PHOTOELECTRON DIFFRACTION - SPACE, TIME, AND SPIN DEPENDENCE OF SURFACE-STRUCTURES

The current status of photoelectron-diffraction studies of surface str uctures is briefly reviewed, and several recent developments and propo sals for future areas of application are then discussed. The applicati on of full-solid-angle diffraction data, together with simultaneous ch aracterization by low-energy electron-diffraction and scanning-tunneli ng microscopy, to epitaxial growth is considered. Several new avenues that are being opened up by third-generation synchrotron-radiation sou rces are also considered. These include photoelectron diffraction from surface and interface atoms, the possibility of time-resolved measure ments, and circular dichroism in photoelectron angular distributions. The addition of spin to the photoelectron-diffraction measurement is a lso considered, and can be achieved either through core-level multiple t splittings or by circular-polarized excitation of spin-orbit-split l evels. This last development should make it possible to study short-ra nge magnetic order, perhaps even in a holographic fashion.