Low volatility organic compounds (LVOC) from the oxidation of isoprene hydroxy hydroperoxide (ISOPOOH) were observed during the FIXCIT chamber study (Caltech, January 2014; Nguyen et al., Atmos. Chem. Phys. Disc. 2014). Data were obtained using a high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) during the study, and afterward in laboratory experiments using an ion mobility CIMS (IMS-CIMS). Both were equipped with a nitrate-ion (NO3‑) chemical ionization source. Decreases in LVOC concentrations correlated with the appearance and growth in organic aerosol, suggesting that LVOC are condensing onto pre-existing particles with a mass yield of roughly 0.5% (from ISOPOOH). Elemental composition of the condensing LVOCs (O:C, H:C, absence of N) match those of the organic aerosol formed as quantified by an Aerosol Mass Spectrometer (AMS). The AMS organic aerosol spectrum shows very little C5H6O+ fraction, a tracer of aerosol formation via heterogeneous uptake of IEPOX onto acidic seeds, which suggests that the LVOC aerosol formation pathway observed in this study is separate and not explained by previously understood IEPOX uptake. The results of an aerosol uptake model with physical constants for the system, as well as volatility information using potential structures of the observed ions will be presented. Finally, correlations with field data during the SOAS field study ground site (Centreville, AL, USA; summer 2013) from both the same NO3--CIMS instrument as well as the IMS-CIMS will be explored.

Detection of low-volatility gas-phase organic compounds from the OH-initiated oxidation of isoprene hydroxyhydroperoxide and their relevance to organic aerosol production

249th National Meeting (2015)

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