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

在化学结构、动力学和机理(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，休斯顿大学的杨丁雪正在使用先进的电子成像方法来观察分子薄膜受光照射时发生的结构变化。考虑到分子的尺寸和分子运动的短时间域，收集分子的图像或在电影中捕捉分子的运动是一个巨大的挑战。杨博士和他的团队将使用时间分辨电子衍射，以分子级别的分辨率记录沉积在固体衬底上的液体的快速结构变化的动力学。他们的发现可以加深对能量流动基本机制的理解，并使清洁能源生产和储存技术中使用的固液界面能够进行合理设计。该项目还将为杨课题组的研究生、本科生和博士后学者提供研究机会。此外，杨小组将在大休斯顿地区为高中生举办化学奥林匹克竞赛。超快电子衍射(UED)具有同时的时空分辨率和高表面灵敏度，将作为一种时间分辨的直接结构探测技术，在亚埃尺度上可视化激光诱导的运动。对于固体-分子界面系统，薄膜结构上的微小差异可以显著改变能量传输的时间尺度和潜在机制。为了阐明结构与行为的关系，研究小组将研究不同组装顺序对固体衬底上纳米级分子薄膜结构和能量传输动力学的影响。具有不同分子间作用力的分子和具有不同堆积顺序的自组装单分子膜被选作这一领域的系统研究。该项目与纳米尺度的能源和热管理直接相关，清楚地了解分子薄膜中发现的结构决定行为的差异可能会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，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.