The Polarizabilities of Ions from Spectra

The polarizabilities of the gaseous alkali ions, and several other ions of rare gas structure, have been calculated by the Born-Heisenberg method from the corresponding spectra. Correction has been made for the effect due to "penetration" and for higher order distortion of the ion. The quantum mechanical derivation of the method has been given. The values of the polarizabilities of the alkali ions so obtained are found to be somewhat lower than those previously assumed. The polarizabilities of the gaseous negative ions must be correspondingly higher. The decrease in polarizability of the negative ion and increase of the positive ion on inclusion in a crystal is in agreement with known frequency shifts.