XRD from O-Cu

Both XRD [34] and EMT [20] measurements confirmed that the oxygen adsorbates are located underneath the MR top layer to form the zigzag O-Cu-0 chains (refer to Fig. 3.3) along the [110] direction. Referring to the inset in Fig. 3.2, in which the vertical displacement of the dipole (labeled 3) is denoted as D3j. The 

Column 111 is preferred for tetrahedron bond formation, which is the same happened in the (001) surface (reprinted with permission from [1]) 

The CU3O2 pairing-tetrahedron evolves from the -induced pyramid on the Cu(OOl) surface. In the precursor phase, the 0 locates eccentrically above the fourfold hollow site of the c(2 x 2)-20 domain to form an off-centered pyramid. The off-center shift of the 0 is DO 1.807 — [1.85 x (1 — 0.12)] X 0.18 A, which is comparable to the values of 0.10-0.13 A [7, 19]. The vertical distance of the 0 to the surface is 0.1 A above the surface. The absence of the lone-pair DOS features implies that no jp-orbital hybridization occurs of oxygen in the -induced precursor phase. 

Except for the Cu(001)-c(2 x 2)-2 , all the available phases on the -Cu(OOl) and the -Cu(llO) surfaces are composed of the primary Cu2 tetrahedron. The parameters for the Cu2 tetrahedron are nearly the same, as summarized in Table 3.8. The work function is reduced by 1.2 eV and the inner potential constant decreases from 11.56eV for the clean Cu(OOl) surface to 10.50 eV upon being oxidized. The SPB parameters vary from site to site on the surface [46]. At the dipole site, z = zo, a = The metal dipoles enhance the SPB through the outward shift of the wave function. Dipole formation also strengthens the degree of saturation of both the real and the imaginary part of the SPB at the dipole site. 

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