Flame structure and flame reaction kinetics VIII. Structure, properties and mechanism of a rich

Following the early work of Klaukens & Wolfhard (I948) and Gaydon & Wolfhard (1952), the increase of flame thickness which accompanies a reduction in ambient pressure has led to the extensive use of subatmospheric pressure flames for structure studies. Both spectroscopic and probe techniques have been employed; and most of the work has been concerned with flames of hydrocarbons in air, from which much useful information has been obtained. Low-pressure flames (around 7 Torr) supported by the hydrogen + oxygen reaction were examined spectroscopically by Gaydon & Wolfhard (I949), who found that the OH emission in the ultraviolet is very weak compared with that from the reaction zones of organic flames, and that the rotational temperature of the OH band agrees with the theoretically calculated flame temperature. More recently, hydrogen atom concentrations in a number of fuel-rich hydrogen + nitrogen + oxygen flames at pressures between 30 and 100 Torr have been measured by Bascombe (i965), and profiles of the concentrations of hydrogen, oxygen, water, hydrogen atoms and hydroxyl radicals have been investigated by Eberius, Hoyermann & Wagner (I97I) in such flames at pressures around 10 Torr, supported on cooled porous plate burners. Extensive investigations of the structure and properties of rich hydrogen + nitrogen + oxygen flames at atmospheric pressure, described by Dixon-Lewis, Sutton &