Electronic states in solids investigated by means of synchrotron radiation

Recent progress is reviewed in the investigation of deep valence and core states in solids by means of continuous and intense vacuum ultraviolet radiation from electron synchrotons and storage rings. The basic theoretical concepts involved in the interpretation of spectroscopic data for the range from the ultraviolet to the X-ray region are outlined and a short account is given of the experimental aspects of work with synchrotron radiation. In addition to optical reflectivity and absorption measurements the advantages are pointed out of investigating photoelectric yield, energy distributions of photoemitted electrons and luminescence excitation spectra with a tunable light source. A selection of more recent experimental results is given in order to illustrate the following topics concerned with the electronic structure of solids: band structure effects, localized excitations such as excitons, decay processes of elementary excitations, unoccupied surface states, surface excitons and electronic states of adsorbates, and many-body effects. The common origin and close correspondence of many features of inner-shell absorption spectra from atoms, molecules and solids is pointed out.