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Wyszukujesz frazę "surface diffusion" wg kryterium: Wszystkie pola


Wyświetlanie 1-7 z 7
Tytuł:
Field Stimulated Surface Diffusion of Lithium on Germanium (100) and (111) Planes
Autorzy:
Suchorski, Yu.
Powiązania:
https://bibliotekanauki.pl/articles/1892563.pdf
Data publikacji:
1992-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.70.+q
68.35.Fx
Opis:
Field stimulated surface diffusion of lithium on atomically clean (100) and (111) germanium single crystal planes has been investigated by means of field emission method. Sealed-off field emission tube with a channel multiplier was used. The surface density of lithium adatoms on the germanium surface was determined applying a standard tungsten (112) crystal plane. The dependences of the surface diffusion activation energy on the applied electric field at different lithium coverages lave been obtained. The initial dipole moment of Li adatoms on the Ge (100) and (111) planes was then determined. The values 1.3 ± 0.2 and 1.0 ± 0.2 debye obtained for the Li-Ge (100) and Li-Ge (111) systems respectively are in good agreement with the ones calculated from the work function measurements. The reverse effect of the field influence on the surface diffusion of lithium on Ge (100) and (111) planes has been observed as the second lithium layer is filling. Relative contributions of the peculiarities of semiconductor substrate and alkali adsorbate on the properties of adsystems are discussed on the basis of experimental results.
Źródło:
Acta Physica Polonica A; 1992, 81, 2; 295-302
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adsorption of H$\text{}_{2}$O on Pt Field Emitter: Surface Diffusion and Field-Induced Effects
Autorzy:
Blaszczyszynowa, M.
Błaszczyszyn, R.
Bryl, R.
Powiązania:
https://bibliotekanauki.pl/articles/1933649.pdf
Data publikacji:
1995-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.90.+b
68.35.Fx
79.70.+q
Opis:
Adsorption of an Η$\text{}_{2}$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$\text{}_{2}$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$\text{}_{2}$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.
Źródło:
Acta Physica Polonica A; 1995, 88, 3; 511-526
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Self-Diffusion of Iridium: Field Electron Emission Study
Autorzy:
Antczak, G.
Błaszczyszyn, M.
Błaszczyszyn, R.
Powiązania:
https://bibliotekanauki.pl/articles/2014253.pdf
Data publikacji:
2000-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
61.16.-d
68.35.Fx
68.90.+g
68.55.-a
Opis:
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.
Źródło:
Acta Physica Polonica A; 2000, 98, 4; 383-388
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analytical Solution of Nonlinear Diffusion Equation in Two-Dimensional Surface
Autorzy:
Janavičius, A. J.
Turskienė, S.
Powiązania:
https://bibliotekanauki.pl/articles/2044566.pdf
Data publikacji:
2005-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
66.30.-h
Opis:
We considered practically important case of nonlinear diffusion in the anisotropic plane where diffusion coefficients for diffusion in x and y axis directions can be different. This equation was transformed using similarity variables. The approximate analytical solution of the transformed equation expressed by power-series expansion for two variables about the zero point including only the first terms. The graphic representations show sufficient accuracy of the obtained analytical solution.
Źródło:
Acta Physica Polonica A; 2005, 108, 6; 979-983
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Some Remarks on Diffusion Model of Positron Reemission and/or Positron Surface Trapping
Autorzy:
Dębowska, M.
Świątkowski, W.
Powiązania:
https://bibliotekanauki.pl/articles/2007963.pdf
Data publikacji:
1999-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.35.Wm
Opis:
The problem of a role of boundary conditions in a diffusion model of positron reemission is discussed. It was shown that a sink rate cannot change from zero up to infinity but has an upper limit equal to a half of a mean positron velocity. Some additional relations connected with this result are presented as well.
Źródło:
Acta Physica Polonica A; 1999, 95, 4; 515-520
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Diffusion Length Studies in CdMnTe by the Surface Photovoltage Method
Autorzy:
Płaczek-Popko, E.
Szaro, L.
Jędral, L.
Powiązania:
https://bibliotekanauki.pl/articles/1879853.pdf
Data publikacji:
1991-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.40.+w
Opis:
The surface phototovoltage method provides a nondestructive means of measuring minority carriers diffusion length and is suitable for process control applications and for material acceptance tests. Application of the method in the case of CdMnTe compounds has been studied in the present paper. The optimum measurement conditions have been investigated by studying the dependence of measured diffusion length on the experimental conditions. As the surface photovoltage method requires the exact values of absorption coefficient as a function of wavelength, α = f(λ), the dependence has been determined. The minority carrier diffusion length for the sample investigated has been found to be equal to several tenth of μm.
Źródło:
Acta Physica Polonica A; 1991, 79, 2-3; 187-190
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast Diffusion of Metastable Vacancies in Surface of Excited Si Crystals
Autorzy:
Janavičius, A. J.
Turskienė, S.
Powiązania:
https://bibliotekanauki.pl/articles/2047100.pdf
Data publikacji:
2006-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
66.30.-h
66.30.Hs
78.70.Ck
Opis:
We considered the practically interesting, very fast nonlinear diffusion of metastable vacancies in the surface of Si crystal, excited by soft X-rays. Here we used experimentally defined diffusion coefficients of singly and doubly negatively charged very fast vacancies generated by soft X-rays. These high concentration (about 10$\text{}^{13}$ cm$\text{}^{-3}$) metastable vacancies at room temperature can diffuse and exist in the crystal for a very long time (about 24 hours for not so fast neutral vacancies) changing electrical conductivity, the Hall mobility of carriers and generating some resonance phenomena in the lattice of Si crystal. We measured superdiffusivity of negatively charged vacancies, generated by the Auger effect in the regions of the sample, where X-rays did not acted. In the paper we modified the formerly obtained analytical solution of nonlinear diffusion equation for calculation of distribution of vacancies in two-dimensional surface.
Źródło:
Acta Physica Polonica A; 2006, 110, 4; 505-510
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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