Surface Studies with Slow Positron Beaks

Abstract

Slow-positron physics is an exciting and rapidly advancing field. The continuing progress in the development of intense monochromatic beams of low-energy positrons has made it possible to perform a number of landmark experiments, where the interaction of the positron with solid surfaces plays a central role. These experiments either deal with fundamental atomic physics (positronium spectroscopy) or focus on the electronic and atomic properties of the surface region, using positrons as a probe. In the former category, the surface is involved just as an efficient source of positronium-like atoms. On the other hand, in the second category of experiments the surface i s the main object of study, and has to be prepared and maintained under carefully monitored conditions. The challenge is then to understand the various aspects of the positron-surface interaction and to correlate the observations with microscopic surface information. I shall concentrate on discussing the positron surface physics from a theoretical viewpoint, with emphasis on the new developments and future prospects. For background material and more detailed 1 discussion, the reader is referred to a number of recent reviews^1–3.