Enhanced Electron-Phonon Coupling at Metal Surfaces

处理固体中电子与原子或分子的动态相互作用是困难的，但如果要将功能设计成先进的材料，这是必不可少的。在教科书中，这种相互作用是通过波恩-奥本海默近似（BOA）来处理的，该近似允许科学家认为，当能量更大的电子做自己的事情时，缓慢移动的原子被冻结在空间的平均位置。但是，许多重要的化学、物理和生物现象都是由违反该原则引起的。BOA的击穿是由于靠近费米能量耦合的固体振动激发的电子的低能激发引起的。由此产生的振动相互作用是任何形成或破坏共价键的过程或由电子-晶格相互作用驱动的传统超导性的必要成分。复杂材料或人工纳米结构材料的许多新特性是由固有各向异性系统中电子和晶格（原子）运动的耦合引起的。该项目将使用一种新开发的数据分析程序，从高分辨率光谱数据中提取电子和晶格之间耦合的细节。本科生、研究生和博士后将参与最先进的仪器和材料制备。该奖项由美国国家科学基金会材料研究部和能源部基础能源科学办公室共同资助。***技术***该个人研究者奖支持金属表面电子-声子耦合（EPC）的实验研究。一种新开发的数据分析程序使这种耦合的光谱特征能够从高分辨率角分辨光发射光谱（ARPES）数据中获得。在非常各向异性的系统中，第一次有可能“看到”哪些振动模式与哪些电子耦合。该程序将应用于各种材料，包括层状过渡金属氧化物，MBE生长的MgB2薄膜，以及清洁和修饰的表面。ARPES的测量将与扫描隧道光谱的EPC测量和表面声子色散的非弹性电子散射测量相关联。为了充分利用这一领域的理论和实验进展，世界范围的合作已经建立起来。这个研究项目为本科生、研究生、博士后和访问科学家提供了一个理想的训练基地，让他们接触到最先进的仪器、复杂的生长过程和与理论的紧密结合。该奖项由美国国家科学基金会材料研究部和能源部基础能源科学办公室共同资助。

***NON_TECHNICAL***Treating the dynamic interaction of the electrons and the atoms or molecules in a solid is difficult but essential if functionality is to be designed into advanced materials. In textbooks this interaction is handled by using the Born-Oppenheimer Approximation (BOA), which allows scientists to consider the slow-moving atoms to be frozen in space in their average positions while the more energetic electrons do their thing. But a multitude of important chemical, physical, and biological phenomena are driven by violations of the BOA. Breakdown in the BOA results from low-energy excitations of the electrons near what is known as the Fermi energy coupling with vibrational excitations of the solid. The resulting vibronic interactions are a necessary ingredient in any process that makes or breaks a covalent bond or in conventional superconductivity, which is driven by the electron-lattice interaction. Many of the emergent properties of complex materials or artificially nanostructured materials result from coupling of the electronic and lattice (atom) motion in systems that are inherently anisotropic. This project will use a newly developed data analysis procedure to extract the details of this coupling between the electrons and the lattice from high-resolution spectrocopic data. Undergraduates, graduates and post docs will be involved with state-of-the-art instrumentation and materials preparation. This award is co-funded by NSF's Division of Materials Research and the Department of Energy's Office of Basic Energy Sciences.***TECHNICAL***This individual investigator award supports an experimental investigation of the electron-phonon coupling (EPC) at metal surfaces. A newly developed data analysis procedure enables the spectroscopic features of this coupling to be exacted from high-resolution angle-resolved photoemssion spectroscopy (ARPES) data. For the first time in very anisotropic systems it is possible to "see" which vibrational modes couple to which electrons. This procedure will be applied to a variety of materials, ranging from layered transition-metal oxides, MBE grown thin films of MgB2, and clean and modified surfaces. ARPES measurements will be correlated with scanning tunneling spectroscopy measurements of the EPC and inelastic electron scattering measurements of the phonon dispersion at the surface. A world wide collaboration has been created to take full advantage of theoretical and experimental advances in this field. This research project offers an ideal training ground for undergraduates, graduate students, post docs and visiting scientists, exposing them the state-of-the-art instrumentation, sophisticated growth procedures and close coupling with theory. This award is co-funded by NSF's Division of Materials Research and the Department of Energy's Office of Basic Energy Sciences.