A SHOCK-TUBE STUDY OF THE REACTIONS OF CH WITH CO2 AND O-2

The formation and consumption of CH radicals during shock-induced pyro lysis of a few ppm ethane diluted in argon was measured by a ring-dye laser spectrometer. Absorption-overtime profiles, measured at a resona nce line in the e-branch of the A(2) Delta - X(2) Pi band of CH at lam bda = 431.1311 nm, were recorded and transformed into CH concentration s by known absorption coefficients. By adding some hundred ppm of CO2 or O-2 to the initial mixtures, the CH concentration profiles were sig nificantly perturbed. Both the perturbed and unperturbed CH concentrat ion profiles have been compared with calculations based on a reaction kinetic model. A sensitivity analysis revealed that the perturbation p rocess was dominated by direct reactions of CH with the added molecule s. By fitting calculated to observed CH profiles the following rate co efficients were obtained [GRAPHICS] The experiments were performed in the temperature range between 2500 K and 3500 K. (C) 1996 John Wiley & Sons, Inc.