RESONANCE LINES AND ENERGY-LEVELS OF CSIII, BAIV, AND LAV

The spectra of Cs III, Ba IV, and La V are photographed in a sliding spark discharge on the 10. 7 m normal-incidence vacuum spectrograph at the U. S. National Bureau of Standards. New analyses are given for Cs III and Ba IV and the first analysis is reported for La V. The analyses are based on transitions to the **2P ground term from levels of the low excited configurations. Ionization energies are 33. 38 plus or minus 0. 25 eV for Cs III; 47. 1 plus or minus 0. 6 eV for Ba IV; and 61. 6 plus or minus 0. 6 eV for La V.