Observation of the 717 nm electric quadrupole transition in triply charged thorium

A. G. Radnaev, C. J. Campbell, A. Kuzmich

We excite the 717 nm electric quadrupole 6$D_{3/2}$ $\leftrightarrow$ 7$S_{1/2}$ transition in a laser-cooled ${}^{232}$Th${}^{3+}$ ion crystal. The transition frequency and the lifet…