Shock-Tube Study of Cr* Chemiluminescence During the Induction Period of the C2H2–O2 Reaction

The Cr* (a7S–y7P) chemiluminescence at 360 nm during the induction period of the C2H2–O2 reaction was studied behind reflected shock waves. When the reaction gas mixture containing 10 p.p.m. Cr(CO)6, 0.5% C2H2, 1.0% O2, and 98.5% Ar was shock heated to 1650 °K, the emission intensity of Cr* grew exponentially with a growth constant equal to the chain branching constant. This observation indicates that reaction(s) leading to Cr* chemiluminescence involve only one chain carrier during the induction period of the C2H2–O2 reaction. The mechanism of the chemical excitation of Cr is discussed.