title: Properties and Atmospheric Implication of Methylamine-Sulfuric Acid-Water Clusters.
abstract: 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)3 are 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 H2SO4 and 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.
authors.affiliation: †School of Physics and Materials Science, Anhui University, Hefei, Anhui 230039, People's Republic of China.
authors.forename: Sha-Sha
authors.initials: SS
authors.lastname: Lv
authors.forename: Shou-Kui
authors.initials: SK
authors.lastname: Miao
authors.forename: Yan
authors.initials: Y
authors.lastname: Ma
authors.forename: Miao-Miao
authors.initials: MM
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Wen
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Wang
authors.forename: Yu-Peng
authors.initials: YP
authors.lastname: Zhu
authors.affiliation: †School of Physics and Materials Science, Anhui University, Hefei, Anhui 230039, People's Republic of China.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
mesh_terms: D000465:Algorithms; D006813:Humidity; D008027:Light; D008744:Methylamines / Q000737:chemistry*; D008956:Models, Chemical; D011522:Protons; D012542:Scattering, Radiation; D013464:Sulfuric Acids / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry*
chemical_list: D008744:Methylamines; D011522:Protons; D013464:Sulfuric Acids; D014867:Water; C027451:methylamine; C033158:sulfuric acid