The spectrum of fluorine, F II, F III, F IV

The spectrum of fluorine extending from 125A to 620A has been obtained by using a two-meter grazing-incidence spectrograph. A large number of these lines, including nearly all of the stronger ones, have been classified as transitions in the F II, F III and F IV ions. This has made possible the classification of additional lines measured by Dingle in the longer wave-length regions. These analyses yield the following ionization potentials: F II 34.81 volts, F III 62.35 volts, F IV 87.34 volts.