PHOTOMETRIC MEASUREMENTS ON THE DEVIATIONS FROM THE EQUILIBRIUM STATE IN BURNT FLAME GASES
CALIFORNIA UNIV SANTA BARBARA DEPT OF PHYSICS
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Photometric investigations are reported in laminar, premixed shielded flames above the reaction zone, burning at atmospheric pressure. In these CO N2O2 - C2H2N2O2 - and H2O2N2 - flames metal vapor was introduced. Flame temperatures ranged from 2000 to 2500K, rise-velocities from 5 to 15 msec. The question is discussed as to what extent thermodynamic equilibrium does exist in certain parts of the flame. The meaning of local flame temperature and its relation to calculated adiabatic temperature and excitation temperature is considered. Complications due to suprathermal chemiluminescence and radiative nonequilibrium effects are discussed. Recombination of excess radicals causes an initial rise in temperature with height and leads to suprathermal chemiluminescence of metal lines and to continuous background radiation. Radiative non-equilibrium causes underpopulation of excited metal states and can be studied by excitation temperature measurements. From departures from metal- ionization equilibrium conclusions are drawn about the ionization mechanism, effective cross-sections and relaxation times. Chemi-ionization is also dealt with. The negligible of influence of excess O-radicals in CO flames on the dissociative equilibrium makes possible to exclude particular dissociation reactions. From the measured equilibrium population of the visible alkaline- earth bands molecular excitation energies were derived and conclusions about the kind of emitters were drawn.
- Combustion and Ignition
- Inorganic Chemistry