Elucidating Structures and Order-Determined Energy Transport Dynamics of Solid-Supported Molecular Assemblies

在化学结构，动力学和机制-A（CSDM-A）计划的支持下，以及化学系化学测量和成像（CMI）计划的部分支持下，休斯顿大学的Ding-Shyue Yang正在使用先进的电子成像方法来观察分子膜受到光照射时发生的结构变化。收集分子的图像，或在电影中捕捉它们的运动，是一个重大的挑战，因为分子的尺寸和分子运动的时间域很短。Yang博士和他的团队将使用时间分辨电子衍射，以分子水平的分辨率记录沉积在固体基底上的液体中快速结构变化的动力学。他们的发现可以更深入地了解能量流动的基本机制，并能够合理设计用于清洁能源发电和储存技术的固液界面。该项目还将为杨研究小组的研究生、本科生和博士后学者提供研究机会。 此外，Yang团队还将在大休斯敦地区举办高中生化学奥林匹克竞赛。超快电子衍射（UED）具有同步时空分辨率和高表面灵敏度，将被用作时间分辨的直接结构探测技术，以可视化亚埃尺度的激光诱导运动。对于固体-分子界面系统，薄膜结构的微小差异可以显著改变能量传输的时间尺度和基本机制。为了阐明结构-行为关系，研究小组将研究不同组装顺序对固体基底上纳米分子薄膜结构和能量传输动力学的影响。具有不同强度的分子间力和自组装单分子膜具有不同的包装顺序已被选择在这方面的系统研究。该项目与纳米级的能量和热管理直接相关，对分子薄膜中发现的结构决定行为差异的清晰理解可能对相关结构类型的材料系统产生深远影响。该奖项反映了NSF的法定使命，并被认为值得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来支持。

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program and partial support from the Chemical Measurement and Imaging (CMI) program in the Division of Chemistry, Ding-Shyue Yang of the University of Houston is using advanced electron-imaging methods to watch the changes in structure that occur when a molecular film is struck by light. Collecting images of molecules, or capturing their motion in a movie, is a significant challenge given molecular dimensions and the short time domain for molecular motion. Dr. Yang and his group will use time-resolved electron diffraction in an effort to record the dynamics of fast structural changes in liquids deposited on solid substrates with molecular-level resolution. Their discoveries could provide a deeper understanding of the fundamental mechanisms of energy flow and enable the rational design of solid–liquid interfaces used in clean energy generation and storage technologies. The project will also provide research opportunities for graduate students, undergraduate students, and postdoctoral scholars in the Yang research group. In addition, the Yang group will host Chemistry Olympiad competitions for high school students in the Greater Houston area.Ultrafast electron diffraction (UED), with simultaneous spatiotemporal resolution and high surface sensitivity, will be employed as a time-resolved, direct structure-probing technique to visualize laser-induced motions at the sub-Angstrom scale. For solid-molecule interfacial systems, small differences in thin-film structure can dramatically change the time scale and the underlying mechanism of energy transport. To elucidate structure-behavior relations, the research team will examine the influence of different assembly orders on the structure and energy transport dynamics of nanoscale molecular thin films supported on solid substrates. Molecules with varied strengths of intermolecular forces and self-assembled monolayers with different packing orders have been chosen for systematic studies in this area. The project has direct relevance to energy and thermal management at the nanoscale, and a clear understanding of structure-determined behavioral differences found in molecular thin films could have far-reaching implications for materials systems of related structural types.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.