Low-energy electron diffraction

**Figure 1**: LEED pattern of a Si(100) reconstructed surface. The underlying lattice is a square lattice, while the surface reconstruction has a 2×1 periodicity. As discussed in the text, the pattern shows that reconstruction exists in symmetrically equivalent domains oriented along different crystallographic axes. The diffraction spots are generated by acceleration of elastically scattered electrons onto a hemispherical fluorescent screen. Also seen is the electron gun that generates the primary electron beam; it covers up parts of the screen.

Low-energy electron diffraction (LEED) is a technique for the determination of the surface structure of single-crystalline materials by bombardment with a collimated beam of low-energy electrons (30–200 eV)^[1] and observation of diffracted electrons as spots on a fluorescent screen.

LEED may be used in one of two ways:

Qualitatively, where the diffraction pattern is recorded and analysis of the spot positions gives information on the symmetry of the surface structure. In the presence of an adsorbate the qualitative analysis may reveal information about the size and rotational alignment of the adsorbate unit cell with respect to the substrate unit cell.
Quantitatively, where the intensities of diffracted beams are recorded as a function of incident electron beam energy to generate the so-called I–V curves. By comparison with theoretical curves, these may provide accurate information on atomic positions on the surface at hand.

^ K. Oura; V. G. Lifshifts; A. A. Saranin; A. V. Zotov; M. Katayama (2003). Surface Science. Springer-Verlag, Berlin Heidelberg New York. pp. 1–45. ISBN 9783540005452.

[Oura-1] K. Oura; V. G. Lifshifts; A. A. Saranin; A. V. Zotov; M. Katayama (2003). Surface Science. Springer-Verlag, Berlin Heidelberg New York. pp. 1–45. ISBN 9783540005452.

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