Advanced Real-Space Measurements with STM: Application to Molecular Monolayers, Monolayer Defects, and Surface Chemistry

在化学系化学测量和成像项目的支持下，Bumm和Huang教授及其俄克拉何马大学的学生正在研究改进表面分子排列和运动测量的方法，以了解这些细节如何影响分子的化学和物理性质。最终的目标是了解分子的性质，从而了解分子所在的表面，是如何依赖于分子如何聚集在一起的。了解这种关系对于设计具有更好生物相容性的独特表面以及用于防腐和润滑的涂层至关重要。这项工作的目标是开发改进的高精度测量和分析工具。这个跨学科的团队结合了Bumm（实验物理化学）和Huang（理论化学工程）的研究小组，为从事该项目的研究生和本科生提供了一个独特的训练基地。俄克拉何马大学是路易斯·斯托克斯-俄克拉何马少数民族参与联盟（LS-OKAMP）的联合成员，此外还运营多元文化工程项目（MEP）。范教授和黄教授都在积极地从代表性不足的少数群体中招募学生，包括美国原住民学生。扫描隧道显微镜（STM）可以对表面进行亚纳米分辨率的成像，揭示表面原子和分子的排列。尽管具有显著的分辨率，但由于STM固有的图像畸变，精确的测量变得复杂。Bumm小组在图像后处理方面的最新进展可以消除这种失真，从而实现精确的真实空间测量。该项目建立在这一成功的基础上，并开发了新的先进的图像分析方法来表征分子在图像序列中的运动。该项目在自组装单层（SAMs）上开发和测试了这些方法，这是一种二维结晶有机薄膜，一个分子厚。地对空导弹广泛应用于许多科学技术领域。虽然它们已经被研究得很好，但是关于它们的结构和性质仍然存在许多基本问题。正在开发的分析方法可以测量图像中每个分子的位置，精度优于30 pm。研究引入点缺陷的分析方法有待发展，并应用于其他方法难以研究的地对空导弹的基本特性。Huang团队在分子动力学和DFT建模方面提供专业知识，这是连接观察到的STM图像与潜在分子结构的关键组成部分。

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professors Bumm and Huang and their students at University of Oklahoma are investigating ways to improve measurements of the arrangement and motion of molecules on surfaces to understand how these details affect the chemical and physical properties of the molecules. The ultimate goal is to understand how the properties of molecules, and therefore the surface on which they reside, depend on how molecules pack together. Understanding this relationship is crucial for design of unique surfaces of better bio compatibility and the coatings for corrosion protection and lubrication. The goal of this work is to develop improved tools for measurement and analysis with high precision. This interdisciplinary team combines the research groups of Bumm (experimental physical chemistry) and Huang (theoretical chemical engineering) which provides a unique training ground for graduate and undergraduate students working on the project. University of Oklahoma is a consortial member of the Louis Stokes-Oklahoma Alliance for Minority Participation (LS-OKAMP) in addition to operating the Multicultural Engineering Program (MEP). Both Professors Bumm and Huang are working on actively recruiting students from underrepresented minority groups to their programs, including Native Americans students.The scanning tunneling microscope (STM) can image surfaces with sub-nanometer resolution, revealing the arrangement of atoms and molecules on the surface. Despite the remarkable resolution, accurate measurements are complicated by the image distortion inherent in the STM. Recent advances in image post-processing by the Bumm group can remove this distortion to a level where accurate real-space measurements to be achieved. This project builds on that success and develops new advanced image analysis methods to characterize motion of molecules in sequences of images. The project develops and tests these methods on self-assembled monolayers (SAMs)--a 2D crystalline organic film, one molecule thick. SAMs are widely used in many areas of science and technology. Although they are well studied, many fundamental questions remain concerning their structure and properties. The analysis methods being developed can measure the position of each molecule in the image to better than 30 pm. Analysis methods to study point defects introduced into SAMs are to be developed and applied to fundamental characteristics of SAMs difficult to perform in other ways. The Huang group provide expertise in molecular dynamics and DFT modeling which is a critical component to bridge the observed STM images with the underlying molecular structure.