Ionization and Resonance Potentials in Gallium and Indium

The critical potentials of gallium and indium have been experimentally determined by the method of inelastic impact. A simple three-electrode tube and the Hertz-differential tube as a simple three-electrode tube or as a four-electrode tube were used. Ionization was detected by the modified space charge method, by the Lenard method, and by the change in the gap resistance. The following critical potentials below ionization were observed: in gallium vapor 3.07 v. (2p₂-2s), 4.22 v. (2p₂-3d₂), 2.70 v. (2p₁-2s), 3.8 v. (2p₁-3d); in indium vapor 0.30 v. (2p₂-2p₁), 3.03 v. (2p₂-2s), 4.07 v. (2p₂-3d₂), 2.8 v. (2p₁-2s). Two ionization potentials were observed: in gallium vapor 5.8 and 13.2 v.; in indium vapor 6.3 and 14.1 v. The ionization potentials are judged to be accurate to 0.5 volts.