Low-Energy Electron Diffraction: Some Basic Conceptual Tools

This chapter provides a few of the basic conceptual tools necessary for dealing with low-energy electron diffraction (LEED). It presents one-dimensional analyses that provide an easy way of understanding and predicting some major aspects of LEED. One of the most common tasks that the experimental surface scientist undertakes is to convert between real-space and reciprocal-space lattices, usually assuming that such lattices are two dimensional. In principle, the conversion between real space and reciprocal space is done by taking the Fourier transform of the initial lattice. The Ewald circle, or the Ewald sphere, is a geometrical construction that can predict the positions of diffraction spots. The Ewald sphere or circle is quite useful as a basis for understanding qualitatively the diffraction data obtained in a typical LEED apparatus.