Photoelectron diffraction: New dimensions in space, time, and spin

The current status of photoelectron diffraction studies of surface structures is briefly reviewed, and several recent developments and proposals for future areas of application are then discussed. The application of full-solid-angle diffraction data, together with simultaneous characterization by low energy electron diffraction and scanning tunneling microscopy, to epitaxial growth is first considered. New instrumentation for carrying out such studies with third-generation synchrotron radiation is then presented and several types of results obtained with it are discussed. These results include photoelectron diffraction from surface and interface atoms, the possibility of time-resolved measurements, and circular dichroism in photoelectron angular distributions, The addition of spin to the photoelectron diffraction measurement is also considered, and can be achieved either through core-level multiplet splittings or by circular-polarized excitation of spin-orbit-split levels. This last development makes it possible to study short-range magnetic order, perhaps even in a holographic fashion.