On-line Excited-State Laser Spectroscopy of Trapped Short-Lived Ra\(^+\) Ions

As an important step towards an atomic parity violation experiment in one single trapped Ra\(^+\) ion, laser spectroscopy experiments were performed with on-line produced short-lived \(^{212,213,214}\)Ra\(^+\) ions. The isotope shift of the \(6\,^2\)D\(_{3/2}\)\,-\,\(7\,^2\)P\(_{1/2}\) and \(6\,^2\)D\(_{3/2}\)\,-\,\(7\,^2\)P\(_{3/2}\) transitions and the hyperfine structure constant of the \(7\,^2\)S\(_{1/2}\) and \(6\,^2\)D\(_{3/2}\) states in \(^{213}\)Ra\(^+\) were measured. These values provide a benchmark for the required atomic theory. A lower limit of \(232(4)\) ms for the lifetime of the metastable \(6\,^2\)D\(_{5/2}\) state was measured by optical shelving.