Observation of Visible and uv Magnetic Dipole Transitions in Highly Charged Xenon and Barium

We have observed an unusual transition which is predicted to result in visible and near-uv emission from very highly charged titaniumlike ions spanning the entire upper half of the periodic table. Measurements of the wavelengths of the ${3d}^4{}_{}{}^5{}_{}{}^{}D_2^{}{}_{}{}^{}$- ${}_{}{}^5{}_{}{}^{}D_3^{}{}_{}{}^{}$ transitions in B${\mathrm{a}}^{+34\mathrm{}}$ and X${\mathrm{e}}^{+32\mathrm{}}$ are in surprisingly poor agreement with ab initio calculations. This work was carried out in an electron beam ion trap and demonstrates that such a device can be an important tool for visible spectroscopy of highly charged ions.