Property Characterization and Continuous-Flow Measurements of Dark and Irradiated Methylglyoxal-Ammonium-sulfate Aqueous Aerosols

ERIN O'LEARY, Maia Merriman, Bruno Loyola San Martin, Katherine Pierre-Louis, Joseph Woo, Lafayette College

     Abstract Number: 617
     Working Group: Aerosol Chemistry

Abstract
Methylglyoxal (MGLY), a commonly-observed carbonyl-containing volatile organic compound, has been observed to undergo a variety of shifts in composition and physical properties (e.g. UV-visible absorbance, surface tension, etc.) when processed with nitrogen-containing compounds and/or ultraviolet radiation. However, comparisons between aged and irradiated aerosol mimic solutions containing both MGLY and ammonium sulfate (AS) under bulk and small, hanging droplet (10µL) solutions have yielded discrepancies in SOA product compositions when exposed to UV light. As MGLY and proposed oligomeric products are expected to exhibit surfactant properties, it is proposed that SOA pathways that would not otherwise be possible are occurring at gas-droplet interfaces where surfactant SOA concentrations are locally high. This work expands on this comparison by assessing the relative yields of irradiated MG/AS reaction products under bulk, µL-scale hanging-droplet, and polydisperse aerosol measurements. UV/visible absorbance and ESI-MS data are reported. Effective amounts of oligomerization in irradiated MGLY/AS aerosol solutions are found to vary depending on duration of exposure to UV light and type of UV radiation applied (i.e. UV-A vs UV-C radiation.)