Secondary organic aerosol (SOA) are produced via gas phase oxidation reactions of volatile organic compounds (VOCs). Recent work in identifying oxidation pathways for relevant SOA precursors, such as cis-3-hexenyl acetate (CHA), has led to a greater understanding of SOA formation and the underlying mechanisms. Investigations of SOA formation from CHA, however, have been conducted almost exclusively under dry conditions. This does not take into account tropospheric RH environments, where RH values can reach upwards of 85%. Furthermore, a general statement regarding SOA production as a function of relative humidity (RH) cannot be made, necessitating the investigation of individual GLV systems. Here, the investigation of CHA ozonolysis products formed under high RH conditions is presented. Specifically, a Scanning Mobility Particle Sizer (SMPS), Electrical Low Pressure Impactor (ELPI), Thermal Desorption Gas Chromatography Mass Spectrometer (TD-GC-MS), and Near-Infrared Laser Desorption-Ionization Aerosol Mass Spectrometer (NIR-LDI-AMS) were utilized to probe both physical and chemical properties of SOA formed. Under high RH conditions, CHA derived SOA exhibited larger particle diameters, lower mass loadings, and more liquid-like phase behavior compared to low RH conditions. Additionally, the chemical composition of the resulting SOA was altered under high RH conditions, as different product formations and a higher prevalence of larger molecular weight compounds was observed. This work demonstrates that the presence gaseous water at the time of particle genesis does indeed significantly affect the chemical and physical properties of CHA derived SOA. Therefore, changes in RH consequently determine the nature of the SOA products formed, which has important implications for the distribution, abundance, and transport of atmospheric gases, as well as Earth’s radiative budget via light scattering, light absorbance, and cloud formation.

Effect of relative humidity on the phase and chemical properties of cis-3-hexenyl acetate derived secondary organic aerosol

256th National Meeting (2018)

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