Spectra and critical potentials of fifth group elements

Revised values of the critical potentials of As, Sb, and Bi are given.The resonance potentials of the neutral atoms correspond to the mean excitation voltages of groups of spectral lines.Photographs of the thermionic discharge in Bi were used to separate the excitation stages of the Bi atom; groups of spark lines appear at 14 ± i and 25^5 volts.The Bi absorption spectrum was studied.Classifications of lines of N+, As, Sb, Bi, and Bi+ were obtained.As, Sb, and Bi have doublet spectra.To describe phenomena connected with the existence of very narrow doublet levels in A1+, Bi, and other elements it is proposed to introduce a new quantum number called the fine quantum number.