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 Title: LOW-TEMPERATURE REACTION KINETICS USING CHIRPED PULSE ROTATIONAL SPECTROSCOPY Author(s): Gurusinghe, Ranil Contributor(s): Suits, Arthur ; Suas-David, Nicolas ; Broderick, Bernadette M.; Dias, Nureshan Subject(s): Dynamics and kinetics Abstract: In the past few years, the Suits group has successfully adapted the chirped-pulsed rotational spectroscopy technique to study reaction dynamics. A clear advantage of this method is its ability to simultaneously detect the appearance/disappearance of products/reactants of reactions within the frequency range of a single chirp. However, kinetic studies require a well-known, uniform density and temperature environment throughout the course of the reaction. Our Chirped Pulse Uniform Flow (CPUF) spectrometer achieves these conditions by the uniform supersonic flow produced from a Laval nozzle expansion following the pioneering CRESU technique developed in France. However, high densities in the uniform flow (10$^{14}$ – 10$^{17}$ molecules/cm$^{3}$) can attenuate the molecular coherence through collisions and therefore limit the MW/mmW spectroscopic detection. To overcome this, we adapted an airfoil sampling technique in which the reaction takes place in the uniform supersonic flow and then expands into a cold, low-density sampling region that is optimal for MW/mmW spectroscopic detection. This airfoil sampling CPUF spectrometer, in the 70 – 90 GHz range, has been used to study the low-temperature kinetics of bimolecular reactions and preliminary results will be presented. Initiated by a pulsed photolysis laser at 193 nm, appearance of products/disappearance of reactants have been probed as a function of time with a 5 $\mu$s resolution. The data were fitted to pseudo first-order or second-order rate equations to determine the rate constants for chemical reactions. Issue Date: 25-Jun-20 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/107499 Date Available in IDEALS: 2020-06-26
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