Combining Experimental and Theoretical Approaches to Probe the Enhancement of Particle Formation From Methanesulfonic Acid and Amine by Ammonia
Abstract
While new particle formation events have been measured in different places of the world, our fundamental understanding on which species combine and how they combine together is still an open question. Understanding this fundamental process would support the development of mitigation to address climate change, visibility and air pollution as well as related public health issues. In this context, experimental investigations and quantum chemical calculations have previously shown that small alkyl amines and ammonia (NH3) play an important role in sub-3 nm particle formation through reactions with acids such as sulfuric acid (H2SO4) and methanesulfonic acid (MSA). However, in the atmosphere, amines and ammonia co-exist, and synergism between NH3 and amines have been reported for sulfuric acid reactions. We report here combined experimental and theoretical studies of the impact of ammonia on particle formation from the reactions of MSA with small amines (methylamine, dimethylamine, trimethylamine). Experiments were carried out in a 1-m long glass flow reactor. Particles were measured at various reaction times ranging from 0.3 to 6 sec using several particle counters in the absence or presence of water vapor. Experimental results show that particle formation from the reaction of MSA and a selected amine is systematically enhanced when ammonia is present, but to various degrees depending on the amine investigated. In order to characterize the nature of the interaction between the species involved (proton transfer and/or hydrogen bonding), ab initio calculations were performed on small clusters. Those provide essential molecular insights into particle formation and growth from methanesulfonic acid + amine and the critical role that ammonia plays in those systems.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.A11H1966P
- Keywords:
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- 0317 Chemical kinetic and photochemical properties;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0340 Middle atmosphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0394 Instruments and techniques;
- ATMOSPHERIC COMPOSITION AND STRUCTURE