Photoelectron spectroscopy of solids -UVU bandstructure studies

The electronic bandstructure of solids, including states specific to the surface, may now be explored in very great detail by photoelectron spectroscopy. Variable energy photon sources (synchroton radiation sources) coupled with advanced angle resolving electron spectrometers permit access to emission from specific points within the complete Brillouin zone. The technique of band mapping has now reached a stage where the small k-dependent changes to individual valence bands due to the effects of introduced lattice strain can be observed. The relative importance of emission from surface states, as opposed to bulk band states, can be demonstated dramatically using off-normal emission data. Angle resolved constant initial state spectroscopy has recently been shown to provide details of excited state bandstructure and has clarified the involvement of surface and bulk Umklapp scattering in the photoemission process. The above capabilities of photoelectron spectroscopy are discussed, using metallic and semiconducting examples, and are related to interface problems in general. 10 refs., 13 fig