Tin is the chemical element with the largest number of stable isotopes. Its complete proton shell, comparable with the closed electron shells in the chemically inert noble gases, is not a mere precursor to extended stability; since the protons carry the nuclear charge, their spatial arrangement also drives the nuclear electromagnetism. We report high-precision measurements of the electromagnetic moments and isomeric differences in charge radii between the lowest 1/2+, 3/2+, and 11/2− states in 117–131Sn, obtained by collinear laser spectroscopy. Supported by state-of-the-art atomic-structure calculations, the data accurately show a considerable attenuation of the quadrupole moments in the closed-shell tin isotopes relative to those of cadmium, with two protons less. Linear and quadratic mass-dependent trends are observed. While microscopic density functional theory explains the global behaviour of the measured quantities, interpretation of the local patterns demands higher-fidelity modelling.

Atomic spectral lines from different isotopes display a small shift in energy, commonly referred to as the line isotope shift. One of the components of the isotope shift is the field shift, which depends on the extent and the shape of the nuclear charge density distribution. The purpose of this work is to investigate how sensitive field shifts are with respect to variations in the nuclear size and shape and what information of nuclear charge distributions can be extracted from measurements. Nuclear properties are obtained from nuclear density functional theory calculations based on the Skyrme-Hartree-Fock-Bogoliubov approach. These results are combined with multiconfiguration Dirac-Hartree-Fock methods to obtain realistic field shifts and it is seen that phenomena such as nuclear deformation and variations in the diffuseness of nuclear charge distributions give measurable contributions to the isotope shifts. Using a different approach, we demonstrate the possibility to extract information concerning the nuclear charge densities from the observed field shifts. We deduce that combining methods used in atomic and nuclear structure theory gives an improved description of field shifts and that extracting additional nuclear information from measured isotope shifts is possible in the near future with improved experimental methods.

Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C i – iv. The Multiconfiguration DiracâHartreeâFock and relativistic configuration interaction methods were used in the present work. To improve the quality of the wave functions and reduce the relative differences between length and velocity forms for transition data involving high Rydberg states, alternative computational strategies were employed by imposing restrictions on the electron substitutions when constructing the orbital basis for each atom and ion. Transition data, e.g., weighted oscillator strengths and transition probabilities, are given for radiative electric dipole (E1) transitions involving levels up to 1s22s22p6s for C i, up to 1s22s27f for C ii, up to 1s22s7f for C iii, and up to 1s28g for C iv. Using the difference between the transition rates in length and velocity gauges as an internal validation, the average uncertainties of all presented E1 transitions are estimated to be 8.05%, 7.20%, 1.77%, and 0.28%, respectively, for C i – iv. Extensive comparisons with available experimental and theoretical results are performed and good agreement is observed for most of the transitions. In addition, the C i data were employed in a reanalysis of the solar carbon abundance. The new transition data give a line-by-line dispersion similar to the one obtained when using transition data that are typically used in stellar spectroscopic applications today.