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 Title: D KINETIC ISOTOPE EFFECTS MEASUREMENT IN THE REACTIONS OF CH4 WITH O(1D) USING CAVITY RING-DOWN SPECTROSCOPY Author(s): Chen, TzuLing Contributor(s): Okumura, Mitchio ; Ober, Douglas Subject(s): Dynamics and kinetics Abstract: As a long-lived greenhouse gas, methane plays a major role in the chemistry of the Earth's atmosphere. Most atmospheric methane is removed by oxidations by OH (84\%) and O($^1$D) (8\%). The study of kinetic isotope effects (KIEs) on the reaction rate constants involving the transfer between hydrogen atoms is of importance but challenging experimentally because they are quite small. In this work, the $^D$KIE for the singly substituted methane (CH$_3$D and CH$_4$) with O($^1$D) radicals have been measured using frequency-stabilized cavity ring down spectroscopy (FS-CRDS), where the isotopic composition is determined based on a dual near-infrared DFB laser system. The high sensitivity of the FS-CRDS system, with a detection limit of 6.0$\times$10$^{-12}$~cm$^{-1}$, enables the KIE to be measured with low depletion to minimize possible secondary effects. In this experiment, the O($^1$D) radicals are produced by the 193~nm photolysis of N$_2$O. The preliminary result of $^D$KIE is 1.052(39). Issue Date: 26-Jun-20 Publisher: International Symposium on Molecular Spectroscopy Citation Info: APS Genre: CONFERENCE PAPER/PRESENTATION Type: Text Language: English URI: http://hdl.handle.net/2142/107627 Date Available in IDEALS: 2020-06-26
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