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1

Adsorption of Oxygen on HF-Etched Si(111) Surfaces: XPS Study

100%

Iwanowski R. J., Sobczak J. W.

Acta Physica Polonica A

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1997

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vol. 91

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issue 4

793-796

EN

X-ray photoelectron spectroscopy studies of the Si(111) surfaces, after dilute HF etching and methanol rinse, are reported. These included a detailed analysis of the main core-levels (Si 2p, O 1s) and the valence band spectra. The observed asymmetry of the O 1s lines was attributed to two contributing subpeaks: the main (1) and the minor one (2), shifted ≈ 1.5 eV to higher binding energies. Their relative intensity was found to depend on the air exposure time and on the take-off angle. The peaks were assigned to two different positions of surface oxygen: (1) O chemisorbed with methoxy group, (2) bridging O atom. The valence band X-ray photoelectron spectroscopy spectra reveal the influence of surface states induced by the "chemisorbed O"-Si bond.

2

Ellipsometrical and SEM Study of Ferritin Adsorption οn a Gold Surface

51%

Vladimirova L., Tsutsumanova G., Gritzkow A., Savov V.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

705-707

EN

The adsorption of horse spleen ferritin on gold surface is studied with null ellipsometry and scanning electron microscopy. The high sensitivity and in situ advantage of ellipsometry make it very attractive for studies of ultrathin biomolecular layers. The influence of pH and protein concentration in solution on the adsorption kinetics was interpreted using ex situ scanning electron microscopy shots and computer modeling of the system "prism-gold film-adsorbed layer-solution". It seems that the first fast stage comprises nucleation process occurring at active sites and the following slow multistage process of a protein film growth. The data about adsorption kinetics of protein and the structure of the adsorbate layers obtained in this study enable understanding of such processes in real biological system, e.g. the protein adsorption on blood vessels and tissues in pathological processes.

3

Thermal Desorption of Potassium from Clean and Sulfur Covered Nickel

51%

Błaszczyszyn R., Błaszczyszynowa M., Gubernator W.

Acta Physica Polonica A

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1995

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vol. 88

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issue 6

1151-1160

EN

Activation energy for thermal desorption of potassium from clean and sulfur covered surfaces of nickel was determined by means of the field emission method. For the low potassium coverage limit (Θ_{K} ≈ 0.02) the desorption was detected from the whole emitter surface in the temperature range of 825-1000 K for the atoms and of 725-825 K for the species of atoms and ions of the potassium. The activation energies of neutral desorption were found to be E^{a}_{Ni} = 3.8 eV for the clean nickel and E^{a}_{S/Ni} = 3.0 eV for the sulfur covered nickel, Θ_{s} ≈ 0.5. The activation energies for the desorption of the species of atoms and ions increased from E^{a+i}_{Ni} = 2.5 eV for the clean nickel to E^{a+i}_{S/Ni} = 2.9 eV for the sulfur covered nickel Θ_{s} ≈ 0.5. Also, a value of E^{a+i}_{S'/Ni} = 4.1 eV was found for a higher coverage of sulfur, Θ_{s} ≈ 1. The results are discussed in terms of Gurney model.

4

An Ellipsometrical and AFM Study οf Ferritin Adsorption Kinetics on a Gold Surface

51%

Vladimirova L., Andreeva A., Savov V., Gritzkow A., Burova M.

Acta Physica Polonica A

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2009

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vol. 116

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issue 4

687-689

EN

The kinetics of ferritin adsorption on gold (Au) surface was studied with ellipsometry and atomic force microscopy. The thickness and the refraction index of the adsorbed layer were determined using a theoretical model system: air-interface layer-solution-adsorbed layer-gold surface. The relations between the parameters of the adsorbed layer and pH and the protein concentration are obtained. It seems that the ferritin adsorption is a relatively slow multi-stage process. The obtained results enable modelling of the protein adsorption on blood vessels and tissues in pathological processes. The kinetics of protein adsorption could be implemented in medical applications and in development of new biosensor systems.

5

Modelling of SubPc Self-Assembly on Ag(111)

51%

Petrauskas V., Tornau E., Lapinskas S.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

388-391

EN

The ordering of subphthalocyanine molecules into honeycomb and hexagonal close packed patterns on Ag(111) is described using complex Lennard-Jones-type intermolecular potential. We rescale Ag(111) lattice, and take into account an infinite exclusion of first, second, and third neighbours, attraction - of fourth and fifth, and repulsion - of sixth and seventh. The phase diagram is obtained by the lattice gas model using Monte Carlo simulations. Very strong first order phase transitions, causing the two-phase co-existence, are found between disordered and honeycomb as well as between disordered and hexagonal closed packed phases.

6

Adsorption Properties of the Cu(115) Surface: Basic Interfaces

51%

Godowski P., Groso A., Hoffmann S., Onsgaard J.

Acta Physica Polonica A

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2010

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vol. 117

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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.

7

Photoemission Study of the Initial Growth of Co on Ru(0001)

51%

Godowski P., Onsgaard J., Trzebiatowska-Gusowska M., Pater K., Li Z.

Acta Physica Polonica A

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2007

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vol. 111

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issue 2

263-271

EN

The growth process of cobalt on Ru(0001) was characterized by photoelectron spectroscopy excited by X-ray and synchrotron radiation. The binding energy position and intensity of the Co 2p_{3/2} and Ru 3d_{5/2} core levels as well as the shape and structure of the valence band spectra corresponding to the different stages of the deposition were investigated. An observed small positive binding energy shift is a consequence of an increase in the cobalt adatoms coordination number. The core-level shift between bulk and surface Ru atoms is determined as -360 meV. Upon adsorption of cobalt, the interface peak appears with a shift of -(70÷80) meV relative to the bulk one. On the basis of unchanged energy positions and widths of the Ru-derived features of the valence band spectra, a weak interaction between cobalt and substrate is suggested. The measured valence band could be reproduced by superimposing the spectra of the pure elements.

8

Structural and Optoelectronic Properties of In-Zn-S sprayed Layers

51%

Lazzez S., Boubaker K., Ben Nasrallah T., Amlouk M., Belgacem S., Mnari M., Chtourou R.

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

869-880

EN

In this work, In-Zn-S thin layers were prepared using the spray pyrolysis technique on glass substrates at 320°C. The molar ratio between zinc and indium x=[Zn^{2+}]/[In^{3+}] was varied in 0-0.4 domain whereas [S^{2-}]/[In^{3+}] one was taken constant equal to 2. The atomic composition was carried out with the atomic absorption. The structural study of all layers via X-ray diffraction and atomic force microscopy shows that the layer, obtained using x=0 is formed by binary material In_2S_3 with a principal orientation along (400). When the composition increases the same study depicts the presence of other materials such as ZnO, ZnS, and ZnIn_2S_4. On the contrary, for x=0.4, the film is mainly formed by the ternary compound ZnIn_2S_4 which crystallizes in cubic phase. Moreover, the optical analysis via the transmittance, reflectance as well as the photocurrent reveals that the band gap energy E_g increases slightly as a function of the x composition (E_g varies from 2.6 to 2.9 eV).

9

Residual Gas Effect on Photofield Emission from Tungsten (111) Face

51%

Hądzel P., Radoń T., Jaskółka S.

Acta Physica Polonica A

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1997

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vol. 91

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issue 6

1141-1147

EN

Using the photofield emission method, surface states and bulk excitations from clean and residual gas adsorbed (111) face of tungsten were measured. Residual gas shaded the surface states and diminished photoemission from the bulk excitations. Gas of the artificially increased background pressure 10^{-8} Pa adsorbed during the measurement deforms the photocurrent-voltage characteristic; the optical excitations observed for clean surfaces are exhibited, diminished or lost. For the adsorbed (111) face the state related to the metal-gas surface has been observed.

10

Formation of Excess Silicon on 6H-SiC(0001) during Hydrogen Etching

45%

Grodzicki M., Wasielewski R., Surma S., Ciszewski A.

Acta Physica Polonica A

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2009

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vol. 116

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issue S

S-82-S-85

EN

The surface of 6H-SiC(0001) samples was subjected to etching under H_{2}/Ar gas mixture in a cold-wall tubular furnace. Its topography and properties were characterized by atomic force microscopy and X-ray photoelectron spectroscopy before and after hydrogen etching. The conditions have been found, under which surface polishing-related damages could be removed. Si droplets were observed under certain etching conditions. The effect of the samples' cooling rate on the obtained surface morphology and chemistry was investigated to unveil the mechanism of Si recrystallization onto the crystal surface upon etching.

11

Phase transitions in the adsorbed molecular chains

38%

Lykah V., Syrkin E.

Open Physics

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2005

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vol. 3

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issue 1

61-68

EN

Rotational excitations of molecular adsorbed layers are studied theoretically. Nonlinear dynamical equations are obtained with accounting of quadrupolar interactions between molecules and freezing of translational degrees of freedom. The equilibrium positions of the molecules are found to be experimentally observed structures with alternating rotational ordering of planar rotors along the direction to the nearest neighbor (for linear or square structures) under low temperature. Dynamical analysis gives an integral of motion (energy) of the chain that in the long-wave limit leads consequently to the existence of four phases. The first one corresponds to oscillations near equilibrium ordered states. The second phase corresponds to low-energy rotational excitations along ‘valleys’ (easy directions in the effective potential) that do not destroy strong correlations between molecules while structural data can show rotational disorder (melting). The third phase corresponds to an energy that is enough to travel between ‘valleys’; only some ‘islands’ in the angle space are forbidden. Complete destruction of correlation when the energy is over the peaks of the effective potential corresponds to the fourth phase. Therefore rotational melting is a complex phenomenon that has several stages.

Refine search results

Adsorption of Oxygen on HF-Etched Si(111) Surfaces: XPS Study

Ellipsometrical and SEM Study of Ferritin Adsorption οn a Gold Surface

Thermal Desorption of Potassium from Clean and Sulfur Covered Nickel

An Ellipsometrical and AFM Study οf Ferritin Adsorption Kinetics on a Gold Surface

Modelling of SubPc Self-Assembly on Ag(111)

Adsorption Properties of the Cu(115) Surface: Basic Interfaces

Photoemission Study of the Initial Growth of Co on Ru(0001)

Structural and Optoelectronic Properties of In-Zn-S sprayed Layers

Residual Gas Effect on Photofield Emission from Tungsten (111) Face

Formation of Excess Silicon on 6H-SiC(0001) during Hydrogen Etching

Phase transitions in the adsorbed molecular chains