Direct determination of the dominant CH(A) formation reaction and its rate coefficient for 1200 < T < 2300 K Conference Paper uri icon


  • Visible emission from CH(A2Δ→X2φ) chemiluminescence, CH∗, near 431 nm has been measured in a shock tube and its kinetics studied at high temperatures (1200 - 2300 K) and atmospheric pressures. Test mixtures were composed of CH4/H2/O2highly diluted in Ar, with varying levels of O2addition. Chemical kinetics simulations indicated that the shape of the maximum-intensity curve as a function of equivalence ratio (for T = constant) is most strongly sensitive to the key CH∗ formation reaction, C2+OH=CH∗+CO so that its rate coefficient could be measured directly by fitting the experimental curves. It was found that the addition of excess O2to the experimental mixtures significantly reduced the CH∗ yield and that the extent of this reduction, relative to the stiochiometric point, was most sensitive to the formation rate measured. These data constitute strong evidence in favor of the classical formation path through C2. The reduction in concentration with O2addition was sufficient to establish the dominant formation path for the conditions herein and provide an estimate of its rate coefficient. Alternate formation reactions are considered, and suggestions are made for the further optimization of a CH∗ kinetics model.

author list (cited authors)

  • Hall, J. M., & Petersen, E. L.

publication date

  • January 2005