FINGERPRINTING TECHNIQUE IN LOW-ENERGY-ELECTRON DIFFRACTION

The most important part in solving complex surface structures is a pro mising guess of the starting configuration if an automated structure r efinement is employed. The ''fingerprinting technique'' is able to pro vide such information quasi-directly from experimental low-energy elec tron diffraction (LEED) data for a class of surface structures. The ap plication of this method to LEED is based on the local scattering pict ure. Because of the short mean-free path of LEED electrons, the energy dependence of LEED intensities of fractional-order beams is mainly in fluenced by the local geometry of the adsorbate complex. By comparing experimental IV curves (fractional-order beams) of an unknown structur e with those whose structure has been successfully analyzed, it is fre quently possible to obtain information on the basic structural element s of the unknown surface system. For instance, similar IV curves sugge st similar structural elements. In this paper, the fingerprinting idea will be substantiated by several representative examples.