Nanodroplets to nanoparticles: Integretated studies of freezing

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This award, funded by the Chemical Structure, Dynamics and Mechanisms program of the Division of Chemistry, supports the research of Prof. Barbara Wyslouzil and her students at The Ohio State University. The overarching goal of the proposed research is to explore the physics of freezing including the limits to which liquids can be supercooled, the transformation kinetics and the structure of the emerging solid phase. This research integrates experimental and molecular modeling. The specific experimental objectives include: 1) measurement of liquid-solid nucleation rates as nanodroplets freeze, 2) the exploration of the role of molecular structure on the relative importance of the surface versus bulk freezing and 3) the development to x-ray scattering techniques to follow the transformations in situ. Molecular modeling is used to understand the driving force for the surface freezing in chain-like molecules and to calculate liquid-solid nucleation rates to compare directly to the measured values. Freezing, or crystallization from the melt, is a fundamental physical process that plays a central role in a broad range of industrial and natural processes. Developing a deeper understanding of this phenomenon, measuring phase transition rates and exploring the role free surfaces play in freezing are all crucial for developing accurate models of industrial processes, atmospheric chemistry and global climate.In a broader context, this work develops novel applications of small angle scattering, aerosol spectroscopy, and molecular modeling techniques that address fundamental problems in aerosol science. The results stemming from this work are of interest to researchers in nucleation, polymer physics, materials science, and aerosol and cloud physics. The program provides a rich and varied research environment for students, from high school to graduate level that is highly interdisciplinary.