Chemiluminescence from the reactions of atomic and molecular fluorine withphosphorous trichloride and tribromide

Visible emission (500-850 nm) from electronically-excited ClF(B) and BrF(B) can be generated chemically in the gas-phase reactions of atomic and molec ular fluorine with PCl3 and PBr3, respectively, at pressures < 5 mbar. The vibrational distributions of the excited products are effectively relaxed a t these pressures. It is concluded that the excited states are produced by three-body recombination of the appropriate halogen atoms in the case of th e atomic fluorine reactions whilst a direct reaction may produce the chemil uminescent products for the molecular fluorine reactions. Ultraviolet emiss ion (270-400 nm) from the ion-pair states of molecular bromine is observed from the reaction of atomic fluorine with PBr3 but there is no analogous ch lorine emission in the case of the F + PCl3 reaction.