Negative Ion Photoelectron Spectroscopy Reveals Thermodynamic Advantage of Organic Acids in Facilitating Formation of Bisulfate Ion Clusters: Atmospheric Implications.
Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. Such findings have stimulated theoretical studies with the aim of understanding the interaction of organic acids with common aerosol nucleation precursors like bisulfate (HSO4(-)). We report a combined negative ion photoelectron spectroscopic and theoretical investigation of molecular clusters formed by HSO4(-) with succinic acid (SUA, HO2C(CH2)2CO2H), HSO4(-)(SUA)n (n = 0-2), along with HSO4(-)(H2O)n and HSO4(-)(H2SO4)n. It is found that one SUA molecule can stabilize HSO4(-) by ca. 39 kcal/mol, three times the corresponding value that one water molecule is capable of (ca. 13 kcal/mol). Molecular dynamics simulations and quantum chemical calculations reveal the most plausible structures of these clusters and attribute the stability of these clusters to the formation of strong hydrogen bonds. This work provides direct experimental evidence showing significant thermodynamic advantage by involving organic acid molecules to promote formation and growth in bisulfate clusters and aerosols.
†Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Gao-Lei
GL
Hou
§Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
Wei
W
Lin
S H M
SH
Deng
Jian
J
Zhang
†Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
Wei-Jun
WJ
Zheng
§Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, United States.
Francesco
F
Paesani
Xue-Bin
XB
Wang
H-bonding; atmospheric aerosol; bisulfate clusters; photoelectron spectroscopy