Magneto-Optic Trapping of ${}^{210}$Fr

The alkali element francium has no stable isotopes and has eluded extensive study because sufficient quantities have not been available for detailed investigations. More than 1000 ${}^{210}\mathrm{Fr}$ atoms have now been contained in a magneto-optic trap. This number is sufficient to allow extensive studies of Fr atomic properties that are necessary input for future tests of fundamental interactions.