RUI: Photoisomerization Potential of Molecular Switches on Surfaces

西华盛顿大学（WWU）的Andreas Riemann教授在化学系大分子、超分子和纳米化学（MSN）项目的支持下，研究了螺吡喃分子开关的行为。分子开关是一种可以在两种或两种以上的稳定状态之间来回摆动的分子。在每种状态下，分子都具有独特的形状、结构以及电子和光学特性。这些分子在受到外界刺激（如光）的作用下从一种状态切换到另一种状态。目标是控制开关机制并创建由功能分子开关组成的表面结构。分子开关是电子器件中分子电子学的重要组成部分。世界海洋大学的本科生是这个项目的组成部分，他们将获得相关的经验，为他们未来在科学研究或工业领域的发展做准备。此外，Riemann教授还参与了西华盛顿大学（Western Washington University）发起的“校园指南针”（Compass 2 Campus）项目，旨在通过激发学生对研究的兴趣，并为他们提供接受高等教育的途径，提高传统上代表性不足背景学生的科学素养。本研究的目标是研究分子/底物组合，这些组合能够经历光异构化过程，具有足够大的横截面，使其适合于进一步应用于分子电子学。所研究的体系是沉积在贵金属衬底和石墨上的螺吡喃/merocyanine异构体。在分子薄膜中，单个分子可以被激发来改变它们的结构。这些分子的构象行为和光异构化过程的控制被研究使用各种实验表面科学技术，如STM， LEED和XPS以及计算化学方法，包括DFT和分子力学计算。本项目分三个阶段进行：1)分析各种螺吡喃基分子在不同温度和底物覆盖率下的吸附行为；2)利用光和热触发和监测异构化开关；3)利用计算化学模拟了螺吡喃基异构体的吸附行为。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。

Professor Andreas Riemann of Western Washington University (WWU) is supported by the Macromolecular, Supramolecular, and Nanochemistry (MSN) Program of the Division of Chemistry to investigate the behavior of spiropyran molecular switches. A molecular switch is a molecule that can swing back and forth between two or more stable states. In each state, the molecule has a distinctive shape, structure, and electronic and optical properties. The molecules switch from one state to another in response to external stimuli, such as light. The goal is to control the switching mechanism and create surface structures consisting of functional molecular switches. Molecular switches are important components of molecular electronics used in electronic devices. Undergraduate students at WWU are an integral part of this project and are given relevant experiences for their futures in scientific research or in industry. Additionally, Professor Riemann is involved in outreach through "Compass 2 Campus," a Western Washington University initiative to increase science literacy of students from traditionally underrepresented backgrounds, by stimulating their interest in research and providing them with pathways to higher education. The goal of this research is to study molecule/substrate combinations which are able to undergo a photoisomerization process with a large enough cross-section to make it suitable for further application in molecular electronics. The systems under investigation are spiropyran/merocyanine isomers deposited on noble metal substrates and graphite. Thin molecular films where individual molecules can be excited to switch their configuration are created. Conformational behavior of these molecules and control of the photoisomerization process are investigated using a variety of experimental surface science techniques such as STM, LEED and XPS as well as computational chemistry methods including DFT and Molecular Mechanics calculations. The project is conducted in three stages: 1) the analysis of adsorption behavior of various spiropyran-based molecules at various temperatures and substrate coverages; 2) the use of light and heat to trigger and monitor isomerization switching; and 3) the use of computational chemistry to simulate the adsorption behavior of spiropyran-based isomers.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.