Date of Award

Spring 2002

Project Type

Dissertation

Program or Major

Earth Sciences

Degree Name

Doctor of Philosophy

First Advisor

Robert W Talbot

Abstract

There has long been an interest for in situ analysis of single atmospheric aerosols. To this end, the Flytrap instrument was developed under a NASA Phase I and Phase II Small Business Innovative Research Grant. The centerpiece of the instrument was a spherical void electrodynamic levitator that was used to suspend and optically characterize the physical and chemical properties of individual aerosols. Physical measurements of the aerosols were conducted with the aid of a Mie scattering system while chemical characterization was conducted with a Raman spectroscopy microprobe. A large effort focused on development of a system for charging and trapping atmospheric aerosols using a corona discharge. Testing of this charging device indicated that only aerosols larger than twenty microns in diameter could be successfully charged and trapped.

Once assembled, calibrated and tested, the Flytrap instrument was used to study the interaction between acidic trace gases and artificial sea-salt aerosols in a laboratory environment. The chamber housing the spherical void electrodynamic levitator was designed to simulate conditions found in a polluted marine boundary layer. The reactive uptake coefficient between nitric acid and sea-salt aerosols under a variety of relative humidity and alkalinity conditions was measured. The uptake coefficient varied strongly with changes in relative humidity, time and alkalinity. In addition, oxidation of sulfur dioxide to sulfate in sea-salt aerosols was studied under a variety of alkalinity conditions. It was found that these reaction rates also varied strongly with oxidant type, changes in relative humidity, time and alkalinity.

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