Show simple item record

dc.contributor.advisor Curl, Robert F., Jr.
dc.creatorUnfried, Kenneth Gary
dc.date.accessioned 2009-06-04T00:46:42Z
dc.date.available 2009-06-04T00:46:42Z
dc.date.issued 1991
dc.identifier.urihttps://hdl.handle.net/1911/16490
dc.description.abstract High resolution infrared diode laser kinetic spectroscopy has been used to study reaction kinetics and spectroscopy of short-lived species. These unstable molecules were produced in a flowing system by excimer laser photolysis of suitable precursors. Their concentrations were monitored using an infrared diode laser with fast InSb detectors. Time resolution of better than 1$\mu$s was achieved. HNO production is predicted by the reaction sequence NH$\sb2$ + NO $\to$ HN$\sb2$ + OH, HN$\sb2$ + NO $\to$ HNO + N$\sb2$ in the Miller mechanism for the thermal deNOx process. A search was made for the HNO molecule in the reaction system NH$\sb2$ + NO at room temperature using diode laser infrared kinetic spectroscopy to search for NH stretch absorptions of HNO. No HNO attributable to the deNOx process was observed. Sensitivity calibration measurements using known amounts of HNO produced from the reaction of HCO with NO were used to set an upper bound of 1% for the conversion of NH$\sb2$ into HNO. The high resolution infrared spectrum of the heavy atom antisymmetric stretch of the ketenyl radical (HCCO) was observed by means of infrared kinetic spectroscopy. Ketenyl was produced by 193 nm photolysis of ketene. The resulting transient absorption was probed with an infrared diode laser. Individual rovibrational transitions have been identified and molecular parameters have been determined from a least-squares fit of the data. The band origin is located near 2023 cm$\sp{-1}$. Acquisition of ketenyl infrared spectra allowed for determination of reaction rate constants by directly observing ketenyl decay. Kinetic studies of the ketenyl radical's reaction with nitric oxide, oxygen, acetylene and ethylene were conducted. A second order rate constant of 4.4(10) $\times$ 10$\sp{-11}$ cm$\sp3$molecule$\sp{-1}$s$\sp{-1}$ was obtained for the reaction with NO and a second order constant of 6.5 $\times$ 10$\sp{-13}$ cm$\sp3$molecule$\sp{-1}$s$\sp{-1}$ was obtained for the reaction with O$\sb2$. Acetylene appeared not to react with the ketenyl radical. An upper limit of 3.8 $\times$ 10$\sp{-13}$ cm$\sp3$molecule$\sp{-1}$s$\sp{-1}$ for the rate constant was determined by measuring the ketenyl decay in the presence of acetylene. The addition of ethylene appeared to slow the ketenyl decay. This behavior was attributed to the reaction of ethylene with a chemical species (probably H atoms) responsible for depletion of ketenyl.
dc.format.extent 168 p.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subjectPhysical chemistry
dc.title Diode laser kinetic spectroscopy
dc.type.genre Thesis
dc.type.material Text
thesis.degree.department Chemistry
thesis.degree.discipline Natural Sciences
thesis.degree.grantor Rice University
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy
dc.identifier.citation Unfried, Kenneth Gary. "Diode laser kinetic spectroscopy." (1991) Diss., Rice University. https://hdl.handle.net/1911/16490.


Files in this item

Thumbnail

This item appears in the following Collection(s)

Show simple item record