Ionization Potentials and Probabilities for the Formation of Multiply Charged Ions in the Alkali Vapors and in Krypton and Xenon

A mass-spectrograph analysis has been made of the ions formed by electron impact in Na, K, Rb, Cs vapors and in Kr and Xe. The electron energy varied from zero to 700 electron-volts. Multiply charged ions were formed in all cases when the electron energy was sufficiently high. The ionization potentials for the various ions are given in the table. In general the curves showing likelihood of formation of these ions as a function of electron energy are of the usual shape. In the cases of K⁺, Rb⁺, Cs⁺ and Cs²⁺ there are evidences of additional mechanisms of formation which appear at the following potentials: for K⁺ at 15.5 and 150 volts; for Rb⁺ at 12.5 volts; for Cs⁺ at 10; 17.5, and 60 volts; for Cs²⁺ at 80 volts.