Portland State University. Department of Physics.
Robert J. O'Brien
Date of Award
Master of Science (M.S.) in Physics
1 online resource (vii, 113 p.)
Nitrogen dioxide -- Measurement -- Equipment and supplies
Nitrogen oxides control the photochemical production of ozone 03 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, N02 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 N02 measurements. The purpose of the present study was to further develop a low pressure laser-excited fluorescence technique for measuring N02 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:Y AG pumped dye laser (100mW@564nm, 30Hz) and a supplied N02 concentration of lOOppm. The theoretical results suggest that the concept of a Two-Chamber-N02- Fluorescence-Cell yields an improved sensitivity compared to present direct techniques for measuring N02 In addition, experimental results give a better understanding of how to realize the initial idea of an operating Two-Chamber-N02- Fluorescence-Cell.
Schmid, Volker, "Design of a Two-Chamber-NO2-Fluorescence-Cell" (1996). Dissertations and Theses. Paper 5263.