THE VIBRATIONAL DYNAMICS OF THE ORDERED METALLIC Pd/Cu(100) SURFACE ALLOYS

2012 ◽  
Vol 19 (01) ◽  
pp. 1250007
Author(s):  
R. CHADLI ◽  
A. KHATER ◽  
R. TIGRINE
Keyword(s):  
Local Density ◽  
Matching Theory ◽  
Metallic Surface ◽  
Surface Boundary ◽  
Surface Alloys ◽  
Vibrational Dynamics ◽  
Boundary Force ◽  
Catalyzed Reactions ◽  
Pure Cu ◽  
Density Of Phonon States

The vibrational properties of the three ordered metallic surface alloys, Cu(100) -c(2 × 2)- Pd , Cu(100)-(2 × 1)-Pd , and Cu(100)-(2 × 2)-Pd , are presented. The phonon dispersions of vibrational modes as well as the local density of phonon states (LDOS) are calculated using matching theory associated with Green's function formalism. The calculated results are discussed and interpreted. In particular, the transfer of charge between the Pd and Cu atoms in the surface alloys modifies the surface boundary force constants, with resultant remarkable differences for the vibrational LDOS on the Pd and Cu atomic sites at the Pd/Cu(100) surface, compared to the LDOS at the pure Cu(100) surface. This may favor new Pd -catalyzed reactions at such surface alloys systems.

SURFACE PHONONS IN THE ORDERED c(2 × 2) PHASE OF Pd ON Au(100)

2013 ◽  
Vol 20 (02) ◽  
pp. 1350019 ◽  
Author(s):  
R. CHADLI ◽  
A. KHATER ◽  
R. TIGRINE
Keyword(s):  
Local Density ◽  
Structural Characteristics ◽  
Harmonic Approximation ◽  
Surface Alloy ◽  
Matching Theory ◽  
Metallic Surface ◽  
Vibrational Properties ◽  
High Symmetry ◽  
Surface Modes ◽  
Density Of Phonon States

The vibrational properties of the Au(100)-c(2 × 2)-Pd ordered phase, which is a stable system in the temperature range of 500 K to 600 K, are presented. This surface alloy is formed by depositing Pd atoms onto the Au(100) surface, and annealing at higher temperatures. The equilibrium structural characteristics, phonon dispersions as well as the local density of phonon states are calculated using the matching theory associated with Green's function formalism evaluated in the harmonic approximation. New surface modes have been found on the ordered metallic surface alloy along the three directions of high symmetry [Formula: see text], [Formula: see text], and [Formula: see text], in comparison with the clean surface Au(100) . Three of them are observed above the bulk bands spectrum.

Vibrational dynamics of crystalline silicon dioxide with charged Ge impurities

2016 ◽  
Vol 30 (30) ◽  
pp. 1650206
Author(s):  
A. N. Kislov
Keyword(s):  
Silicon Dioxide ◽  
Atomic Structure ◽  
Lattice Dynamics ◽  
Crystalline Silicon ◽  
Local Density ◽  
Local Atomic Structure ◽  
Vibrational States ◽  
Vibrational Dynamics ◽  
Equilibrium Structures ◽  
Localized Vibrations

The effects of differently charged Ge impurities on the local atomic structure and lattice dynamics of [Formula: see text]-quartz were studied. We have determined the equilibrium structures and calculated the symmetrized local density of vibrational states for the Ge-doped [Formula: see text]-quartz. The frequencies of localized vibrations of [Formula: see text]- and [Formula: see text]-symmetries induced by Ge impurities were obtained. Besides, we have analyzed what contribution the vibrations of atoms located around the Ge impurities make to the localized symmetrized vibrations.

Vibrational dynamics of a stepped metallic surface: Step‐edge phonons and terrace softening on Ni(977)

1995 ◽  
Vol 102 (22) ◽  
pp. 9077-9089 ◽  
Author(s):  
L. Niu ◽  
D. D. Koleske ◽  
D. J. Gaspar ◽  
S. J. Sibener
Keyword(s):  
Step Edge ◽  
Metallic Surface ◽  
Vibrational Dynamics ◽  
Surface Step

scholarly journals Composite materials on the manufacturing of metallic surface alloys

2020 ◽  
Author(s):  
O.S.I. Fayomi ◽  
K.O. Babaremu ◽  
I.G. Akande ◽  
A.P.I Popoola
Keyword(s):  
Composite Materials ◽  
Metallic Surface ◽  
Surface Alloys

A vibrational dynamics of molecule chain on metallic surface

2012 ◽  
Vol 57 (2) ◽  
pp. 20701
Author(s):  
D. Zerirgui ◽  
R. Tigrine ◽  
B. Bourahla ◽  
A. Khater
Keyword(s):  
Metallic Surface ◽  
Vibrational Dynamics

Electronic structure and atomic positions of metallic surface alloys

2008 ◽  
Vol 281 (1-2) ◽  
pp. 9-13 ◽  
Author(s):  
M.F. Carazzolle ◽  
G.G. Kleiman ◽  
R. Landers ◽  
A. Pancotti ◽  
A. de Siervo ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Metallic Surface ◽  
Surface Alloys

scholarly journals Isolated copper–tin atomic interfaces tuning electrocatalytic CO2 conversion

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Wenhao Ren ◽  
Xin Tan ◽  
Jiangtao Qu ◽  
Sesi Li ◽  
Jiantao Li ◽  
...  
Keyword(s):  
Surface Science ◽  
Interface Design ◽  
Density Functional ◽  
High Surface ◽  
Critical Role ◽  
Single Atom ◽  
Surface Alloys ◽  
Functional Theory ◽  
Faradaic Efficiency ◽  
Pure Cu

AbstractDirect experimental observations of the interface structure can provide vital insights into heterogeneous catalysis. Examples of interface design based on single atom and surface science are, however, extremely rare. Here, we report Cu–Sn single-atom surface alloys, where isolated Sn sites with high surface densities (up to 8%) are anchored on the Cu host, for efficient electrocatalytic CO2 reduction. The unique geometric and electronic structure of the Cu–Sn surface alloys (Cu97Sn3 and Cu99Sn1) enables distinct catalytic selectivity from pure Cu100 and Cu70Sn30 bulk alloy. The Cu97Sn3 catalyst achieves a CO Faradaic efficiency of 98% at a tiny overpotential of 30 mV in an alkaline flow cell, where a high CO current density of 100 mA cm−2 is obtained at an overpotential of 340 mV. Density functional theory simulation reveals that it is not only the elemental composition that dictates the electrocatalytic reactivity of Cu–Sn alloys; the local coordination environment of atomically dispersed, isolated Cu–Sn bonding plays the most critical role.

Vibrational dynamics of alpha-quartz with neutral silicon vacancies

2017 ◽  
Vol 31 (33) ◽  
pp. 1750315
Author(s):  
A. Kislov
Keyword(s):  
Atomic Structure ◽  
Local Structure ◽  
Lattice Dynamics ◽  
Theoretical Study ◽  
Local Density ◽  
Vibrational States ◽  
Vibrational Dynamics ◽  
Localized Vibrations

The effects of neutrally charged silicon vacancies on the atomic structure and the lattice dynamics of [Formula: see text]-quartz were studied. This theoretical study focuses on modeling of the equilibrium local structure and the symmetrized local density of vibrational states. The frequencies of localized vibrations of A- and B-symmetries induced by silicon vacancies were obtained. The contribution of atoms located around silicon vacancies in the formation of localized symmetrized vibrations was analyzed.

Vibrational properties at the ordered metallic surface alloy system Au(110)-1×2-Pd

2016 ◽  
Vol 30 (20) ◽  
pp. 1650126 ◽  
Author(s):  
Sedik Kheffache ◽  
Rabah Chadli ◽  
Antoine Khater
Keyword(s):  
Phonon Dispersion ◽  
Harmonic Approximation ◽  
Reaction Rates ◽  
Surface Alloy ◽  
Matching Theory ◽  
Metallic Surface ◽  
Spectral Signature ◽  
Vibrational Properties ◽  
High Symmetry ◽  
Surface Phonon

We present a calculation for the vibrational properties of the ordered surface alloy Au(110)-1×2-Pd on a crystalline substrate of Au. The surface phonon dispersion curves and the local vibrations densities of states (LDOS) are calculated in the harmonic approximation for the system, using the phase field matching theory (PFMT) method and associated real space Green’s functions. In particular, it is shown that the surface alloy presents optic vibrational modes above the Au bulk bands, along the directions of high-symmetry [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] of the corresponding two-dimensional Brillouin zone. Measurements of the surface phonon dispersion branches can hence be made by different techniques such as helium atom scattering (HAS) to compare with. The calculated LDOS for Au and Pd atomic sites in the four top surface atomic layers span a wider range of frequencies than those for the individual Au(110) or Pd(110) metallic surfaces. These LDOS provide a spectral signature for the progressive transition from the surface dynamics to that of the Au crystal bulk. Knowledge of these LDOS for the surface alloy can also serve as an input for modeling the diffusion and reaction rates of chemical species at its surface.

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