Advancing our understanding of the organic aerosol lifecycle by building a next generation mass spectrometer
EMSL Project ID
51328
Abstract
Aerosol particles impact climate directly by absorbing and scattering radiation and indirectly by modifying cloud properties and lifetimes. All cloud droplets form on an aerosol particle and the impact of aerosol particles on clouds remains a significant source of uncertainty for climate models. The majority of the total non-refractory aerosol mass is organic aerosol and the majority of this organic mass is secondary organic aerosol (SOA). SOA is formed when more volatile organic compounds undergo oxidation and partition into the condensed phase. Condensation of SOA is largely responsible for the growth of ultrafine particles to sizes capable of nucleating a cloud droplet. Thus, accurately understanding SOA formation and growth is key for assessing the impact of aerosol particles on cloud properties and the Earth’s radiation balance.Models are challenged to predict the SOA mass loading, size distribution, and other microphysical and chemical properties. This deficiency is in part due to an incomplete understanding of the complex chemical reactions and interactions that lead to SOA formation. Understanding SOA formation requires measurements of the chemical composition of both the gas and particle phases, ideally with the same instrument and in real-time. Current instruments have limitations that limit the molecular identification of SOA. Advancing the science requires advancing the instrumentation.
We propose building a new, first of its kind instrument that will revolutionize particle analysis. This will be a collaboration between EMSL, the University of Washington, and PNNL’s Atmospheric Science and Global Change (ASGC) division. Our plan is to couple the University of Washington Chemical Ionization Mass Spectrometry (CIMS) FIGAERO inlet and ionization region to an EMSL Orbitrap mass analyzer. CIMS is a soft ionization technique that is sensitive to most oxidized organic compounds found in the SOA. The UW FIGAERO inlet enables in-situ, near real-time analysis of both the gas and particle phase chemical composition with the same instrument. Coupling CIMS ionization to an orbitrap mass analyzer will overcome two limitations of the current generation of commercial instrumentation. First, the dramatically improved mass resolving power of the orbitrap will allow for separation of molecules with similar mass. Second, the orbitrap mass analyzer is capable collisional dissociation experiments, which can be used to elucidate molecular structure and differentiate structural isomers. The combination of improved mass resolution and tandem mass spectrometry capability will allow us to identify SOA molecular components with unparalleled accuracy in both the gas and the particle phase.
Identifying the key molecules that drive SOA formation will allow us to intelligently parameterize the SOA lifecycle in models. This will lead to better representations of SOA formation and particle growth in models, which in turn would lead to better predictions of CCN number size distributions and ultimately better predictions of cloud formation and properties.
Project Details
Project type
Scientific Partner
Start Date
2020-08-20
End Date
2023-07-20
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members