Isotope Shifts in the 7s$\to$8s Transition of Francium: Measurements and Comparison to \textit{ab initio} Theory

M. R. Kalita, J. A. Behr, A. Gorelov +10

We observe the electric-dipole forbidden $7s\to 8s$ transition in the francium isotopes ${}^{208-211}$Fr and ${}^{213}$Fr using a two-photon excitation scheme. We collect the at…