The absorption of sunlight drives most of the chemistry that transforms emissions into secondary products in the atmosphere. Our group studies the photochemical and oxidative mechanisms that govern this chemistry, from the reactions of carbonyls and Criegee intermediates in the gas phase to the aqueous reactions that generate secondary brown carbon and other light-absorbing products in atmospheric water and aerosol. We combine experimental and theoretical approaches to characterize reaction pathways, products, and optical properties, with the goal of constraining the mechanisms that current atmospheric and climate models still represent only approximately. 

Publications:

•  Z. Cornwell, J. J. Enders, B. Ferris, C. Murray, and A.W. Harrison.* Structure-Activity Relationships for 1,3-Dipolar Cycloaddition Reactions of Criegee Intermediates with Carbonyls.  ACS Earth and Space Chem. Article ASAP (2026). 

• N. Kondapalli, O. Cernero, A. Welch, A.W. Harrison.* Atmospheric Photochemical Oxidation of 4-Nitroimidazole. Atmosphere 16, 5, 624, (2025).

• A. Kharazmi, A.W. Harrison; M. Shaw, Miranda; M. Jordan, and S. Kable. The Effect of β-Hydrogens on the Tropospheric Photochemistry of Aldehydes: Norrish Type 1, Triple Fragmentation, and Methylketene Formation from Propanal.  Journal of American Chemical Society. 146, 31, 21308-21319 (2024). 

• A. W. Harrison, A. M. Waterson, and W. J. de Bruyn  “Spectroscopic and Photochemical Properties of Secondary Brown Carbon from Aqueous Reactions of Methylglyoxal.” ACS Earth and Space Chemistry. 4, 5, 762 (2020). [link] 

• A. W. Harrison,* M. F. Shaw, and W. J. de Bruyn. “Theoretical Investigation of the Atmospheric Photochemistry of Glyoxylic Acid in the Gas-Phase.” J. Phys. Chem. A, 123, 8109 (2019). 

• . A.W. Harrison, A. Kharazmi, M. F. Shaw, M. S. Quinn, M. J. T. Jordan and S. H. Kable. “Dynamics and Quantum Yields of H2 + CH2CO as a Primary Photolysis Channel in CH3CHO.” Phys Chem Chem Phys., 21, 14284 (2018). 

• A.W. Harrison and S. H. Kable. “Photodissociation Dynamics of Propanal and Isobutanal: The Norrish Type I Pathway.” J. Chem. Phys. 148, 164308 (2018). 

Water-soluble organic matter (WSOM) is found across environmental systems — in rivers, lakes, oceans, soils, atmospheric water, and the water-soluble fraction of aerosols. Its light-absorbing and fluorescent components, often referred to as chromophoric or fluorescent dissolved organic matter (CDOM/FDOM), absorb sunlight in the near-UV and visible regions and play important roles in carbon cycling, aquatic photochemistry, and the radiative properties of atmospheric particles. Despite their shared chemical character, WSOM in natural waters and in aerosols has historically been studied by separate communities using overlapping but not always consistent methods. Our group uses excitation-emission matrix (EEM) spectroscopy  and time-resolved fluorescence to characterize WSOM across both environments, with the goal of clarifying which optical signatures are universal to chromophoric organic matter and which are diagnostic of system-specific chemistry. 

Recent Publications

• W.J. de Bruyn, D. Manickam, A.W. Harrison, C.D. Clark. Time-resolved fluorescence measurements of dissolved organic matter (DOM) as a function of environmental parameters in estuarine waters. Environmental Science and Pollution Research, 32, 4, 1952-1970 (2025). 

• W. J. De Bruyn, A. W. Harrison, E. Kocik, D. Manickam, and E. Truong. Time-resolved fluorescence of oils and oil distillates in artificial seawater at low excitation wavelengths: assessing the use of lifetimes to decouple oil and dissolved organic matter (DOM) fluorophores in natural waters. Marine Pollution Bulletin. 206, 117073 (2024). 

• A. W. Harrison, B. Ferris, A. Rushdi, C. Sofos, and W. J. de Bruyn  “Reaction of Glyoxal and Ammonium as a Potential Contributor to Protein-like Fluorescence in Atmospheric Measurements.” ACS Earth and Space Chemistry 6, 11, 2698 (2022). 

• K. Juetten, A.L. Strecker, A. W. Harrison, Z Landram, W.J. De Bruyn, and C.D. Clark. “Chromophoric Dissolved Organic Matter (CDOM) Across An Elevational Gradient from Sea Level to Mountain Lakes.”  Earth and Space Science 9, 12, e2022EA002503 (2022). 

Welch Foundation Research Grant:  From Atmospheric Aerosols to Photodynamic Therapy: Microviscosity Effects on Singlet Oxygen Photosensitization  (2026)

Research Corporation for Scientific Advancement Cottrell Scholar Award:  Resolving Brown Carbon and Bioaerosol Fluorescence in Atmospheric Studies (2025)

Enson Flores (Chemistry;  UTSW Medical School)

Bridget Ferris (Chemistry and Mathematics; Washington University in St. Louis) 

Pavi Upadhya (Biology; University of Oklahoma Medical School)

Carlos Suarez (Chemistry; Columbia University)

Nayan Kondapalli (Biochemistry; Medical School)