Many body effects at surfaces and interfaces

The past two decades have experienced the development of angle-resolved pho toemission to the point that it can now provide crucial information on an e nergy scale that is relevant to many key problems in condensed matter physi cs. At the same time, our ability to prepare and characterize surfaces, int erfaces, and thin films has improved to the extent that many exotic phases can be produced with a high degree of perfection. The combination of these two developments suggests many interesting experiments can be performed tha t probe the coupling between charge, lattice, and spin degrees of freedom i n the context of surface and interface physics. In this paper we briefly re view a few groundbreaking experiments that have initiated this effort. We a lso speculate on future developments in this area. (C) 2001 Elsevier Scienc e B.V. All rights reserved.