Abstract
The effect of photochemical reaction time on glyoxal and hydrogen peroxide at the air-liquid (a-l) interface is investigated using in situ time-of-flight secondary ion mass spectrometry (ToF-SIMS) enabled by a system for analysis at the liquid vacuum interface (SALVI) microreactor. Carboxylic acids are formed mainly by reaction with hydroxyl radicals in the initial reactions. Oligomers, cluster ions, and water clusters formed due to longer photochemistry. Our results provide direct molecular evidence that water clusters are associated with proton transfer and the formation of oligomers and cluster ions at the a-l interface. The oligomer formation is facilitated by water cluster and cluster ion formation over time. Formation of higher m/z oligomers and cluster ions indicates the possibility of highly oxygenated organic components formation at the a-l interface. Furthermore, new chemical reaction pathways, such as surface organic cluster, hydration shell, and water cluster formation, are proposed based on SIMS spectral observations, and the existing understanding of glyoxal photochemistry is expanded. Our in situ findings verify that the a-l interfacial reactions are important pathways for aqueous secondary organic aerosol (aqSOA) formation.
| Original language | English |
|---|---|
| Pages (from-to) | 10236-10245 |
| Number of pages | 10 |
| Journal | Environmental Science and Technology |
| Volume | 53 |
| Issue number | 17 |
| DOIs | |
| State | Published - Jun 19 2019 |
| Externally published | Yes |
Funding
This work was supported by the funding from Pacific Northwest National Laboratory (PNNL), Materials Synthesis and Simulation across Scales (MS3), Initiative Laboratory Directed Research and Development (LDRD), the Earth and Biological Sciences Directorate (EBSD), Mission Seed LDRD, National Natural Science Foundation of China (No. 21527814), the Ministry of Science and Technology of China (No. 2016YFC0202700, 2016YFE0112200, 2014BAC22B01), and Marie Skłodowska-Curie Actions (690958-MARSU-RISE-2015). The research was conducted at W. R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national Science User Facility sponsored by the office of Biological and Environmental Research (OBER). F.Z. is grateful for the support from the China Scholarship Council (CSC) and X.S. thanks the PNNL Alternate Sponsored Fellowship (ASF). F.Z. thanks Rachel Komorek for editing and Prof. Hartmut Herrmann for comments and discussions. This work was supported by the funding from Pacific Northwest National Laboratory (PNNL), Materials Synthesis and Simulation across Scales (MS3), Initiative Laboratory Directed Research and Development (LDRD), the Earth and Biological Sciences Directorate (EBSD), Mission Seed LDRD, National Natural Science Foundation of China (No. 21527814) the Ministry of Science and Technology of China (No. 2016YFC0202700 2016YFE0112200, 2014BAC22B01).