Francium is an ideal candidate for atomic parity nonconservation (APNC) measurements, since APNC effects scale roughly with a $Z^3$ dependence. Knowledge of francium's atomic structure is key to interpreting APNC measurements, and can be studied through properties such as the Stark shift of the $7s\rightarrow8s$ transition. In our experiment we use magneto-optical traps to suspend francium atoms in vacuum between indium tin oxide coated field plates to measure the Stark shift. In this talk I will discuss our latest measurement for the single photon Stark shift of the $7s\rightarrow8s$ transition in francium 211.
We gratefully acknowledge UMGF and GETS support by the University of Manitoba.