- The pressure and temperature dependence of the OH + C2H2 reaction above 800 K
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The rate constant for the reaction OH + C2H2 has been measured at 900,1100, and 1300 K.The experimental method was that of laser pyrolysis/laser fluorescence, in which a pulsed COZ laser heats a mixture of SF6, N2, H2O, and C2H2.The rate constant is determined from the rate of decay of laser-induced fluorescence signals in OH, formed by pyrolysis of the peroxide and consumed by reaction with the acetylene.At the two higher temperatures the rate constant is independent of pressure between 10 and 120 Torr but at 900 K it was observed to be pressure dependent over a similar range.The rate constant at 1100 K is 2.7+/-0.6 X 10-3 cm3 s-, and rises to 5.8+/-0.8 X 10-13 cm3 s-1 at 1300 K.Calculations of the temperature and pressure dependence of the addition channel OH + C2H2 + MC2H2OH + M were made using Troe's approach, based on flow tube data at a lower temperature.These theoretical calculations are consistent with the present results as well as previous experimental measurements, showing a decrease in the importance of the addition channel with increasing temperature and the onset of a direct route in the region of 1000 K.These considerations of combined pressure and temperature dependence of reaction rates, and changes in mechanism, must be properly taken into account in detailed combustion chemistry models which cover a large range in temperature and pressure.
- Smith, Gregory P.,Fairchild, Paul W.,Crosley, David R.
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- Reactions of laser-ablated Be and Mg atoms with C2H2: Infrared spectra and density functional calculations of novel metal-acetylene species
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Reactions of laser-ablated Be and Mg atoms with C2H2, 13C2H2, and C2D2 upon condensation in excess argon at 10 K give new infrared absorptions that are assigned to the insertion and decomposition products HBeCCH, BeCCH, and MgCCH with the help of density functional theory isotopic frequency calculations. The 2019-cm-1 C≡C stretching fundamental for BeCCH is between values for BCCH and AlCCH, which are all slightly blue shifted from acetylene itself.
- Thompson, Craig A.,Andrews, Lester
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- FTIR and computational studies of gas-phase hydrogen atom abstraction kinetics by t-butoxy radical
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By using Fourier-Transform Infrared (FTIR) absorption spectroscopy, rate coefficients in the range of 10-16 to 10-14 cm3 molecule-1 s-1 have been determined for the hydrogen atom abstraction reactions of several substrates including halogenated organic compounds and amines by t-butoxy radical generated from the uv photolysis of t-butyl nitrite in the gas phase. Arrhenius parameters for selected reactions have been measured in the temperature range 299-318 K. Transition states and activation barriers for such reactions have been computed with the help of Gaussian 03 software and found to match very well with the experimental values.
- Li, Shuping,Fan, Wai Yip
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p. 276 - 280
(2007/10/03)
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