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计划的支持下，俄克拉荷马大学的Bumm和Huang教授及其学生正在研究如何改进分子在表面的排列和运动的测量方法，以了解这些细节如何影响分子的化学和物理性质。最终目标是了解分子的性质以及它们所在的表面是如何取决于分子如何堆积在一起的。了解这一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工具，用于高精度的测量和分析。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独特的培训场所。俄克拉荷马大学是路易斯斯托克斯-俄克拉荷马州少数民族参与联盟(LS-OKAMP)的财团成员之一，此外还运营着多元文化工程计划(MEP)。Bumm和Huang教授都在积极地从代表不足的少数族裔群体中招募学生到他们的项目中，包括美洲原住民学生。扫描隧道显微镜(STM)可以亚纳米分辨率成像表面，揭示表面上原子和分子的排列。尽管分辨率非常高，但由于扫描隧道显微镜固有的图像失真，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将这种失真消除到可以实现精确的真实空间测量的水平。该项目建立在这一成功的基础上，并开发了新的先进图像分析方法来表征图像序列中分子的运动。该项目开发了这些方法，并在自组装单分子膜(SAM)上进行了测试。自组装单分子膜是一种单分子厚的2D晶体有机薄膜。SAMS被广泛应用于许多科学和技术领域。尽管人们对它们进行了很好的研究，但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。将开发研究引入SAMS的点缺陷的分析方法，并将其应用于SAMS的基本特征，这些特征很难以其他方式执行。Huang团队提供分子动力学和DFT建模方面的专业知识，这是连接观察到的STM图像与潜在分子结构的关键组件。

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.