| Isoprene is the most abundant non-methane hydrocarbon emitted into Earth's atmosphere and although recognized as the single largest source of global secondary organic aerosol (SOA), the exact manner in which isoprene-derived SOA is formed remains unclear. Recently, epoxides produced from isoprene oxidation have been shown to be critical in SOA formation. In this work an acetate chemical ionization mass spectrometer (CIMS) was characterized and utilized to measure SOA yields from two proposed isoprene-derived epoxides, isoprene epoxydiol (IEPOX) and methacrylic acid epoxide (MAE), under varying particle acidities. The resulting SOA yield and CIMS characterization showed the kinetics associated with MAE uptake is likely slower then IEPOX, but results for IEPOX were promising. This work also resulted in a much better understanding of the acetate CIMS operation and showcased its ability to measure these epoxides in real time. |
