Inclusion of off-normal incidence data in a low-energy electron diffraction crystallographic analysis for the Cu(100)-(2 × 2)-S surface structure

1990 ◽  
Vol 68 (4-5) ◽  
pp. 353-356 ◽  
Author(s):  
H. C. Zeng ◽  
R. A. McFarlane ◽  
K. A. R. Mitchell
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Polar Angle ◽  
Normal Incidence ◽  
Crystallographic Analysis ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron ◽  
Cu Interlayer

A low-energy electron diffraction (LEED) crystallographic analysis has been undertaken to assess the lateral and vertical relaxations for the Cu(100)-(2 × 2)-S surface structure. The study uses five normal-incidence beams and seven beams with an off-normal direction for a polar angle of incidence equal to 8°. Both lateral and vertical relaxations in the copper structure are small (0.03 Å or less) compared with the structure in bulk copper, but the senses are unchanged from the recent normal-incidence analysis (H. C. Zeng, R. A. McFarlane, and K. A. R. Mitchell, Phys. Rev. B, 39, 8000 (1989)). The new LEED-determined S—Cu bond length is 2.23 ± 0.06 Å, while the S to topmost Cu interlayer spacing is 1.28 ± 0.03 Å.

Further observations with low-energy electron diffraction for the Cu(100)-(2 × 2)-S surface structure: spot-profile and multiple-scattering analyses

1987 ◽  
Vol 65 (5) ◽  
pp. 500-504 ◽  
Author(s):  
H. C. Zeng ◽  
K. A. R. Mitchell
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Polar Angle ◽  
Low Energy ◽  
Energy Electron ◽  
Angle Of Incidence ◽  
Low Energy Electron Diffraction ◽  
Adsorption Sites ◽  
Low Energy Electron ◽  
Cu Interlayer

This study involves analyses by low-energy electron diffraction (LEED) for surface structures formed by S adsorbed on the (100) surface of copper. A LEED spot-profile investigation for a surface that shows a (2 × 2) diffraction pattern, supplemented by the effects of antiphase scattering, indicates that the domain boundaries do not correspond to microregions with local c(2 × 2) structure but rather that the beam elongations observed are consistent with local regions of the c(4 × 2) type in the approach to ¼ monolayer coverage. Diffracted-beam intensity-versus-energy curves calculated for the (2 × 2), c(2 × 2), and (2 × 1) translational symmetries, for fixed adsorption sites and S–Cu interlayer spacings, show that the intensity curves of corresponding beams can remain closely independent of actual symmetry and coverage even as the polar angle of incidence θ departs from the normal (although differences between the curves do tend to increase with θ). This observation can help simplify calculations of LEED intensities from adsorption systems with large unit meshes when the adsorbed species are in a constant environment; also, it provides an economical route for checking values of θ estimated from positions of diffraction spots on conventional LEED screens. When the latter is tested on the off-normal intensity data used in our previous analysis of the Cu(100)-(2 × 2)-S surface structure (Surf. Sci. 177, 329 (1986)), θ is indicated to be modified by 1° from the previously estimated value, but this does not significantly affect the determined S–Cu nearest neighbour bond length.

Determination of the surface structure of layered compounds by low-energy electron diffraction

1977 ◽  
Vol 38 (2) ◽  
pp. 387-395 ◽  
Author(s):  
B. J. Mrstik ◽  
R. Kaplan ◽  
T. L. Reinecke ◽  
M. Van Hove ◽  
S. Y. Tong
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Low Energy ◽  
Energy Electron ◽  
Layered Compounds ◽  
Low Energy Electron Diffraction ◽  
Low Energy Electron

INCOMMENSURATE METALLIC SURFACTANT LAYER ON TOP OF InN FILM

2006 ◽  
Vol 13 (06) ◽  
pp. 815-818 ◽  
Author(s):  
Y. LIU ◽  
J. WANG ◽  
M. H. XIE ◽  
H. S. WU
Keyword(s):  
Electron Diffraction ◽  
Surface Structure ◽  
Buffer Layer ◽  
Low Energy ◽  
Energy Electron ◽  
Low Energy Electron Diffraction ◽  
Incommensurate Structure ◽  
Low Energy Electron ◽  
Gan Buffer Layer

The surface structure of InN film heteroepitaxially grown on a GaN buffer layer by MBE is followed by low energy electron diffraction (LEED). The metallic surfactant layers on top of the InN surfaces show an incommensurate structure rather than being disordered. The metal in the incommensurate structure induces additional diffraction spots in the LEED. Based on the Auger experiments, not only In atoms but also Ga are present on the surface of the InN films.

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