| An ultra-high vacuum scanning tunneling microscope has been used in the study and modification of metal surfaces. Its novel design features a dual sample and tip exchange mechanism, a packaged tip-amplifier assembly and an integrated cooling finger. Representative results for the well-known surfaces of graphite, gallium arsenide and gold are included.; The (111) surface of gold films evaporated onto mica substrates was characterized using scanning tunneling microscopy (STM), x-ray photoelectron spectroscopy and low energy electron diffraction. The step structure, native (22 x 1) reconstruction and its domain structure, and surface contamination of the Au(111) surface were investigated.; Nucleation and layer-by-layer epitaxial growth of gold and silver on Au(111) and Ag(111) surfaces at room-temperature have also been studied under ultra-high vacuum conditions, from the initial stages up to the completion of several layers. Quantitative information, such as cluster size distributions and spatial correlation functions, was extracted from STM topographs, demonstrating generally applicable techniques. The results reveal the relation between the Au(111) (22 x 1) surface reconstruction and its domain structure, the absence of a reconstruction for Ag(111), and the nucleation and growth of the four possible substrate-overlayer metal combinations in this system.; Furthermore, we report a study on the evolution of the surface topography of ion-bombarded gold films, from the initial stages of sputter damage to the removal of several layers. Energy-dependent sputter yields and crater size distributions are derived from STM images which show the progressing surface erosion. A duality in the behavior of surfaces prepared by deposition of atoms (evaporation) and deposition of vacancies (sputtering) is revealed.; Another experiment investigates the room-temperature Stranski-Krastanov growth of the compound insulator silver bromide on the silver(111) surface, illustrating the effects of lattice mismatch and doping on the observed topography.; Finally, several techniques for the nanometer-scale modification of metallic surfaces by voltage pulses or mechanical indentation are described. In particular, permanent hole patterns in graphite with 100 A resolution and chain-scission of ultra-thin polymer films are presented. |
