Secondary Organic Aerosol Formation Mechanisms and Growth Dynamics
EMSL Project ID
48412
Abstract
Recent theoretical and laboratory studies have revealed that the timescales of secondary organic aerosol (SOA) partitioning and the associated aerosol size distribution growth dynamics depend on the complex interplay between SOA volatility, particle phase state/viscosity, and particle-phase reactivity. A proper representation of these physicochemical parameters in the next generation SOA models is therefore needed to reliably predict not only the total SOA mass, but also the composition and number size distributions, all of which together determine the aerosol's climate-relevant properties. The objectives of this project are to: a) Investigate SOA formation mechanisms for selected volatile organic compounds (in an environmental chamber) by simultaneously observing evolution of the SOA size distribution (i.e., growth dynamics) and size-dependent phase/viscosity, morphology, and molecular composition with EMSL's SPLAT II, microscopy, and ultra-high resolution orbitrap mass spectrometry techniques; b) Use the resulting data sets to develop a fundamental molecular-level understanding of SOA formation processes and a compact parameterization for use in climate models.
SPLAT II is uniquely suited for the proposed study because of its multidimensional approach to single particle characterization, high sensitivity to small particles, high temporal resolution, and a sub-nanometer sizing precision. SPLAT II measures in real time particle size, mass, composition, morphology, density, viscosity, shape, and evaporation kinetics. Very recently SPLAT II was equipped with pulsed VUV lamp with an exceptional brilliance and high resolution bipolar mass spectrometer that will be used for IR-laser layer-by-layer evaporation followed by soft VUV ionization to yield quantitative information on morphology and composition of individual particles. To further the online measurements by SPLAT II, we will collect aerosol samples for detailed offline analysis of particle composition and morphology with electron microscopy, micro-spectroscopy, ultra-high resolution orbitrap mass spectrometry, and nuclear magnetic resonance spectroscopy techniques available at EMSL that can provide detailed information on the molecular components present in organic aerosol material.
The detailed data sets will be used to constrain and evaluate a newly developed SOA modeling framework that takes into account the effects of volatility, phase/viscosity, and particle phase reactions on SOA formation mechanisms and growth dynamics. The proposed work addresses EMSL's Atmospheric Aerosol Systems (AAS) Science theme and is directly relevant to the three research themes of the DOE's Atmospheric System Research (ASR) Program's "SOA Formation Focus Group": 1) Particle Viscosity/Phase, 2) SOA Growth Mechanisms, and 3) Sulfate as Trigger for SOA (part of ASR Working Group on Aerosol Life Cycle).
Project Details
Project type
Large-Scale EMSL Research
Start Date
2014-10-01
End Date
2016-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Zaveri RA, JE Shilling, A Zelenyuk-Imre, J Liu, DM Bell, E D'Ambro, C Gaston, JA Thornton, A Laskin, P Lin, JM Wilson, RC Easter, Jr, J Wang, AK Bertram, ST Martin, JH Seinfeld, and D Worsnop. 2018. "Growth kinetics and size distribution dynamics of viscous secondary organic aerosol." Environmental Science & Technology 52(3):1191-1199. doi:10.1021/acs.est.7b04623