Low energy electron diffraction: The technique and its application to metallurgical science

Abstract

The technique of low energy electron diffraction has greatly contributed to our increasing knowledge of surface phenomena. During the past several years it has proven to be an invaluable tool for the study of surface properties. It has revealed that clean solid surfaces can undergo structural rearrangements at temperatures where there is no apparent change in the bulk crystal structure and that the adsorption and reaction of gases may proceed via several ordered intermediate surface structures. In addition, the investigations of clean metal surfaces and the reactions which take place upon them, such as oxidation, epitaxy, thin-film growth, etc., have provided information on surface processes which could not have been obtained by any other technique. These include surface phase transformations, possible reconstruction of the surface atoms in the presence of adsorbed gases, the periodic nature of the adsorbed atoms and the sensitivity of epitaxial growth to the presence of chemisorbed gases. Such results have scientific as well as practical importance and are especially interesting to the metallurgist. The technique continues to develop and is often used in conjunction with other measurements, such as mass spectroscopy, work function studies, etc. Once a reliable theoretical foundation for the analysis of intensity data is established, the role of low energy electron diffraction (LEED) in surface studies will be similar to that of x-ray diffraction in studies of the solid state.