AVS 52nd International Symposium
    Surface Science Wednesday Sessions
       Session SS1-WeA

Paper SS1-WeA4
Atomic-Scale Visualization of Surface Alloys: Sb/Au(110)

Wednesday, November 2, 2005, 3:00 pm, Room 200

Session: Surface Structure and Morphology Modification
Presenter: S.S. Parihar, University of Wisconsin-Milwaukee
Authors: S.S. Parihar, University of Wisconsin-Milwaukee
V.L. Shneerson, University of Wisconsin-Milwaukee
R. Fung, University of Wisconsin-Milwaukee
H.T. Johnson-Steigelman, University of Wisconsin-Milwaukee
E.D. Lu, University of Wisconsin-Milwaukee
D.K. Saldin, University of Wisconsin-Milwaukee
P.F. Lyman, University of Wisconsin-Milwaukee
Correspondent: Click to Email
Surface x-ray diffraction (SXRD) allows quantitative, high-resolution determinations of surface structure via @chi@@super 2@ refinement of a model structure to the observed data. However, the most difficult step in this process is often generating model structures to refine. While this is often possible based, e.g., on chemical intuition, a model-independent method of generating accurate starting structures is sorely needed. We have developed an iterative algorithm to supply the phases, normally not accessible to experiment, from data that are oversampled (relative to the Nyquist frequency of the normal dimensions of the selvedge) along the crystal truncation rods. The algorithm alternately satisfies known constraints of these oversampled data in real and reciprocal space, and incorporates knowledge of the bulk structure, to progressively determine the surface structure factor phases. An inverse Fourier transform then constructs an "image" of the atomic contents of a unit cell of the selvedge.@footnote 1@ We have discovered a rich sequence of Sb-induced reconstructions on Au(110). A c(2x2) appears at 0.5 ML, changing continuously to a (@sr 3@x@sr 3@)R54.7° structure at higher Sb coverages; finally, a p(5x6) structure emerges for several ML Sb deposition. We have applied our novel SXRD algorithm to these surfaces to directly visualize the Sb and Au atomic locations, and thereby solve these structures. This breakthrough affords an automated, model-independent method of determining unknown structures of the outermost few atomic layers of a crystal surface. @FootnoteText@ @footnote 1@ P.F. Lyman, V.L. Shneerson, R. Fung, R.J. Harder, E. D. Lu, S.S. Parihar, and D.K. Saldin, Phys. Rev. B 71, 081402(R) (2005).