Paschen-Back Effect of Hyperfine Structure and Polarization of Resonance Radiation: Sodium

Preliminary measurements on the polarization of resonance radiation of the second doublet of sodium when a magnetic field is applied with its direction parallel to the incident light beam shows that the polarization changes from a value of about 10 per cent in zero magnetic field to a value of 34 per cent in fields less than 100 gausses. In order that a Paschen-Back effect of the hyperfine structure of the 52P 1/2 , 3/2 levels should occur in field strengths of this order of magnitude the hyperfine separation constant for these levels must be of the order.0005 x 10-3 cm-1