Electronic and Atomistic Effects in Nanostructures

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Technical abstract This project is a study of the electronic structure, morphology, stability, and atomistic behavior of selected surface-based nanoscale systems prepared by deposition, self-assembly, and self-organization. The systems of interest include films of Ag, Pb, and Bi deposited on surfaces of Si and Ge that are smooth, stepped, or modulated by nanowire arrays. Electrons in these systems, confined or modulated by the geometry, can organize into novel configurations including quantum well states, resonances, and localized states; their interactions with the atomic lattice can lead to substantial changes in atomic organization, symmetry, and thermodynamic behavior. These effects and phenomena are of central importance to "nanoscale science and technology," a prevailing national research theme. The primary tool used in these investigations is angle-resolved photoemission, performed at the Synchrotron Radiation Center in Stoughton, Wisconsin, which is a national user facility supported by the National Science Foundation. Through cutting-edge research, this project affords education to students and postdoctoral fellows and extends services to the community via consultation, collaboration, and sharing of experience and expertise. The rigorous student training including working at national facilities contributes directly to the personnel needs of industry, universities, and national laboratories. Non-technical abstract Metal atoms such as Ag (silver), Pb (lead), and Bi (bismuth), upon deposition onto electronic substrate materials such as Si (silicon) and Ge (germanium), can form smooth films or self-organize into novel configurations including arrays of clusters, islands, pyramids, and other geometrical shapes of nanoscale dimensions. Electrons in these systems are forced to adapt to the geometry, and the atomic lattice structure reacts to the electronic structure modification. Novel and useful properties often emerge as a result. The underlying scientific principles of these nanoscale phenomena present intellectual challenges and have important technological implications in areas such as nanoelectronics, quantum devices, coatings, catalysts, and solar cell and battery technologies. This project utilizes synchrotron radiation to perform fundamental studies on this topic. The work is primarily carried out at the Synchrotron Radiation Center in Stoughton, Wisconsin, a national user facility supported by the National Science Foundation. Through cutting-edge research, this project affords education to students and postdoctoral fellows and extends services to the community via consultation, collaboration, and sharing of experience and expertise. The rigorous student training including working at national facilities contributes directly to the personnel needs of industry, universities, and national laboratories.