Spectroscopic measurements of Ba+

Our goal is to measure the atomic structure of Ba$^{+}$ to a new degree of accuracy. We confine and laser-cool a single barium ion in an RF quadrupole. We intend on measuring the branching ratios for the 6P$_{3/2 }$ - 5D$_{5/2}$ and the 6P$_{3/2 }$ - 5D$_{3/2}$ decays in Ba$^{+}$. The measurement is achieved by first exiting the ion to the 6P$_{3/2}$ state with a short duration of a 455 nm shelving laser. We then allow the ion to decay, which will result in one of three states: 5D$_{5/2}$, 5D$_{3/2}$, and 6S1$_{/2}$. Next we use a 650 nm laser to re-pump the ion out of the 5D$_{3/2}$ into the 6P$_{1/2}$ and another 493nm to transition from 6S$_{1/2}$ to 6P$_{1/2}$. If the ion fluoresces in this 6S$_{1/2}$ - 6P$_{1/2}$ - 5D$_{3/2}$ cycle then we know the original decay out of 6P$_{3/2}$ was into either 5D$_{3/2}$ or 6S$_{1/2}$. By incrementally increasing the duration of the 455 nm excitation the probability of decay into the 6S$_{1/2}$ is exponentially decreased. With enough data points we can extrapolate the saturation between the probabilities of fluorescent and non- fluorescent cycles. The branching ratio between the decays into the 5D$_{5/2}$ and 5D$_{3/2 }$states is the ratio of these probabilities in this limit. Our future experiments include the precision RF spectroscopy of the 5D$_{5/2}$ state in $^{137}$Ba$^{+}$ and the measurement of the 5D$_{5/2}$ state lifetime.