Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

The application of a hollow waveguide (HW) was investigated as a gas cell for analytical infrared analysis. The analysis was the measurement of carbon monoxide (CO) and nitric oxide (NO) in sidestream cigarette smoke. An FT-IR analysis system was setup with a 3m multi-pass gas cell and a 55cm by 2mm i.d. Ag/AgI coated HW in tandem with individual CO and NO gas analyzers. The HW demonstrated response times an order of magnitude less than the larger volume multi-pass gas cell and slightly faster than the single analyte gas analyzer. Furthermore, it has been demonstrated that the HW provides up to approx. 60% greater sensitivity on a per meter optical path basis than the multi-pass gas cell of the analytes investigated due to increased optical efficiency maximizing the light concentration within the gaseous sample volume. Simulations in 3-D showed the sensitivity could theoretically improve by more than an order of magnitude if the IR beam was coupled more efficiently into the waveguide. Both FT-IR configurations gave statistically equivalent results for CO to the independent analyzers. With the HW increased temporal resolution, inter-puff measurements comparable to the gas analyzer were achieved at a lower spectral resolution. The HW optical configuration was modeled for ray tracing in MATLAB. Simulations in 2-D and 3-D were accomplished. The simulations show a major drawback to HW optimization is the coupling of the infrared beam into the waveguide. As demonstrated in a 3-D simulation, approximately 97% of the rays are rejected when an off-axis parabolic mirror with 25.4mm focal length is used to focus the IR beam into the 2mm i.d. waveguide. Repeating the simulation with longer focal length mirrors showed improved in IR coupling into the waveguide from 3% to 85%. Simulations applying a compound parabolic concentrator show comparable performance to the traditional design of two OAP mirrors to collect rays from the HW and focus onto the detector, but in a much smaller configuration. The simulation routines can be used to further improve the design of this and other optical sensing systems and enhanced by incorporating a spectral component to the simulation.

No description available.

Soot and other products of incomplete combustion play an important role in the chemistry of the atmosphere. As particles are exposed to trace gases, such as ozone, their chemistry and physical properties can be altered leading to changes in their optical properties, as well as their cloud condensation nuclei and ice nucleation abilities. These alterations can lead to changes in the global radiative budget and cloud microphysical processes, which in turn affect the climate. In this study, the chemical and physical changes associated with the oxidation of pyrene, anthracene, and carbon (lampblack) by ozone were investigated. Fourier Transform Infrared Spectroscopy was used to identify oxidation products and track reaction progress for these representative aerosols. A C=O band attributed to a carboxylic acid formation was observed for all three substances, at each level of exposure to ozone - 20 ppm, 40 ppm, and 80 ppm. Second order reaction rate constants ranged from 9.58 x 10-16 cm2 molecules-1 s-1 to 7.71 x 10-13 cm2 molecules-1 s-1. Measurements of water uptake, ice nucleation efficiency, and optical properties were obtained to determine whether any physical changes associated with the oxidation process occurred. Optical measurements show an increase in the ultra-violet absorption of anthracene, but not for pyrene, while an increase in the visible absorption for pyrene was observed, but not for anthracene. Oxidized soot froze at a warmer temperature (-22.8 degrees C) then fresh soot (-25.6 degrees C), showing an increase in ice nucleation efficiency. Our data indicates that oxidation by ozone does alter the chemistry and physical properties of the substances study, leading to possible changes in how they interact with atmospheric processes.

Thesis (Ph. D.)--University of Missouri-Columbia, 2000. / Typescript. Vita. Includes bibliographical references (leaves 132-137). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 134-139). Also available on the Internet.

Thesis (M.Sc.-Res.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf 91-95.

Thesis (M.S.)--Mechanical Engineering, Georgia Institute of Technology, 2004. / Fedorov, Andrei, Committee Member ; Mahan, J. Robert, Committee Member ; Zhang, Zhuomin, Committee Chair. Includes bibliographical references (leaves 80-82).

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 134-139). Also available on the Internet.

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: clean extinguishing agent; c₆f-ketone; novec 1230; thermal decomposition products; halon alternative. Includes bibliographical references.