π* ← π Shakeup Satellites for the Analysis of Structure and Bonding in Aromatic Polymers by X-Ray Photoelectron Spectroscopy

1986 ◽  
Vol 40 (2) ◽  
pp. 224-232 ◽  
Author(s):  
Joseph A. Gardella ◽  
Susan A. Ferguson ◽  
Roland L. Chin
Keyword(s):  
Quantitative Analysis ◽  
Surface Analysis ◽  
Photoelectron Spectroscopy ◽  
Polymer Surface ◽  
Surface Region ◽  
Initial State ◽  
Final State ◽  
Near Surface ◽  
Peak Fitting ◽  
Pi Orbitals

The applications of ESCA to polymer surface analysis include the use of the secondary final-state effects which lead to satellite structure near the core-level photoemission (PE) lines. Specifically, unsaturated and aromatic functionalities in organic compounds and polymers lead to π* ← π shakeup peaks of less than 10 eV lower kinetic energy (higher binding energy). In the surface analysis of polymers, these features can be utilized for qualitative analysis, identification of the presence and structure of aromatic bonding, and quantitative analysis in determining the amount of a particular block or the aromatic containing function in the near-surface region. Carbon Is shakeups are most often used, but the present study includes detailed qualitative and quantitative analysis of shakeup structures from PE lines from each type of atom in hydrocarbon-, siloxane-, and sulfur-containing polymers. These results show the importance of including the shakeup intensity in quantitative peak area calculations and in peak fitting of complex PE envelopes. These studies prove in a variety of systems that the effects of third-row atoms on the final state lead to the presence of shakeup features in atoms with orbitals which do not participate in the aromatic orbital initial state, thus complicating interpretation of structure from the presence of these features. Results from the siloxane and sulfone polymers indicate that previously held assumptions about the nature of the initial-state molecular orbital may overlook the contribution of empty 3d orbitals or increased charge density on the Si or S atom which would spread the pi orbitals to the oxygen in the aromatic siloxane or sulfone systems. Finally, analysis of these features can provide quantitative analysis of polymeric surface structure by monitoring the relative intensity of the feature to the main PE line.

The Use of X-Ray Photoelectron Spectroscopy in Materials Science

1991 ◽  
Vol 35 (B) ◽  
pp. 869-882 ◽  
Author(s):  
James Castle
Keyword(s):  
Surface Analysis ◽  
Photoelectron Spectroscopy ◽  
Materials Science ◽  
Polymer Surface ◽  
Surface Region ◽  
Binding Energies ◽  
Particulate Composites ◽  
X Rays ◽  
Additional Advantage ◽  
X Ray

AbstractThis review will attempt to show how XPS now makes an important contribution to Materials Science and to highlight the developments which have brought it to this position. XPS is now a mature technique for surface analysis but it has in addition a major role as a specialised tool, being essential to studies in which derivitization methods are used to tag surface groups.The requirements of users in this field have led to the development of X-ray sources which were not envisaged in the early development of the spectroscopy. The usual sources of aluminium Kα and magnesium Kα have limitations for those elements beyond magnesium in the periodic table which would have the Is lino as the principal peak - aluminium, silicon, oulphur and phosphorus for example. Higher energy sources such as silicon Kα or zirconium and silver Lα have made it possible to utilise the Is lines up to chlorine and have the additional advantage that a strong and well resolved series of Auger lines also becomes available. The higher energy radiations are thus particularly suited to the determination of relaxation energies in materials by use of relative shifts between the photo- and Auger lines of the spectrum. Such has been the utility of such relaxation energies that use is often made of Auger lines derived from the Bremmstrahlung component of the normal x-ray sources to make a similar measurement. This measurement is used in the study of insulating ceramics in which electrostatic charging makes measurement of binding energies uncertain.Modern materials technology is particularly concerned with the manufacture of composites; particulate, fibre and laminate composites are all well known and the key to their success often lies within the interface between the phases. Transfer of load across the interface places particular requirements on adhesion at the phase boundary and an understanding of the locus of failure during destructive testing is crucial to the development of satisfactory bonding processes. In coated and laminated products there is no problem in the use of XPS, with its excellent chemical sensitivity but there is a problem of increasing magnitude in fibre and particulate composites as the substructures become finer. This stems, of course, from the difficulty of providing a focused source of X-rays of sufficient magnitude. Imaging XPS is slowly becoming a reality with several systems having a capability of 10μm now available, and one of the markets for such instruments is that of composite materials.There are important areas of Materials Science in which XPS has been displaced by other techniques such as SIMS. One such area is that of polymer surface analysis. The selectivity of XPS for substituent groups in the surface region is not good. Derivitization methods have made an impact, enabling acidic or basic groups to be determined, but SIMS, which has the ability to detach molecular clusters, has obvious advantages which will become increasingly exploited aa the problems of charging become solved. Until then however XPS will continue to find a role in polymer research and development.

Revealing the mechanism of the early stages of Ni–W RABiTS oxidation

2010 ◽  
Vol 25 (12) ◽  
pp. 2362-2370 ◽  
Author(s):  
Andrey V. Blednov ◽  
Oleg Yu. Gorbenko ◽  
Dmitriy P. Rodionov ◽  
Andrey R. Kaul
Keyword(s):  
Internal Oxidation ◽  
Photoelectron Spectroscopy ◽  
Oxidation Mechanism ◽  
Surface Oxidation ◽  
Surface Region ◽  
Near Surface ◽  
Precise Position ◽  
X Ray ◽  
Early Stages ◽  
Phase And Chemical Composition

The early stages of surface oxidation of biaxially textured Ni–W tapes were studied using thermodynamic calculations along with experimental tape oxidation at low P(O2). Tape phase and chemical composition, surface morphology, and roughness were examined using x-ray diffraction (XRD), energy-dispersive x-ray analysis (EDX), secondary ion mass spectroscopy (SIMS), x-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). For a Ni0.95W0.05 alloy tape, the precise position of the tape oxidation line in P(O2)–T coordinates was established. This line includes a break at T ≈ 650 °C that originates from the change of the W oxidation mechanism from internal oxidation to oxidation on a free surface accompanied by segregation of the alloy components in the tape near-surface region. The surface roughness of a polished tape increased drastically during internal oxidation of W; further tape oxidation did not affect the integral roughness parameters, but introduced numerous small (˜;100 nm) features on the tape surface comprising NiO precipitates.

scholarly journals Microstructure and Mechanical Properties of Ti + N Ion Implanted Cronidur30 Steel

Materials ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 427 ◽  
Author(s):  
Jie Jin ◽  
Wei Wang ◽  
Xinchun Chen
Keyword(s):  
Mechanical Properties ◽  
Ion Implantation ◽  
Photoelectron Spectroscopy ◽  
Structural Modification ◽  
Surface Region ◽  
Grazing Incidence ◽  
Bearing Steel ◽  
Near Surface ◽  
X Ray ◽  
Ion Implanted

In this study, Ti + N ion implantation was used as a surface modification method for surface hardening and friction-reducing properties of Cronidur30 bearing steel. The structural modification and newly-formed ceramic phases induced by the ion implantation processes were investigated by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and grazing incidence X-ray diffraction (GIXRD). The mechanical properties of the samples were tested by nanoindentation and friction experiments. The surface nanohardness was also improved significantly, changing from ~10.5 GPa (pristine substrate) to ~14.2 GPa (Ti + N implanted sample). The friction coefficient of Ti + N ion implanted samples was greatly reduced before failure, which is less than one third of pristine samples. Furthermore, the TEM analyses confirmed a trilamellar structure at the near-surface region, in which amorphous/ceramic nanocrystalline phases were embedded into the implanted layers. The combined structural modification and hardening ceramic phases played a crucial role in improving surface properties, and the variations in these two factors determined the differences in the mechanical properties of the samples.

scholarly journals Observation of Ionization of Laser Excited Atoms by Synchrotron Radiation

1984 ◽  
Vol 86 ◽  
pp. 128-131
Author(s):  
J.M. Bizau ◽  
F. Wuilleumier ◽  
P. Gerard ◽  
P. Dhez ◽  
B. Carré ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Photoelectron Spectroscopy ◽  
Oscillator Strengths ◽  
Final States ◽  
Initial State ◽  
Final State ◽  
Core Electron ◽  
Output Mirror ◽  
Initial States ◽  
A New Technique

We have begun a program to measure oscillator strengths of autoionizing resonances that result from a transition in the VUV between a laser excited initial state and a final state in which a core electron is promoted. These measurements demonstrate a new technique to combine synchrotron radiation, laser pumping, and photoelectron spectroscopy.Measurements of the energy positions of autoionizing resonances have been honed to a fine art over the past 50 years. Total cross section measurements and the parameters that describe autoionizing resonances have been determined. Most of these studies have been made from the dipole allowed ground state. Recently autoionizing resonances have been observed from excited initial states and from ion initial states. We have heard several talks, at this meeting which described some of this type of research. In the measurements to be described in this paper, laser radiation is combined with synchrotron radiation, as shown schematicaly in Figure 1, to study the photoionization from excited initial states to continuum final states or to autoionizing final states. Continuum radiation from the Aneau de Collisions d’Orsay (ACO), which is installed at the Universite de Paris-Sud, in Orsay France, is monochromatized by a toroidal grating monochromator (TGM) and is focused by a toroidal output mirror on to a weakly collimated sodium beam emanating from a furnace mounted on the axis of a cylinderical mirror analyzer (CMA). This electron spectrometer is used to study the kinetic energy distribution of the ejected photoelectrons produced by the interaction of the photon beam with the focused synchrotron radiation.

An Examination of Kernite (Na2B4O6(OH)2·3H2O) Using X-Ray and Electron Spectroscopies: Quantitative Microanalysis of a Hydrated Low-Z Mineral

2011 ◽  
Vol 17 (5) ◽  
pp. 718-727 ◽  
Author(s):  
Douglas C. Meier ◽  
Jeffrey M. Davis ◽  
Edward P. Vicenzi
Keyword(s):  
Electron Beam ◽  
Photoelectron Spectroscopy ◽  
High Vacuum ◽  
Stoichiometric Composition ◽  
Surface Region ◽  
Variable Pressure ◽  
Sampling Depth ◽  
Electrical Insulator ◽  
Near Surface ◽  
X Ray

AbstractMineral borates, the primary industrial source of boron, are found in a large variety of compositions. One such source, kernite (Na2B4O6(OH)2·3H2O), offers an array of challenges for traditional electron-probe microanalysis (EPMA)—it is hygroscopic, an electrical insulator, composed entirely of light elements, and sensitive to both low pressures and the electron beam. However, the approximate stoichiometric composition of kernite can be analyzed with careful preparation, proper selection of reference materials, and attention to the details of quantification procedures, including correction for the time dependency of the sodium X-ray signal. Moreover, a reasonable estimation of the mineral's water content can also be made by comparing the measured oxygen to the calculated stoichiometric oxygen content. X-ray diffraction, variable-pressure electron imaging, and visual inspection elucidate the structural consequences of high vacuum treatment of kernite, while Auger electron spectroscopy and X-ray photoelectron spectroscopy confirm electron beam-driven migration of sodium and oxygen out of the near-surface region (sampling depth ≈ 2 nm). These surface effects are insufficiently large to significantly affect the EPMA results (sampling depth ≈ 400 nm at 5 keV).

ELECTRONIC AND STRUCTURAL PROPERTIES OF Si–Gd–O ELECTRON EMITTER

2019 ◽  
Vol 27 (01) ◽  
pp. 1950089
Author(s):  
M. I. FEDORCHENKO ◽  
P. V. MELNIK ◽  
M. G. NAKHODKIN ◽  
O. I. GUDYMENKO ◽  
V. P. KLADKO ◽  
...  
Keyword(s):  
Rare Earth ◽  
Work Function ◽  
Photoelectron Spectroscopy ◽  
Alkali Metals ◽  
Rare Earth Metals ◽  
Film Surface ◽  
Surface Region ◽  
Kelvin Probe ◽  
Surface Distribution ◽  
Near Surface

Rare earth metals, when deposited and oxidized on semiconductor surfaces, can be an alternative to unstable compounds of alkali metals while creating stable and effective emitters with a low work function. A procedure giving rise to the adsorption of Gd and O atoms on the Si(100) surface and the formation of a Si–Gd–O film with a work function of about 1 eV in the near-surface region is described. The films have been studied using the Auger electron and photoelectron spectroscopy, as well as X-ray diffraction, atomic force and Kelvin probe force microscopy techniques. Information about their electronic properties, structure, surface morphology, and surface distribution of potential was obtained. The main component of the film formed on the Si surface is a polycrystalline Gd2O3 phase, which plays the role of a matrix containing textured microcrystallites of one of the following phases: SiO2, GdO2, or GdSi2. The film surface consists of salient clusters 20[Formula: see text]nm to 80[Formula: see text]nm in diameter and up to 20[Formula: see text]nm in height, as well as craters up to 90[Formula: see text]nm in depth. The surface relief inhomogeneities correlate with the surface distribution of the local work function. This correlation can also be a result of the piezoelectric effect in the strained crystallites of the textured phase located in the bulk of the film. The obtained system was stable in time under vacuum conditions and heating up to [Formula: see text]C. The method proposed for the formation of surfaces with a low work function making use of rare earth metals can be applied to create effective and stable electron emitters.

Polyhedral Oligomeric Silsesquioxane/PDMS Hybrid Coating Protecting Polyimide from Atomic Oxygen Erosion

2011 ◽  
Vol 189-193 ◽  
pp. 336-339 ◽  
Author(s):  
Shu Wang Duo ◽  
Mi Mi Song ◽  
Ting Zhi Li ◽  
Ying Luo ◽  
Mei Shuan Li
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hybrid Film ◽  
Surface Region ◽  
Polyimide Film ◽  
Hybrid Films ◽  
Near Surface ◽  
X Ray ◽  
Oligomeric Silsesquioxane ◽  
Atomic Oxygen Erosion ◽  
Inorganic Organic Polymers

Hybrid inorganic/organic polymers have been prepared by copolymerizing a silanol terminated polydimethylsiloxane (PDMS) with an Octa(aminophenyl) -silsesquioxane (POSS). The AO resistance of these POSS/PDMS hybrid films was tested in the ground-based AO simulation facility. Exposed and unexposed surfaces have been characterized by X-ray photoelectron spectroscopy. The XPS data indicate that the carbon content of the near-surface region is decreased from 65.3 to 18.9 at% after AO exposure. The oxygen and silicon concentrations in the near-surface region increase after AO exposure. The data reveal the formation of a passive inorganic SiO2 layer on the POSS/PDMS hybrid films during the AO exposure, which serves as a protective barrier preventing further degradation of the underlying polymer with increased exposure to the AO flux. The erosion yield of the POSS/PDMS (20 wt%) hybrid film was 1.7×10-26 cm3/atom, decreased by two orders of magnitude compared with the value of 3.0×10-24 cm3/atom of the polyimide film.

Surface chemical states of barium titanate: Influence of sample processing

1995 ◽  
Vol 10 (6) ◽  
pp. 1502-1507 ◽  
Author(s):  
Sharmila M. Mukhopadhyay ◽  
Tim C.S. Chen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Reduction ◽  
Surface Region ◽  
Annealing Atmosphere ◽  
Near Surface ◽  
X Ray ◽  
Reducing Atmosphere ◽  
Special Surface ◽  
Chemical States ◽  
Photoelectron Peak

The composition and chemistry of the near-surface region of BaTiO3 have been studied using x-ray photoelectron spectroscopy (XPS). It is found that the Ba3d photoclectron peak shows two chemical states, one of which is attributed to the bulk perovskite and the other to a special surface state unrelated to contamination. The bulk component is reduced and the surface component increases when the material is annealed at high temperatures (either in reducing or oxidizing atmosphere). Both the components are unaltered if the sample is exposed to air, solvents, or water: processes that lead to adsorption of impurities. The surface peak, therefore, attributed to a relaxation related and not contamination-related state, has been compared with those in other Ba-containing oxides. The oxygen photoelectron peak consists of a normal perovskite peak typical of most titanates and a higher energy component clearly related to surface contamination. Annealing in reducing atmosphere results in drastically different optical and electrical properties, and in chemical reduction of some Ti4+ ions to Ti3+. The overall stoichiometry, however, does not change with annealing atmosphere. These results have been discussed in light of our current understanding of this and other related oxides.

Spectroscopic Ellipsometry Study of HgCdTe Epilayer Surfaces During Electron Cyclotron Resonance Plasma Etching

1996 ◽  
Vol 450 ◽  
Author(s):  
J. N. Johnson ◽  
J. H. Dinan ◽  
K. M. Singley ◽  
M. Martinka ◽  
B. Johs
Keyword(s):  
Plasma Etching ◽  
Photoelectron Spectroscopy ◽  
Cyclotron Resonance ◽  
Electron Cyclotron Resonance ◽  
Surface Region ◽  
Auger Spectroscopy ◽  
Electron Cyclotron ◽  
Ex Situ ◽  
Process Conditions ◽  
Near Surface

ABSTRACTSpectroscopie ellipsometry has been used to monitor optical characteristics of HgCdTe surfaces during plasma etching in an electron cyclotron resonance reactor. Commonly used process conditions were found to induce changes in the ellipsometric parameters Δ and φ. A model was constructed to account for these changes in terms of process-induced roughness and mercury depleted sub-surface layers An independent characterization of the near-surface region was earned out ex situ after etching using Auger spectroscopy and x-ray photoelectron spectroscopy. Plasma process parameters were varied to isolate their influence on surface conditions and a set of parameters is given for which changes are minimized.

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