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Geometry of (22)S/Cu(001) determined with use of angle-resolved-photoemission extended fine structure

Journal Article · · Phys. Rev. B: Condens. Matter; (United States)

We have measured the adsorption geometry for the (2 x 2)S/Cu(001) surface, including the reconstruction and relaxation of the copper substrate. Multiple-scattering spherical-wave calculations were compared with angle-resolved-photoemission extended-fine-structure data and these results were then compared with a Fourier analysis of the data. The sulfur atoms are located in the fourfold hollow site, with a S--Cu bond distance of 2.26(1) A. With (1/4) monolayer ''p(2 x 2)'' sulfur coverage the symmetry of the copper substrate is necessarily lowered from (1 x 1) to (2 x 2). Accordingly, the sulfur adsorption induces reconstruction and relaxation of the two topmost Cu layers. All the movement occurs in Cu/sub 5/S moieties, as if the surface were forming Cu/sub 5/S clusters embedded in the bulk. The first-layer Cu atoms are shifted approx. =0.06 A towards the third Cu layer and 0.05(2) A laterally towards S. The second-layer Cu atoms under S atoms mimic the surface texture, in that they are 0.13 A farther from the third layer than the bulk spacing would predict. Second-layer Cu atoms under fourfold open sites are close to positions predicted by the bulk spacing. Details of the data analysis and extraction of surface-structural parameters are presented.

Research Organization:
Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720 and Department of Chemistry and Department of Physics, University of California, Berkeley, California 94720
DOE Contract Number:
AC03-76SF00098
OSTI ID:
6986599
Journal Information:
Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 35:8; ISSN PRBMD
Country of Publication:
United States
Language:
English