**Authors:****S. Speller****T. Rauch****J. Bömermann****P. Borrmann**Phone: +49-(0)441-798-3362 Fax: +49-(0)441-798-3201**W. Heiland**Fax: +49-(0)541-969-2670**Files:****Surface Science 441 (1999) 107-116**

**for local use only**

**Date:**19990526**Article:**published in Surface Science 441 (1999) 107-116**Keywords:**- Low energy electron diffraction (LEED); Chemisorption; Palladium;Scanning tunneling microscopy; Sulfur; Surface segregation; Surface structure, morphology, roughness, and topography; X-ray photoelectron spetroscopy
**Abstract:**- S is adsorbed on Pd(111) from the gas phase using H
_{2}S as 'carrier' gas. After adsorption at room temperature a (sqpr(3)*sqrt(3))R30° LEED pattern is observed. Using STM coexisting (sqrt(3)*sqrt(3))R30°, (sqrt(7)*sqrt(7))R19.1° (2*2) stripes, (2*2) triangles and disordered S structures are found. Annealing favors the formation of (sqrt(7)*sqrt(7))R19.1° areas on the surface. The structure, produced by H_{2}S adsorption are compared with S structures produced by segregation. A detailed model for the (sqrt(7)*sqrt(7))R19.1° is developed on the basis of AES and XPS data and FLAPW calculations.

Upload by Thomas Severiens on 16 November 1999