New phase of S adsorbed on Au(111)

MIAO YU; H. ASCOLANI; G. ZAMPIERI; D. P. WOODRUFF

San Carlos de Bariloche, Argentina

Conferencia; 13th International Conference on solid films and surfaces; 2006

Centro Atomico Bariloche (CNEA)

The two known phases of S adsorbed on Au(111) are a (√3x√3)R30 phase at low coverage and a phase with a complex LEED pattern, thought to correspond to a compound (sulfide), at coverages above 1/3 ML. We have found, however, that the √3 phase actually occurs only in a very narrow range of coverages. From coverages up to around 0.3 ML we have identified a new phase characterized by a LEED pattern in which every fractional order beam expected for the √3 phase is replaced by a triangle of three beams. This LEED pattern is very stable against both S dosing and temperature increase. By contrast, the √3 LEED pattern is obtained only for coverages close to 1/3 ML and is rather unstable, transforming readily into the complex LEED pattern of the high-coverage phase. We shall discuss the main characteristics of the new phase as seen with LEED and Normal-Incidence X-ray Standing Wave. TIPO DE PRESENTACION: POSTER