Quantum Chemical Studies of the Thermal and Photo-induced Chemistry of Criegee Intermediates.

该项目由环境化学科学(ECS)和化学部的化学理论、建模和计算(CTMC)计划以及既定的激励竞争研究计划(EPSCoR)共同资助。路易斯安那大学拉斐特分校的Tolga Karsili教授和他的学生正在使用和开发最先进的量子化学和动力学方法来研究Criegee中间体(CI)的化学。CI是由臭氧与大气中挥发性有机化合物反应而形成的。这样的反应是羟基自由基的重要来源，羟基自由基可以分解污染物并‘净化’大气。它们通常被称为大气洗涤剂，对提高大气的氧化能力很重要。该项目涉及研究生和本科生，以及高中生，包括代表人数不足的群体的成员。学生们还有机会前往合作者华国教授(新墨西哥大学)所在的小组学习新技术。该项目专注于热化、振动和电子激发的顺式原子的单分子衰变。顺式化合物以过剩的内能形成，因此可能会发生进一步的反应，如单分子衰变或异构化。或者，高振动激发的CI可能通过与近邻分子的碰撞而经历振动能量弛豫。然后，稳定的顺式离子可以经历单分子衰变，与几种痕量大气物种反应，或者可能经历紫外线激发。热化和高振动激发的CI的单分子衰变是众所周知的羟基自由基的来源。Karsili教授和他的团队正在计算研究与最简单的CI相关的振动和电子激发的量子动力学，该CI源于乙烯的臭氧分解，然后系统地与分子日益复杂的CI进行比较。这一奖项反映了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。

This project is being jointly funded by the Environmental Chemical Sciences (ECS) and the Chemical Theory, Modeling, and Computation (CTMC) Programs of the Chemistry Division, as well as the Established Program to Stimulate Competitive Research (EPSCoR). Professor Tolga Karsili of the University of Louisiana at Lafayette and his students are using and developing state-of-the-art quantum chemical and dynamics methods to study the chemistry of Criegee intermediates (CI). CIs are formed by the reaction of ozone with volatile organic compounds in the atmosphere. Such reactions are an important source of hydroxyl radicals which break down pollutants and ‘clean’ the atmosphere. They are often referred to as atmospheric detergents and are important in increasing the oxidizing capacity of the atmosphere. The project involves graduate and undergraduate students, as well as high-school students, including members of underrepresented groups. The students also have opportunities to travel to the group of the collaborator, Professor Hua Guo (University of New Mexico), to learn new techniques. The project focusses on the unimolecular decay of the thermalized and vibrationally and electronically excited CIs. CIs are formed with excess internal energy and thus may undergo further reactions, such as unimolecular decay or isomerization. Alternatively, the highly vibrationally excited CI may undergo vibrational energy relaxation through collisions with proximal molecules. The stabilized CIs can then undergo unimolecular decay, react with several trace atmospheric species or may undergo UV-excitation. Unimolecular decay of thermalized and highly vibrationally excited CI is a well-known source of hydroxyl radicals. Professor Karsili and his group are computationally studying the vibrationally and electronically excited quantum dynamics associated with the simplest CI, derived from the ozonolysis of ethene and then systematically comparing with CIs of increasing molecular complexity.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.