Aggregations- und Evaporationsdynamik von Clustern und Aerosolpartikeln im H2SO4-H2O-System

Aggregation and Evaporation Dynamics of Clusters and Aerosol Particles in the H2SO4-H2O-System

by Daniel Becker
Doctoral thesis
Date of Examination:2022-06-29
Date of issue:2022-11-28
Advisor:Prof. Dr. Thomas Zeuch
Referee:Prof. Dr. Thomas Zeuch
Referee:Prof. Dr. Philipp Vana
Persistent Address: http://dx.doi.org/10.53846/goediss-9571

 

 

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Abstract

English

Sulfuric acid and water are two key compounds in the formation of atmospheric aerosols and are therefore relevant in the context of climate research. In this work, a modified experimental setup is presented, using the ozonolysis of 2-butene in presence of sulfur dioxide to obtain a highly supersaturated atmosphere of sulfuric acid vapor. A newly implemented SMPS-system as well as an optimized sampling procedure allow for real-time monitoring of the resulting particle formation in the early phase of the experiment. This process is very sensitive with respect to the initial amount of sulfur dioxide and thus, different scenarios of sulfuric acid driven particle growth can be prepared and studied. The corresponding experimental time profiles of individual particle size classes and particle size distributions serve as references for the validation of a kinetic model, also incorporating predicted cluster decomposition rates based on quantum chemical calculations. The strong dependence of simulation results on those decomposition rates allows evaluation of the corresponding predictions. Furthermore, binary systems (e.g. H2SO4-H2O, but also other additives) are investigated, indicating stabilization of hydrated sulfuric acid clusters. To study evaporation of pure water clusters, another kinetic model is presented and simulated cluster distributions are compared to mass spectra of Na-doped water clusters from a molecular beam experiment.
Keywords: sulfuric acid clusters; water clusters; cluster evaporation; new particle formation; butene ozonolysis; kinetic modeling
 
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