A novel reaction between ammonia and Criegee intermediates can form amines and suppress oligomers from isoprene
- Sci Total Environ. 2024 Dec 15:956:177389. doi: 10.1016/j.scitotenv.2024.177389.
- 1. State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
- 2. State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China; College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: [email protected].
Isoprene and ammonia (NH3) are essential precursors for organic and inorganic aerosol in the atmosphere, but their molecular interactions are unclear. The fundamental role of NH3 in secondary organic aerosol (SOA) formation from ozonolysis of isoprene was investigated based on chamber experiments. The molecular information was determined based on high-resolution orbitrap mass spectrometry. Results show that NH3 significantly reduces SOA yields by inhibiting oligomer formation from Stable Criegee intermediates (SCI). Direct evidence shows that NH3 can react with C4-SCIs (C4H6OO) to generate a hydroperoxide alkylamine (m/z 104.07, C4H9O2N), hindering the oligomerization reaction of SCIs. Meanwhile, many nitrogen-containing organic compounds were newly formed in the particle phase, primarily with m/z < 200, resulting from the reaction between acids and C4H9O2N. This study discovered a new pathway for NH3 to change SOA composition through a novel reaction with Criegee intermediates, which highlights that the roles of NH3 in biogenic SOA are more complex than their representation in atmospheric chemistry models and need to be reevaluated as the chemistry between NH3 and isoprene was revealed.