Electronic Properties of Impurities, Surfaces, and Quantum Structures

9975470Chiang该项目是使用高分辨率角分辨光电子能谱对所选金属系统的电子性质进行基础研究。目标是了解对电磁刺激的反应以及准粒子和集体激发的行为。光电发射截面，线形和线宽将被测量为在k空间中精确指定的点处的结合能的函数。杂质散射，磁相互作用，空间相干性，声子散射和量子限制的影响将被检查。感兴趣的系统将包括掺杂有磁性和磁性杂质的表面和块体材料，以及用于探测特定性质（包括费米液体或非费米液体行为）的薄膜和多层膜。我们已经证明，原子级均匀的银膜可以在铁单晶上制备。这些薄膜形成了一个电子干涉仪，可以进行高精度的光谱测量。将研究导致形成这种膜的潜在生长机制，并将进行实验以探索制造其他材料的均匀膜的可能性。%涉及薄层和掺杂剂的人工结构可以表现出有趣且潜在有用的电子性质。现代技术允许以原子精度进行层配置。这种系统中的电子可以被层边界和掺杂剂捕获、反射或散射，从而产生新的特性，为应用提供机会。本研究计画将着重于原子层形成的基本物理与化学问题，以及原子结构与电子性质之间的关系。 部分工作将在同步辐射中心进行，这是一个由国家科学基金会资助的国家用户设施。该项目将为研究生的研究和培训提供极好的机会。

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.***