I. Synthesis and properties of low-dimensional materials. II. A new metastable copper oxide.

摘要

In the first part of this thesis, we discuss the synthesis and properties of one dimensional materials. Chapter one reviews the physical properties of low dimensional materials and previous synthetic work. Challenges and opportunities arising from the lack of general methods to rationally synthesize one dimensional nanostrucutres and from the need to make measurements on individual nanostructures are discussed.; In chapter two, we present a new method for the synthesis of one dimensional materials. Our synthetic method exploits laser ablation to create small clusters that act as catalysts in a vapor-liquid-solid growth process. This new method was used to synthesize crystalline silicon and germanium nanowires. Based on mechanistic studies, a new growth mechanism in which laser ablation generates nanometer size particles that act as the critical catalysts was proposed and tested. We termed this new method Laser Assisted Vapor-Liquid-Solid Growth. The generality of this synthetic method was explored in studies of silicon and germanium nanowire growth. Photoluminescence measurements and electron microscopy studies indicate that these nanowires can be used to test predictions regarding quantum confinement and reduced dimensionality.