Understanding the Novel Surface-Promoted RedOx (SPRO) Mechanism in the Context of Fundamental Chemistry and Atmospheric Chemistry

Redox reactions are of central importance in the atmosphere as they govern the formation of gas molecules and aerosol particles that are influential to the environment and climate.

However, the current knowledge of the redox mechanism is insufficient, which leads the incomplete and even missing formation pathways and sources of critical atmospheric components, such as the sulfate formation pathways and the sources of nitrous acid.

Recently, a novel surface-promoted redox (SPRO) mechanism is discovered on solvating inorganic salt particles, which is hypothetically responsible for some unexplained atmospheric processes.

In this project, a state-of-the-art technique with high surface-sensitivity, ambient pressure X-ray photoelectron spectroscopy (APXPS), will be used to investigate the mechanism in detail. Conventional kinetics experiments will be conducted to quantify this mechanism and characterize the governing factors.

Water is the key molecule for the SPRO mechanism, and other trace molecules of crucial atmospheric importance (SO2, NO2, NH3) will also be studied for their fates during the surface-promoted redox reaction.

In addition to laboratory model systems, representative natural samples will be collected and studied to verify the existence of the mechanism in nature.

The improved understandings of the mechanism will complement the classical theory under the current thermodynamic framework, which will be beneficial for further model developments of various levels.