Isotope shifts of Sm i measured by diode-laser-based Doppler-free spectroscopy

High-resolution Doppler-free spectra of Sm were measured in the 635–690-nm wavelength region by means of Doppler-free spectroscopy with a single-mode diode laser and a long vapor cell. Isotope shifts were determined to an accuracy of better than 8 MHz for 20 transitions originating mostly from the 4f66s2 7FJ (J=0 to J=6) to 4f66s6p9D°, 9F°, and  7G° levels. Specific mass shifts, field shifts, and changes in the mean-square nuclear charge radii were evaluated by King-plot analysis.