The absorption of sunlight drives the vast majority of chemistry in the atmosphere.  With the growing concern over atmospheric pollution and climate change, characterizing the photochemical reactions in the atmosphere and their corresponding mechanisms is of central importance for making predictive climate models.  Chromophoric organic matter referred to as brown carbon (BrC) directly impacts radiative forcing in the atmosphere and drives aerosol photochemistry through radical formation and excited state-sensitization reactions. Secondary formation of BrC in atmospheric water and aqueous secondary organic aerosols (aqSOA) has been indicated as an important source of BrC, however, the chemical formation and aging is poorly understood.   Consequently, there are still many gaps in the current understanding and modelling. To tackle this problem, our research involves a combination of experimental and theoretical methods to study the multi-phase formation and photochemistry of atmospheric brown carbon. 

Recent Publications:

• 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). 

• 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] 

Chromophoric dissolved organic matter (CDOM) is a subset of the dissolved organic matter (DOM) found in natural waters that can absorb light, particularly in the near UV and visible regions of the solar spectrum.CDOM plays a crucial role in the carbon cycle, acting as a source and sink of carbon in aquatic environments. It can originate from terrestrial plant material, microbial activity, and in situ production in terrestrial and marine water . This research uses excitation-emission matrix (EEM) spectroscopy to characterize CDOM in environmental water samples providing insight into the optical properties of these samples as well as a means of classifying spectral features and their molecular origin.  

Recent Publications

• 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). 

Carbonyl oxides or Criegee intermediates (CIs) are critical transitional states in the ozonolysis of alkenes and are very important in oxidation chemistry fundamental to atmospheric processes. For instance, the ozonolysis of isoprene, an organic compound released from plants, is a significant source of CIs on a global scale having an impact on the atmospheric oxidizing capacity and generation of secondary organic aerosol and hydroxyl radicals in the troposphere. Despite the importance of these species, until recently, there were no experimental means of directly measuring the gas phase kinetics of these highly reactive intermediates. Though some experimental data on the reaction kinetics of CIs has now been collected, there are still many gaps in experimentally measured rate constants. In this research, the reaction rates of CIs with a range of carbonyls  which are important hydrocarbon oxidation products will be investigated using computational chemistry in conjunction with experimental measurements. Furthermore, frontier molecular orbital theory and known rate constants will be utilized to develop structure-activity relationships to expand predictive capabilities to similar carbonyl species with unknown rate constants

Recent Publications

• Z. A. Cornwall, J. J. Enders,  A. W. Harrison, and C. Murray "Temperature-Dependent Kinetics of the Reactions of the Criegee Intermediate CH2OO  with Hydroxyketones." J. Phys. Chem. A 128, 10, 1880 (2024) .

•  Z. A. Cornwall, J. J. Enders,  A. W. Harrison, and C. Murray “Temperature‐dependent Kinetics of the Reactions of CH2OO with Acetone, Biacetyl, and Acetylacetone.” International Journal of Chemical Kinetics 55, 3, 154-166 (2023). 

Christina Sofos (Chemistry)

Ahmed Rushdi (Biochemistry)

Enson Flores (Chemistry;  UTSW Medical School)

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

Pavi Upadhya (Biology)

Henry Esses (ENSURE Program; Physics)

Carlos Suarez (Chemistry; Columbia University)

Nayan Kondapalli (Biochemistry)

Oliver Cernero (Chemistry)

Thomspon Mcleod (ENSURE Program; Engineering)