Date of Award

Spring 1-1-2011

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry & Biochemistry

First Advisor

Gayfree Barney Ellison

Second Advisor

Veronica M. Bierbaum

Third Advisor

Veronica Vaida

Abstract

A droplet mass spectrometer has been built to study the oxidation of salt-water droplets coated by organic surfactants. These studies are to model the complex interfacial chemistry of nascent organic marine aerosols. The model predicts the aerosols to have a structure of an "inverted micelle" where a core salt-water droplet is coated by surfactants. Reactions with atmospheric oxidants are predicted to transform the hydrophobic surface to hydrophilic, making the aerosols better cloud condensation nuclei. A small review on single particle mass spectrometry details the consideration for the design and development criteria for the construction of the instrument. The design and development of this laser based instrument is discussed in detail, describing each component of the spectrometer. The essence of the experiment is to oxidize the surfactant coating, and then to vaporize with a laser pulse the water droplet to release the ions from solution (similar to MALDI), for subsequent analysis with a quadrupole mass analyzer. Quantitative experiments were carried out to understand water evaporation in an aerodynamic lens inlet used in single particle mass spectrometers. Also, the process of generating surfactant coated water droplets in the laboratory is described. Finally, experiments to study the microphysical characterization of common hygroscopic particles coated by surfactants are discussed.

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