Surface Structure Spread Single Crystals (SC): Preparation and characterization

a r t i c l e i n f o Keywords: Surface structure Structure sensitivity STM Single crystal High Miller index A set of six spherically curved Cu single crystals referred to as Surface Structure Spread Single Crystals (S 4 Cs) has been prepared in such a way that their exposed surfaces collectively span all possible crystallographic surface orientations that can be cleaved from the face centered cubic Cu lattice. The method for preparing these S 4 Cs and for finding the high symmetry pole point is described. Optical profilometry has been used to determine the true shapes of the S 4 Cs and show that over the majority of the surface, the shape is extremely close to that of a perfect sphere. The local orientations of the surfaces lie within ± 1° of the orientation expected on the basis of the spherical shape; their orientation is as good as that of many commercially prepared single crystals. STM imaging has been used to characterize the atomic level structure of the Cu(111) ± 11°-S 4 C. This has shown that the average step densities and the average step orientations match those expected based on the spherical shape. In other words, although there is some distribution of step–step spacing and step orientations, there is no evidence of large scale reconstruction or faceting. The Cu S 4 Cs have local structures based on the ideal termination of the face centered cubic Cu lattice in the direction of termination. The set of Cu S 4 Cs will serve as the basis for high throughput investigations of structure sensitive surface chemistry on Cu. Many phenomena occurring on the surfaces of materials are sensitive to the atomic level structure of the surface. Such processes include catalysis, corrosion, etching, adsorption, etc. As a consequence, understanding the influence of surface structure on surface chemistry is one of the central problems of surface science. In fact, one of the great achievements of modern surface science has been the unequivocal demonstration of structure sensitivity in catalysis [1,2]. Much of the work on this problem has been accomplished through the careful and painstaking study of adsorption and surface reaction kinetics on small sets of single crystal surfaces. Most commonly these are the high symmetry, low Miller index planes of metal crystals. These studies have been complemented by studies on high Miller index surfaces that expose monoatomic steps and kinks which, …