Date of Award

Summer 2018

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Physics and Astronomy

Committee Chair

Dr. Christopher B. Winstead

Committee Chair Department

Physics and Astronomy

Committee Member 2

Dr. Khin Maung Maung

Committee Member 2 Department

Physics and Astronomy

Committee Member 3

Dr. Michael D. Vera

Committee Member 3 Department

Physics and Astronomy

Committee Member 4

Dr. Jeremy Scott

Committee Member 4 Department

Physics and Astronomy

Abstract

This paper documents modifications to an existing vacuum system to allow laser-induced fluorescence spectroscopy measurements within simulated atmospheres under a variety of conditions. This added capability will expand the laboratory’s ability to experimentally validate a computational model that calculates the effects of radiation within the atmosphere. The computational model could reveal radiation-induced chemical products that can be used to develop an alternative detection method that can be implemented from a safe distance. The selection of molecules for experimental validation has been limited to those which can be detected utilizing cavity ringdown spectroscopy. The current model indicates nitric oxide and ozone to be the primary reactants that dictate production rates and concentrations for many of the resulting chemical products. Because strong absorption cross sections for nitric oxide are too deep in the ultraviolet to effectively use the cavity ringdown method, laser-induced fluorescence spectroscopy was seen as a viable alternative. Using a certified mix of NO2 and a second mix of NO, the system is validated by stepping a dye laser through wavelengths from 225.9 nm to 227.1 nm. The data collected was used to produce an excitation spectrum to compare with a simulated spectrum. These mixes were diluted with an ultra-high purity grade of N2 so that an experimental detection limit could be approximated. The excitation spectrum produced is in excellent agreement with that of the simulated spectrum and an experimental approximation of the detection limit for NO was found to be 3 ± 2 parts-per-billion in a background of N2.

ORCID ID

https://orcid.org/0000-0002-1685-6503?lang=en

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