Characterizing Fluorine and Chlorine Atom Flow Rates Using Iodine Atom Spectrometry

The production of F and Cl atoms in an electrical discharge of F 2 or Cl 2 has been examined in a flow reactor. A tunable diode laser was used to probe the concentration and translational temperature of I atoms produced by F and Cl atom reactions with HI. Kinetic modeling codes were used to determine the discharge efficiencies from the titration plots and the observed trends for atom concentration as a function of F 2 or Cl 2 and pressure. These calculations indicate that the de discharge used in these experiments is 100% efficient for F 2 flow rates ≤0.5 mmol s -1 and reactor pressure ≤20 torr. The highest F 2 -free F atom flow rate that we can generate is 1.0 mmol s -1 . Preliminary data for the Cl 2 discharge indicate that this is a much less efficient source of Cl atoms with yields of less than 50%.