Bidirectional Interaction of Alanine with Sulfuric Acid in the Presence

Mar 21, 2016 - Amino acids are recognized as important components of atmospheric aerosols, which impact on the Earth's climate directly and indirectly...
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Bidirectional Interaction of Alanine with Sulfuric Acid in the Presence of Water and the Atmospheric Implication Chun-Yu Wang, Yan Ma, Jiao Chen, Shuai Jiang, Yi-Rong Liu, Hui Wen, Ya-Juan Feng, Yu Hong, Teng Huang, and Wei Huang J. Phys. Chem. A, Just Accepted Manuscript • DOI: 10.1021/acs.jpca.5b11678 • Publication Date (Web): 21 Mar 2016 Downloaded from http://pubs.acs.org on March 22, 2016

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The Journal of Physical Chemistry

Bidirectional Interaction of Alanine with Sulfuric Acid in the Presence of Water and the Atmospheric Implication Chun-Yu Wang,1,2 Yan Ma,1 Jiao Chen,1,2 Shuai Jiang,1 Yi-Rong Liu,1 Hui Wen,1 Ya-Juan Feng,1 Yu Hong,1,2 Teng Huang,1 Wei Huang1,3,4* 1

Laboratory of Atmospheric Physico-Chemistry, Anhui Institute of Optics & Fine Mechanics, Chinese

Academy of Sciences, Hefei, Anhui 230031, China 2

University of Science and Technology of China, Hefei, Anhui 230026, China

3

School of Environmental Science & Optoelectronic Technology, University of Science and Technology

of China, Hefei, Anhui 230026, China 4

Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese

Academy of Sciences, 1799Jimei Road, Xiamen, 361021, China *E-mail: [email protected]

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ABSTRACT Amino acids are recognized as important components of atmospheric aerosols, which impact on the Earth’s climate directly and indirectly. However, much remains unknown about the initial events of nucleation. In this work, the interaction of alanine [NH2CH(CH3)COOH or Ala], one of the most abundant amino acids in the atmosphere, with sulfuric acid (SA) and water (W) has been investigated at the M06-2X/6-311++G(3df, 3pd) level of theory. We have studied thermodynamics of the hydrated (Ala)(SA) core system with up to four water molecules. We found that Ala, with one amino group and one carboxyl group, can interact with H2SO4 and H2O in two directions, and that it has a high cluster stabilizing effect similar to that of ammonia, which is one of the key nucleation precursor. The corresponding Gibbs free energies of the (Ala)(SA)(W)n (n=0~4) clusters formation at 298.15 K predicted that Ala can contribute to the stabilization of small binary clusters. Our results showed that the hydrate distribution is temperature-dependent and that a higher humidity and temperature can contribute to the formation of hydrated clusters.

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The Journal of Physical Chemistry

INTRODUCTION The frequent appearance of the haze weather in China, receives considerable interest. Recently studies1-2 showed that the particle compositions in Beijing consistent with the chemical constituents dominated by secondary aerosol formation. New particle formation (NPF) via nucleation is a significant source of atmospheric aerosols,3 which plays an important role in the Earth’s climate and atmospheric chemistry. A substantial pool of neutral and thermodynamically stable clusters (TSCs) that are