Isotope-induced partial localization of core electrons in the homonuclear molecule N2

Nature ◽  
2005 ◽  
Vol 437 (7059) ◽  
pp. 711-715 ◽  
Author(s):  
Daniel Rolles ◽  
Markus Braune ◽  
Slobodan Cvejanović ◽  
Oliver Geßner ◽  
Rainer Hentges ◽  
...  
Keyword(s):  
Core Electrons ◽  
Homonuclear Molecule

Extended Core Edge Fine Structure in the E.M.

1980 ◽  
Vol 38 ◽  
pp. 120-121
Author(s):  
R.D. Leapman
Keyword(s):  
Fine Structure ◽  
Electron Scattering ◽  
Inelastic Electron ◽  
High Resolution Imaging ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Core Electrons ◽  
Resolution Imaging ◽  
X Ray Absorption

Extended X-ray Absorption Fine Structure (EXAFS) analysis makes use of synchrotron radiaion to measure modulations in the absorption coefficient above core edges and hence to obtain information about local atomic environments. EXAFS arises when ejected core electrons are backscattered by surrounding atoms and interfere with the outgoing waves. Recently, interest has also been shown in using inelastic electron scattering1-4. Some advantages of Extended X-ray-edge Energy Loss Fine Structure (EXELFS) are: a) small probes formed by the analytical electron microscope give spectra from μm to nm sized areas, compared with mm diameter areas for the X-ray technique, b) EXELFS can be combined with other techniques such as electron diffraction or high resolution imaging, and c) EXELFS is sensitive to low Z elements with K edges from ˜200 eV to ˜ 3000 eV (B to Cl).

Thermal Properties of Divalent Metal Oxides: CaO as a Prototype

2013 ◽  
Vol 209 ◽  
pp. 190-193
Author(s):  
Nisarg K. Bhatt ◽  
Brijmohan Y. Thakore ◽  
P.R. Vyas ◽  
A.Y. Vahora ◽  
Asvin R. Jani
Keyword(s):  
Density Functional ◽  
Tight Binding ◽  
Mean Field ◽  
Field Potential ◽  
Theoretical Data ◽  
Test Case ◽  
Generalized Gradient ◽  
Core Electrons ◽  
Vibrational Free Energy ◽  
Semi Empirical

Commonly employed quasiharmonic approximation (QHA) is inadequate to account for intrinsic anharmonism such as phonon-phonon interaction, vacancy contribution, etc. Though anharmonic contributions are important at high temperatures and low pressure, complete ab initio calculations are scanty due largely to laborious computational requirements. Nevertheless, some simple semi-empirical schemes can be used effectively to incorporate the anharmonism. In this regards, in the present study we have proposed a simple computational scheme to include the effect of vacancy directly into the description within the mean-field potential approach, which calculates vibrational free energy of ions. Validity of the scheme is verified by taking calcium oxide as a test case. Equilibrium properties at (T,P) = (0,0) condition is obtained within the tight-binding second-moment approximation (TB-SMA), whose parameters were determined through first principles density functional theory. Kohn-Sham equations for core electrons were solved using ultrasoft plane-wave pseudopotential employing the generalized gradient approximation for exchange and correlation. Present findings for thermal expansion and high-T EOS clearly show perceptible improvement over the case when vacancy contribution was not included. Some related thermodynamic properties are also calculated and compared with the available experimental and theoretical data.

History and Cross-Disciplinary Perspective of Compositional Imaging and Mapping With Nexafs Microscopy

1998 ◽  
Vol 4 (S2) ◽  
pp. 154-155
Author(s):  
H. Ade
Keyword(s):  
Electronic Structures ◽  
Chemical Shifts ◽  
Electronic States ◽  
Inorganic Materials ◽  
Chemical Bonds ◽  
Fundamental Physics ◽  
X Ray ◽  
Disciplinary Perspective ◽  
Core Electrons ◽  
X Ray Absorption

In Near Edge X-ray Absorption Fine Structure (NEXAFS) microscopy, excitations of core electrons into unoccupied molecular orbitals or electronic states provide sensitivity to a wide variety of chemical functionalities in molecules and solids. This sensitivity complements infrared (IR) spectroscopy, although the NEXAFS spectra are not quite as specific and “rich” as IR spectra. The sensitivity of NEXAFS to distinguish chemical bonds and electronic structures covers a wide variety of samples: from metals to inorganics and organics. (There is a tendency in the community to use the term NEXAFS for soft x-ray spectroscopy of organic materials, while for inorganic materials or at higher energies X-ray Absorption Near Edge Spectroscopy (XANES) is utilized, even though the fundamental physics is the same.) The sensitivity of NEXAFS is particularly high to distinguish saturated from unsaturated bonds. NEXAFS can also detect conjugation in a molecule, as well as chemical shifts due to heteroatoms.

Positron Annihilation with Core Electrons in the Noble Metals

1974 ◽  
Vol 52 (4) ◽  
pp. 336-339 ◽  
Author(s):  
E. H. Becker ◽  
A. G. Gould ◽  
E. M. D. Senicki ◽  
B. G. Hogg
Keyword(s):  
Simple Model ◽  
Fermi Surface ◽  
Single Crystals ◽  
Positron Annihilation ◽  
Angular Correlation ◽  
Noble Metals ◽  
Correlation Data ◽  
Core Electrons

Experimental angular correlation curves for identically oriented single crystals of copper, silver, and gold have been obtained using "a point geometry" apparatus. The differences between these angular correlation data are compared to the differences predicted using a simple model of the Fermi surface combined with calculations of the theoretical core distributions.

Auger electron angular distributions following excitation or ionization from the Xe 3d and F 1s levels in xenon difluoride

2022 ◽  
Author(s):  
Ruaridh Forbes ◽  
Paul Hockett ◽  
Ivan Powis ◽  
John D. Bozek ◽  
Stephen T. Pratt ◽  
...  
Keyword(s):  
Electron Spectroscopy ◽  
Auger Electron ◽  
Angular Distributions ◽  
Xenon Difluoride ◽  
Core Electrons ◽  
Molecular Bonding

Electron spectroscopy following Xe 3d and F 1s ionization in XeF2 elucidates the influence of core electrons on molecular bonding.

The effect of core electrons on the spin transfer parameters

1982 ◽  
Vol 60 (5) ◽  
pp. 636-639 ◽  
Author(s):  
M. E. Ziaei
Keyword(s):  
Hyperfine Interaction ◽  
Electron Distribution ◽  
Spin Transfer ◽  
Unpaired Spin ◽  
Core Electrons ◽  
Transfer Parameters

ENDOR measurements and covalency arguments have been used to investigate the electron distribution in CsCdF3 crystals containing Mn2+ and Ni2+. The bond structure is of the form M—F−—Cd2+ (M = Mn2+ or Ni2+) and the measured isotropic supertransferred hyperfine interaction (sthfi) at the Cd site is related to the unpaired spin fraction fσ in the 2pσ orbital of F− by three different theoretical approximations. In these three methods it is assumed that [Formula: see text] orbital of the 3d ion, and the 2pz orbital of the F− ion make eovalent bonds with the (4s), (3s,4s,5s), and (1s,2s,3s,4s,5s) sets of orbitals of the Cd2+ ion respectively. The results show that cadmium core s electrons make important contributions to the isotropic sthfi. However, it seems that fσ values obtained are fairly insensitive to the approximations used.

scholarly journals Towards the Search for Thallium Nuclear Schiff Moment in Polyatomic Molecules: Molecular Properties of Thallium Monocyanide (TlCN)

Atoms ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 62 ◽  
Author(s):  
A. Kudrin ◽  
A. Zaitsevskii ◽  
T. Isaev ◽  
D. Maison ◽  
L. Skripnikov
Keyword(s):  
Inner Core ◽  
Molecular Properties ◽  
Basis Set ◽  
Cluster Method ◽  
Coupled Cluster ◽  
The Core ◽  
Complete Basis Set ◽  
Core Electrons ◽  
Complete Basis Set Limit ◽  
Potential Energy Minimum

Molecular properties of the thallium monocyanide (Tl·CN) system in its ground electronic state are studied using high-precision ab initio relativistic two-component pseudopotential replacing 60 inner-core electrons of Tl. A relativistic coupled-cluster method with single, double and perturbative triple amplitudes is employed to account for electronic correlations. Extrapolation of results to the complete basis set limit is used for all studied properties. The global potential energy minimum of Tl·CN corresponds to the linear cyanide (TlCN) isomer, while the non-rigid isocyanide-like (TlNC) structure lies by approximately 11 kJ/mol higher in energy. The procedure of restoration of the wavefunction in the “core” region of Tl atom was applied to calculate the interaction of the Tl nuclear Schiff moment with electrons. The parameter X of the interaction of the Tl nuclear Schiff moment with electrons in the linear TlCN molecule equals 7150 a.u. The prospects of using the TlCN molecule for the experimental detection of the nuclear Schiff moment are discussed.

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