SOME OBSERVATIONS ON THE RADIATIVE COMBINATION OF ATOMIC HYDROGEN WITH ATOMIC HALOGENS IN BURNER FLAMES

When small quantities of gaseous molecular halogens chlorine, bromine, and iodine are introduced into the supply to premixed hydrogen-oxygen-nitrogen flames one of the most important spectroscopic features appearing is an apparently continuous emission in the visible, sometimes extending into the near ultraviolet. The intensity of this continuous emission has been studied as a function of amount of halogen, and of temperature, composition, and position with respect to the reaction zone in a wide variety of flames. In oxygen-rich flames it has been attributed to an over-all process, where X denotes an atom of halogen; one of the atoms may be in an excited state. Most of the work concerns hydrogen-rich flames, where a very strong correlation between the intensity and the product [H][X] is obtained. The over-all process may be written as The efficiency of this over-all process is measured as 1 quantum emitted for about 10 10 ordinary kinetic collisions of the atoms. The mechanism is discussed from the aspects of direct radiative recombination and of stabilization by collision of an intermediate excited HX* before radiation.