The chemistry of sulfur cycle contributes significantly to the atmospheric nucleation process,which is the first step of new particle formation(NPF).In the present study,cycloaddition reaction mechanism of sulfur trio...
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The chemistry of sulfur cycle contributes significantly to the atmospheric nucleation process,which is the first step of new particle formation(NPF).In the present study,cycloaddition reaction mechanism of sulfur trioxide(SO_(3))to hydrogen sulfide(H_(2)S)which is a typical air pollutant and toxic gas detrimental to the environment were comprehensively investigate through theoretical calculations and atmospheric cluster dynamic code ***-phase stability and nucleation potential of the product thiosulfuric acid(H_(2)S_(2)O_(3),TSA)were further analyzed to evaluate its atmospheric *** any catalysts,the H_(2)S+SO_(3)reaction is infeasible with a barrier of 24.2 kcal/*** nucleation precursors formic acid(FA),sulfuric acid(SA),and water(H_(2)O)could effectively lower the reaction barriers as catalysts,even to a barrierless reaction with the efficiency of cis-SA>trans-FA>trans-SA>H_(2)***,the gas-phase stability of TSA was investigated.A hydrolysis reaction barrier of up to 61.4 kcal/mol alone with an endothermic isomerization reaction barrier of 5.1 kcal/mol under the catalytic effect of SA demonstrates the sufficient stability of ***,topological and kinetic analysis were conducted to determine the nucleation potential of *** clusters formed by TSA and atmospheric nucleation precursors(SA,ammonia NH_(3),and dimethylamine DMA)were thermodynamically ***,the gradually decreasing evaporation coefficients for TSA-base clusters,particularly for TSA-DMA,suggests that TSA may participate in NPF where the concentration of base molecules are relatively *** present new reaction mechanismmay contributes to a better understanding of atmospheric sulfur cycle and NPF.
It is well established that oxidation products of volatile organic compounds (VOCs) play a major role in atmospheric new-particle formation (NPF). However, the mechanism of their effect and the corresponding influence...
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It is well established that oxidation products of volatile organic compounds (VOCs) play a major role in atmospheric new-particle formation (NPF). However, the mechanism of their effect and the corresponding influence under various atmospheric conditions remain unclear. Meanwhile, considering the difficulty of experiment in determining the water content of the cluster and performing at low temperature, we combine Density Functional Theory (DFT) and atmosphericclusters dynamiccode (ACDC) model to investigate a multicomponent system involving lactic acid (LA) and atmospheric nucleation precursors (sulfuric acid (SA), dimethylamine (DMA), water (W)) under a wide range of atmospheric conditions (relative humidity (RH) from 20% to 100%, temperature (T) from 220 K to 300 K). Conformational analysis shows that LA could enhance NPF in two direction due to its two highly oxidized function groups. Then, the results from ACDC simulation present a direct evidence of its enhancement effect on NPF when the concentration of LA is larger than 10(10) molecules cm(-3). The corresponding enhancement strength presents a positive dependence on its concentrations and a negative dependence on RH and T, respectively. Besides, *** (n = 0-1) reflect their enhancement effect on the cluster growth paths by acting as "bridge", which contributes to pure SA-DMA-W-based clusters by evaporating LA contained clusters. The corresponding contribution presents a positive dependence on the concentration of LA, RH and T, respectively. We hope our study could provide theoretical clues to better understand the characteristic of NPF in polluted area, where NPF commonly involves oxidized organics, sulfuric acid, amine and water. (C) 2017 Elsevier Ltd. All rights reserved.
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