Browsing by Author "Gaulin, Maylis"

Secondary Organic Aerosols (SOA), which cause adverse effects on health and climate, are formed through the oxidation of Volatile Organic Compounds (VOCs). One of the most abundant SOA precursors is α-pinene, a biogenic VOC. Eight different chamber experiments were performed in two different chambers, six experiments in ACD-C, at TROPOS, in Leipzig, and two experiments in COALA, INAR, in Helsinki to study α-pinene-derived accretion products as a result of OH and O3 oxidation with seed particles of varying acidities. The aim was to identify possible novel formation and degradation pathways of oxidation accretion products in the gas- and particle phase. It was found that more accretion products were observed in ozonolysis experiments in the particle phase and under OH oxidation and neutral seed particle conditions in the gas phase. The following degradation reactions were identified in high acidity conditions in the particle phase: C7H9O5 + C7H11O5 C14H20O8 + O2 and C7H9O5 + C10H17O4 C17H26O7 + O2. Furthermore, the contribution of HOMs to organic aerosol content was estimated for the high acidity conditions, 6.17 x 1014 molecules cm-3 ncps (normalised counts per second) for OH oxidation, and 1.02 x 1014 molecules cm-3 ncps for O3 oxidation, however, a linear growth for the formation of organic content had to be assumed.