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1
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Diffusion of Palladium on Tantalum Microcrystal

100%
Antczak G., Błaszczyszyn R.
Acta Physica Polonica A
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2003
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vol. 103
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issue 1
57-65
EN
Surface diffusion of palladium,Θ=2 ML, on a tantalum microcrystal was studied by means of field electron emission microscopy within the temperature range 665-790 K. The observed sharp moving boundary-diffusion proceeds with an activation energy ranging from 1.25 to 1.7 eV/atom, depending on the crystallographic direction.
2
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Self-Diffusion of Tungsten on Some Facets of Tungsten Microcrystal

100%
Biernat T., Błaszczyszyn R.
Acta Physica Polonica A
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2008
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vol. 114
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issue S
S-11-S-16
EN
The field emission current fluctuation method was applied to investigate surface self-diffusion of tungsten on the (311) and (711) regions (along the zone line (211)-(100)) of a tungsten microcrystal (in the form of the field emitter tip of radius about 300 nm) in the temperature range 500-850 K. The surface diffusion parameters were obtained from spectral analysis of the current fluctuations. The results are discussed from the aspects of the substrate structure.
3
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Diffusion of Potassium on Nickel

100%
Błaszczyszynowa M., Błaszczyszyn R.
Acta Physica Polonica A
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1992
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vol. 81
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issue 2
285-294
EN
The surface diffusion of a potassium dose corresponding to the average coverage Θ̅_{K} = 1.5 on nickel was studied using the field emission technique in the temperature range of 78-133 K. In general, under such conditions diffusion proceeds with the sharp moving boundary and the activation energy Q from 0.16 eV to 0.36 eV dependently on the crystallographic directions. Free boundary migration with the energy Q < 0.16 eV is expected on the close-packed regions {111} and {001} already at liquid N_{2} temperature. The results are discussed in relation to the atomic structure of the nickel substrate taking into account the interaction in the adsorption layer.
4
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Surface Self-Diffusion of Iridium: Field Electron Emission Study

81%
Antczak G., Błaszczyszyn M., Błaszczyszyn R.
Acta Physica Polonica A
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2000
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vol. 98
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issue 4
383-388
EN
The self-diffusion of iridium was studied by means of field electron microscopy. The measurements, based on the well-known process of surface build-up, were carried out under the UHV conditions within the temperature range of 790-935K. The activation energy for the diffusion was determined to be equal to 2.10±0.10eV/atom (48.4±2.3kcal/mol). This value is compared with activation energies for self-diffusion on other metal surfaces, as well as with those for self-diffusion of single iridium atoms and clusters on iridium, known from the field ion microscopy measurements.
5
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Thermal Desorption of Au from W(001) Surface

81%
Błaszczyszyn R., Chrzanowski J., Godowski P.
Acta Physica Polonica A
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2002
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vol. 102
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issue 6
785-794
EN
Adsorption of Au on W(001) at 450 K up to multilayer structures was investigated. Temperature programmed desorption technique was used in determination of coverage dependent desorption energy (region up to one monolayer). Results were discussed in terms of competitive interactions of Au-Au and Au-W atoms. Simple procedure for prediction of faceting behavior on the interface, basing on the desorption data, was postulated. It was deduced that the Au/W(001) interface should not show faceting tendency after thermal treatment.
6
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Interaction of Hydrogen with Vanadium Layers Preadsorbed on Tungsten Field Emitter Tip

81%
Błaszczyszyn R., Wachowicz E., Błaszczyszynowa M.
Acta Physica Polonica A
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1998
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vol. 93
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issue 5-6
763-773
EN
Interaction of hydrogen with vanadium layers preadsorbed on a thermally cleaned tungsten field emitter was studied at room temperature and 78 K through measurements of the total work function changes. An increase in the work function followed by its slight decrease at higher exposure can be understood taking into account the possibility of negatively (β^{-}) and positively (β^{+}) polarized adspecies formation on thin vanadium layer. This process leads to vanadium hydride formation. The work function results suggest that hydrogen diffusion into the vanadium layer is meaningful at room temperature. Thermal desorption of hydrogen adsorbate carried out within the temperature range 409-461 K from thin vanadium layer (Θ_{V} = 40) provided a value of 127 ± 6 kJ/mol for the activation energy for desorption.
7
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Diffusion of Potassium on the W(112) Plane Preadsorbed by Ni Atoms: Field Emission Current Fluctuations - Autocorrelation Study

81%
Biernat T., Błaszczyszyn R., Kleint C.
Acta Physica Polonica A
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2001
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vol. 99
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issue 6
665-672
EN
Diffusion of potassium adsorbate on the W(112) plane with preadsorbed nickel was investigated by means of the autocorrelation function of field emission current fluctuations. A comparison of the experimental autocorrelation function with that of a theoretical calculation by Gesley and Swanson gives the surface diffusion coefficient of potassium. From its temperature dependence the diffusion activation energy at several Ni pre-coverages for a constant potassium coverage (Θ_K=0.4) is derived. The dependence of the activation energy for potassium surface diffusion on the nickel coverage - first reduction and then an increase with increasing Ni coverage - is observed. This is in agreement with the results obtained from the spectral analysis of the field emission current fluctuations of the same system. The decrease is understood to be a result of the smoothing effect caused by Ni atoms on the W(112) plane.
8
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Adsorption of H_{2}O on Pt Field Emitter: Surface Diffusion and Field-Induced Effects

81%
Blaszczyszynowa M., Błaszczyszyn R., Bryl R.
Acta Physica Polonica A
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1995
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vol. 88
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issue 3
511-526
EN
Adsorption of an Η_{2}O layer onto a Pt field emitter tip under the influence of an electric field and the surface diffusion of water were studied by using the field electron microscopy method. The presence of a negative field (field electron microscopy mode of operation), examined in the range of 33-44 MV/cm, significantly reduced the water coverage on the emitter at temperatures above 120 K. The reduction could also occur upon drawing a high density field emission current when the emitter was kept at 78 K. Surface diffusion of water, which was observed in the temperature range 120-132 K, corresponded to the "unrolling the carpet" mechanism and started from a water multilayer to a surface region water- and/or hydrogen-submonolayer covered. This was accompanied by the transition process from the state of the current- and field-induced redistribution of Η_{2}O to the state of thermal equilibrium. The activation energy of the diffusion was found to be 19 and 25 kJ/mol depending on the crystallographic direction. A positive electric field of 44 MV/cm, which was applied at temperatures of the substrate in excess of 121 K, decreased the field emission of the system and raised the desorption temperature of the layer over 720 K. It is assumed that the negative electric field causes reorientation of Η_{2}O molecules at the surface of platinum tip. The positive as well as negative electric fields promote the field desorption of water, which is in accordance with the results reported before.
9
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Thermal Desorption of Potassium from Clean and Sulfur Covered Nickel

81%
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.
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