Chemiluminescence from the reactions of atomic and molecular fluorine with phosphorous trichloride and tribromide

Abstract

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 molecular fluorine with PCl₃ and PBr₃, respectively, at pressures <5 mbar. The vibrational distributions of the excited products are effectively relaxed at these pressures. It is concluded that the excited states are produced by three-body recombination of the appropriate halogen atoms in the case of the atomic fluorine reactions whilst a direct reaction may produce the chemiluminescent products for the molecular fluorine reactions. Ultraviolet emission (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 chlorine emission in the case of the F+PCl₃ reaction.