Hydrogen atoms in a methane-air Bunsen-type flame were detected by the flame-in-cavity ESR method. The addition of a halogenated compound to the secondary air was found to reduce the H-atom concentration linearly with an increase in the additive concentration. The eight halogenated compounds examined showed an increased effectiveness in scavenging H atoms in this order; HCl<CF2Cl2<CHCl3<CH3Cl<CH2Cl2<CFCl3<CCl4<CH3Br. This chemical effect of the halogenated compounds on the combustion reactions agrees well with the inhibitor index for these compounds.

No abstract