Photolysis of Aqueous Atmospheric Aerosol Mimics

The chemical composition of atmospheric aerosol is complex and poorly understood. Aqueous reactions of aldehydes (e.g., glyoxal and glycolaldehyde) with amines or ammonium salts have been shown to be important for atmospheric brown carbon formation processes. Recent work has started to identify the products of these reactions, especially those responsible for visible light absorbance. While the aqueous phase reactions of many small aldehydes follow similar mechanisms, they produce a variety of products that interact differently with ultraviolet and visible light. Photolysis of these compounds can break down the chromophores into non-absorbing compounds and drastically change the chemical composition of these systems. We present photolysis rates for reaction systems of aqueous carbonyls and ammonium sulfate. Mass spectral analysis shows that many of the most abundant compounds disappear while others are formed during photolysis.