Theoretical Studies of Heterogeneous Halogen Chemistry on Stratospheric and Tropospheric Ice

平流层和对流层冰非均相卤素化学的理论研究

• 批准号: 9613802
• 负责人: James Hynes
• 金额: $ 36万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-15 至 2000-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9613802&HistoricalAwards=false
• 关键词: Theoretical; Studies; Heterogeneous; Halogen; Chemistry

9613802 Hynes In this project, quantum chemical electronic structure methods and molecular dynamics computer simulations will be carried out to study the rates and mechanisms of a number of reactions of chlorine and bromine species on the surface of atmospherically relevant particles. These range from pure water ice to more complex surfaces which include nitrate and/or sulfate ions. Heterogeneous reactions involving chlorine and bromine have been strongly implicated in the catalytic destruction of ozone in the Antarctic stratosphere and in the Arctic troposphee. Specific examples include the one-step reaction of chlorine nitrate with hydrochloric acid and the two- step version involving chlorine nitrate hydrolysis forming hypochlorous acid which then reacts with hydrochloric acid to form molecular chlorine. The bromine analogs of these reactions as well as the mixed bromine/chlorine cases will also be considered. This study will provide reaction mechanisms and reaction rates which are needed as input for global chemistry and climate models. It is hypothesized that the ice lattice plays an essential catalytic role in these reactions via proton transfers. It is often difficult to determine experimentally whether a process occurs in one or several steps, and whether reactions are ionic in character or not.

在本项目中，将采用量子化学电子结构方法和分子动力学计算机模拟来研究大气相关粒子表面氯和溴的一些反应速率和机理。这些范围从纯水冰到更复杂的表面，包括硝酸盐和/或硫酸盐离子。涉及氯和溴的非均相反应与催化破坏南极平流层和北极对流层中的臭氧密切相关。具体的例子包括硝酸氯与盐酸的一步反应，以及硝酸氯水解形成次氯酸的两步反应，次氯酸随后与盐酸反应形成氯分子。这些反应的溴类似物以及溴/氯混合情况也将被考虑。这项研究将提供作为全球化学和气候模式输入所需的反应机制和反应速率。假设冰格通过质子转移在这些反应中起着重要的催化作用。通常很难从实验上确定一个过程是发生在一个步骤还是几个步骤中，以及反应是否具有离子性质。