Separations in Hyperfine Structure
The quantum mechanics conception of a spinning electron in an s state makes it probable that its interaction energy with a nuclear moment i is simply proportional to the average of is cos (is). Expressions for this average cosine have been obtained and applied to different examples. In more complicated cases it can only be said that the interaction energy is proportional to ij cos (ij), which makes the interval rule hold for hyperfine structure.
© 1929 The American Physical Society. Received 12 November 1929.
Published - PhysRev.34.1501.pdf