A System For Conducting Laser-Induced Fluorescence Measurements On Gas Mixtures Exposed To Alpha Radiation

<p>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 NO₂and 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 N₂so 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.</p>

Name thesis:degree_name

Master of Science (MS)

Level thesis:degree_level

Masters Thesis

Discipline thesis:degree_discipline

Physics and Astronomy

Year dc:date.available

2018

Author dc:creator

• Ables, Patrick

Contributors dc:contributor

• Christopher B. Winstead
• Khin Maung Maung
• Michael D. Vera

• laser-induced fluorescence
• LIF
• NO
• nitric oxide
• excitation spectrum
• NO2
• Atomic, Molecular and Optical Physics
• Environmental Chemistry
• Optics
• Radiochemistry

Repository record dc:identifier

https://aquila.usm.edu/masters_theses/371

OAI identifier oai:identifier

oai:aquila.usm.edu:masters_theses-1422