Electronic Properties of Impurities, Surfaces, and Quantum Structures

9975470 jiang本项目是利用高分辨率角分辨光谱学对选定金属体系的电子特性进行基础研究。目标是了解对电磁刺激的响应以及准粒子和集体激励的行为。光发射截面、线形和线宽将作为结合能在k空间中精确指定点的函数来测量。杂质散射，磁相互作用，空间相干，声子散射和量子约束的影响将被检查。感兴趣的系统将包括掺杂磁性和非磁性杂质的表面和块状材料，以及用于探测特定性质（包括费米液体或非费米液体行为）的薄膜和多层材料。我们已经证明了原子均匀的银膜可以在铁单晶上制备。这些薄膜形成一个电子干涉仪，允许高精度的光谱测量。将研究导致这种薄膜形成的潜在生长机制，并进行实验以探索制作其他材料均匀薄膜的可能性。涉及薄层和掺杂剂的人工结构可以表现出有趣的和潜在有用的电子特性。现代技术允许以原子精度制造层构型。这种系统中的电子可以被层边界和掺杂物捕获、反射或散射，从而产生新的特性，为应用提供了机会。本研究项目将重点研究原子层形成的基本物理和化学问题以及原子结构与电子性质的关系。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.***