Surface-Structure Analysis by Optical Simulation of LEED Patterns

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Abstract
The principles governing the coherent scattering of low‐energy electrons are considered for the purpose of determining the degree of correspondence between LEED patterns and Fraunhofer optical diffraction patterns from plane gratings representing the arrangement of atoms at a crystal surface. The analysis indicates that an optical diffraction pattern approximates a composite LEED pattern which contains all beams observed over a range of electron energies. Accordingly, the technique of optical simulation is employed in the analysis of LEED patterns obtained from complicated surface structures. The experimental method is described and applied to the determination of the arrangement of atoms responsible for several characteristic LEED patterns: Au (100) 5×10, Cu (100) + O2, and W (100) + H2. In addition, models proposed previously to account for the Si (111) 7×7 and Ge (100) 8×8 patterns are examined.