Angle-resolved photoemission study of the clean and hydrogen-covered Pt(111) surface

We report the results of a high-resolution angle-resolved photoemission study of the surface electronic structure of clean and hydrogen-covered Pt(111). Several surface-resonance bands and one surface state are observed on the clean surface. These exhibit qualitative similarities to, as well as some differences from, previous studies and calculations for Pd(111). Unlike the results for Pd(111), essentially all surface bands are quenched upon hydrogen exposure, even at room temperature. There is no clear support in our data for a structural model placing the hydrogen atoms in an underlayer adsorption site, as had been suggested from a previous photoemission study. The significance of our results to a recently proposed correlated-quantum-liquid model is investigated. We also discuss the relevance of our bands near EF to a recent controversy about the possible existence of phonon anomalies on this surface.