Zeeman effect in the polarization spectroscopy of Na

The Doppler-free polarization spectrum of the D₁ line has been studied in fields of about 50 G and in zero field. Although the principal Zeeman resonances are resolved, the signals are confusing because of the very large number of cross-over resonances. Cross-over resonances also seriously distort well-resolved resonances in zero field. An interpretation is given, based on combining a first-order theory of optical pumping with the theory of Faraday rotation and dischroism.