Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




Rachel O'Brien

Committee Members

Elizabeth Harbron

Nathanael Kidwell

Linda Morse


Organic aerosols are a complex mixture of organic compounds that can react in the environment, especially in the atmosphere. These organic aerosols have a huge global impact on the climate and human health. To better understand and characterize how the compounds in organic aerosols react in the atmosphere, we must understand how they change through photolytic or chemical aging. Brown carbon (BrC) is a type of organic aerosol composed of a class of organic compounds that can absorb solar radiation present in the ultraviolet/visible (UV/Vis) wavelength range. Research in this field has been focused on characterizing the formation and composition of BrC, however, the removal mechanisms and rates of BrC are not as well understood. Understanding the aging and lifetime properties of BrC can provide more insight into organic aerosol’s atmospheric lifetime.

Previous work has been done with aqueous solutions of BrC using methylglyoxal with ammonium sulfate to produce light-absorbing aerosol chromophores. In this work, we probe BrC photolysis of a similar system to investigate how the aging can occur in organic versus aqueous phases. We utilize UV/Vis spectrometry to characterize the photolysis of BrC to better understand the influence of the environment (the solvent) and the BrC concentrations on the photo decay process and rates. In addition, mass spectrometry was used to further characterize the molecular composition of the mixture as a first step towards understanding how the chemicals are modified during the aging process. Our goal is to understand how the concentration of the BrC in organic versus aqueous phase represented solvents (water vs. acetonitrile) affects the light absorptivity as a function of time.

On-Campus Access Only