Carbenium ion-mediated oligomerization of methylglyoxal for secondary organic aerosol formation

• DOI: 10.1073/pnas.1912235117
• Publication Date: 2020-06-03T23:56:52Z
• Authors: Yuemeng Ji; Qiuju Shi; Yixin Li; Taicheng An; Jun Zheng; Jianfei Peng; Yanpeng Gao; Jiangyao Chen; Guiying Li; Yuan Wang; Fang Zhang; Annie L. Zhang; Jiayun Zhao; Mario J. Molina; Renyi Zhang
• Keywords: econdary organic aerosol; 550; aqueous; 01 natural sciences; oligomerization; Climate Action; 13. Climate action; Physical Sciences; 11. Sustainability; brown carbon; cationic; secondary organic aerosol; 0105 earth and related environmental sciences

Significance Secondary organic aerosol (SOA) from photochemical oxidation of volatile organic compounds represents one of the most dominant constituents of fine particulate matter in the troposphere, with profound implications for air quality and climate. However, the fundamental chemical mechanisms leading to SOA formation remain highly uncertain. Here, we show oligomer formation from methylglyoxal with the carbenium ions as the key intermediate using quantum chemical calculations. This cationic oligomerization is demonstrated to proceed via barrierless pathways and occurs at fast rates on weakly acidic aqueous aerosols and/or cloud droplets under typical tropospheric conditions. In contrast to a previously proposed hydration mechanism, out results reveal that the carbenium ion-mediated oligomerization of methylglyoxal provides a major SOA source from anthropogenic and biogenic emissions.