Hyperfine interaction in the 4D32 and the 4D52 levels of sodium

We have excited the $\text{4D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{4D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ levels of sodium using Doppler-free two-photon excitation. By measuring the polarization rate in zero magnetic field of the fluorescence lines, we have deduced the following values for the hyperfine interaction $\text{|A(}\text{4D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{) | =}\text{0.23 ± 0.12 MHz}$ and $\text{|A(}\text{4D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)| <}\text{0.28 MHz}$. The value of $\text{A(}\text{4D}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}$ is in disagreement with the one reported by Schenk and Pillof.