Quantum Origin of Anomalous Isotope Effects

本项目的重点是研究氧原子(O)和分子氧(O2)复合反应生成臭氧(O_3)的量子动力学，以研究平流层臭氧的反常大同位素浓缩。为了减少计算成本并仍然捕捉相关的量子效应，将开发一个适当近似的层次结构。整个臭氧形成过程将使用两步能量转移机制来表示。第一步，亚稳臭氧分子(O_3~*)的形成，将用全量子反应散射公式来描述。第二步，第三体碰撞稳定O_3~*，将用近似半经典方法处理。这种方法应该对第一步中的零点能量效应和第二步中的对称性效应提供适当的描述。该项目将与美国和国外的其他理论和实验小组建立合作伙伴关系。更好地了解臭氧中的反常同位素效应可能有助于更好地了解其在大气中的产生和损失。该奖项将用于博士后研究人员和本科生的教育和培训。其他更广泛的影响包括以当地和地区环境问题为重点的公开讲座，开发量子化学和分子动力学的研究生课程，以及将研究纳入本科生和研究生课程。该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)提供资金的。

The focus of this project is on quantum dynamics studies of the recombination reaction of oxygen atoms (O) and molecular oxygen (O2) to form ozone (O3), in order to study the anomalously large isotopic enrichment of stratospheric ozone. A hierarchy of suitable approximations will be developed in order to reduce computational costs and still capture the associated quantum effects. The overall ozone formation process will be represented using a two-step energy transfer mechanism. The first step, formation of metastable ozone molecules (O3*), will be described with a fully quantum reactive scattering formalism. The second step, stabilization of O3* by third body collisions, will be treated using an approximate semi-classical method. This approach should provide a proper description of the zero-point energy effect during the first step and of symmetry effects during the second step. The project will involve partnerships with other theoretical and experimental groups in the U.S. and abroad.A better understanding of the anomalous isotope effects in O3 could lead to an improved understanding of its production and loss in the atmosphere. This award will provide for the education and training of a postdoctoral researcher and undergraduate students. Other broader impacts include public lectures focused on local and regional environmental issues, development of a graduate course on quantum chemistry and molecular dynamics, and integration of the research into undergraduate and graduate courses. This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).