SREM observation of the interaction between the in-situ deposited Pd small particles and MgO cleavage surface

Author(s):  
H.-J. Ou

The understanding of the interactions between the small metallic particles and ceramic surfaces has been studied by many catalyst scientists. We had developed Scanning Reflection Electron Microscopy technique to study surface structure of MgO hulk cleaved surface and the interaction with the small particle of metals. Resolutions of 10Å has shown the periodic array of surface atomic steps on MgO. The SREM observation of the interaction between the metallic particles and the surface may provide a new perspective on such processes.

1989 ◽  
Vol 113 (2) ◽  
pp. 421-430 ◽  
Author(s):  
A. V. Latyshev ◽  
A. L. Aseev ◽  
A. B. Krasilnikov ◽  
S. I. Stenin

Author(s):  
С.В. Ситников ◽  
Е.Е. Родякина ◽  
А.В. Латышев

AbstractBy means of in situ ultrahigh vacuum reflection electron microscopy, the nucleation of vacancy islands on wide terraces of the Si(100) surface is investigated. The temperature dependence of the displacement of a vacancy island nucleation center is determined in the process of heating a sample with a dc electric current. On the basis of a theoretical model, the effective electric charge of addimers is estimated in the direction across dimer rows of the surface. The effective charge has a positive sign and does not exceed 15 units of the elementary charge in the temperature range of 1020–1120°C.


1998 ◽  
Vol 05 (03n04) ◽  
pp. 653-663 ◽  
Author(s):  
Koyu Aoki ◽  
Hiroki Minoda ◽  
Yasumasa Tanishiro ◽  
Katsumichi Yagi

Initial stages of Au adsorption processes on Si(111)-(7 × 7) surfaces at ~780°C, a temperature range where the surface structure undergoes successive phase transitions [(7 × 7)–("1 × 1")–(5×2)–("1 × 1")], were observed in situ by reflection electron microscopy. All of the phase transitions are heterogeneous on the surface and start at surface atomic steps. During Au adsorption on Si(111)-(7 × 7), and subsequently on Si(111)-("1 × 1") surface with wide terraces, steps advance toward the step-down direction. At a Au coverage of ~0.3 ML, the 5 × 2 structure nucleates at step edges, and the nuclei expand both to the lower side terraces and to the higher side terraces. At this stage, an effect of current for heating the specimen was noted. From measurements of such movements of the steps and the domain boundaries, the density of Si atoms in the "1 × 1" phase is estimated to be 1.3–1.7 ML at a Au coverage of ~0.3 ML. Au adsorption on Si(111) surfaces with narrow terraces causes bunching of the steps. After nucleation of the 5 × 2 structure, the bunched [Formula: see text] steps become straight along the [Formula: see text] direction, and are transformed into the (335) facet planes at a Au coverage of 0.50 ML. It was found that the (335) facet planes are stabilized by adsorbed Au atoms. Destruction of the (335) facet is noted at a Au coverage of 0.73 ML.


2011 ◽  
Vol 6 (2) ◽  
pp. 65-76
Author(s):  
Ekaterina E. Rodyakina ◽  
Sergey S. Kosolobov ◽  
Aleksandr V. Latyshev

Existence of adatom gradient concentration on surface between step bunches was shown under sublimation, homoepitaxial growth and near equilibrium conditions on silicon (111) surface at above 900 ºС by means of in situ ultrahigh vacuum reflection electron microscopy and ex situ atomic force microscopy. It is experimentally confirmed that adatom have negative (at 1 100 ºС) and positive (at 1 300 ºС) effective charge. We found out the sign of adatom effective charge independent on the supersaturation volume on the surface. On the hasement of experimental data we evaluated the effective charge of adatom at 1 280ºС; this quantity is placed between 0,07 ± 0,01 and 0,17 ± 0,02 of electron unit


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