邻苯二甲酸-硫酸成核机理理论研究

Theoretical Study on Mechanism of Nucleation of Phthalic Acid and Sulfuric Acid

大气气溶胶对地球环境和人类健康有着重要的影响。对流层中的二次气溶胶是大气气溶胶的主要来源之一,其形成一般分为两个阶段,首先是形成临界核阶段,然后是快速生长的过程。邻苯二甲酸和硫酸作为大气中常见的成核前体物,目前对它们的成核机制研究较少。通过高精度的量化计算得到了团簇的结构和热力学参数,蒸发速率分析表明相对于硫酸二聚体,邻苯二甲酸和硫酸形成的异二聚体更加稳定,即邻苯二甲酸的加入极大降低了硫酸团簇的蒸发速率,说明邻苯二甲酸具有促进硫酸成核的作用;光学属性分析表明团簇尺寸与瑞利散射以及各向同性平均极化率呈现正相关;红外谱分析也表明了邻苯二甲酸-硫酸形成的异二聚体内存在着氢键,这有利于形成稳定的成核团簇。

Atmospheric aerosols have an important impact on the global environment and human health.Secondary aerosols generated in the troposphere are one of the main sources of atmospheric aerosols.Its formation is generally divided into two stages,the formation of critical nuclear and the following rapid growth process.Phthalic acid and sulfuric acid are common nucleation precursor in the atmosphere,however,their nucleation mechanism is still seldom studied.The structure and thermodynamic parameters of the cluster are obtained by high-precision quantitative calculation.The evaporation rate analysis shows that compared to sulfate clusters,the heterodimer formed by phthalic acid and sulfuric acid is more stable,that is,the addition of phthalic acid greatly reduces theevaporation rate of the sulfuric acid cluster,which indicates that phthalic acid has the effect of promoting nucleation of sulfuric acid.Optical property analysis shows that the cluster size is positively correlated with Rayleigh scattering and isotropic average polarizability.Moreover,infrared spectrum analysis also confirms the presence of hydrogen bonds in the heterodimer,which is in favor of the formation of stable nucleation clusters.