Long range periodicity of S/Au(111) structures at low and intermediate coverages

P. N. ABUFAGER; M. L. MARTIARENA; G. ZAMPIERI; K. REUTER; H. F. BUSNENGO

Edimburgo

Conferencia; 29 ECOSS European Conference on Surface Science; 2012

<!-- @page { margin: 2cm } P { margin-bottom: 0.21cm } -->Sulfur on metals at the sub-monolayer and monolayer levels has attracted considerable attention in the fields of surface science, catalysis, and nanotechnology. In spite of the large amount of work done in this field, many questions remain unanswered. Particularly intriguing is the origin of the rich variety of structures formed by S atoms on Au(111) under different experimental conditions, which suggests a complex picture of the S/Au(111) interaction [1-4]. Through DFT calculations, we have studied the adsorption of S on Au(111) at low and intermediate coverages (coverages lower than 1/3 monolayers, ML). The only stable structure characterized by a short range periodicity is sqrt{3}xsqrt{3}R30°, the stability of which, however, seems restricted to a very narrow coverage window [0.28, 0.33] ML. Our calculations predict for coverages lower than 0.28ML several structures which are all characterized by a 5x5 periodicity, in line with recent experiments [3,4]. In addition, our results unambiguously reveal a crucial role of S-induced substrate relaxation. The complex coverage dependent scenario described above is dictated by long range substrate mediated S-S interactions which: i) favour 5x5 arrangements due to a slight S-S attraction at ~15 Å, and ii) disfavour large sqrt{3}xsqrt{3}R30° patches because of a strong S-S repulsion at ~10 Å. References [1] Rodríguez et al. J. Am. Chem. Soc. 125 (2003) 277 [2] Lustemberg et al. J. Phys. Chem. C 112 (2008) 11394 [3] Yu et al. J. Phys. Chem. C 111 (2007) 10904 [4] Bienner et al Surf. Sci. 601 (2007) 1659