Characterization of reordered (001) Au surfaces by the combined techniques of positive ion channeling spectroscopy (PICS), LEED--AES, and computer simulation

The applicability of positive-ion channeling techniques for studying the structure of single-crystal surfaces was investigated. Characterization of the (001) surface of epitaxially grown Au single crystals by LEED and AES showed that, when the (001) surface was sputter-cleaned and annealed in ultrahigh vacuum, the normal (1 x 1) symmetry of the (001) surface reordered into a structure which gave a complex (5 x 20) LEED pattern as previously reported. The yield and energy distributions of 1-MeV He ions scattered from the Au surfaces were used to determine the effective number of monolayers contributing to the normal and reordered surfaces. Computer simulation calculations were used to correlate the ion scattering results with model constructions for the normal and reordered surfaces. The combined techniques of PICS, LEED-AES, and computer simulation enabled the nature of the restructured surface to be characterized as one monolayer of hexagonal symmetry superimposed on the (001) substrate. 7 figures, 1 table