Resonant photo-ionization of Yb+ to Yb2+.

We demonstrate the controlled creation of a ion by photo-ionizing with weak continuous-wave lasers at ultraviolet wavelengths. The photo-ionization is performed by resonantly exciting transitions of the ion in three steps. Starting from an ion crystal of two laser-cooled ions localized in a radio-frequency trap, the verification of the ionization process is performed by characterizing the properties of the resulting mixed-species ion-crystal. The obtained results facilitate fundamental studies of physics involving ions. [ABSTRACT FROM AUTHOR]