RTM-Untersuchungen von Inseln auf Kupfer- und Platinoberflaechen

This thesis deals with quantitative studies of equilibrium and non-equilibrium phenomena on Pt(111) and Cu(100) surfaces using scanning tunneling microscopy (STM). The aim of this work is apply theoretical methods based on statistical physics to determine atomistic energy parameters of surface diffusion processes on metal substrates which cannot be directly detected, and hence, analyzed as individual atomic hopping events. In this thesis, the theoretical methods were applied to Pt(111) and Cu(100) substrates and step free energies were measured, dominant mass transport processes were identified and the relevant activation energies were obtained. On Pt(111), for instance, the equilibrium shape and the equilibrium edge fluctuations of monatomic high islands were studied between 533 K and 713 K. The ratio between the step free energies of A- and B-steps on Pt(111) was analyzed for the first time as a function of temperature. Absolute values for the free energies for A- and B-steps on Pt(111) could be determined experimentally for the first time. As a non-equilibrium phenomena, the Ostwald ripening of single-layer deep vacancy islands on Cu(100) was investigated between 323 K and 398 K. From the temperature dependence of the decay rate, the relevant activation energy has been obtained. A further island decay process was studied in this work which has been discovered only recently to accelerate island decay on fcc(111) surfaces, the rapid island decay. In this thesis, it is shown that this fast decay channel exists also on Pt(111). Finally, a coarsening process is discussed which has a great importance on fcc(100) surfaces, the island coalescence. Here, the coalescence of single-layer deep vacancy islands on Cu(100) was investigated between 303 K and 353 K. (orig.)SIGLEAvailable from: http://deposit.ddb.de/cgi-bin/dokserv?idn=972719156 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman