Photoemission studies of adsorbates on metal surfaces

A brief review is presented of the general field of synchrotron radiation photoemission of adsorbates on well characterized metal surfaces, contrasting some of the earliest work of the 1970s with more recent experiments, and highlighting some of the likely future developments that may derive from the use of third-generation synchrotron radiation facilities. Four general types of study are identified: shallow core-level photoemission either for the fingerprinting of the chemical state, or for quantitative structural studies via photoelectron diffraction, and valence-level photoemission either to study the two-dimensional band structure of adsorbate-induced surface-localized states, or to investigate the orientation of molecular adsorbates through the use of symmetry selection rules.