| The Introduction (Chapter 1) and Conclusion (Chapter 6) of this dissertation were prepared by Prof. Thomas P. Beebe, Jr., after the untimely death of Jennifer Dawn Alexander in 2002, in order to award her a posthumous Ph.D. degree. Chapters 2-5 are based on Jennifer's publications in the Journal of Physical Chemistry and Langmuir.;In Chapter 2, the surface chemistry of highly oriented pyrolytic graphite (HOPG) bombarded with energetic Cs+ ions was investigated. Defects in the HOPG created by the Cs+ ion bombardment act as nucleation sites for O2 oxidation at elevated temperatures, producing "molecule corral" pits. By varying the Cs+ dose density and bombardment energy, the pit density, yield, and depth can be accurately controlled.;In Chapter 3, gold and silicon nanostructures were produced by condensing the vacuum-evaporated elements onto nanometer-sized etch-pits on the HOPG surface. Annealing then results in the formation of metal and semiconductor nanostructures in pits on the graphite basal plane. By varying the ratio of the total amount of material evaporated to the diameter of the etch-pit templates, three distinct types of nanostructures were observed to form: rings, disks, and mesas.;In Chapter 4, surface defects on HOPG were controllably produced by bombardment with Cs+ ions. Defects thus created were oxidized at 650°C in air to produce nanometer-size monolayer and multilayer molecule corrals (pits). The controlled production of both monolayer and multilayer pits was realized and studied. The measured pit growth rates for multilayer pits are in good agreement with a new model of the pit growth rate acceleration by adjacent layers, and the separate contributions of surface diffusion and collision were extracted.;In Chapter 5, etch pits on HOPG were used to form gold nanostructures. Etch pit edges act as nucleation and growth sites for gold nanostructures and also fix gold nanostructures in place for study by scanning probe techniques. Hexagonal-shaped, flat-topped, and other gold nanostructures were formed in multilayer etch pits. Oxygen is found to adsorb molecularly onto surfaces of gold nanostructures at room temperature and atmospheric pressure. In contrast, no oxygen adsorption was observed on the surface of a Au(111) single crystal, thus demonstrating a significant cluster size effect. |
