The Role of Radical-Water Complexes in the Atmosphere

Brigham Young University, Provo UT

Investigators

Abstract

This project will investigate the effects of atmospheric water vapor on the formation of organic nitrates and secondary organic aerosol. Measurements of the product branching ratio for the reaction HOCH2CH2O2 (HEP, 2-hydroxyethyl peroxy) + NO as a function of temperature and water vapor are predicted to show that high concentrations of atmospheric water vapor can lead to the increased formation of organic nitrates. Additionally, this research will investigate the potential that under certain conditions, hydroperoxyl radicals (HO2) in the presence of water vapor can form complexes that become nucleating seeds for the formation of secondary aerosols. The results will connect the gas phase chemistry of peroxy radicals (HO2 and RO2) with the formation of secondary aerosol as a function of water vapor concentration, initial radical concentration, temperature, and reaction time. High levels of water vapor in the atmosphere may have an important effect on the formation of organic nitrates and secondary organic aerosol (from gas-to-particle transformations). Organic nitrates in the atmosphere are relatively inert and can provide a mechanism for long-range transport of pollution from one region to another. Understanding and quantifying the formation of secondary organic aerosol is critical for predicting their direct and indirect effects on climate change.