CAREER: Probing Chemistry of Surface-Supported Nanostructures at the Angstrom-Scale

扫描隧道显微镜（STM）技术是近40年前发明的。STM产生了表面上单个原子的第一张图像。大约在同一时间，人们发现，如果分子位于纳米级金属尖端，振动分子发出的光信号可以被放大100多万倍。在这个由化学学部化学结构动力学和机制（CSDM-A）项目资助的项目中，伊利诺伊大学芝加哥分校化学系的蒋楠教授正在开发一种最先进的技术，该技术将扫描隧道显微镜（STM）与尖端增强拉曼光谱（TERS）相结合，以埃尺度的空间分辨率（一埃是一厘米的一亿分之一）研究单个分子中的键拉伸。蒋教授和他的学生们利用他的透射电镜技术研究了单个分子在表面上是如何相互排列的。Jiang的研究小组试图揭示单个分子如何与表面相互作用的细节。这项研究可能最终为控制表面支持的分子结构和反应提供基础知识。作为CAREER项目的一部分，江教授和他的团队为社区大学和当地高中生提供了化学研究的机会，为他们提供了单分子水平物理化学的实践研究经验。蒋博士通过在UIC建立为期一周的物理化学研讨会，提高了本科生对实验化学研究的参与度。在这个研讨会上，来自不同背景的芝加哥城市学院的学生将接触到科学的职业道路。Jiang博士的团队为芝加哥地区的社区大学生提供手持式拉曼设备，并提供在线培训材料和数据分析程序。这种设备和数据的共享丰富了一般化学实验室的经验。这个项目的重点是在不同的化学环境中，使用新的方法在埃级尺度上形成和破坏化学键的机制。STM成像与拉曼光谱提供的详细化学信息相结合，可以用空间和光谱分辨率探测固体表面上有机吸附剂和特定结合位点之间的相互作用。此外，以埃尺度空间分辨率实现的拉曼一维（1D）线轮廓和二维（2D）映射提供了这些振动模式在表面上的位置，从而定义了这些分子与特定结合位点之间的相互作用。对表面支撑结构形成的基本步骤的详细机理研究有望导致设计具有定制化学性质的新型原子和节能材料和分子组件的改进。参与这项研究和教育项目的学生在扫描显微镜和光谱学以及量子力学理论计算方面获得了宝贵的经验，这些经验有助于解释实验数据。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Scanning tunneling microscopy (STM) technology was invented nearly 40 years ago. STM produced the first images of single atoms on a surface. Around the same time, it was discovered that light signals emitted from a vibrating molecule could be amplified more than a million times if the molecule was on the tip of a nanometer-scale metal tip. In this project funded by the Chemical Structure Dynamics and Mechanisms (CSDM-A) program of the Chemistry Division, Professor Nan Jiang of the Department of Chemistry at the University of Illinois at Chicago is developing a state-of-the-art technique that combines scanning tunneling microscopy (STM) with tip-enhanced Raman spectroscopy (TERS) to study bond stretching in an individual molecule with angstrom-scale spatial resolution (an angstrom is one hundred millionths of a centimeter). Using his TERS technique, Professor Jiang and his students study how individual molecules align relative to each other on surfaces. The Jiang research group seeks to uncover the details of how single molecules interact with surfaces. This research may ultimately provide fundamental knowledge that will able the control of surface-supported molecular structures and reactions. As part of this CAREER project, Professor Jiang and his group are bringing the excitement of chemistry research opportunities to community college and local high school students by offering them hands-on research experience in physical chemistry at the single molecule level. Dr. Jiang improves the participation of undergraduate students in experimental chemistry research by establishing a One-Week Physical Chemistry Workshop at UIC. In this workshop, Chicago City Colleges students from diverse backgrounds are exposed to scientific career paths. Dr. Jiang's group provides handheld Raman equipment to community college students in the Chicago area with online training materials and data analysis procedures. This sharing of equipment and data enriches the general chemistry laboratory experience.This project focuses on interrogating the mechanisms of forming and breaking chemical bonds at the angstrom-scale in various chemical environments using novel approaches. The combination of STM imaging with the detailed chemical information provided by Raman spectroscopy allows the interactions between organic adsorbates and specific binding sites on solid surfaces to be probed with spatial and spectroscopic resolution. Furthermore, Raman one-dimensional (1D) line profiles and two-dimensional (2D) mapping achieved with angstrom-scale spatial resolution provide the location of these vibrational modes on the surface, and hence, define the interactions between these molecules and specific binding sites. Detailed mechanistic studies of the elementary steps of surface-supported structure formation are expected to lead to improvements in designing new atom- and energy-efficient materials and molecular assemblies with tailored chemical properties. The students engaged in this research and education project gain valuable experience in both scanning microscopy and optical spectroscopy, as well as quantum mechanics theory calculations which aid in the interpretation of experimental data.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.