Aerosol Photochemistry Group Research

The Earth's atmosphere can be viewed as an enormous reaction vessel where thousands of different physicochemical processes take place in parallel in a highly inhomogeneous and dynamic environment. Atmospheric chemists understand many of these reactions well. For example, gas-phase photodissociation processes involving simple atmospheric molecules such as NO₂, NO₃, O₃, H₂O₂, etc. have been studied extensively over a broad range of experimental conditions. Chemical mechanisms of many critical atmospheric gas-phase reactions, such as oxidation of volatile organic hydrocarbons by OH, are also reasonably well understood. On the other hand, our knowledge of chemical reactions involving aerosols, small particles of liquid or solid material suspended in air, is far from complete. Our lack of understanding of atmospheric aerosol represents an important gap in our knowledge because aerosols play a critical role in controlling climate, driving atmospheric chemistry, and contributing to air pollution problems worldwide. Aerosols are also key components in a wide spectrum of practical engineering problems including climate modeling, air pollution regulation and medical inhalation treatment. The goal of our research is to improve our understanding of atmospheric aerosol chemistry through laboratory and field measurements on different types of aerosols. Go to the following links to learn more about the on-going and previous research projects.

On-Going Projects

	Molecular Composition and Properties of Organic Aerosols The molecular make up of aerosols dictates their health effects and climate effects. We are using state-of the-art high resolution mass spectrometry methods to characterize the composition of organic aerosol particles, with a focus on secondary organic aerosol (SOA) and biomass-burning organic aerosol (BBOA). We also study how the important propeties of organic aerosols, such as their viscosity, are linked to their molecular composition.
	Photochemical and Dark Aging of Organic Aerosols Solar radiation drives complicated photochemical processes not only in the gas phase but also inside organic aerosol particles and inside cloud/fog droplets containing dissolved organic compounds. We are investigating mechanisms of these photochemical reactions and their effect on the composition and properties of organic aerosols using various photochemical instruments designed by our group members. We also study aging driven by thermal processes, such as acid-catalyzed hydrolysis.
	Chemistry of Brown Carbon Reactions between various aerosol constituents can change important properties of aerosols including their toxicity, ability to absorb solar energy, and ability to form clouds. Our group members investigate the mechanisms of these processes with a particular focus on the formation of organic aerosols that absorb near-UV and visible radiation, known as "brown carbon"

Previous Projects

	Water Uptake by Nanoparticles Condensation of water on particles is one of the most important physical processes in the atmosphere. We previously investigated the effects of size, shape and chemical composition of nanoparticles on their ability to absorb water from the environment using experiments, molecular dynamics simulation, and theory.
	Indoor Air Chemistry People spend more than 90% of their lives indoors, yet so little is known about chemistry of indoor air. We published a few papers on reactions between common air pollutants such as ozone and molecules emitted by common household products such as carpet cleaners.
	Pre-UCI Research This link describes graduate research on ionic complexes and postdoctoral research on atmospheric kinetics, spectroscopy, and reaction dynamics done by Prof. Nizkorodov before he came to UCI.