HIGH-RESOLUTION ULTRAVIOLET-SPECTRA OF SYMPATHETICALLY-LASER-COOLED CD+ IONS

Cadmium ions (Cd+) have been cooled sympathetically below 1 K by means of Coulomb interactions with laser-cooled Bet ions that are trapped s imultaneously in a Penning trap. The ultraviolet resonance lines (5s S -2(1/2)<----> 5p P-2(3/2), lambda = 214.5 nm) of the cooled Cd+ ions w ere observed using a frequency-doubled cw dye laser. This radiation is based on efficient frequency doubling in a nonlinear crystal [beta-Ba B2O4 (BBO)] with an external enhancement cavity. The spectra of the si x isotopes (A = 110-114, and 116) were obtained using a natural isotop e mixture, and the reliability of the measured isotope shifts is discu ssed.