Mixing, hyperfine-induced

Hyperfine-induced mixing of fine structure components is well known and was first observed and explained in 1932 by Schuler and Jones and... 

When hyperfine-induced mixing of the fine structure components cannot be neglected, the same procedure as described for pure states at the end of the previous section can be followed to account for the hyperfine structure of perturbed msnd Rydberg states. Choosing the wave functions msnd I, F) [cf. Eqs. (62)-(65)] as basis, the Hamiltonian Hq is... 

Figure 53. Hyperfine structure of Sr predicted for the 5s 9d D2 Rydberg state, neglecting hyperfine-induced mixing of D2 and fine structure components (upper part). Experimentally observed and theoretical line positions of the hyperfine components of the 5sl9d D2 and states are shown in the lower part. (Taken from Ref. 84.)...

---