Structural analysis of surfaces by LEED

Abstract

The field of low energy electron diffraction (LEED) is reviewed with respect to its potential to surface structure determination. The present status of both theory and experiment is described. Different techniques of data collection are compared with emphasis on recent developments providing fast and sensitive detectors combined with high resolution. The description of the full dynamical theory is presented to demonstrate its limits of practical application. In turn approximative methods are described constructed to overcome these limits and to approach more complex structures. Special attention is payed to the retrieval of structural data by comparison of experimental and calculated intensities using reliability factors, whereby the present standards of accuracy and precision are discussed. Moreover, it is demonstrated strated that LEED applies no longer to long range order structures only, but is on its way to extend to partially disordered surfaces as well, as surfaces with defects or after disordered adsorption. Emphasis is on the investigation of surface phase transitions as well. Here the extension of LEED to time resolved measurements opens the door to monitor the kinetics of transitions. Finally it is tried to identify some trends likely to develop in the near future LEED.