SOA yields from C₁₀ alkanes and oxygenates and their relation to highly oxygenated organic molecules (HOM)

Abstract. Alkanes are hydrocarbons that are emitted to the atmosphere mainly by human activities such as combustion processes and via the use of volatile chemical products (VCPs). They are an important group of volatile organic compounds (VOCs) that can produce secondary organic aerosol (SOA) in the atmosphere via hydroxyl (OH) radical initiated reactions. For many other compound groups (e.g., aromatics and monoterpenes), highly oxygenated organic molecules (HOMs) formed via autoxidation have been shown to be an important link between VOCs and SOA. Although alkane SOA has been intensively studied over the last decades, the importance of autoxidation and HOM in this system has received limited attention. The first HOM observations were only recently reported, but their relation so SOA has not been directly studied. Here, we show results of SOA yields from seven C10 alkanes and their oxygenated derivatives in oxidation flow reactor experiments. We observe the well-known behaviour of increased SOA yield with different structure in the order of cyclic > linear > branched. We also measured HOMs, and all seven SOA precursors produced detectable amounts of products, but HOM quantification was not possible due to the experimental setup configuration focusing on SOA formation. However, a comparison to previously reported HOM yields for the same precursors was conducted, showing an overall correlation between HOM and SOA yields. Although not quantifiable, our own HOM observations did indicate that multi-generation OH oxidation played an important role in the SOA formation in our study.