Landolt-Börnstein - Group III Condensed Matter Structure determination


This chapter discusses the effect of temperature on low-energy electron diffraction (LEED) intensities, and structure determination using LEED. One of the most important factors affecting LEED intensities is temperature. The electron-phonon interaction is typically inelastic. However, the energy loss necessary for creating a phonon is so small that one can again treat as elastic the scattering by a rigid lattice, averaged over the different momentary distortions. Because of multiple scattering the effect cannot be simply described as a Debye-Waller factor, as in the X-ray diffraction, and an appropriate treatment is necessary. The generally adopted method is to consider effective temperature-dependent phase shifts. The overall effect of temperature on the intensity curves is a general decrease in intensity, without any peak spreading. The effect was described by means of an effective Debye-Waller factor, obtained in a kinematic approximation. The normal procedure for structure determination is that of the trial and error method, i.e. a model of the structure is hypothesized and the calculated intensity curves are compared to the experimental ones. The model is varied until good agreement between theory and experiment is reached. The LEED technique is currently considered the most reliable technique for surface crystallography, and the most accurate structure determinations have been made by using the reliability factors (R factors).

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Title Structure determination
Book Title
Interaction of Charged Particles and Atoms with Surfaces
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Landolt-Börnstein - Group III Condensed Matter
  • G. Chiarotti
  • Authors
  • E. Zanazzi
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