CCONFOA

 

Chemical Composition Newly-Formed Organic Aerosols by Spot-Sampler nano-DESI

1 April 2016 - 30 September 2017

Lead Scientist: Susanne Hering

Observatory: sgp, sgp

One of the important challenges in elucidating the role of atmospheric particles in global climate is to identify the chemical pathways by which nanometer-sized particles grow to sufficient size to become cloud condensation nuclei. Although too small when first formed to directly affect climate, their number concentrations and observed growth rates are large, and significant numbers may reach the sufficient size to serve as cloud condensation nuclei, and thereby influence the physical characteristics and lifetime of clouds. Of specific interest is the role played in the growth of these newly formed particles by amines, and sulfonated organic compounds and other organic species. Proposed is detailed, off-line characterization of ambient nanoparticle aerosol samples using the nano-Desorption Electrospray Ionization Mass Spectrometry (nano-DESI-MS) at Environmental Molecular Sciences Laboratory (EMSL). Samples will be collected with an aerosol concentrator–collector (the Spot Sampler) that provides highly focused deposits tailored to the nano-DESI-MS analysis. With its high-resolution mass spectrometer, the EMSL nano-DESI-MS provides the molecular formula of individual compounds, thereby readily identifying the presence of amines, nitrated and sulfonated organics, and oxygen-to-carbon ratios. The data will be used in conjunction with other measurements at the site to elucidate pathways by which newly formed particles grow, and to characterize differences between nucleation and non-nucleation periods. This research was performed under the EMSL-ARM Pilot Program for Joint Research Projects and used resources at the Environmental Molecular Sciences Laboratory and the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains site in Oklahoma.

Co-Investigators

James Smith

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