RII Track-4:NSF: Unveiling the structure and thermodynamic stability of pre-nucleation clusters and their role in multistep nucleation

成核会影响后续的结晶过程，从而影响我们的日常生活。然而，由于其特性有限，其机制仍然知之甚少。这项研究的目的是确定在盐溶液成核的早期阶段发生了什么。拟议的工作将利用研究金提供的创新实验设备克服目前的障碍。这一项目的结果将促进目前对成核早期阶段发生的事情的了解，这将有助于更好地理解盐溶液的成核机理。该奖学金项目将导致爱荷华州立大学、爱荷华大学、艾姆斯实验室和橡树岭国家实验室之间新的多学科合作。一名博士生将获得分子动力学模拟方面的技能，并获得广泛的实践经验。西班牙裔专业工程师协会(SHPE)的两名本科生将加入该项目，并在SHPE全国大会上展示他们的工作。爱荷华州立大学现有的三个外展计划将被用来与K-12学生、教师和家长分享该奖学金项目。越来越多的材料，包括蛋白质、电解质溶液、生物矿物和胶体，被观察到在成核之前以多步成核的形式形成预成核团簇(PNC)。显然，PNC在多步成核(MSN)中起着至关重要的作用，但人们对它们的性质知之甚少。提出这项研究的理由是，从机理上理解MSN很可能为开发控制所需晶相的形核和生长的方法提供新的机会。为此，该项目旨在确定PNC在氯化钠水溶液中的结构、热力学稳定性和作用。PI团队将通过将PI团队开发的溶液静电悬浮器(SEL)与橡树岭国家实验室的中子散射相结合，克服目前的实验障碍。该项目的长期目标是开发一个预测框架，以预测和控制各种水溶液中的MSN。拟议的研究将导致在阐明电解质溶液中MSN的机理方面取得纵向进展，并将提供更深入的见解，以更好地了解其他材料系统中的MSN。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。

Nucleation influences the subsequent crystallization process which impacts our daily life. However, its mechanism remains poorly understood due to limited characterization. The purpose of the research is to identify what occurs at the early stage of nucleation of salt solutions. The proposed work will overcome the current barriers using innovative experimental apparatus enabled by the fellowship. The results of this project will advance the current knowledge on what occurs in the early stage of nucleation, which will lead to a better understanding of the nucleation mechanism of salt solutions. The fellowship project will result in new multidisciplinary collaborations among Iowa State University, the University of Iowa, Ames Laboratory, and Oak Ridge National Laboratory. One doctoral student will acquire skills in molecular dynamics simulation and gain extensive hands-on experience. Two undergraduate students from the Society of Hispanic Professional Engineers (SHPE) will join the project and present their work at the SHPE National Convention. Three existing outreach programs at Iowa State University will be leveraged to share the fellowship project with K-12 students, teachers, and parents. A growing number of materials, including proteins, electrolyte solutions, biominerals, and colloids, have been observed to nucleate in multistep forming pre-nucleation clusters (PNCs) prior to nucleation. It is apparent that PNCs play a critically important role in multistep nucleation (MSN), yet their nature is poorly understood. The rationale for the proposed research is that a mechanistic understanding of MSN is likely to provide new opportunities to develop a method to control the nucleation and growth of desired crystal phases. For this reason, the project aims to identify the structure, thermodynamic stability, and role of PNCs in an aqueous NaCl solution. The PI team will overcome the current experimental obstacles by integrating the solution electrostatic levitator (SEL) developed by the PI team with neutron scattering at Oak Ridge National Laboratory. The long-term goal of the project is to develop a predictive framework to anticipate and control the MSN in various aqueous solutions. The proposed research will lead to a vertical-step advancement towards elucidating the mechanism of MSN in electrolyte solutions and would give deeper insights to better understand the MSN in other material systems.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.