大气中颗粒物成核与生长的分子机理

Formation of particulate matter in the atmosphere is closely related to climate and environment issues. It is thus very desirable to systematically study the formation mechanisms of these aerosol particles. Field observations indicate that sulfuric acid has played a key role in the nucleation and growth of particles in the atmosphere. Comparing field observations with laboratory research results suggests that there are some other relevant species. Although rapid progresses in analytical instruments and measurement methods have led to plenty of experimental data, molecular mechanisms behind the nucleation and growth of atmospheric particles are still elusive. In this project, we will combine several methods including quantum chemistry calculations and statistical mechanics analysis based on molecular simulations to study the nucleation and growth mechanisms. Geometry and stability of relevant clusters and nanoparticles will be studied, and their evolution/reaction paths will be given, with possible synergistic effects revealed. Finally we will obtain the dependence of particle formation rate on climate and other conditions, and provide theoretical insight for pollution control.

大气颗粒物的形成与气候、环境等都密切相关，因此需要对这些气溶胶粒子的形成规律进行深入研究。结合外场观测和实验室研究可以发现硫酸在大气颗粒物成核与生长过程中起着关键作用，同时除硫酸外还有一些重要的物种参与成核与生长。尽管近年来随着分析仪器和测量手段的飞速进步，实验上得到了很多新的观测数据，但是目前对这种多物种参与的大气颗粒物成核与生长过程的微观机理还不是很清楚。本项目拟结合量子化学计算、统计力学模拟等多种理论方法，对大气颗粒物成核与生长机理进行系统深入的研究，得到相关团簇和纳米粒子的结构与稳定性信息，给出它们之间相互演化的动力学过程或反应路径，阐明其中可能存在的多物种协同作用机制，揭示出不同环境条件下颗粒物形成的规律，为大气污染防控提供理论依据和指导。

大气颗粒物的形成与气候、环境等密切相关。本项目结合量子化学计算、统计力学模拟等多种方法，对大气颗粒物成核与生长机理开展研究，通过相关团簇和纳米粒子的结构与稳定性信息，获得它们之间相互演化的动力学过程或反应路径，进而阐明其中可能存在的多物种协同作用机制，揭示出不同环境条件下颗粒物形成的规律。项目执行期间，申请人及课题组成员对硝酸、氨气和水分子团簇体系进行了量子化学计算，通过结构搜索得到稳定结构，进而揭示不同湿度条件下团簇之间相互转化的规律。对水纳米粒子中羟基自由基的结构以及氢转移反应、液滴表面Criegee中间体与醇反应等进行了第一性原理分子动力学模拟，理解了一些重要的微观机理。应用和发展动力学成核理论以及相关算法，完成了相关程序包的开发以及对水分子颗粒成核与生长的模拟，后期可以进一步对更复杂体系的成核与生长开展研究。