FEASIBILITY STUDIES OF THE THREE-DIMENSIONAL DETECTOR FOR SOFT X-RAY EMISSION SPECTROSCOPY

2002 ◽  
Vol 09 (01) ◽  
pp. 515-520
Author(s):  
M. OURA ◽  
K. KOBAYASHI ◽  
M. WATANABE ◽  
Y. HARADA ◽  
T. SUZUKI ◽  
...  
Keyword(s):  
Emission Spectroscopy ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Feasibility Studies ◽  
Many Body ◽  
Pump Probe ◽  
X Ray ◽  
Electron Hole Plasma ◽  
The Many ◽  
Many Body Interactions

A time-resolving two-dimensional position-sensitive detector was applied to soft X-ray emission spectroscopy (SXES) and its feasibility was successfully studied by using synchrotron radiation. A soft X-ray emission spectrum synchronously acquired with bunch signal of the storage ring has elucidated that a threefold higher signal-to-noise ratio could at least be achieved. By adopting a pump–probe technique to SXES, we have preliminarily studied the effect of the electron–hole plasma (EHP) on the Si 2p soft X-ray emitting processes of Si crystal. A meaningful change in the excitation curve for the elastic scattering yields near the 2p thresholds was found to be probably due to the many-body interactions caused by the EHP.

scholarly journals Layer-resolved many-electron interactions in delafossite PdCoO2 from standing-wave photoemission spectroscopy

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Qiyang Lu ◽  
Henrique Martins ◽  
Juhan Matthias Kahk ◽  
Gaurab Rimal ◽  
Seongshik Oh ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Standing Wave ◽  
Three Dimensional ◽  
Photoemission Spectroscopy ◽  
Electronic Coupling ◽  
Many Body ◽  
X Ray ◽  
Charge Transfer Excitons ◽  
Many Body Interactions ◽  
Electron Interactions

AbstractWhen a three-dimensional material is constructed by stacking different two-dimensional layers into an ordered structure, new and unique physical properties can emerge. An example is the delafossite PdCoO2, which consists of alternating layers of metallic Pd and Mott-insulating CoO2 sheets. To understand the nature of the electronic coupling between the layers that gives rise to the unique properties of PdCoO2, we revealed its layer-resolved electronic structure combining standing-wave X-ray photoemission spectroscopy and ab initio many-body calculations. Experimentally, we have decomposed the measured VB spectrum into contributions from Pd and CoO2 layers. Computationally, we find that many-body interactions in Pd and CoO2 layers are highly different. Holes in the CoO2 layer interact strongly with charge-transfer excitons in the same layer, whereas holes in the Pd layer couple to plasmons in the Pd layer. Interestingly, we find that holes in states hybridized across both layers couple to both types of excitations (charge-transfer excitons or plasmons), with the intensity of photoemission satellites being proportional to the projection of the state onto a given layer. This establishes satellites as a sensitive probe for inter-layer hybridization. These findings pave the way towards a better understanding of complex many-electron interactions in layered quantum materials.

Revealing the many-body interactions and valley-polarization behavior in Re-doped MoS2 monolayers

2021 ◽  
Vol 118 (11) ◽  
pp. 113101
Author(s):  
Xiaoli Zhu ◽  
Siting Ding ◽  
Lihui Li ◽  
Ying Jiang ◽  
Biyuan Zheng ◽  
...  
Keyword(s):  
Many Body ◽  
Polarization Behavior ◽  
Valley Polarization ◽  
Mos2 Monolayers ◽  
The Many ◽  
Many Body Interactions

Dislocation Generation and Crack Propagation in Metals Examined in Molecular Dynamics Simulations

1992 ◽  
Vol 278 ◽  
Author(s):  
J. A. Rifkin ◽  
C. S. Becquart ◽  
D. Kim ◽  
P. C. Clapp
Keyword(s):  
Crack Propagation ◽  
Atomistic Simulations ◽  
Many Body ◽  
Dislocation Generation ◽  
Embedded Atom ◽  
Stress Levels ◽  
Different Temperatures ◽  
The Many ◽  
Dynamics Simulations ◽  
Many Body Interactions

AbstractWe have carried out a series of atomistic simulations on arrays of about 10,000 atoms containing an atomically sharp crack and subjected to increasing stress levels. The ordered stoichiometric alloys B2 NiAl, B2 RuAl and A15 Nb3AI have been studied at different temperatures and stress levels, as well as the elements Al, Ni, Nb and Ru. The many body interactions used in the simulations were derived semi-empirically, using techniques related to the Embedded Atom Method. Trends in dislocation generation rates and crack propagation modes will be discussed and compared to experimental indications where possible, and some of the simulations will be demonstrated in the form of computer movies.

Possible weakening of the many-body interactions in the organic quasi-two-dimensional metal α-(BETS)2NH4Hg(SCN)4

2009 ◽  
Vol 109 (4) ◽  
pp. 664-666 ◽  
Author(s):  
S. I. Pesotskiĭ ◽  
R. B. Lyubovskiĭ ◽  
M. V. Kartsovnik ◽  
W. Biberacher ◽  
N. D. Kushch ◽  
...  
Keyword(s):  
Two Dimensional ◽  
Many Body ◽  
The Many ◽  
Many Body Interactions

scholarly journals The Resolution in X-ray Crystallography and Single-Particle Cryogenic Electron Microscopy

Crystals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 580
Author(s):  
Victor R.A. Dubach ◽  
Albert Guskov
Keyword(s):  
Electron Microscopy ◽  
Single Particle ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Particle Analysis ◽  
Biological Macromolecules ◽  
Single Particle Analysis ◽  
X Ray ◽  
X Ray Crystallography ◽  
The Fourier Transform

X-ray crystallography and single-particle analysis cryogenic electron microscopy are essential techniques for uncovering the three-dimensional structures of biological macromolecules. Both techniques rely on the Fourier transform to calculate experimental maps. However, one of the crucial parameters, resolution, is rather broadly defined. Here, the methods to determine the resolution in X-ray crystallography and single-particle analysis are summarized. In X-ray crystallography, it is becoming increasingly more common to include reflections discarded previously by traditionally used standards, allowing for the inclusion of incomplete and anisotropic reflections into the refinement process. In general, the resolution is the smallest lattice spacing given by Bragg’s law for a particular set of X-ray diffraction intensities; however, typically the resolution is truncated by the user during the data processing based on certain parameters and later it is used during refinement. However, at which resolution to perform such a truncation is not always clear and this makes it very confusing for the novices entering the structural biology field. Furthermore, it is argued that the effective resolution should be also reported as it is a more descriptive measure accounting for anisotropy and incompleteness of the data. In single particle cryo-EM, the situation is not much better, as multiple ways exist to determine the resolution, such as Fourier shell correlation, spectral signal-to-noise ratio and the Fourier neighbor correlation. The most widely accepted is the Fourier shell correlation using a threshold of 0.143 to define the resolution (so-called “gold-standard”), although it is still debated whether this is the correct threshold. Besides, the resolution obtained from the Fourier shell correlation is an estimate of varying resolution across the density map. In reality, the interpretability of the map is more important than the numerical value of the resolution.

scholarly journals Cliques Are Bricks for k-CT Graphs

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1160
Author(s):  
Václav Snášel ◽  
Pavla Dráždilová ◽  
Jan Platoš
Keyword(s):  
Complex Networks ◽  
Simplicial Complex ◽  
Dynamic Properties ◽  
Simplicial Complexes ◽  
Many Body ◽  
Chemistry Industry ◽  
The Past ◽  
Pairwise Interactions ◽  
The Many ◽  
Many Body Interactions

Many real networks in biology, chemistry, industry, ecological systems, or social networks have an inherent structure of simplicial complexes reflecting many-body interactions. Over the past few decades, a variety of complex systems have been successfully described as networks whose links connect interacting pairs of nodes. Simplicial complexes capture the many-body interactions between two or more nodes and generalized network structures to allow us to go beyond the framework of pairwise interactions. Therefore, to analyze the topological and dynamic properties of simplicial complex networks, the closed trail metric is proposed here. In this article, we focus on the evolution of simplicial complex networks from clicks and k-CT graphs. This approach is used to describe the evolution of real simplicial complex networks. We conclude with a summary of composition k-CT graphs (glued graphs); their closed trail distances are in a specified range.

scholarly journals A hybrid model of Skyrme- and Brueckner-type interactions for neutron star matter

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Soonchul Choi ◽  
Myung-Ki Cheoun ◽  
K S Kim ◽  
Hungchong Kim ◽  
H Sagawa
Keyword(s):  
Neutron Star ◽  
Hybrid Model ◽  
Clear Understanding ◽  
Neutron Skin ◽  
Neutron Star Matter ◽  
Many Body ◽  
Hartree Fock ◽  
Nuclear Incompressibility ◽  
The Many ◽  
Many Body Interactions

Abstract We suggest a hybrid model for neutron star matter to discuss the hyperon puzzle inherent in the 2.0 M$_{\odot}$ of the neutron star. For the nucleon–nucleon ($NN$) interaction, we employ the Skyrme–Hartree–Fock approach based on various Skyrme interaction parameter sets, and take the Brueckner–Hartree–Fock approach for the interactions related to hyperons. For the many-body interactions including hyperons, we make use of the multi-pomeron-exchange model, whose parameters have been adjusted to the data deduced from various hypernuclei properties. For clear understanding of the physics in the hybrid model, we discuss fractional functions of related particles, symmetry energies, and chemical potentials in dense matter. Finally, we investigate the equations of state and mass–radius relation of neutron stars, and show that the hybrid model can properly describe the 2.0 M$_{\odot}$ neutron star mass data with the many-body interaction employed in the hybrid model. Recent tidal deformability data from the gravitational wave observation are also compared to our calculations, especially in terms of the neutron skin of $^{208}$Pb and nuclear incompressibility.

A Spherically Bent Crystal X-Ray Specteometer with Variable Curvature

1973 ◽  
Vol 17 ◽  
pp. 521-530
Author(s):  
Donald L. Parker
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
High Signal ◽  
X Rays ◽  
X Ray ◽  
Bent Crystal ◽  
Variable Curvature ◽  
The Face ◽  
Low Levels ◽  
And Performance

AbstractThe design and performance of a spherically bent crystal x-ray spectrometer with variable curvature are given. A thin crystal with the diffracting planes parallel to the face is mounted on a vacuum chuck consisting of an O-ring in a brass mounting. A controlled partial vacuum is applied behind the crystal to cause spherical deformation of the lattice. Thus, rays from a point source on the focusing circle are diffracted to a line image also on the focusing circle. The differential pressure is automatically varied such that the source-to-crystal and crystal-to-image distances are equal and constant for all Bragg angles and hence the simple θ-2θ motion of a one flat crystal spectrometer is used.The data are accumulated by a scanning proportional counter tube placed behind a vertical slit (perpendicular to the scattering plane) located at the image line. The fixed chord length is 22 cm and the instrument is designed to scan from zero up to 120° 2θ. Crystals are easily interchanged and the automatic vacuum regulator has sufficient flexibility to allow tailoring the spherical bending to crystals of materials of various thicknesses. The resolution is easily adjusted by either the size of the x-ray source or the width of the detector slit. The performance of the spectrometer has been evaluated by characteristic x-rays produced by various samples placed in a demountable x-ray tube. The main advantages of this three-dimensional focusing instrument are the very high signal-to-noise ratio and the very low levels of x-ray flux required.

First Principles Calculation of Phase Stability of High Temperature Intermetallic Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
J. Mikalopas ◽  
P.A. Sterne ◽  
M. Sluiter ◽  
P.E.A. Turchi
Keyword(s):  
First Principles ◽  
Strong Dependence ◽  
Cluster Variation Method ◽  
First Principles Calculation ◽  
Variation Method ◽  
Many Body ◽  
Coherent Phase Diagram ◽  
Cluster Variation ◽  
The Many ◽  
Many Body Interactions

ABSTRACTOne way to calculate the coherent phase diagram of an alloy based on first principles methods is to compute the ground state total energy for various ordered configurations, from which many-body interactions can be calculated and employed in a thermodynamic model. If the Connolly and Williams method (CWM) is used to extract the many-body interactions from the calculated total energies, the resulting many-body interactions can exhibit a strong dependence on the choice of ordered configurations and multi-site clusters, and the accuracy and convergence of the CWM energy expansion is not assured. To overcome this difficulty, a successful systematic method for implementing the CWM is proposed. This approach is applied to a study of the fcc-based Ni-V and Pd-V substitutional alloys and these interaction parameters together with the cluster variation method (CVM) are used to calculate phase diagrams.

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