use of higher temperatures resulted in lower nitrogen and chlorine content. The chemical nature of the films was studied by XPS peaks deconvolution which enabled us to propose a possible, temperature‐enhanced hydrolytical degradation mechanism. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
13.
R. WinterP.G. Nixon R.J. TerjesonJ. Mohtasham N.R. HolcombD.W. Grainger D. GrahamD.G. Castner G.L. Gard 《Journal of fluorine chemistry》2002,115(2):107-113
A new perfluorinated acrylate monomer containing the SF5(CF2)6-perfluorinated side chain was synthesized and polymerized into films. Bulk monomer characterization is consistent with the molecular structure based on FTIR, mass spectrometry and NMR analyses. The surface properties of polymer coatings were studied with aqueous wetting (contact angle) and X-ray photoelectron spectroscopy (XPS) methods. The surface composition is shown to be highly enriched in the terminal side chain SF5-chemistry and exhibits properties consistent with a highly apolar, non-wetting perfluorinated polymer surface. Depth-dependent XPS studies using angular-resolved methods (ADXPS) confirmed a non-stoichiometric enrichment of sulfur and fluorine at the film ambient interface, consistent with a surface presence of the terminal SF5-group and possibly film structural anisotropy in the surface zone. Time-of-flight (TOF) secondary ion mass spectrometry (SIMS) analysis supplements the XPS data by showing the presence of all expected SF5-acrylate chemistry components in the outer 15 Å of the film surface. 相似文献
14.
Daniel M. Chipman 《Theoretical chemistry accounts》2002,107(2):80-89
Alternative ways are examined for representing a reaction field to treat the important effects of long-range electrostatic
interaction with a solvent in electronic structure calculations on the properties of a solute. Several extant boundary element
methods for approximate representation of the solvent reaction field in terms of surface charge distributions are considered,
and analogous new methods for approximate representation in terms of surface dipole distributions are introduced. Illustrative
computational results are presented on representative small neutral and ionic solutes to evaluate the relative accuracy of
various methods.
Received: 2 July 2001 / Accepted: 10 September 2001 / Published online: 19 December 2001 相似文献
15.
Jessie Casimiro Bénédicte Lepoittevin Caroline Boisse-Laporte Marie-Geneviève Barthés-Labrousse Pascale Jegou Fran?ois Brisset Philippe Roger 《Plasma Chemistry and Plasma Processing》2012,32(2):305-323
With the aim of introducing primary amino groups on the surface of poly(ethylene terephthalate) (PET), two methods were compared—the
use of ammonia or a combination of nitrogen and hydrogen low-pressure microwave plasma. Several plasma parameters were optimized
on the reactor to increase the –NH2 surface density, which was estimated by colorimetric titration and X-ray photoelectron spectroscopy (XPS). These techniques
show that whatever the plasma treatment, almost 2 –NH2/nm2 are incorporated on PET films. Emission spectroscopy highlighted a correlation between the density of primary amino groups
and the ratio between an NH peak intensity and an Ar peak intensity (INH/IAr). Variation in surface hydrophilicity with aging in air after plasma treatment was monitored with contact angle measurements
and showed a hydrophobic recovery. This was confirmed by XPS, which suggests also that surfaces treated by NH3 plasma are more stable than surfaces treated by N2/H2. 相似文献
16.
Steffen Oswald Wolfgang Häßler Rainer Reiche Johannes Lindner François Weiss 《Mikrochimica acta》2000,133(1-4):303-306
New BaTiO3-SrTiO3 (BTO-STO)-superlattices which may be interesting for future electronic applications have been investigated by X-ray photoelectron
spectroscopy (XPS) depth profiling. At first XPS measuring conditions were optimized for that non-conducting and thin layer
systems (21 nm double layer thickness) considering the practical instrumental limitations. Second a simulation of the sputtering
process for the concrete experimental conditions were done by a dynamic T-DYN code. By comparison of experimental and simulated
depth profiles the maximum sample roughness could be estimated to be in the range of 2 nm. 相似文献
17.
Noushine Shahidzadeh Mohamed M. Chehimi Farzaneh Arefi-Khonsari Jacques Amouroux Michel Delamar 《Plasmas and Polymers》1996,1(1):27-45
Acid-base properties of ammonia plasma-treated polypropylene (APTPP) were characterized by X-ray photoelectron spectroscopy
(XPS) in conjunction with the molecular probe technique and using chloroform (TCM) as a reference Lewis acid. It is shown
that TCM is retained by the basic surfaces of APTPP but not by the untreated PP. The retention of TCM is shown to be entirely
due to the formation of TCM:APTPP acid-base complexes. This is supported by the C12p3/2 binding energy (BE) and the shape of the Cl2p peak from the adsorbed TCM. ΔHAB, the heat of TCM:APTPP acid-base interaction was found to be in the range of 3.1–4.3 kcal/mol using a published Cl2p3/2 BE−ΔHAB correlation. This ΔHAB compares remarkably well with the values of 4.3–4.9 kcal/mol determined for TCM:amine complexes, and shows indeed that TCM
is complexed by nitrogen containing basic groups grafted at the surface. However, the TCM/N ratio has an optimal value up
to 1 second of plasma treatment and then decreases sharply, showing that less specific interaction sites are accessible at
the surface for longer treatment times. This parallels previous findings about the metallization of APTPP by aluminium which
was found to be optimal for treatment times lower than 1 second in our experimental conditions. This work shows that XPS can
now indeed be used to quantitatively assess the acid-base properties of modified polymer surfaces. 相似文献
18.
Ricardo J. N. Bettencourt da Silva Maria Filomena G. F. C. Camões 《Accreditation and quality assurance》2010,15(12):691-704
The dispersion of results from proficiency tests for the analysis of pesticide residues in foodstuffs suggests that improvements
in the compatibility of measurement results are needed. Currently observed divergences can make the evaluation conclusion
on foodstuffs compliance with certain legislation dependent on the consulted laboratory. This work discusses the origin and
impact of this lack of compatibility, following the metrological concepts presented at the latest version of the “International
Vocabulary of Metrology” (VIM3), thus allowing for a clear diagnostic of the problem. The reporting of results from different
measurement methods uncorrected for the observed analyte recovery makes them traceable to different “operationally defined
measurement procedures” (VIM3) and, therefore, not comparable. When results from different measurement methods are reported
corrected for analyte recovery, R, and R is different for spiked and incurred residues, measurement results may be not compatible if this effect is not considered
on the uncertainty budget. This discussion is illustrated with metrological models for any possible combination of “measurement
performance” and “maximum residue level”. These models are complemented with experimental data of the analysis of pesticide
residues in a sample of ginseng powder from a proficiency test. The adopted experimental design allowed the identification
of additional threats to metrological compatibility in this field. Solutions to the faced problem are discussed for practicability
and impact on regulatory issues. The use of a universal “reference measurement procedure” proves to be the most feasible way
of ensuring comparability of measurements in this field. 相似文献
19.
Itani H Duchoslav J Arndt M Steck T Gerdenitsch J Faderl J Preis K Winkler W Stifter D 《Analytical and bioanalytical chemistry》2012,403(3):663-673
Zn–Cr alloyed coatings electrochemically deposited are of high interest for leading steel manufacturing companies because
of their novel properties and high corrosion resistance compared with conventional Zn coatings on steel. For tuning and optimizing
the properties of the electrodeposited Zn–Cr coatings, a broad range of the deposition conditions must be studied. For this
reason, two different types of material were investigated in this study, one with a low electrolyte temperature and one with
an elevated electrolyte pH, compared with the standard values. Because different corrosion performance and delamination behaviour
of the layers were observed for the two types, advanced surface analysis was conducted to understand the origin of this behaviour
and to discover differences in the formation of the coatings. The topmost surface, the shallow subsurface region, and the
whole bulk down to the coating–steel interface surface were analysed in detail by X-ray photoelectron spectroscopy (XPS) and
high-resolution scanning Auger electron spectroscopy to determine the elemental and the chemical composition. For better understanding
of the resulting layer structure, multiple reference samples and materials were measured and their Auger and XPS spectra were
fitted to the experimental data. The results showed that one coating type is composed of metallic Zn and Cr, with oxide residing
only on the surface and interface, whereas the other type contains significant amounts of Zn and Cr oxides throughout the
whole coating thickness. 相似文献
20.
Monodispersed poly(styrene-co-acrylonitrile) [P(St-co-AN)] microspheres were prepared by emulsifier-free emulsion copolymerization of St with AN. Fourier transform IR spectroscopy
and elemental analysis were used to measure the content of AN in the poly(St-co-AN) microspheres. X-ray photoelectron spectroscopy (XPS) measurements indicated the presence of an AN unit on the surface
of the microspheres. The combined results of the elemental analysis and the XPS measurements showed that the copolymer on
the surface of the P(St-co-AN) particles was rich in AN compared with that in the interior of the particles. P(St-co-AN)–metal composite particles were prepared by chemical metal deposition. The addition of nickel could improve the distribution
of cobalt on surface of the polymer microspheres. The preparation of polymer–bimetal composite particles was tried. Transmission
electron microscopy and XRD were used to study the distribution and structure of the deposited metal particles.
Received: 30 June 1999/Accepted in revised form: 16 September 1999 相似文献