Studies Of Electronic Structures And Micro-solvation Of SO₃^- And HSO₃^- In The Atmospheric Aerosols

In recent years,haze weather presents an increasing trend generally in China.Pollutant particles represented by sulfate aerosols are an important factor of haze.Therefore,researches on the formation and evolution mechanism of sulfate have always been a research hotspot,which are of great significance for scientific governance of haze.Especially,it is important to study the electronic structures of small scale sulfonic acid clusters at the atomic and molecular levels to reveal their nucleation mechanism.However,sulfonic acid anions are unstable in gas phase thus it is difficult to directly detect the electronic structure characteristics of these anions.In addition,there is a lack of a reliable theoretical calculation strategy for the simulation of negative ion photoelectron spectroscopy.To handle these challenges mentioned above,we focus on exploring and applying suitable theoretical methods and models by combining with density functional theory,time-dependent density functional theory and nuclear ensemble approach based on photoelectron spectroscopy experiment.Through the simulation of spectrum,we are able to resolve the experimental spectra more accurately and efficiently.In this dissertation,we not only combine a variety of research methods,but also choose"multi-level"cluster systems,including one nucleation clusters for SO₃^-and HSO₃^-,binary nucleation clusters for bisulfite-hydration,triplet nucleation clusters for sulfonic acid,nitrogen dioxide and water.It is believed that this work can provide microscopic information on the formation of sulfate in atmospheric aerosols and is expected to provide a theoretical basis for solving problems such as haze.The dissertation consists of four chapters and the content is as follows:The first chapter gives a brief introduction of the classification of electronic spectrum and its research significance based on the theoretical basis of spectroscopy.At the same time,the research background of SO₃^-and HSO₃^-clusters at home and abroad is concisely introduced based on the formation mechanism of sulfate in the atmosphere.The second chapter describes the relevant theoretical methods involved in this dissertation briefly,including an emphasis on the development and current status of density functional theory and a brief introduction of nuclear ensemble approach along with its advantages and disadvantages.The third chapter performs a combined experimental negative ion photoelectron spectroscopy and quantum chemical calculation to explore the electronic structures,ionization conditions and stabilization mechanism of SO₃^-and HSO₃^-that widely existed in the atmosphere.In addition,the micro-solvation effect of HSO₃^-(H₂O)n(n=0-5)is studied.Last but not least,the reaction mechanism of triplet nucleation clusters for sulfonate and its tautomer with NO₂ and H₂O is further explored from the perspective of geometric configurations and weak interaction.Chapter 4 is a summary of the content of this dissertation and an outlook on the subsequent work.