Measurement of hyperfine structure and isotope shifts in Gd II

- Extensive set of new precision laser spectroscopy data on Gd II.
- Hyperfine structure of 68 levels measured.
- Isotope shifts of 73 optical transitions measured.
- Important atomic data for astrophysical stellar spectroscopy.

We have applied fast-ion-beam laser-fluorescence spectroscopy to measure the isotope shifts of 73 optical transitions in the wavelength range 421.5-455.8 nm and the hyperfine structures of 35 even parity and 33 odd parity levels in Gd II. Many of the isotope shifts and hyperfine structure measurements are the first for these transitions and levels. These atomic data can be used to correct for saturation and blending in the analysis of stellar spectra to determine chemical abundances. As a result, they have an important impact on studies of the history of nucleosynthesis in the Universe and on the use of photospheric abundance anomalies in Chemically Peculiar stars to infer indirect information about stellar interiors.