Spectroscopy of electric dipole and quadrupole transitions in ${}^{224}$Ra${}^{+}$

We report on spectroscopy of the low-lying electronic transitions in ${}^{224}$Ra${}^{+}$. The ion’s low charge to mass ratio and convenient wavelengths make ${}^{224}$Ra${}^{+}$ a promising optical clock candidate. We measured the frequencies of the the ^2{S}_{1/2} \$\leftrightarrow$${}^2{P}_{1\mathrm{/}2}$ cooling transition, the ^2{S}_{1/2}\$\leftrightarrow$${}^2{D}_{5\mathrm{/}2}$ clock transition, the ^2{D}_{3/2} \$\leftrightarrow$${}^2{P}_{3\mathrm{/}2}$ electric dipole transition, and the ^2{D}_{5/2} \$\leftrightarrow$${}^2{P}_{3\mathrm{/}2}$ cleanout transition. From these measurements we calculate the frequencies of the ^2{D}_{3/2}\$\leftrightarrow$${}^2{P}_{1\mathrm{/}2}$ repump transition, the ^2{S}_{1/2} \$\leftrightarrow$${}^2{D}_{3\mathrm{/}2}$ electric quadrupole transition, and the ^2{S}_{1/2} \$\leftrightarrow$${}^2{P}_{3\mathrm{/}2}$ electric dipole transition.