Theoretical Study On The Interaction Mechanism Of Sulfuric Acid Aerosol With N₂O/NO₃ And Nitric Acid With N₂O In The Atmosphere

A detailed knowledge of the interaction mechanisms between atmospheric species is of practical significance for the investigations on the formation of atmospheric aerosols and the transformation and degradation of atmospheric species.In this study,the interaction mechanisms between the sulfuric acid aerosol and N₂O/NO₃ as well as the interaction between HNO₃ and N₂O have been systematically investigated at the B3LYP/6-311++G?3df,3pd?level of theory in combination with the NBO,AIM,and ab initio molecular dynamics methods.Moreover,the dynamics of the electron capture behavior for the formed complexes has also been explored.Expectedly,the present results not only can enable us a better understanding of the potential role of sulfuric acid aerosols and HNO₃,but also can provide new insights into the degradation and transformation of N₂O and NO₃ in the atmosphere.This study is mainly divided into three parts:Firstly,the interaction mechanisms between sulfuric acid aerosol and N₂O have been systematically investigated as well as the dynamics of the electron capture for the formed complexes.It was shown that two H-bonding complexes A and B have been formed between the sulfuric acid aerosol and N₂O.The formation processes of these complexes are an exothermic reaction.Further ADMP molecular dynamics calculations suggest that those complexes can exist within a certain timescale.Three complexes A?,A??,and B?can be obtained upon electron capture for complexes A and B.As for the electron capture of complex A,hydrogen transfer occurs to form complex A?containing the HNNO radical.Moreover,complex A?can be converted into complex A??via proton transfer.As for the electron capture of complex B,N₂ and OH radical can be produced via the cleavage of the N-O bond of N₂O and the dissociation of the H atom of H₂SO₄.Moreover,those products can be further confirmed by the ADMP molecular dynamics calculations,providing an alternative source of HNNO,OH radical,and N₂ in the atmosphere.Secondly,the interaction mechanisms between sulfuric acid aerosol and NO₃ have been systematically investigated as well as the dynamics of the electron capture for the formed complexes.It was found that three complexes N1,N2,and N3 can be formed through H-bonding interactions between sulfuric acid aerosol and NO₃.The formation processes of these complexes are an exothermic reaction.At the same time,molecular dynamics calculations suggest that these complexes can exist within a certain timeacle.As for the electron capture of complexes N1 and N3,HNO₃ and HSO₄^–anion can be produced via the hydrogen transfer.As for the electron capture of complex N2,the original intermolecular H-bonds have been further enhanced.Moreover,the electron capure processes for those complexes have been further confirmed by the ADMP molecular dynamics calculations,providing an alternative source of HNO₃ in the atmosphere.Finally,the interaction mechanisms between nitric acid and N₂O have been systematically investigated as well as the dynamics of the electron capture for the formed complexes.It was found that two relatively stable complexes A and B can be formed through intermolecular H-bonds between nitric acid and N₂O.After the electron capture,complex A can spontaneously undergo H atom transfer to form HNNO free radical.However,the OH and NO₂ can be produced for the complex B upon electron capture via the cleavage of the N-O bond of N₂O.Moreover,those products have been further confirmed by the ADMP molecular dynamics calculations,providing an alternative source of HNNO,OH and NO₂.