Abstract
We report isotope-selective loading and trapping of doubly ionized ytterbium into an rf quadrupole trap. Isotopically pure clouds of Yb174⊃+ ions were first loaded into the rf trap via a multistage photoionization process. The Yb 2+ ions were then produced by electron impact ionization of the trapped Yb⊃+ ions. The Yb 2+ ions were subsequently detected by rf excitation of their secular motion in the trap, which led to sympathetic heating and changes in the fluorescence of the laser-cooled Yb⊃+ ions. The presence of doubly charged Yb ions was further verified by the appearance of a dark band in the center of Yb⊃+ ion cloud after electron impact ionization. We discuss the possible formation of Yb 2+ H and similar compounds and the schemes for the direct optical detection of the Yb 2+ ions. © 2010 The American Physical Society.