Electronic Properties of Impurities, Surfaces, and Quantum Structures

这个项目是利用高分辨率角度分辨光电子能谱对选定的金属系统的电子性质进行的基础性研究。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。光电子发射截面、线形和线宽将作为k空间中精确指定点的结合能的函数来测量。我们将考察杂质散射、磁相互作用、空间相干性、声子散射和量子限制的影响。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，以及为探测特定性质而设计的薄膜和多层膜，包括费米液体或非费米液体行为。我们已经证明了可以在铁单晶上制备原子均匀的银膜。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。将研究导致这种薄膜形成的潜在生长机制，并将进行实验，以探索用其他材料制备均匀薄膜的可能性。包含薄层和掺杂剂的人工结构可以显示出有趣的和潜在有用的电子性质。现代技术可以实现原子精度的层状结构。这类系统中的电子可能会被层边界和掺杂剂捕获、反射或散射，从而产生新的性质，为应用提供机会。这项研究将集中在原子层形成的基本物理和化学问题，以及原子结构和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.***