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1
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Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

100%
Wachowicz E., Sznajder M., Majewski J.
Acta Physica Polonica A
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2012
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vol. 122
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issue 6
1045-1048
EN
Changes in the atomic and electronic structure of Si- and C-terminated 4H-SiC{0001} surfaces resulting from aluminium and gallium adsorption have been studied within density functional theory framework. Al and Ga coverages ranging from a submonolayer to one monolayer were considered. Our results show that Al binds more strongly to both surfaces than Ga. The binding is stronger to the C-terminated surface for both metals. The sites occupied by Al and Ga atoms at 1 monolayer are different and it is due to a different charge transfer from metal to the substrate.
2
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Adsorption Properties of the Cu(115) Surface: Basic Interfaces

100%
Godowski P., Groso A., Hoffmann S., Onsgaard J.
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issue 6
928-935
EN
The interfaces: K/Cu(115) and CO/Cu(115) have been characterized using surface sensitive techniques, including low energy electron diffraction and photoelectron spectroscopy. K adatoms show tendency to occupy the sites close to the step edges. At low temperature (near 125 K), after completion of two layers, potassium grows in 3D islands (the Stranski-Krastanov mode). At higher temperature, e.g. at room temperature, potassium introduces reconstruction of the substrate even at low coverages. Calibration of the alkali coverage, up to completion of the first layer, using the work function changes curve has been confirmed as a very convenient and precise procedure. The adsorbed state of CO at 130 K has been identified by registration of core levels obtained by the use synchrotron radiation photoelectron spectroscopy. The characteristics of the main 1s and satellite peaks have been analyzed in context of substrate geometry and compared with the ones of other copper planes. There are no indications of dissociative adsorption of CO, only residual carbon and oxygen were found after adsorbate desorption around 220 K. CO molecules show a strong tendency to "on top" adsorption in sites far from the step edges of the Cu(115) surface.
3
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Theoretical Simulations of 0.25 Monolayer Iodine Adsorption on Cu(100)

100%
Mikołajczyk P., Stankiewicz B.
Acta Physica Polonica A
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2008
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vol. 114
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issue S
S-71-S-76
EN
Simulations of adsorption 0.25 monolayer of iodine on Cu(100) were performed using a local-orbital minimal basis technique based on density functional theory and compared with plane-wave basis results. It was found that iodine adsorption changes the spacings between surface layers of copper substrate and can cause the reconstruction of this surface to rhombus-like arrangement with a stable threefold hollow adsorption site. The calculated structure of I/Cu(100) is presented together with the simulated scanning tunneling microscopy images of this surface. The obtained results are discussed in comparison with experimental results.
4
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Structure Characterization and Catalytic Properties of Cr_2O_3 Doped with MgO Supported on MgF_2

100%
Goslar J., Wojciechowska M., Zieliński M., Tomska-Foralewska I., Przystajko W.
Acta Physica Polonica A
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2005
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vol. 108
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issue 2
323-330
EN
A characterization of double oxide systems containing Cr_2O_3 doped with MgO and supported on MgF_2 was carried out. The catalysts were prepared by impregnation and co-impregnation methods and characterized by the Brunauer-Emmett-Teller method, EPR, and temperature programmed reduction. The results proved the interactions between supported oxides and the presence of spinel-like phase after treatment at 400ºC. Magnesium oxide clearly influences the catalytic activity as well as selectivity of chromium catalysts supported on MgF_2. The MgO-Cr_2O_3/MgF_2 systems were active and selective in the reaction of CO oxidation at the room temperature and in the dehydrogenation of cyclohexene.
5
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Simulation of Hydrogen-Induced Reconstruction of Oxygen on Pd(111)

100%
Petrauskas V., Tornau E.
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EN
The oxygen and hydrogen atoms co-adsorption experiment on Pd(111) is modelled using kinetic Monte Carlo method. We consider O-O, H-H, and O-H interactions and several kinetic processes (diffusion, surface and subsurface H-atoms exchange and water-formation reaction) leading to the phase transition (2×2)_O → (√3×√3)_O with increase in H-coverage. We also demonstrate how reverse phase transition (√3×√3)_O → (2×2)_O occurs due to hydrogen dissolution into subsurface in the absence of hydrogen gas. At higher temperature we observe the disappearance of (2×2)_O oxygen islands due to water-formation reaction.
6
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Simulation of Reaction-Induced Phase Separation in Surface Alloy

100%
Zvejnieks G., Tornau E.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
1099-1102
EN
Using kinetic Monte Carlo method we simulate the dynamics of biatomic Au_{0.3}Ni_{0.7} surface alloy separation on Ni(111) due to Ni(CO)_4 out-reaction. The experiment of Vestergaard et al. is modeled by counterbalancing dynamical processes and interactions between reactants. The simulations demonstrate step flow rate increase with CO coverage, c_{CO}, in qualitative agreement with the experiment only for c_{CO} ≲ 0.45 monolayer. Moreover, we demonstrate both CO influence on reaction process and Au domain formation.
7
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Surface diffusion of Pb on clean Si surfaces

63%
Dolbak A., Zhachuk R., Olshanetsky B.
Open Physics
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2004
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vol. 2
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issue 2
254-265
EN
Pb diffusion on clean Si(111), (100), and (110) surfaces was studied by Auger electron spectroscopy and low energy electron diffraction in the temperature range from 100 to 300°C. It is shown that lead transport along sillicon surfaces takes place via the mechanism of solid-phase spreading with a sharp moving boundary. The temperature dependence of the Pb diffusion coefficients on Si(111), (100) and (110) surfaces have been obtained. A Si(110)-4×2-Pb surface structure has been observed for the first time.
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