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

University Of Houston, Houston TX

Investigators

Abstract

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.