Chemistry in Nanometer Particles: Unique breeding sites for oligomers?

• Applicant: Professor Dr. Thorsten Hoffmann
• Subject Area: Atmospheric Science
• Term: since 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 416710328

Understanding new particle formation and their subsequent growth in the troposphere has a critical impact on our ability to predict atmospheric composition and global climate change. After nanometer particles are formed by nucleation, their growth is governed by organic molecules. Today the formation of the extremely low volatile compounds needed to grow nanometer particles is discussed exclusively based on gas phase chemistry. However, the particle embryos itself offer a unique nanoscale chemical environment influencing chemical reactions within the newly formed condensed phase. One physicochemical peculiarity of smaller particles is the increasing internal pressure (Laplace pressure). Since bond-forming chemical reactions (e.g. oligomerization) are favored at higher pressures, such reactions gain importance in the smallest particles, so exactly those particles that need matter for growth to not get lost by coagulation. Therefore, particle size-dependent chemical reactions can play a decisive role in the lifecycle of atmospheric aerosols, bridging the gap between the initial formation of particle embryos and their growth into sizes where their survival probability is larger and on which cloud droplets may eventually form. Although motivated from atmospheric chemistry, the acquired knowledge about particle size-dependent chemistry will also result in a better understanding of equilibrium reactions in organic nanoreactors, an emerging research field in synthetic organic chemistry, and in a very general sense might as well deliver contributions to understand the origin of life.

• DFG Programme: Reinhart Koselleck Projects