Isotope shifts in the NdI spectrum

Isotope shifts in about fifty lines of the Nd 1 spectrum emitted by a hollow cathode tube, in the region 5200 to 6000 $\overset{\circ}{\mathrm A}$, have been recorded on a Fabry-Perot spectrometer equipped with a photoelectric detector. The results are used to examine the existing classification of the spectrum. The structure of the line 5525.7 $\overset{\circ}{\mathrm A}$ suggests the inversion of the odd-even staggering phenomenon for $^{143}$Nd.