Electronic Properties of Impurities, Surfaces, and Quantum Structures

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9975470ChiangThis project is a fundamental study of the electronic properties of selected metal systems using high-resolution angle-resolved photoemission spectroscopy. The goal is to understand the response to electromagnetic stimulation and the behavior of quasiparticles and collective excitations. Photoemission cross sections, lineshapes, and linewidths will be measured as a function of binding energy at precisely specified points in k space. Effects of impurity scattering, magnetic interaction, spatial coherence, phonon scattering, and quantum confinement will be examined. Systems of interest will include surfaces and bulk materials doped with magnetic and nonmagnetic impurities as well as films and multilayers designed for probing specific properties including the Fermi-liquid or non-Fermi-liquid behavior. We have demonstrated that atomically uniform films of silver can be prepared on iron single crystals. These films form an electron interferometer allowing highly accurate spectroscopic measurements. The underlying growth mechanism leading to the formation of such films will be investigated, and experiments will be carried out to explore the possibility of making uniform films of other materials. %%%Artificial structures involving thin layers and dopants can exhibit interesting and potentially useful electronic properties. Modern techniques allow layer configurations made with atomic precision. Electrons in such systems can become trapped, reflected, or scattered by the layer boundaries and dopants, resulting in new properties that offer opportunities for applications. This research project will focus on basic physics and chemistry issues of atomic layer formation and the relationship between atomic structure and electronic properties. Part of the work will be carried out at the Synchrotron Radiation Center, a national user facility funded by the National Science Foundation. This project will offer excellent opportunities for graduate student research and training.***