New Tools and Applications for Kinetics and Dynamics with Broadband Rotational Spectroscopy

宽带旋转光谱动力学和动力学的新工具和应用

• 批准号: 2247776
• 负责人: Arthur Suits
• 金额: $ 50万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-07-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2247776&HistoricalAwards=false
• 关键词: New; Tools; Applications; Kinetics; Dynamics

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program in the Division of Chemistry, Professor Arthur Suits of the University of Missouri-Columbia is developing new tools to permit applications of Chirped-Pulse Fourier-Transform Micro/Millimeter Wave Spectroscopy to study low temperature kinetics of radical-radical reactions. The first reactions to be studied include formyl and acetyl radicals with the stable open shell molecules NO and O2 as well as reactions involving hydrogen atoms and amino radicals. The radical-radical reactions that will be the subject of these studies are important in a wide range of extreme environments. However, they are very challenging to investigate experimentally, and are not readily treated by the “gold standard” theoretical approaches. These studies could lead to a better understanding of chemical reactivity in complex systems, benchmark the theoretical characterization of inherently multireference systems that are the subject of active investigation by electronic structure theorists, and have implications for astrochemistry, atmospheric chemistry, and combustion. Students and post-docs will be trained in state-of-the-art instrument development methods, in reaction dynamics and photochemistry, in kinetics and kinetic modeling, in data analysis, and issues in astrochemistry and atmospheric chemistry. Techniques developed will be freely shared with the broader community.Broadband rotational spectroscopy is a powerful, near-universal probe technique but there are challenges in coupling it to the low temperature flow environment for kinetics measurements. Sampling the flow to a separate detection region is possible but this can introduce shocks and produce nonequilibrium conditions that interfere with the measurements. Professor Suits and his students will instead develop an extended nozzle in which the reactions take place, which is then followed by a shock-free second expansion to low pressure ideal for detection by rotational spectroscopy. Professor Suits and his students will also couple Resonance Enhanced Multiphoton Ionization (REMPI) to the low temperature flow environment to probe low temperature kinetics, product branching, and dynamics for these challenging radical-radical reactions. This strategy will be used to detect hydrogen atoms and other atomic species for kinetics measurements which are otherwise difficult or impossible to probe in the flow environment. They will also adapt the REMPI technique to determine the conditions inside the extended nozzle which will be essential to validate the conditions used for the rate determinations.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.

在化学系化学结构、动力学和机理 A (CSDM-A) 项目的支持下，密苏里大学哥伦比亚分校的 Arthur Suits 教授正在开发新工具，以允许啁啾脉冲傅里叶变换微技术的应用/毫米波光谱研究自由基-自由基反应的低温动力学 首先要研究的反应包括甲酰基和乙酰基自由基以及稳定的开壳分子 NO 和 O2。作为涉及氢原子和氨基自由基的反应，自由基-自由基反应在各种极端环境中都很重要，但是，它们的实验研究非常具有挑战性，并且不容易通过“这些研究可以更好地理解复杂系统中的化学反应性，对固有多参考系统的理论表征进行基准测试，这些系统是电子结构理论家积极研究的主题，并对天体化学、大气化学、和燃烧。学生博士后将接受最先进的仪器开发方法、反应动力学和光化学、动力学和动力学建模、数据分析以及天体化学和大气化学方面的问题的培训。宽带旋转光谱是一种强大的、近乎通用的探针技术，但将其与低温流动环境耦合以进行动力学测量可能存在挑战。但这可能会引入冲击并产生干扰测量的非平衡条件，而 Suits 教授和他的学生将开发一种加长喷嘴，在其中发生反应，然后进行无冲击的第二次膨胀，以适合检测。 Suits 教授和他的学生还将共振增强多光子电离 (REMPI) 与低温流动环境耦合，以探测这些具有挑战性的自由基-自由基的低温动力学、产物分支和动力学。该策略将用于检测氢原子和其他原子种类，以进行动力学测量，否则在流动环境中很难或不可能探测这些原子，他们还将采用 REMPI 技术来确定扩展喷嘴内的条件，这将是至关重要的。验证用于利率确定的条件。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力优点和更广泛的影响审查标准进行评估，被认为值得支持。