Recently, the high radiance of synchrotron sources was used to enhance FTIR
spectrometer performance. However, excessive channel spectra when synchrotron
sources are used degrade the quality of retrieved spectral parameters. In the
research reported in this thesis, seven different techniques for handling channel
spectra were investigated. These techniques were used to reduce channel spectra
for a test group of seven samples of CO2 mixed with air recorded using the
synchrotron source at the Canadian Light Source. The increases in signal to noise
ratio (SNR) of spectra handled with each technique were calculated. SNR results
showed that transmission spectra, produced using synthetic background spectra
with simulated channel spectra, achieved the highest SNR improvement. However,
when the spectra groups were fitted using nonlinear least square fit algorithm, the
technique using channel spectra fitting produced the smallest fitting residual.
Moreover, the retrieved intensities and air broadening coefficients of 21 spectral
lines showed that the spectral fitting technique produced the most accurate values
as compared to the HITRAN 2008 database. Although the spectral fitting technique
was accurate in retrieving spectral line parameters, applying the technique at wider
spectral ranges was less accurate.
A modification to the channel spectra fitting technique by performing
iterations of channel fitting was introduced to process wider spectral ranges.
Carbon dioxide laser band I centred at 961 wavenumber was analyzed using 24
spectra recorded under different experimental conditions. The intensity and air-and self-broadening coefficients were retrieved for 48 spectral lines with average
deviations from HITRAN database values of 2.11%, 1.25% and 4.14%, respectively,
using the Voigt profile. These average deviations lie within the uncertainty limits
listed by the database. The deviation between our results and other results reported
in the literature were also examined and it is found to be also within the range of
HITRAN uncertainties. The effect of errors in fitting channel spectra parameters was
examined and found to be mitigated by the inclusion of channel-free spectra in the
multispectral fit. / xiv, 134 leaves : ill. ; 29 cm
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:ALU.w.uleth.ca/dspace#10133/2638 |
| Date | January 2010 |
| Creators | Ibrahim, Amr, University of Lethbridge. Faculty of Arts and Science |
| Contributors | Predoi-Cross, Adriana, Teillet, Philippe |
| Publisher | Lethbridge, Alta. : University of Lethbridge, Dept. of Physics and Astronomy, c2010, Arts and Science, Department of Physics and Astronomy |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Relation | Thesis (University of Lethbridge. Faculty of Arts and Science) |
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