Direct determination of atom and radical concentrations in thermal reactions of hydrocarbons and other gases

This is the sixth annual progress report on this project. During the period covered by the first five reports (June 1976 through December 1980) a shock tube and optical systems to measure H, D and O atom concentrations were built and fully characterized. The performance of our microwave discharge lamps was defined by numerous high-resolution spectroscopic profiles, while empirical calibrations were also made for all three of the above species. H, D and O atom concentrations were measured in gas mixtures containing H2, D2, O2, CD4, C2H6, C2D6, C3H8 and C3D8 in various proportions, and rate constants of several elementary reactions were deduced from the data. During the period covered by this report (January 1 to November 30, 1981) we have made an extensive series of measurements of O concentrations in shock-heated mixtures of C2H6-O2-AR, C2D6-O2-Ar, C3H8-O2-Ar and C3D8-O2-Ar. We have made kinetic modelling calculations for these mixtures to correlate these observed O concentrations, and also our earlier measurements of H and D atom concentrations in similar mixtures, with elementary reaction rate constants. From these calculations we expect to deduce rate constants for a number of reactions. We have also completed a series of O atom measurements in H2-N2O-Ar and D2-N2O-Ar mixtures, from which we have obtained good rate constant data for the reactions O + H2 → OH + H and O + D2 → OD + D. Our immediate future plans involve meaurements of H and D atoms in the dissociation of benzene, toluene, neopentane and their deuterium analogs leading to direct evaluation of rate constants for the unimolecular dissociation of these substances