Properties and Atmospheric Implication of Methylamine Sulfuric Acid-Water Clusters
Properties and Atmospheric Implication of Methylamine Sulfuric Acid-Water Clusters
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甲胺硫酸-水团簇的性质及其对大气的影响
DOI：
10.1021/acs.jpca.5b03325
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发表时间：
2015
影响因子：
2.9
通讯作者：
Huang Wei
中科院分区：
文献类型：
--
作者：
Lv Sha-Sha;Miao Shou-Kui;Ma Yan;Zhang Miao-Miao;Wen Yang;Wang Chun-Yu;Zhu Yu-Peng;Huang Wei
胺的存在可增加气溶胶形成速率。大多数的研究都是以二甲胺为代表的胺，而对甲胺的研究较少。本文对CH_3 NH_2（H_2SO_4）_m（H_2 O）_n（m= 0-3，n= 0-3）团簇进行了理论计算。除了结构和能量学之外，我们还着重研究了以下特性：（1）水合物的生长机制，（2）水合物的分布以及湿度和温度的影响，（3）瑞利散射特性。我们从热力学角度探讨了团簇的生长机制，通过计算在三个大气相关温度下逐步加入水或硫酸分子的吉布斯自由能。讨论了每一步反应的相对容易程度。通过对水合物分布的分析，发现大气中最可能存在的水合物是CH 3 NH 2（H2SO 4）（H2O）2、CH 3 NH 2（H2SO 4）2和CH 3 NH 2（H2SO 4）3。在所有情况下，水化的总趋势是更广泛的相对湿度（RH）的增长，而分布并不显着改变与温度。对瑞利散射特性的分析表明，H2SO 4和H2O分子均能增加瑞利散射强度和各向同性平均极化率，硫酸分子的影响更大.为进一步研究大气中含有甲胺的新粒子形成机理提供了理论依据。
The presence of amines can increase aerosol formation rates. Most studies have been devoted to dimethylamine as the representative of amine; however, there have been a few works devoted to methylamine. In this study, theoretical calculations are performed on CH3NH2(H2SO4)m(H2O)n(m= 0–3,n= 0–3) clusters. In addition to the structures and energetics, we focused on determining the following characteristics: (1) the growth mechanism, (2) the hydrate distributions and the influences of humidity and temperature, (3) Rayleigh scattering properties. We explored the cluster growth mechanism from a thermodynamics aspect by calculating the Gibbs free energy of adding a water or sulfuric acid molecule step by step at three atmospherically relevant temperatures. The relative ease of the reaction at each step is discussed. From the analysis of hydrate distributions, we find that CH3NH2(H2SO4)(H2O)2, CH3NH2(H2SO4)2, and CH3NH2(H2SO4)3are most likely to exist in the atmosphere. The general trend of hydration in all cases is more extensive with the growing relative humidity (RH), whereas the distributions do not significantly change with the temperature. Analysis of the Rayleigh scattering properties showed that both H2SO4and H2O molecules could increase the Rayleigh scattering intensities and isotropic mean polarizabilities, with greater influence by the sulfuric acid molecules. This work sheds light on the mechanism for further research on new particle formation (NPF) containing methylamine in the atmosphere.