Surface chemistry LEED studies

The polar (0001)-Zn and (000 1 )-0 surfaces and the nonpolar (10 10) surface (m-plane) have also been the object of experimental and theoretical investigations. Of these surfaces, the nonpolar (10 10) surface is of particular interest from the viewpoint of surface chemistry, because the surface is terminated with the same number of O and Zn atoms. The low-energy electron diffraction (LEED) studies have revealed that the surface undergoes relaxation, which is characterized by downward shift (spatially) of both surface Zn and O atoms, with a greater shift for the Zn atom... 

Abstract Thermally stable, ordered surface alloys of Sn and Pt that isolate threefold Pt, twofold Pt, and single-Pt atom sites can be produced by controlled deposition of Sn onto Pt single crystals and annealing. The strnctnre was established by characterization with several techniques, including ALISS, XPD, LEED, and STM. Chemisorption and catalysis studies of these well-defined, bimetallic surfaces also define the overall chemical reactivity of Pt-Sn alloys, clarify the role of a second-metal component in altering chemistry and catalysis on Pt alloys, and develop general principles that describe the reactivity and selectivity of bimetallic alloy catalysts. 

However, electron diffraction was originally a difficult and costly process because it was essential to carry out the measurements in very high vacuum (meaning very low pressure, less than 10 bar). The technology for achieving such low pressures became widely available only in the 1950s. This development opened the door for studies of solid surfaces and their chemistry, using LEED to determine before the experiment how clean and flat the surface was. 

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