Date of Award

2020

Document Type

Honors Thesis (Colby Access Only)

Department

Colby College. Chemistry Dept.

Advisor(s)

Greg T. Drozd

Second Advisor

Lindsey R. Madison

Abstract

The oxidation state of organic aerosol is correlated with a number of key aerosol properties including the propensity to form clouds and their correlation with increased mortality and morbidity in urban areas. Widespread, cost-effective monitoring of organic aerosol oxidation would be invaluable in estimating climate and health impacts of organic aerosol. Currently, methods are either cost prohibitive or too slow to provide even hourly measurements that are comprehensive across large geographical regions. This work is a first step towards using solvatochromic dyes, which show spectral changes due to changing solvent qualities such as polarity, as indicators of organic aerosol oxidation. UV-visible and fluorescence spectroscopies were used with three different solvatochromic probes in order to quantify shifts in their spectra due to changing chemical environment (i.e. solvent composition). The solvatochromic dyes of interest were Brooker’s Merocyanine, Reichardt’s Dye and Rhodamine B. Additionally, this project begins the development of a field-deployable sensor capable of using solvatochromic dyes in order to indicate properties, such as oxidation state, of an aerosol particle. The development of this sensor will address the current limitations of field instruments, noted above, to characterize aerosol particles.

Keywords

spectroscopy, atmospheric chemistry, aerosol chemistry, solvatochromism

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