Isotope shifts of four Nd III lines observed by Fourier transform spectroscopy of the Nd–Ar Penning discharge lamp (PDL, solid) and the Nd–Ar hollow cathode lamp (HCL, dash-dotted line). For 4f^{4 5}I6–4f³(⁴Iº)6s , isotope components of ¹⁴²Nd, ¹⁴⁴Nd, ¹⁴⁶Nd, ¹⁴⁸Nd, and ¹⁵⁰Nd are marked tentatively from left to right with red vertical lines in relative abundance ratios from Berglund & Wieser (2011), remaining features are likely hyperfine structures of ¹⁴³Nd and ¹⁴⁵Nd or blended weak lines.