Orientation Specificity of the Tetrahedron

Formation of the oxide tetrahedron and its kinetics is common while the adsorbate-site selectivity, the order of the ionic bonds formation, and the orientation of the oxide tetrahedron vary with the bonding environment. Except for the initial stage of oxidation, the oxygen adsorbate prefers a position inside a tetrahedron. However, the scale and geometry of the lattice, and the electronegativity of the host determine the bond formation order and the site-and-orientation specificity of the tetrahedron. 

Oxygen prefers the hcp(0001) hollow site on both the (Rh, Al)(l 11) surfaces and the Ru(0001) surface. Although the basic tetrahedron remains during the course of reaction, the electronic configurations of the constituent atoms alternate in the process of oxidation. Electron transportation leads to the C3v-radial and then the pairing-row type reconstruction and, finally, H-like bonds domination at the surface. In comparison, oxidation of the Cu(lll) and the Pd(lll) [2] surfaces gives rather comphcated patterns of reconstruction. 

At the -induced precursor phases, 0 forms one bond to a host atom nearby 

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