Halogen Atom Reactions. IV. Recombination into Electronically Excited States

Abstract

Absolute emission intensities of the luminescence resulting from the recombination of ground-state chlorine and bromine atoms have been measured in an effort to determine the proportion of the recombination occurring through electronically excited states. The emitting states [Cl2(3Π0+u), Br2(3Π1u), andBr2(3Π0+u)] are found to be efficiently quenched by the corresponding atomic species and the efficiency is found to be dependent on the total pressure. Direct quenching by ground-state molecules is found to be at least 103 times less efficient. Rate constants for recombination via electronically excited states of Cl2 and Br2 are found to be ≥ 1014 and ≥ 1015 cc 1mole−1·sec−1, respectively. Luminescence is also reported from the recombination of ground-state iodine atoms and assigned to the transition I2(3Π1u → 1Σg+).