312
15 Methodology: Parameterization
of z 0M and λ M also quantify the protrusions in the STM image as that the higher the
islands are, the denser the electron cloud is.
In the missing-row site, z 1 z 0 , α λ
−1 , i.e., the missing-row vacancy is not
occupied by “free electrons”, which depresses the STM image with least SPB saturation. On the O-Cu(001) surface, the lowest saturation degree of the SPB is (λ m /λ(Cu)
= 0.65/0.9≈) 1/
√
2 times that of the Cu(001) surface. Therefore, the electrons of
the O-chemisorbed surfaces are very local. Therefore, the O-metal surface is a nonFermi system absenting freely moving electrons. The O-Cu(001) surface consists
of a dipole layer that lowers the work function. The electron localization is also
responsible for the non-Ohmic rectifying of an oxide surface.
The current non-uniform SPB approach is able to account for the behavior of
electrons on the Cu surfaces with chemisorbed oxygen. The formulations can well
quantify the localized features as revealed by STM and STS. As an important factor
influencing the interaction of incident electrons with the surface, the variation of the
valence DOS can be obtained from the z 0 (E) profile. Because the z 0 (E) profiles vary
with crystal structure, the difficulty of simultaneously quantifying crystal structure
and electronic distribution has thus been overcome with simplified optimizations. The
consistency among the VLEED profiles, z 0 (E) profile and saturation degree, and STM
and STS observations evidences that the current SPB and the tetrahedrally-structured
M 2 O models are essentially appropriate.
15.4 Summary
The fitting of the VLEED spectra of O-Cu(001) surface verifies the essentiality of
the energy dependent 3D-SPB, the tetrahedral M 2 O bond geometry, and the spectrometric decoding skills. The single-variable parameterization provides agreement
of the VLEED spectra at all the azimuth angles with all the compared models.
The geometrical-dependent z 0 (E) profiles offer rich and profound information about
the behavior of atoms and electrons at the surfaces in terms of bond geometry,
valence DOS, and the 3D-SPB. Progress demonstrates the essentiality and efficiency
of the premise of Coordination Bonding and Electronic Dynamics in dealong with
chemical reaction.
References
1. P. Jennings, S. Thurgate, The inner potential in LEED. Surf. Sci. 104(2), L210–L212 (1981)
2. C. Hitchen, S. Thurgate, P. Jennings, A LEED fine structure study of oxygen adsorption on Cu
(001) and Cu (111). Aust. J. Phys. 43(5), 519–534 (1990)
3. G. Hitchen, S. Thurgate, P. Jennings, Determination of the surface-potential barrier of Cu (001)
from low-energy-electron-diffraction fine structure. Phys. Rev. B 44(8), 3939 (1991)
4. H. Zeng, K. Mitchell, Further LEED investigations of missing row models for the Cu (100)-(22
× 2) R45°-O surface structure. Surf. Sci. 239(3), L571–L578 (1990)
15 Methodology: Parameterization
of z 0M and λ M also quantify the protrusions in the STM image as that the higher the
islands are, the denser the electron cloud is.
In the missing-row site, z 1 z 0 , α λ
−1 , i.e., the missing-row vacancy is not
occupied by “free electrons”, which depresses the STM image with least SPB saturation. On the O-Cu(001) surface, the lowest saturation degree of the SPB is (λ m /λ(Cu)
= 0.65/0.9≈) 1/
√
2 times that of the Cu(001) surface. Therefore, the electrons of
the O-chemisorbed surfaces are very local. Therefore, the O-metal surface is a nonFermi system absenting freely moving electrons. The O-Cu(001) surface consists
of a dipole layer that lowers the work function. The electron localization is also
responsible for the non-Ohmic rectifying of an oxide surface.
The current non-uniform SPB approach is able to account for the behavior of
electrons on the Cu surfaces with chemisorbed oxygen. The formulations can well
quantify the localized features as revealed by STM and STS. As an important factor
influencing the interaction of incident electrons with the surface, the variation of the
valence DOS can be obtained from the z 0 (E) profile. Because the z 0 (E) profiles vary
with crystal structure, the difficulty of simultaneously quantifying crystal structure
and electronic distribution has thus been overcome with simplified optimizations. The
consistency among the VLEED profiles, z 0 (E) profile and saturation degree, and STM
and STS observations evidences that the current SPB and the tetrahedrally-structured
M 2 O models are essentially appropriate.
15.4 Summary
The fitting of the VLEED spectra of O-Cu(001) surface verifies the essentiality of
the energy dependent 3D-SPB, the tetrahedral M 2 O bond geometry, and the spectrometric decoding skills. The single-variable parameterization provides agreement
of the VLEED spectra at all the azimuth angles with all the compared models.
The geometrical-dependent z 0 (E) profiles offer rich and profound information about
the behavior of atoms and electrons at the surfaces in terms of bond geometry,
valence DOS, and the 3D-SPB. Progress demonstrates the essentiality and efficiency
of the premise of Coordination Bonding and Electronic Dynamics in dealong with
chemical reaction.
References
1. P. Jennings, S. Thurgate, The inner potential in LEED. Surf. Sci. 104(2), L210–L212 (1981)
2. C. Hitchen, S. Thurgate, P. Jennings, A LEED fine structure study of oxygen adsorption on Cu
(001) and Cu (111). Aust. J. Phys. 43(5), 519–534 (1990)
3. G. Hitchen, S. Thurgate, P. Jennings, Determination of the surface-potential barrier of Cu (001)
from low-energy-electron-diffraction fine structure. Phys. Rev. B 44(8), 3939 (1991)
4. H. Zeng, K. Mitchell, Further LEED investigations of missing row models for the Cu (100)-(22
× 2) R45°-O surface structure. Surf. Sci. 239(3), L571–L578 (1990)