Portland State University. Department of Physics
Robert J. O'Brien
Term of Graduation
Date of Publication
Master of Science (M.S.) in Physics
Nitrogen dioxide -- Measurement -- Equipment and supplies
1 online resource (vii, 113 pages)
Nitrogen oxides control the photochemical production of ozone O3 in the lower atmosphere and influence the concentration of the hydroxyl radical HO in the troposphere. As an important member of the nitrogen oxide family, NO₂ plays a significant role in serving as the only known source of ozone (through photolysis) in the lower atmosphere and as sink for HO via formation of nitric acid. Therefore, accurate measurements of nitrogen dioxide are essential for the understanding of the processes that determine the distribution of tropospheric ozone and for assessing the impact of human activity on the troposphere.
Although reliable and sensitive techniques for the direct measurement of nitric oxide NO have been developed, these results could not be fully applied to direct NO₂ measurements. The purpose of the present study was to further develop a low pressure laser-excited fluorescence technique for measuring NO₂ by introducing the idea of a Two-Chamber-Fluorescence-Cell. Theoretical considerations of the performance of such a cell and the flow regime within the cell were done in order to assess the optimum cell design and the conditions for optimum operation. Measurements on a provided two-chambered test cell were done to verify the theoretical predictions made. This test cell has been explored with a Nd:YAG pumped dye laser (100mW@564nm, 30Hz) and a supplied NO₂ concentration of 100ppm.
The theoretical results suggest that the concept of a Two-Chamber-NO₂-Fluorescence-Cell yields an improved sensitivity compared to present direct techniques for measuring NO₂. In addition, experimental results give a better understanding of how to realize the initial idea of an operating Two-Chamber-NO₂-Fluorescence-Cell.
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Schmid, Volker, "Design of a Two-Chamber-NO₂-Fluorescence-Cell" (1996). Dissertations and Theses. Paper 5263.