Date of Award

Spring 5-18-2026

Document Type

Restricted Thesis

Degree Name

Bachelor of Arts (BA)

Department

Chemistry

First Advisor

Juan Navea

Abstract

Atmospheric particles provide active surfaces for the adsorption of volatile organic compounds, including terpenes. These plant-emitted molecules are abundant in the troposphere, and their interactions with aerosol surfaces influence atmospheric chemistry, climate change, cloud formation, and the Earth’s system as a whole. During atmospheric transport, these organic adsorbates undergo oxidation through reactions with ozone, altering the chemical and physical properties of aerosol particles. However, the mechanisms and rates of these heterogeneous oxidation processes remain poorly understood. There is a growing need to bridge the gap between the well-studied gas-phase reactions of terpenes with O3 and the less understood surface-based reactions that occur at the complex environmental interface. In this Thesis, we present a state-of-the-art environmental flow chamber that enables in-situ vibrational spectroscopic observation of the reaction between ozone and selected terpenes, adsorbed onto alumina, a proxy for mineral dust. This system enables the investigation of chemical changes in surface-bound species within a controlled environment as the reaction occurs. It also provides a means to characterize surface-bound products and gain insight into the synergistic mechanisms driving atmospheric particle aging. Importantly, we found that the reaction proceeds via an Eley-Rideal type of mechanism, with surface-bound Criegee intermediates racting on the surface to form oligomers.  Using in-situ analysis, we examined the chemical kinetics of both pinene and limonene oxidation in an Eley–Rideal reaction with O3, allowing for the characterization and estimation of the kinetics of both chemisorbed and physisorbed pinene on alumina. Ex-situ analysis was conducted to determine the reaction products and better understand the mechanism variation driven by the surface. Overall, this work provides insights into the effects of aerosol interfaces in the atmospheric processing and ageing of terpenes due to O3 oxidation.

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