The sulfur induced reconstruction of the Pt(S)-[6(111)×(100)] surface

Abstract

The sulfur induced reconstruction of the Pt(S)-[6(111)×(100)] surface to other stable structures was investigated using low energy electron diffraction and Auger electron spectroscopy. These reconstructed surfaces involve a doubling of the clean surface terrace width and step height. The conditions of annealing temperature and sulfur coverage leading to the reconstructions were determined from this study. The mechanism for the reconstruction is strongly dependent on the preferential adsorption of sulfur at the step edge, and the reconstruction occurs even for very small sulfur coverages. The observed nucleation of (2×2) and (√3×√3) R30° sulfur overlayers by the step edge at relatively low sulfur coverages further supports this conclusion. Observation of the LEED pattern in real time in the 200–300 °C temperature region indicates that the temperature dependence of the sulfur mobility on the surface defines the reconstruction time. Several possible mechanisms for the reconstruction process are discussed, and the ranges of stability of the various reconstructions are indicated.