ATOM DYNAMICS ON PT, IR AND CU SURFACES - AN EXPERIMENTAL-STUDY USINGVARIOUS TECHNIQUES

Some metallic adsorbed atoms on fee metal surfaces can exchange with s ubstrate atoms well below the room temperature. For homogeneous system s, the atomic exchange is a mechanism for self-diffusion. For heteroge neous systems, it is a mechanism for point alloy formation of only the top surface layer but it will also induce self-diffusion. We present experimental evidence found from FIM, HREELS and LEIS studies. These e xperiments and their relations to available theories and molecular dyn amic simulations of this phenomenon are also mentioned. In addition, w e present evidence for the ascending motion of step edge atoms to the upper terrace for the Ir (111) surface, and the result of a measuremen t of the potential barrier height of the ascending motion and the diss ociation energy of step edge atoms to the lower terrace.