The present status of photoelectron spectroscopy in the to 50- to 500-eV range is discussed in relation to its application to surface science. Instrumentation aspects of synchrotron radiation sources are reviewed. The direct transition model is shown to be applicable in this range with some limitations. Cooper minima and adsorbate sensitivity enhancement for h >100 eV are reviewed. A new effect: condensed-phase photoelectron asymmetry: is noted. Finally, photoelectron diffraction: another new effect: is described and evaluated. Shirley,-D.A. (Materials and Molecular Research Division, Lawrence Berkeley Laboratory; Department-of-Chemistry,-University-of-California,-Berkeley,-California)
