Particle nucleation from gas phase precursors have been observed around the world, however, our fundamental understanding of which species contribute to these new particle formation (NPF) events and mechanisms involved remain uncertain.  Previous studies have shown that acid-base chemistry initiated from the reaction of methanesulfonic acid (MSA) and small alkyl amines leads to the formation of a significant number of particles.  Those early measurements were exclusively comprised of particle number concentrations and/or size distributions.  The development of new techniques for measuring ultrafine particles have accelerated in the recent years, allowing the access to the chemical composition of sub-20 nm particles.  In this study, we present chemical composition measurements of particles with diameters ranging from 4 to 20 nm formed from the reaction of MSA with MA under dry conditions.  Experiments were performed in a custom-built glass flow reactor coupled to a Thermal Desorption Chemical Ionization Mass Spectrometer (TDCIMS) as well as a sequential spot sampler for off-line analysis.  Size-resolved measurements of acid-to-base ratios are presented, and the influence of NH<sub>3</sub> on this system is discussed.

Chemical composition of sub-20 nm particles formed from the reaction of methanesulfonic acid with methylamine

2019 Fall National Meeting

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