- Kinetics of the Reaction of HS and HSO with O3
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The kinetics of the reaction of HS and HSO with O3 have been studied in a discharge flow system coupled to a laser magnetic resonance spectrometer: HS + O3 -> HSO + O2 (1); HSO + O3 -> products (2).Measurements were made at low pressures (1-2.2 Torr) and
- Wang, Niann S.,Howard, Carleton J.
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p. 8787 - 8794
(2007/10/02)
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- Kinetics of SH with NO2, O3, O2, and H2O2
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A low pressure (1-8 torr of He) discharge flow reactor with (a) LIF detection of SH using a high repetition rate (20 kHz) metal atom laser to circumvent severe predissociation of the A2Σ+ state and (b) resonance fluorescence detection of OH has been used to examine the kinetics of the title reactions at 298 K: SH + NO2 -> HSO + NO, k1=(3.0+/-0.8)x10-11 cm3s-1; SH + O3 -> HSO + O2,k2 = (3.2+/- 1.0)x10-12cm3s-1;SH + O2 -> SO + OH,k3 -17 cm3s-1;SH + H2O2 -> H2S + HO2,k4a;SH + H2O2 -> HSOH + OH,k4b;SH + H2O2 -> HSO + H2O,k4c. k4=k4a+k4b+k4c-15 cm3s-1.Regeneration of SH in reaction 2 by HSO + O3 is observed and is used to infer a rate constant for HSO + O3 -> products of (1.0+/-0.4)x10-13cm3s-1.Absence of OH production in that reaction implies that the primary products are SH + 2O2.Isotope experiments with H2S replaced by D2S substantiate that conclusion and yield a reaction rate constant for DSO + O3 -> SD + 2O2 of 9x10-14 cm3s-1.Brief discussions of SH reactivity compared with OH and Br are offered, as well as a summary of the atmospheric chemistry of SH.
- Friedl, Randall R.,Brune, William H.,Anderson, James G.
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p. 5505 - 5510
(2007/10/02)
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- Reactions of HS with NO and NO2 at 298 K
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HS radicals have been generated by the photodissociation of H2S at 193 nm and their disappearence monitored by LIF.The reaction of HS with NO, like the analogous reaction of OH with NO, has been shown to involve a third body.The low pressure rate coefficients have been determined for He, Ar, and N2.The values are 2.1, 2.2, and 2.4*10-31 cm6 molecule-2 s-1, respectivelly, with estimated uncertainities of +/- 10percent.The high oressure limit is (2.8 +/- 1.0)*10-11 cm3 molecule-1 s-1.The reaction with NO2 (HS + NO2 -> HSO + NO) is second order with a rate coefficient of (3.5 +/- 0.4)*10-11 cm3 molecule-1 s-1.An upper limit for the rate coefficient with O2 has been estimated (4*10-17 cm3 molecule-1 s-1).
- Black, G.
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p. 1103 - 1107
(2007/10/02)
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- Mechanism of the O(3P) + H2S Reaction. Abstraction or Addition?
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The question of whether the reaction of O(3P) with H2S proceeds by absraction, O + H2S -> OH + SH, or by addition, O + H2S -> * -> products, was investigated by quntitative gas chromatographic analysis of N2 and CO2 produced in mercury-photosensitized mixtutes of N2O, H2S, and CO.Reactant pressures were chosen so that less than 5 percent of the O atoms formed from N2O would react with CO, but a large fraction of any OH radicals formed from reaction of O with H2S would react with CO to form CO2.The CO2 yields were compared with those calculated from an expression derived by steady-state treatment of a simple mechanism.The CO2 yields indicated that 52 percent of the O + H2S reaction proceeds by abstraction, although it could be as much as 100 percent depending on the extent of H2S2 formation by SH radical recombination and the rate constant for the reaction of O atoms with H2S2.
- Singleton, Donald L.,Paraskevopoulos, George,Irwin, Robert S.
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p. 2605 - 2609
(2007/10/02)
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