Excitation of iodine by singlet molecular oxygen. Part 1.—Mechanism of the I 2 chemiluminescence

The strong I2 chemiluminescence produced when iodine is added to oxygen gas containing singlet molecular oxygen is shown to arise by efficient stepwise excitation I2(X1Σ+g)+O2(1Σ+g)→I2(A3π1u)+O2(3Σ–g)(2), I2(A3π1u)+O2(1Δg)→I2(B3π0+u)+ O2(3Σ–g)(3)Process (2) also yields atomic iodine which recombines to I2 on the flow tube walls. Approximate rate coefficients are derived for these processes.