Atomic Structure of Nd9+ for Highly Charged Ion Clocks

The energy levels arising from the electronic orbital 5p-4f crossing between the ground 5p(2)4f and excited 5p4f(2) configurations in the Nd9+ ion are investigated by using high-accuracy relativistic ab initio calculations. The accurate atomic data of the lifetime, gJ factor, electric quadrupole moment, and hyperfine structure of the magnetic dipole are also presented. The long-lived states that are suitable for making narrow-linewidth (milli-Hz) clock lines are found. Dominant systematics caused by stray electromagnetic interactions in an experiment and the coefficients of the relativistic sensitivityto variation of the fine-structure constant alpha and of the Lorentz invariance violation are evaluated, thus validating that the Nd9+ ion can be a new candidate for high-resolution spectroscopy and precision fundamental studies for probing new physics beyond the Standard Model.