Understanding Particle Growth by Examining the Interactions of Organic Nitrates with Organic Substrates
Abstract
To accurately predict the impacts of secondary organic aerosol (SOA) and specifically understand the mechanisms by which particles grow in the atmosphere, the interactions between gases and particles must be understood at the molecular level. We report here the results of laboratory experiments under dry conditions at ambient pressure and temperature on the interactions of gaseous 2-ethylhexyl nitrate, β-hydroxyhexyl nitrate, and β-hydroxypropyl nitrate with selected organic substrates. These include triacontane, pinonic acid, poly(ethylene adipate) (PEA), and SOA formed by the ozonolysis of α-pinene. Net uptake coefficients (γ) at the shortest times accessible in these experiments and bulk partition coefficients (K) at the equilibrium point were quantified using attenuated total reflection Fourier transform infrared spectroscopy. The trends in γ and K are examined, and ab initio calculations on interactions between the nitrates and one of the substrates (PEA) were carried out to gain insight into these trends. Kinetic modeling showed diffusion throughout the substrates, and the evolution of bulk diffusion coefficients as uptake/desorption occurred. The specific trends in γ and K show that the uptake coefficients do not necessarily follow the trends in partition coefficients/solubility or vapor pressure. The implications for predicting particle growth in the atmosphere will be discussed.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A43K3205V
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0320 Cloud physics and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0368 Troposphere: constituent transport and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES