Synchrotron Photoemission Studies of Surfaces and Overlayers

1988 ◽  
Vol 143 ◽  
Author(s):  
T.-C. Chiang
Keyword(s):  
High Resolution ◽  
Binding Energy ◽  
Electronic Properties ◽  
Atomic Structure ◽  
Chemical Shifts ◽  
Quantitative Description ◽  
Photoemission Spectroscopy ◽  
Electronegativity Difference ◽  
Model Structures ◽  
Reference Samples

AbstractHigh-resolution core-level photoemission spectroscopy allows the distinction of atoms in different layers and in inequivalent sites by their binding energy shifts. By comparison with model structures and reference samples, the number of atoms in each distinct chemical configuration can be determined. The chemical shifts induced by adsorption can be correlated with the electronegativity difference between the substrate and the adsorbate atoms. These observations provide a quantitative description of the interaction and reaction between adsorbates and surfaces, and important information about the atomic structure and the electronic properties can be deduced. Results from several representative systems including the adsorption of In, Ag, and Sn on Si(100) will be discussed.

High Resolution Photoelectron Study of the Optimum Oxygen Doping Levels in High Tc Superconductors

1993 ◽  
Vol 307 ◽  
Author(s):  
R. J. Kelley ◽  
X. C. Cai ◽  
Jian Ma ◽  
D. C. Larbalestier ◽  
M. Onellion
Keyword(s):  
High Resolution ◽  
Electronic Properties ◽  
Cuprate Superconductors ◽  
Underlying Mechanism ◽  
Oxygen Stoichiometry ◽  
Photoemission Spectroscopy ◽  
Standard Material ◽  
Resonant Photoemission ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Photoelectron Study

ABSTRACTThe materials and electronic properties of the new cuprate superconductors are critically dependent upon both the oxygen stoichiometry and annealing history of the material. Improving Jc, Tc, and determining the underlying mechanism of superconductivity depend on a better understanding of these effects. In the study of Bi2Sr2CaCu2O8-δ we have combined standard material characterization techniques with high resolution angle resolved photoemission spectroscopy and resonant photoemission spectroscopy to illuminate these issues. Specifically, we make high quality single crystals of BSCCO and then anneal in different atmospheres and pressures. We correlate this with c-axis resistivity, a, b-plane resistivity, and resonant photoemission spectroscopy. In this way we can explain the macroscopic transport properties in terms of the electronic properties of the material determined from photoemission. We find that we can change the c-axis resistivity from non-metallic to metallic by adding oxygen and that this correlates with increased oscillator strength in the c-axis direction at the Fermi level.

Atomic Structure of the (310) Twin in Niobium: Theoretical Predictions and Comparison with Experimental Observation

1992 ◽  
Vol 295 ◽  
Author(s):  
Geoffrey H. Campbell ◽  
S. M. Foiles ◽  
M. Rühle ◽  
W. E. King
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Atomic Structure ◽  
Mirror Symmetry ◽  
Interatomic Potentials ◽  
Pseudopotential Theory ◽  
Embedded Atom ◽  
Transmission Electron ◽  
Theoretical Predictions ◽  
Model Structures

AbstractHigh - resolution transmission electron microscopy (HREM) has been used to characterize the atomic structure of the symmetric 36.9° tilt grain boundary with [001] tilt axes forming a twin about (310) in Nb. The projected structure was imaged along two different directions in the plane of the boundary and was compared to model structures through high - resolution image simulation. The atomic structure of this Σ5 boundary was predicted with atomistic simulations using interatomic potentials derived from the Embedded Atom Method (EAM), Finnis-Sinclair (FS), and the Model Generalized Pseudopotential Theory (MGPT). The EAM and FS predicted structures with translations of the adjacent crystals which break mirror symmetry. The MGPT predicted one stable structure with mirror symmetry. The atomic structure of the (310) twin in Nb was found by HREM to be mirror symmetric. These findings indicate that the angular dependent interactions modeled in the MGPT are important for determining the grain boundary structures of bcc transition metals.

scholarly journals X-ray Photoemission Spectroscopy Study of Uniaxial Magnetic Anisotropy Induced in a Ni Layer Deposited on a LiNbO3 Substrate

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1024
Author(s):  
Akinobu Yamaguchi ◽  
Takuo Ohkochi ◽  
Masaki Oura ◽  
Keisuke Yamada ◽  
Tsunemasa Saiki ◽  
...  
Keyword(s):  
Binding Energy ◽  
Magnetic Anisotropy ◽  
Chemical Shifts ◽  
Ferromagnetic Layer ◽  
Magnetic Domain ◽  
Ferroelectric Materials ◽  
Photoemission Spectroscopy ◽  
Uniaxial Magnetic Anisotropy ◽  
X Ray ◽  
Domain Structures

The competition between magnetic shape anisotropy and the induced uniaxial magnetic anisotropy in the heterojunction between a ferromagnetic layer and a ferroelectric substrate serves to control magnetic domain structures as well as magnetization reversal characteristics. The uniaxial magnetic anisotropy, originating from the symmetry breaking effect in the heterojunction, plays a significant role in modifying the characteristics of magnetization dynamics. Magnetoelastic phenomena are known to generate uniaxial magnetic anisotropy; however, the interfacial electronic states that may contribute to the uniaxial magnetic anisotropy have not yet been adequately investigated. Here, we report experimental evidence concerning the binding energy change in the ferromagnetic layer/ferroelectric substrate heterojunction using X-ray photoemission spectroscopy. The binding energy shifts, corresponding to the chemical shifts, reveal the binding states near the interface. Our results shed light on the origin of the uniaxial magnetic anisotropy induced from the heterojunction. This knowledge can provide a means for the simultaneous control of magnetism, mechanics, and electronics in a nano/microsystem consisting of ferromagnetic/ferroelectric materials.

scholarly journals The electronic properties of mixed valence hydrated europium chloride thin film

2015 ◽  
Vol 17 (28) ◽  
pp. 18403-18412 ◽  
Author(s):  
M. G. Silly ◽  
F. Charra ◽  
F. Lux ◽  
G. Lemercier ◽  
F. Sirotti
Keyword(s):  
Thin Film ◽  
High Resolution ◽  
Electronic Properties ◽  
Mixed Valence ◽  
Photoemission Spectroscopy ◽  
Resonant Photoemission ◽  
Europium Chloride ◽  
The Eu

We investigate the electronic properties of a model mixed-valence hydrated chloride europium salt by means of high resolution photoemission spectroscopy (HRPES) and resonant photoemission spectroscopy (RESPES) at the Eu 3d → 4f and 4d → 4f transitions.

High-Resolution Core Level Studies of Interdiffusion and Reaction at Metal-Semiconductor Interfaces

1986 ◽  
Vol 77 ◽  
Author(s):  
M. Del Giudice ◽  
J. J. Joyce ◽  
F. Boscherini ◽  
C. Capasso ◽  
J. H. Weaver
Keyword(s):  
High Resolution ◽  
Binding Energy ◽  
Refractory Metal ◽  
Room Temperature ◽  
Chemical Shifts ◽  
Microscopic Investigation ◽  
Core Level ◽  
Semiconductor Surface ◽  
Intensity Attenuation ◽  
Semiconductor Interfaces

ABSTRACTWe present a detailed microscopic investigation of interactions and reactions occurring at refractory-metal silicon interfaces at room temperature. High resolution core level photoemission results for Ti coverages in the range 0.2–16 monolayers on cleaved Si(111)2×1 show that three new distinct Si environments are created by semiconductor surface disruption. In agreement with heats of formation or electronegativity differences, all the chemical shifts are at lower binding energy. Each of them represents a different metal-Si coordination or configuration. Analogous results for Sc overlayers indicate that at least two reacted species are present. For both Ti and Sc, the reaction is started at submonolayer coverages. Analysis of the Si 2p intensity attenuation curves shows an evolution characterized by the sequential growth of the different species. Indeed, each species grows, reaches saturation, and is then attenuated. This is associated with the competition between diffusion and reaction at the interface.

HIGH RESOLUTION CORE LEVEL SPECTROSCOPY AT THE Cu/Ru(0001) INTERFACE

2002 ◽  
Vol 09 (02) ◽  
pp. 723-727 ◽  
Author(s):  
T. H. ANDERSEN ◽  
L. BECH ◽  
J. ONSGAARD ◽  
S. V. HOFFMANN ◽  
Z. LI
Keyword(s):  
High Resolution ◽  
Synchrotron Radiation ◽  
Binding Energy ◽  
Energy Shift ◽  
Core Level ◽  
Photoemission Spectroscopy ◽  
Copper Adsorption ◽  
X Ray ◽  
Level Shifts ◽  
Binding Energy Shift

Copper adsorption on Ru(0001) has been studied by synchrotron radiation. The clean Ru 3d 5/2 spectra were found to consist of two components with a binding energy shift of 400 meV. The component with the lower binding energy represents the first layer of ruthenium atoms. Adsorption of copper gives rise to core level shifts of the Ru 3d 5/2 components, which were studied as a function of Cu coverage. Experiments were carried out with copper coverages varying from the submonolayer range up to two monolayers of copper. The binding energy of the Cu 2p 3/2 level was measured by X-ray photoemission spectroscopy.

Atomic structure imaging of the Si/SiO2 interface with high-resolution electron microscopy

1986 ◽  
Vol 44 ◽  
pp. 390-391
Author(s):  
J.L. Batstone ◽  
J.M. Gibson ◽  
Alice.E. White ◽  
K.T. Short
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Medium Voltage ◽  
Voltage Electron ◽  
Resolution Electron ◽  
Structural Image ◽  
Electron Microscopes ◽  
Point To Point

High resolution electron microscopy (HREM) is a powerful tool for the determination of interface atomic structure. With the previous generation of HREM's of point-to-point resolution (rpp) >2.5Å, imaging of semiconductors in only <110> directions was possible. Useful imaging of other important zone axes became available with the advent of high voltage, high resolution microscopes with rpp <1.8Å, leading to a study of the NiSi2 interface. More recently, it was shown that images in <100>, <111> and <112> directions are easily obtainable from Si in the new medium voltage electron microscopes. We report here the examination of the important Si/Si02 interface with the use of a JEOL 4000EX HREM with rpp <1.8Å, in a <100> orientation. This represents a true structural image of this interface.

Nano-probe x-ray analysis and high-resolution imaging on planar defects in high-pressure synthesized infinite-layer superconductor

1994 ◽  
Vol 52 ◽  
pp. 728-729
Author(s):  
Y. Y. Wang ◽  
H. Zhang ◽  
V. P. Dravid ◽  
H. Zhang ◽  
L. D. Marks ◽  
...  
Keyword(s):  
High Pressure ◽  
High Resolution ◽  
Atomic Structure ◽  
Emission Spectra ◽  
High Resolution Electron Microscopy ◽  
Planar Defects ◽  
X Ray ◽  
Infinite Layer ◽  
Resolution Electron ◽  
Resolution Imaging

Azuma et al. observed planar defects in a high pressure synthesized infinitelayer compound (i.e. ACuO2 (A=cation)), which exhibits superconductivity at ~110 K. It was proposed that the defects are cation deficient and that the superconductivity in this material is related to the planar defects. In this report, we present quantitative analysis of the planar defects utilizing nanometer probe xray microanalysis, high resolution electron microscopy, and image simulation to determine the chemical composition and atomic structure of the planar defects. We propose an atomic structure model for the planar defects.Infinite-layer samples with the nominal chemical formula, (Sr1-xCax)yCuO2 (x=0.3; y=0.9,1.0,1.1), were prepared using solid state synthesized low pressure forms of (Sr1-xCax)CuO2 with additions of CuO or (Sr1-xCax)2CuO3, followed by a high pressure treatment.Quantitative x-ray microanalysis, with a 1 nm probe, was performed using a cold field emission gun TEM (Hitachi HF-2000) equipped with an Oxford Pentafet thin-window x-ray detector. The probe was positioned on the planar defects, which has a 0.74 nm width, and x-ray emission spectra from the defects were compared with those obtained from vicinity regions.

Chemometric Analysis of Substituent Effects. VII. Inductive Effect as a Basic Substituent Effect. Isoeffect Substituent Constant

1995 ◽  
Vol 60 (8) ◽  
pp. 1316-1332 ◽  
Author(s):  
Oldřich Pytela ◽  
Aleš Halama
Keyword(s):  
Inductive Effect ◽  
Chemical Shifts ◽  
Quantitative Description ◽  
Substituent Effects ◽  
Intersection Point ◽  
Chemometric Analysis ◽  
Reaction Centre ◽  
Substituent Constant ◽  
Modified Method ◽  
Substituted Benzoic Acids

The paper deals with chemometric analysis of the inductive effect. The notion of inductive effect is discussed, and unambiguous definitions are given for the notions of triad: reaction centre-basic skeleton-substituent, and the therewith connected definitions of inductive effect. For a quantitative description of inductive effect 7 types of chemical models were selected including noncyclic compounds, cyclic, and bicyclic compounds, derivatives of quinuclidine, 3-substituted benzoic acids, sulfonamides and pyridines. Altogether 139 sets of experimental data from literature have been used including altogether 1 294 points (9.3 points per set, 5 points at least) reflecting substituent effects of 34 substituents. It has been found that for a standard model the dissociation of substituted bicycloalkanecarboxylic acids only is satisfactory, all the other models reflecting also the mesomeric effects to variable extent (up to 10%). A distinctly different substitution behaviour was observed with 19F and 13C NMR chemical shifts of 4-substituted 1-fluoro- or 1-methylbicyclo[2.2.2]octanes. The earlier suggested model of substituent effects based on different way of transmission of substituent effects (3 classes) has been used for separating the inductive and mesomeric effects: it is mathematically presented as a set of straight lines with the intersection point at the so-called isoeffect substituent constant. Using the modified method of conjugated deviations a chemometric scale has been created for the inductive effect which agrees very well with the conventional scales given in literature; the only differences were observed for F and CH=O substituents (which are overestimated and underestimated, respectively, in literature). In the context given the inductive effect appears as a fundamental quantity forming a basis for quantitative description of other effects transferred by electrons.

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