Microwave Studies of Prereactive Molecular Complexes

在这个由化学系化学结构、动力学和机制-A(CSDM-A)计划资助的项目中，Kenneth Leopold教授正在使用最先进的仪器来研究分子相互作用的力。这些力可以影响化学反应的结果，特别是对溶解在水中的物质，因为水中发生了许多重要的化学反应。这项工作是通过首先研究可以相互反应的气态分子对来完成的。然后，当加入额外的分子时，可以观察到它们对反应对的影响。使用的仪器测量分子如何吸收微波。分子或团簇吸收的一组特定的微波频率包含关于其结构和原子如何结合在一起的准确信息。除了基础科学之外，这项工作还可能应用于了解地球大气中气溶胶粒子是如何形成的，从而有助于我们对气候的理解。通过这个研究项目，利奥波德教授实验室的学生在先进的实验方法和严格处理高精度实验数据方面获得了宝贵的经验。旋转光谱被用来阐明包含处于化学变化边缘的分子的裸和微溶剂团簇的分子和电子结构。这为研究聚集和反应之间的关系提供了一个有趣的场所。转动光谱是利用基于腔的微波技术和啁啾脉冲微波技术实现的。精确的转动惯量、超精细耦合常数和隧道频率提供了有关结构和零点振动动力学的信息。微溶剂化团簇的研究加深了我们对溶剂化的理解，溶剂化是影响溶液中热力学和反应活性的关键因素。它为发展理论处理凝聚相物质的模型势提供了实验基准，并提供了建立对感兴趣的相互作用的直观理解的化学质量信息。简单的原型系统的研究主要集中在质子转移或水解的络合物上。当选择与大气化学问题，特别是大气气溶胶成核相关的模型系统时，这项工作的更广泛的影响被增强。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。

In this project funded by the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program in the Division of Chemistry, Professor Kenneth Leopold is using state-of-the-art instruments to study the forces that molecules exert on each other. These forces can influence the outcome of chemical reactions, especially for substances dissolved in water where many important chemical reactions take place. The work is accomplished by first studying pairs of gaseous molecules that could react with each other. Then, when additional molecules are added, their effect on the reactive pair can be observed. The instruments used measure how molecules absorb microwaves. The specific set of microwave frequencies that a molecule or cluster absorbs contains accurate information about its structure and about how atoms are bonded together. Beyond fundamental science, this work has potential applications to understanding how aerosol particles form in the Earth’s atmosphere and, thus, on our understanding of climate. Through this research project the students in Professor Leopold’s lab obtain valuable experience in advanced experimental methods and in the rigorous handling of highly accurate experimental data.Rotational spectroscopy is used to elucidate the molecular and electronic structure of bare and microsolvated clusters containing molecules on the verge of chemical change. This offers an interesting venue for studying the relationship between aggregation and reactivity. The rotational spectroscopy is implemented by exploiting both cavity-based and chirped-pulse microwave techniques. Accurate moments of inertia, hyperfine coupling constants, and tunneling frequencies provide information about structure and zero-point vibrational dynamics. The study of microsolvated clusters deepens our understanding of solvation, a critical factor influencing thermodynamics and reactivity in solution. It offers experimental benchmarks for the development of model potentials for theoretical treatments of condensed phase matter and provides chemical quality information that builds an intuitive understanding of the interactions of interest. Simple prototypical systems are investigated with strong focus on complexes subject to proton transfer or hydrolysis. The broader impact of the work is enhanced when model systems are chosen which are pertinent to problems in atmospheric chemistry, particularly the nucleation of atmospheric aerosols.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.